Variable gain power amplifier

Abstract

To provide a variable gain amplifier with relatively low-power by using a relatively small number of components.SOLUTION: A variable gain power amplifying technique in an illustrated example includes: generating (400) a first oscillating signal by using a network of one or more reactive components included in an oscillator; and outputting (402) a second oscillating signal via one or more taps included in the network of the reactive components. The second oscillating signal is proportional to the first oscillating signal and has magnitude less than that of the first oscillating signal. The power amplifying technique further includes: selecting (404) one of the first and second oscillating signals to use for generating a power-amplified output signal; and amplifying (406) the selected one of the first and second oscillating signals to generate the power-amplified output signal.SELECTED DRAWING: Figure 21

Description

Technical Field

[0001] This application generally relates to electric circuits, and more particularly, to power amplifiers.

Background Art

[0002] For example, transceivers are used in a wide range of applications such as cellular phones, wireless, and wireless communication. A transceiver may use a power amplifier to increase the power of a signal driving an antenna so that the power of the signal is strong enough to reach a relatively far distance. Many types of transceiver applications may be power-limited and / or area-limited. For example, cellular phone wireless may use a battery with a limited amount of power, and the amount of space for transceiver components may be limited. Designing a power amplifier for a low-power, low-area transceiver can present significant challenges.

Summary of the Invention

[0003] In the example described, an integrated circuit includes an oscillator and a power amplifier. The oscillator includes a network of one or more reactive components coupled between a first node, a second node, and the first and second nodes. The network of reactive components has at least one tap between the first and second nodes. The oscillator further includes a first output coupled to the network of reactive components via the second node, and a second output coupled to the network of reactive components via the tap. The power amplifier includes a first input coupled to the first output of the oscillator, a second input coupled to the second output of the oscillator, and an output.

[0004] To further illustrate, the integrated circuit includes a voltage-controlled oscillator (VCO) having one or more reactive components. The integrated circuit further includes a programmable passive attenuation circuit coupled to the VCO. The programmable passive attenuation circuit includes at least some of the one or more reactive components included in the VCO. The integrated circuit further includes a power amplifier coupled to the programmable passive attenuation circuit.

[0005] As an additional example, a method includes generating a first oscillatory signal using a network of one or more reactive components included in a voltage-controlled oscillator (VCO). This method further includes outputting a second oscillatory signal via one or more taps included in the network of reactive components. The second oscillatory signal is proportional to the first oscillatory signal and has a smaller magnitude than the first oscillatory signal. This method further includes selecting one of the first and second oscillatory signals based on gain control for use in generating a power-amplified output signal. This method further includes generating a power-amplified output signal based on the selected one of the first and second oscillatory signals. [Brief explanation of the drawing]

[0006] [Figure 1] This is a block diagram illustrating an exemplary transmitter in accordance with the present disclosure.

[0007] [Figure 2] Figure 1 is a block diagram of the exemplary transmitter, illustrating the exemplary oscillator in accordance with this disclosure in more detail. [Figure 3] Figure 1 is a block diagram of the exemplary transmitter, illustrating the exemplary oscillator in accordance with this disclosure in more detail.

[0008] [Figure 4] Figure 1 is a block diagram of the exemplary transmitter, illustrating in more detail an exemplary power amplifier in accordance with this disclosure. [Figure 5]Figure 1 is a block diagram of the exemplary transmitter, illustrating in more detail an exemplary power amplifier in accordance with this disclosure.

[0009] [Figure 6] This is a schematic diagram illustrating an exemplary reactive component network that may be used in the exemplary oscillators of this disclosure.

[0010] [Figure 7] This is a schematic diagram illustrating an exemplary oscillator incorporating the exemplary reactive component network of Figure 6, in accordance with this disclosure.

[0011] [Figure 8] This is a schematic diagram illustrating another exemplary reactive component network that may be used in the exemplary oscillators of this disclosure.

[0012] [Figure 9] This is a schematic diagram of exemplary reactive components and switching circuits that may be used in the exemplary transmitter of this disclosure.

[0013] [Figure 10] This is a schematic diagram illustrating another exemplary reactive component network that may be used in the exemplary oscillators of this disclosure.

[0014] [Figure 11] This is a schematic diagram illustrating an exemplary oscillator incorporating the reactive component network shown in Figure 10, in accordance with this disclosure.

[0015] [Figure 12] This is a schematic diagram illustrating another exemplary reactive component network that may be used in the exemplary oscillators of this disclosure.

[0016] [Figure 13] This is a schematic diagram illustrating an exemplary amplifier stage that may be used in the power amplifier of this disclosure. [Figure 14]A schematic diagram illustrating an exemplary amplifier stage that can be used in the power amplifier of the present disclosure. [Figure 15] A schematic diagram illustrating an exemplary amplifier stage that can be used in the power amplifier of the present disclosure.

[0017] [Figure 16] A block diagram illustrating an additional exemplary transmitter according to the present disclosure. [Figure 17] A block diagram illustrating an additional exemplary transmitter according to the present disclosure. [Figure 18] A block diagram illustrating an additional exemplary transmitter according to the present disclosure. [Figure 19] A block diagram illustrating an additional exemplary transmitter according to the present disclosure. [Figure 20] A block diagram illustrating an additional exemplary transmitter according to the present disclosure.

[0018] [Figure 21] A flowchart illustrating an exemplary method for amplifying the power of a signal according to the present disclosure.

[0019] [Figure 22] A schematic diagram illustrating an additional exemplary reactive component network that can be used in the exemplary oscillator of the present disclosure. [Figure 23] A schematic diagram illustrating an additional exemplary reactive component network that can be used in the exemplary oscillator of the present disclosure.

MODE FOR CARRYING OUT THE INVENTION

[0020] This disclosure describes a variable-gain power amplifier that may be used to amplify a signal in a transmitter and / or transceiver. In some examples, the power amplifier may include an oscillator that includes a network of one or more reactive components. The network of reactive components may include one or more taps that cause the oscillator to output different voltages that occur across different parts of the network of reactive components. The power amplifier may receive different voltages and selectively amplify one or more of the different voltages to obtain a power-amplified output signal.

[0021] The gain of a power amplifier can be adjusted by selectively amplifying different voltages generated across different parts of the network of reactive components in the oscillator, thereby allowing the output power of the power amplifier to be adjusted based on the dynamic power requirements of the transmitter. By adjusting the output power of the amplifier based on the dynamic power requirements of the transmitter, the total power consumption of the transmitter or transceiver can be reduced. By using one or more taps in the network of reactive components included in the oscillator to obtain different voltages that are selectively amplified, the number of components required to obtain different voltages can be reduced. In this way, a variable-gain, relatively low-power amplifier can be obtained using a relatively small number of components.

[0022] In some examples, a network of one or more reactive components may include one or more inductors connected in series. In such examples, a first voltage may be obtained across a first portion of the inductor, and a second voltage may be obtained across a second portion of the inductor. The second portion may be a subset of the first portion. In further examples, a network of reactive components may include one or more capacitors connected in series. Other examples are also possible and are within the scope of this disclosure.

[0023] In some examples, to selectively amplify multiple voltages, a power amplifier may select one of the voltages based on gain control and amplify the selected voltage using multiple amplifier stages. In further examples, to selectively amplify multiple voltages, a power amplifier may amplify each of the voltages in a separate amplifier signal chain and then select one of the amplified voltages based on gain control.

[0024] In some cases, a power amplifier may include multiple gain controls. For example, a power amplifier may include coarse gain control, which controls the selection of which oscillator voltage to use to generate the power-amplified output signal, and fine gain control, which controls the gain of one or both of the amplifier stages in a multistage amplifier that amplifies the selected oscillator voltage. Fine gain control may, in some cases, provide a continuous gain control function, but the range of gain values ​​over which the gain control function is linear is relatively small. On the other hand, coarse gain control can be linear over a relatively large range of gain values, but it can be a discrete function using discrete gain steps.

[0025] By providing both coarse and fine gain control, the gain of the power amplifier can be finely tuned over a wide range of gain values. In this way, a power amplifier with relatively high-precision gain control over a relatively large range of output power settings can be achieved.

[0026] In some examples, one or more amplifier stages in a power amplifier may include a differential self-bias amplifier. The differential self-bias amplifier may include a first variable resistor coupled between the power supply and the source terminals of one or more pull-up transistors, and a second variable resistor coupled between the ground rail and the source terminals of one or more pull-down transistors.

[0027] Increasing the variable resistor can increase the even-harmonic suppression of the amplifier stage, but it can also decrease the gain of the amplifier stage. Decreasing the variable resistor can have the opposite effect. Therefore, by placing the variable resistor in the differential self-bias amplifier at the positions described above, the trade-off between even-harmonic suppression and amplifier gain can be dynamically adjusted and balanced in the power amplifier.

[0028] In a further example, one or more amplifier stages in a power amplifier may be configured to operate in self-bias mode and nonlinear mode. Self-bias mode may offer a higher degree of linearity than nonlinear mode, but with lower power efficiency. Conversely, nonlinear mode may offer higher power efficiency but with lower linearity. By providing amplifier stages configurable to operate in self-bias mode and nonlinear mode, the trade-off between linearity and power efficiency can be dynamically adjusted and balanced in the power amplifier.

[0029] In an additional example, a power amplifier may be a multi-stage amplifier in which each stage includes a single-ended or differential self-biased amplifier. Each stage may further include an independently adjustable power rail voltage. By adjusting the power rail voltage for a particular amplifier stage, the self-biased amplifier of that stage can be biased with a different bias current, thereby adjusting the gain of the self-biased amplifier. Thus, by using independently adjustable power rail voltages for different self-biased amplifier stages, a multi-stage power amplifier with stage-independent gain adjustment can be achieved using a relatively small number of circuit components.

[0030] Figure 1 is a block diagram illustrating an exemplary transmitter 10 according to the present disclosure. The transmitter 10 includes an oscillator 12, a power amplifier 14, a matching network 16, an antenna 18, connections 20, 22, 24, 28, and a gain control lead 26. The first output of the oscillator 12 is coupled to the first input of the power amplifier 14 via connection 20. The second output of the oscillator 12 is coupled to the second input of the power amplifier 14 via connection 22. The gain control input of the power amplifier 14 is coupled to the gain control lead 26. The output of the power amplifier 14 is coupled to the input of the matching network 16 via connection 24. The output of the matching network 16 is coupled to the input of the antenna 18 via connection 28.

[0031] Each of connections 20, 22, 24, and 28 can be either a single-ended or differential connection and may include one or more leads forming the connection. A single-ended connection can be implemented as a single lead. A differential connection can be implemented using differential pairs of leads.

[0032] Oscillator 12 generates a first vibration signal at its first output and a second vibration signal at its second output. The second vibration signal may be an attenuated version of the first vibration signal. The vibration signals may be single-ended or differential signals. Power amplifier 14 receives the vibration signals at its first and second inputs, respectively, and generates a power-amplified output signal at its output based on the vibration signals. To generate the power-amplified output signal, power amplifier 14 may select one of the vibration signals, generate an amplified version of the selected vibration signal, and output the amplified version of the selected vibration signal as the power-amplified output signal. Power amplifier 14 may generate the amplified version of the selected vibration signal using the gain determined based on the gain control signal received at its gain control input. Matching network 16 receives the power-amplified output signal at its input, converts the power-amplified output signal, and generates the converted power-amplified output signal at its output. The matching network 16 may have an input impedance designed to substantially harmonize with the output impedance of the power amplifier 14, and an output impedance that substantially harmonizes with the impedance of the antenna 18. The antenna 18 receives the converted, power-amplified output signal from the matching network 16 and radiates this signal as electromagnetic radiation.

[0033] To generate vibration signals at the first and second outputs of oscillator 12, oscillator 12 may include a network of one or more reactive components, collectively referred to herein as a reactive component network. The reactive component network may have a first node connected to a first end of the reactive component network, a second node connected to a second end of the reactive component network, and one or more taps connected at respective positions between the first node and the second node.

[0034] In some examples, oscillator 12 may generate a first oscillatory signal based on the voltage at one or both of the first and second nodes, and a second oscillatory signal based on the voltage at one or more taps. In examples where the oscillatory signals are differential signals, the reactive component network may have at least two taps located at two different positions between the first and second nodes. In such examples, the first oscillatory signal may correspond to the voltage between the first and second nodes, and the second oscillatory signal may correspond to the voltage between the first and second taps.

[0035] A reactive component network may include one or more reactive components (e.g., inductors or capacitors). If a reactive component network includes more than one reactive component, the reactive components may be connected in series. In either case, the portion of one or more reactive components between the first tap and the second tap may be a subset of the portion of reactive components between the first node and the second node. Therefore, the reactance (e.g., inductance or capacitance) between the first tap and the second tap may be smaller than the reactance between the first node and the second node. Thus, the second oscillatory signal corresponding to the voltage obtained between the first tap and the second tap may be a damped version of the first oscillatory signal, which corresponds to the voltage obtained between the first node and the second node. The second oscillatory signal may be a damped version of the first oscillatory signal in the sense that the amplification of the second oscillatory signal is proportional to, but smaller than, the amplification of the first oscillatory signal.

[0036] In an example where the vibration signal is a single-ended signal, the first vibration signal may, in some examples, correspond to the voltage between one of the nodes of oscillator 12 and a reference voltage, and the second vibration signal may, in such an example, correspond to the voltage between one of the taps of oscillator 12 and a reference voltage. In some examples, the first node may be coupled to a ground rail or a power rail and act as a reference voltage. In such an example, the first vibration signal may, in some examples, correspond to the voltage between the first node and the second node, and the second vibration signal may, in such an example, correspond to the voltage between one of the taps and the first node.

[0037] A portion of one or more reactive components between the tap and the first node may be a subset of the portion of reactive components between the first node and the second node. Therefore, the reactance (e.g., inductance or capacitance) between the tap and the first node may be smaller than the reactance between the first node and the second node. Thus, the second oscillatory signal corresponding to the voltage obtained between the tap and the first node may be a damped version of the first oscillatory signal corresponding to the voltage obtained between the first node and the second node.

[0038] Oscillator 12 can generate first and second vibration signals based on a control signal. For example, oscillator 12 may be a voltage-controlled oscillator (VCO), and the control signal may be a voltage signal. In some examples, transmitter 10 may generate a control signal based on transmitted data. In such examples, oscillator 12 may use the control signal to frequency modulate and / or phase modulate the vibration signals at its first and second outputs based on the transmitted data. That is, in such examples, each of the vibration signals may be a frequency-modulated (FM) or phase-modulated (PM) signal. In some examples, the vibration signals may be voltage signals.

[0039] In some examples, the power amplifier 14 may include a single amplifier signal chain. In such examples, to generate a power-amplified output signal, the power amplifier 14 may select one of the vibrational signals, amplify the selected vibrational signal using a single amplifier signal chain, and output the amplified version of the selected vibrational signal as the power-amplified output signal.

[0040] In further examples, the power amplifier 14 may include multiple amplifier signal chains. In such examples, to generate a power-amplified output signal, the power amplifier 14 may amplify each of the vibration signals using each amplifier signal chain and select one of the amplified versions of the vibration signal to output as the power-amplified output signal.

[0041] A gain control signal can control the gain of the power amplifier 14. In some examples, the power amplifier 14 may include a selection unit that selects one of the oscillator signals output by the oscillator 12, or an amplified version of one of the oscillator signals, for use in generating a power-amplified output signal. In such examples, the gain control signal may be coupled to the control input of the selection unit, and the selection unit may select one of the signals based on the gain control signal.

[0042] In some examples, a gain control signal may include multiple signal components. For example, a gain control signal may include a first gain control signal component and a second gain control signal component. The first gain control signal component may be coupled to the control input of a selection unit and control the gain (e.g., attenuation) provided by the selection unit, and the second gain control signal component may be coupled to one or more amplifier stages in the power amplifier 14 and control the gain provided by one or more amplifier stages.

[0043] The power amplifier 14 may be either a single-stage amplifier or a multi-stage amplifier. A single-stage amplifier may have a single amplifier stage, while a multi-stage amplifier may have multiple amplifier stages. In an example where the power amplifier 14 is a multi-stage amplifier and the gain control signal includes a gain control signal component coupled to the amplifier stages, the gain control signal component may include a plurality of gain control signal sub-components, each coupled to each stage of the multi-stage amplifier. Each of the gain control signal sub-components can adjust and control the gain of each stage in the multi-stage amplifier. In such an example, the gain of each gain stage in the multi-stage amplifier can be adjusted independently.

[0044] In an example where the power amplifier 14 includes multiple amplifier signal chains, each amplifier signal chain may be either a single-stage amplifier signal chain or a multi-stage amplifier signal chain. In an example where the multiple amplifier signal chains are multi-stage amplifier signal chains, the corresponding amplifier stages in each amplifier signal chain may, in some examples, be controlled based on the same gain control signal sub-component of the gain control signal. In another example, the gains of the corresponding amplifier stages may be independently programmable.

[0045] In an additional example, the power amplifier 14 may be a multistage amplifier in which each stage includes a single-ended or differential self-bias amplifier. Each stage may further have an independently adjustable power rail voltage. By adjusting the power rail voltage for a particular amplifier stage, the self-bias amplifier of that stage may be biased with a different bias current, which can adjust the gain of the self-bias amplifier. Thus, by using independently adjustable power rail voltages for different self-bias amplifier stages, a multistage power amplifier with stage-independent gain adjustment can be achieved using a relatively small number of circuit components.

[0046] In some cases, an adjustable power rail voltage may be supplied by one or more adjustable power sources. For example, an adjustable power source may be an adjustable voltage regulator, such as an adjustable low-dropout regulator (LDO). A voltage regulator and / or LDO may be adjustable in the sense that the regulator and / or LDO can output a voltage level determined based on a control input.

[0047] In an example where one or more amplifier stages in the power amplifier 14 are powered by one or more adjustable power supplies, the control input to each of the adjustable power supplies may be coupled to the respective gain control signal subcomponents of the gain control signal. In such an example, the amplifier stages may be configured to have a gain determined based on the power supply output level (e.g., voltage level).

[0048] In examples where the gain control signal includes multiple signal components, the power amplifier 14 may include multiple gain controls. For example, the power amplifier 14 may include coarse gain control, which controls the selection of the oscillator signal used to generate the power-amplified output signal, and fine gain control, which controls the gain of one or more amplifier stages in a multi-stage amplifier that amplifies the selected oscillator voltage. Fine gain control may, in some examples, provide a continuous gain control function, but the range of gain values ​​over which the gain control function is linear may be relatively small. On the other hand, coarse gain control can be linear over a relatively large range of gain values, but it may be a discrete function using discrete gain steps.

[0049] By providing both coarse and fine gain control, it becomes possible to finely adjust the gain of the power amplifier 14 over a wide range of gain values. In this way, a power amplifier with relatively high-precision gain control over a relatively large range of output power settings can be achieved.

[0050] In some examples, one or more amplifier stages in the power amplifier 14 may be a differential self-bias amplifier stage. The differential self-bias amplifier stage may include a first variable resistor coupled between the power supply and the source terminals of one or more pull-up transistors, and a second variable resistor coupled between the ground rail and the source terminals of one or more pull-down transistors.

[0051] Increasing the variable resistor can increase the even-order harmonic suppression of the amplifier stage, but it can also decrease the gain of the amplifier stage. Decreasing the variable resistor can have the opposite effect. Therefore, by placing the variable resistor in the aforementioned position in the differential self-bias amplifier, the trade-off between even-order harmonic suppression and amplifier gain can be dynamically adjusted and balanced in the power amplifier 14.

[0052] In some examples, the power amplifier 14 may include a differential self-biased amplifier stage with one or more variable resistors, as described in the above example, where the amplifier stage is also powered by an adjustable power supply (e.g., an adjustable LDO). In such examples, coarse gain control may be coupled to the variable resistors, and fine gain control may be coupled to the adjustable power supply.

[0053] In a further example, one or more amplifier stages in the power amplifier 14 may be configured to operate in self-bias mode and nonlinear mode. Self-bias mode may offer a higher degree of linearity than nonlinear mode, but with lower power efficiency. Conversely, nonlinear mode may offer higher power efficiency but lower linearity. By providing amplifier stages that can be configured to operate in self-bias mode and nonlinear mode, the trade-off between linearity and power efficiency can be dynamically adjusted and balanced in the power amplifier 14.

[0054] The matching network 16 may include any components that can be configured to provide impedance matching between the power amplifier 14 and the antenna 18. In some examples, the matching network 16 may include one or more inductors or capacitors configured to match the output impedance of the matching network 16 to the impedance of the antenna 18, and to match the input impedance of the matching network 16 to the output impedance of the power amplifier 14. The antenna 18 may be any type of antenna configured to transmit an electromagnetic signal to a remote device.

[0055] The power amplifier 14 can selectively amplify the oscillator signal output by the oscillator 12 to generate a power-amplified output signal. Each oscillator signal may correspond to a different voltage generated across different parts of the network of reactive components included in the oscillator 12. By selectively amplifying the different voltages generated across different parts of the network of reactive components included in the oscillator 12, the gain of the power amplifier 14 can be adjusted, thereby allowing the output power of the power amplifier 14 to be adjusted based on the dynamic power requirements of the transmitter 10. By allowing the output power of the power amplifier 14 to be adjusted based on the dynamic power requirements, the total power consumption of the power amplifier 14 can be reduced. By using one or more taps in the network of reactive components included in the oscillator 12 to obtain different voltages that are selectively amplified by the power amplifier 14, the number of components required to obtain different voltages can be reduced. In this way, a variable-gain, relatively low-power amplifier can be obtained using a relatively small number of components.

[0056] Figure 2 is a block diagram of the exemplary transmitter 10 of Figure 1, illustrating in more detail an exemplary oscillator 12 in accordance with the present disclosure. In Figure 2, the first and second outputs of the oscillator 12 are single-ended outputs that generate single-ended output signals. The oscillator 12 includes an oscillator circuit element 32, which includes a reactive component network 34. The reactive component network 34 includes a node 36 coupled to a first end of the reactive component network 34, and a node 38 connected to a second end of the reactive component network 34. The reactive component network 34 also includes a tap 40 between the first and second ends of the reactive component network 34, which is coupled to a reactive component in the reactive component network 34.

[0057] Node 38 is coupled to the first input of the power amplifier 14 via lead 42, and tap 40 is coupled to the second input of the power amplifier 14 via lead 44. Node 38 may be coupled to the first output of oscillator 12 and / or may form the first output of oscillator 12. Tap 40 may be coupled to the second output of oscillator 12 and / or may form the second output of oscillator 12. Leads 42 and 44 in Figure 2 may correspond to connections 20 and 22 in Figure 1, respectively.

[0058] During operation, oscillator 12 generates a first vibration signal at its first output and a second vibration signal at its second output. The second vibration signal may be an attenuated version of the first vibration signal. In some examples, the first vibration signal may correspond to the voltage between node 38 and a reference voltage, and the second vibration signal may correspond to the voltage between tap 40 and a reference voltage. In further examples, node 36 may be coupled to a ground rail or a power rail and act as a reference voltage. In such examples, the first vibration signal may correspond to the voltage between node 36 and node 38, and the second vibration signal may correspond to the voltage between tap 40 and node 36.

[0059] In some examples, the transmitter 10 in Figure 2 may be implemented on an integrated circuit. The integrated circuit may include an oscillator 12 having nodes 36, 38, and a reactive component network 34 (i.e., a network of one or more reactive components) coupled between nodes 36 and 38. The reactive component network 34 may have at least one tap 40 between nodes 36 and 38. The oscillator 12 may further include a first output coupled to the reactive component network 34 via node 38, and a second output coupled to the reactive component network 34 via tap 40. The integrated circuit may further include a power amplifier 14 having a first input coupled to the first output of the oscillator 12, a second input coupled to the second output of the oscillator 12, and an output.

[0060] In some examples, node 36 of oscillator 12 is at least one of the power rail or ground rail relative to oscillator 12. In such examples, the reactive component network 34 includes one or more inductors coupled in series between node 36 and node 38 of oscillator 12. In such examples, tap 40 is coupled to one or more inductors, and the inductance between node 36 and node 38 of oscillator 12 is greater than the inductance between tap 40 of the reactive component network 34 and node 36 of oscillator 12.

[0061] In an additional example where node 36 of oscillator 12 is at least one of the power rail or ground rail for oscillator 12, the reactive component network 34 includes one or more capacitors coupled in series between node 36 and node 38 of oscillator 12. In such an example, tap 40 is coupled to one or more capacitors, and the capacitance between node 36 and node 38 of oscillator 12 is greater than the capacitance between tap 40 of the reactive component network 34 and node 36 of oscillator 12.

[0062] Figure 3 is a block diagram of the exemplary transmitter 10 of Figure 1, illustrating in more detail another exemplary oscillator 12 in accordance with this disclosure. As shown in Figure 3, oscillator 12 includes an oscillator circuit element 52, which is similar to oscillator circuit element 32 of Figure 2, except that (1) node 36 is coupled to power amplifier 14 via lead 56, (2) reactive component network 34 includes an additional tap 54 between node 36 and node 38, and (3) tap 54 is coupled to power amplifier 14 via lead 58. Identical or similar components between oscillator circuit element 32 of Figure 2 and oscillator circuit element 52 of Figure 3 are given the same reference numerals.

[0063] In Figure 3, the first and second outputs of oscillator 12 are differential outputs that generate differential output signals. Specifically, nodes 36 and 38 may form the first differential output, and taps 40 and 54 may form the second differential output. Similarly, the first and second inputs of power amplifier 14 may be differential inputs. The first differential output of oscillator 12 is coupled to the first differential input of power amplifier 14 via leads 42 and 56. The second differential output of oscillator 12 is coupled to the second differential input of power amplifier 14 via leads 44 and 58. Collectively, leads 42 and 56 in Figure 3 may correspond to connection 20 in Figure 1. Similarly, leads 44 and 58 in Figure 3 may correspond to connection 22 in Figure 1.

[0064] During operation, oscillator 12 generates a first differential oscillator signal at its first output and a second differential oscillator signal at its second output. The second differential oscillator signal may be an attenuated version of the first differential oscillator signal. The first differential oscillator signal may correspond to the voltage between node 36 and node 38, and the second differential oscillator signal may correspond to the voltage between tap 54 and tap 40 of the reactive component network 34.

[0065] In some examples, the transmitter 10 in Figure 3 may be implemented on an integrated circuit. The integrated circuit includes an oscillator 12 having node 36, node 38, and a reactive component network 34 coupled between node 36 and node 38. The reactive component network 34 may have taps 40, 54 between node 36 and node 38. The oscillator 12 is further coupled to the reactive component network 34 via nodes 36, 38. difference The integrated circuit may include a first output and a second output coupled to a reactive component network 34 via taps 40 and 54. The integrated circuit may further include a power amplifier 14 having a first input coupled to the first output of oscillator 12, a second input coupled to the second output of oscillator 12, and an output.

[0066] In some examples, the reactive component network 34 may have taps 40 and 54 coupled between node 36 and node 38. In such examples, the first output of oscillator 12 is a first differential output having a first terminal coupled to the reactive component network 34 via node 36 and a second terminal coupled to the reactive component network 34 via node 38. In such examples, the second output of VCO is a second differential output having a first terminal coupled to the reactive component network 34 via tap 54 and a second terminal coupled to the reactive component network 34 via tap 40.

[0067] In a further example, the reactive component network 34 includes one or more inductors coupled in series between nodes 36 and 38 of the oscillator 12, and taps 40, 54 are coupled to one or more inductors. In such an example, the inductance between the first and second terminals of the first differential output of the oscillator 12 is greater than the inductance between the first and second terminals of the second differential output of the oscillator 12.

[0068] In an additional example, the reactive component network 34 includes one or more capacitors coupled in series between nodes 36 and 38 of oscillator 12, and taps 40, 54 are coupled to one or more capacitors. In such an example, the capacitance between the first and second terminals of the first differential output of oscillator 12 is greater than the capacitance between the first and second terminals of the second differential output of oscillator 12.

[0069] In the transmitter 10 of Figures 2 and 3, the oscillator 12 can output multiple vibration signals, and the power amplifier 14 can selectively amplify these vibration signals to generate a power-amplified output signal. Each vibration signal may correspond to a different voltage generated across different parts of the network of reactive components included in the oscillator 12. By selectively amplifying the different voltages generated across different parts of the network of reactive components in the oscillator 12, the gain of the power amplifier 14 can be adjusted, thereby allowing the output power of the power amplifier 14 to be adjusted based on the dynamic power requirements of the transmitter 10. By allowing the output power of the power amplifier 14 to be adjusted based on the dynamic power requirements of the transmitter 10, the total power consumption of the power amplifier 14 can be reduced. By using one or more taps in the network of reactive components included in the oscillator 12 to obtain different voltages that are selectively amplified by the power amplifier 14, the amount of components required to obtain different voltages can be reduced. In this way, a variable-gain, relatively low-power amplifier can be obtained using a relatively small number of components.

[0070] Figure 4 is a block diagram of the exemplary transmitter 10 of Figure 1, illustrating in more detail an exemplary power amplifier 14 according to the present disclosure. The power amplifier 14 includes a selector circuit 60, amplifier stages 62, 64, adjustable power supplies 66, 68, connections 70, 72, power lines 74, 76, and gain control leads 78, 80, 82. The first input of the selector circuit 60 is coupled to the first output of the oscillator 12 via connection 20. The second input of the selector circuit 60 is coupled to the second output of the oscillator 12 via connection 22. The output of the selector circuit 60 is coupled to the input of the amplifier stage 62 via connection 70. The output of the amplifier stage 62 is coupled to the input of the amplifier stage 64 via connection 72. The output of the amplifier stage 64 is coupled to the input of the matching network 16 via connection 24.

[0071] The output of the amplifier stage 64 may be coupled to the output of the power amplifier 14 and / or may form the output of the power amplifier 14. The first and second inputs of the selection circuit 60 may be coupled to the first and second inputs of the power amplifier 14 and / or may form the first and second inputs of the power amplifier 14, respectively.

[0072] The output of the adjustable power supply 66 is coupled to the power input of the amplifier stage 62 via the power line 74. The output of the adjustable power supply 68 is coupled to the power input of the amplifier stage 64 via the power line 76. The control input of the selection circuit 60 is coupled to the gain control A lead 78. The control input of the amplifier stage 62 is coupled to the gain control B lead 80. The control input of the amplifier stage 64 is coupled to the gain control C lead 82. The gain control leads 78, 80, and 82 can collectively correspond to the gain control lead 26 shown in Figures 1 to 3.

[0073] Connections 20, 22, 24, 28, 70, and 72 can be single-ended or differential. When connections 20 and 22 are single-ended, oscillator 12 may, in some examples, correspond to oscillator 12 in Figure 2, and connections 20 and 22 may correspond to leads 42 and 44 in Figure 2. When connections 20 and 22 of oscillator 12 are differential, oscillator 12 may, in some examples, correspond to oscillator 12 in Figure 3, and connections 20 and 22 may correspond to leads 42, 44, 56, and 58 in Figure 3.

[0074] During operation, the selection circuit 60 receives oscillation signals from the oscillator 12 via connections 20 and 22, respectively, and, based on the gain control A signal, selects one of the oscillation signals to be used to generate a power-amplified signal, and outputs the selected signal onto connection 70. The amplifier stage 62 receives the selected signal via connection 70, amplifies the selected signal using the gain determined by the gain control B signal, and outputs the amplified signal onto connection 72. The amplifier stage 64 receives the amplified signal from amplifier stage 62 via connection 72, amplifies that signal using the gain determined by the gain control C signal, and outputs the amplified signal as a power-supplied and amplified signal to the power amplifier 14 on connection 24.

[0075] An adjustable power supply 66 may supply power to the amplifier stage 62 via the power line 74. Similarly, an adjustable power supply 68 may supply power to the amplifier stage 64 via the power line 76. The adjustable power supply 66 may generate an output power level (e.g., a voltage level) based on a gain control B signal, and the adjustable power supply 68 may generate an output power level (e.g., a voltage level) based on a gain control C signal. In some examples, one or both of the adjustable power supplies 66, 68 may be adjustable voltage regulators, such as adjustable LDOs. The amplifier stage 62 may amplify the selected signal based on the gain determined by the output power level generated by the adjustable power supply 66. The amplifier stage 64 may amplify the input signal of the amplifier stage 64 based on the gain determined by the output power level generated by the adjustable power supply 68. It can be widened.

[0076] As shown in Figure 4, the power amplifier 14 includes a selector circuit 60. The selector circuit 60 has (1) a first input coupled to the first input of the power amplifier 14, (2) a second input coupled to the second input of the power amplifier 14, and (3) an output. The power amplifier 14 further includes an amplifier stage 62, which has (1) an input coupled to the output of the selector circuit 60, and (2) an output. The power amplifier 14 further includes an amplifier stage 64, which has (1) an input coupled to the output of the amplifier stage 62, and (2) an output. The selector circuit 60 has a control input coupled to a gain control A lead 78.

[0077] The amplifier stages 62 and 64 may be implemented with any combination of the amplifier stages described herein, or with other types of amplifier stages. In some examples, amplifier stage 62 may be implemented with the amplifier stage shown in Figure 13, and amplifier stage 64 may be implemented with the amplifier stage shown in Figure 14.

[0078] In some examples, each of the amplifier stages 62, 64 in the power amplifier 14 may include a single-ended or differential self-bias amplifier (e.g., a self-bias inverter). Each of the amplifier stages 62, 64 may further have independently adjustable power rail voltages, respectively, provided by adjustable power supplies 66, 68. By adjusting the power rail voltage for a particular amplifier stage, the self-bias amplifier of that stage may be biased with a different bias current, thereby adjusting the gain of the self-bias amplifier. Thus, by using independently adjustable power rail voltages for different self-bias amplifier stages, a multi-stage power amplifier with stage-independent gain adjustment can be achieved using a relatively small number of circuit components.

[0079] In some examples, gain control A signal may be coarse gain control, controlling the selection of which oscillator voltage to use to generate the power-amplified output signal. In such examples, gain control B signal and gain control C signal may collectively constitute fine gain control, controlling the gains of amplifier stages 62 and 64 in the multistage power amplifier 14. Fine gain control may, in some examples, provide a continuous gain control function, but the range of gain values ​​over which the gain control function is linear may be relatively small. On the other hand, coarse gain control function may be linear over a relatively large range of gain values, but may be a discrete function with discrete gain steps.

[0080] By providing both coarse and fine gain control, it becomes possible to finely adjust the gain of a power amplifier over a wide range of gain values. In this way, a power amplifier with relatively high-precision gain control can be achieved over a relatively large range of output power settings.

[0081] Figure 5 is a block diagram of the exemplary transmitter 10 of Figure 1, further illustrating an alternative exemplary power amplifier 14 in accordance with the present disclosure. The power amplifier 14 includes amplifier stages 84, 86, 88, 90, a selection circuit 92, adjustable power supplies 94, 96, connections 98, 100, 102, 104, power lines 106, 108, 110, 112, and gain control leads 114, 116, 118.

[0082] The input of amplifier stage 84 is coupled to the first output of oscillator 12 via connection 20. The output of amplifier stage 84 is coupled to the input of amplifier stage 86 via connection 98. The output of amplifier stage 86 is coupled to the first input of selection circuit 92 via connection 100. The input of amplifier stage 88 is coupled to the second output of oscillator 12 via connection 22. The output of amplifier stage 88 is coupled to the input of amplifier stage 90 via connection 102. The output of amplifier stage 90 is coupled to the second input of selection circuit 92 via connection 104. The output of selection circuit 92 is coupled to the input of matching network 16 via connection 24.

[0083] The output of the selection circuit 92 may be coupled to the output of the power amplifier 14 and / or may form the output of the power amplifier 14. The input of the amplifier stage 84 may be coupled to the first input of the power amplifier 14 and / or may form the first input of the power amplifier 14. Similarly, the input of the amplifier stage 88 may be coupled to the second input of the power amplifier 14 and / or may form the second input of the power amplifier 14.

[0084] The output of the adjustable power supply 94 is coupled to the power input of the amplifier stage 84 via power line 106. The output of the adjustable power supply 94 is also coupled to the power input of the amplifier stage 88 via power lines 106 and 110. The output of the adjustable power supply 96 is coupled to the power input of the amplifier stage 86 via power line 108. The output of the adjustable power supply 96 is also coupled to the power input of the amplifier stage 90 via power lines 108 and 112. The control input of the selection circuit 92 is coupled to the gain control A lead 114. The control input of the adjustable power supply 94 is coupled to the gain control B lead 116. The control input of the adjustable power supply 96 is coupled to the gain control C lead 118. The gain control leads 114, 116, and 118 can collectively correspond to the gain control lead 26 shown in Figures 1 to 3.

[0085] Connections 20, 22, 24, 28, 98, 100, 102, and 104 can be single-ended or differential connections. When connections 20 and 22 are single-ended connections, oscillator 12 may, in some examples, correspond to oscillator 12 in Figure 2, and connections 20 and 22 may correspond to leads 42 and 44 in Figure 2. When connections 20 and 22 of oscillator 12 are differential connections, oscillator 12 may, in some examples, correspond to oscillator 12 in Figure 3, and connections 20 and 22 may correspond to leads 42, 44, 56, and 58 in Figure 3.

[0086] During operation, amplifier stage 84 receives a first vibration signal via the first input, amplifies the first vibration signal to generate a first amplified signal, and outputs the first amplified signal via connection 98. Amplifier stage 86 receives the first amplified signal via connection 98, amplifies the first amplified signal to generate a second amplified signal, and outputs the second amplified signal via connection 100. Amplifier stage 86 receives a second vibration signal via the second input, amplifies the second vibration signal to generate a third amplified signal, and outputs the third amplified signal via connection 102. Amplifier stage 86 receives a first amplified signal via connection 102, amplifies the third amplified signal to generate a fourth amplified signal, and outputs the fourth amplified signal via connection 104. The selection circuit 92 receives the third and fourth amplified signals via connections 100 and 104, respectively, selects one of the third and fourth amplified signals to use for generating a power amplified signal based on the gain control A signal, and outputs the selected signal via connection 24.

[0087] Amplifier stages 84 and 86 can form a first amplifier signal chain, and amplifier stages 88 and 90 can form a second amplifier signal chain. The first amplifier signal chain can amplify the vibration signal received at connection 20, the second amplifier signal chain can amplify the vibration signal received at connection 22, and the selection circuit 92 can select which of the amplified signals to output as the power-amplified signal.

[0088] The adjustable power supply 94 can supply power to amplifier stages 84 and 88 via power lines 106 and 110. Similarly, the adjustable power supply 96 can supply power to amplifier stages 86 and 90 via power lines 108 and 112. The adjustable power supply 94 can generate an output power level (e.g., a voltage level) based on a gain control B signal, and the adjustable power supply 96 can generate an output power level (e.g., a voltage level) based on a gain control C signal. In some examples, one or more of the adjustable power supplies 94 and 96 may be voltage regulators for adjustable and / or programmable power-amplified signals, such as an adjustable and / or programmable LDO. The amplifier stages 84 and 88 can amplify their respective input signals based on the gain determined by the output power level generated by the adjustable power supply 94. Similarly, the amplifier stages 86 and 90 can amplify their respective input signals based on the gain determined by the output power level generated by the adjustable power supply 96.

[0089] As shown in Figure 5, the power amplifier 14 includes a first signal chain having amplifier stages 84 and 86. Amplifier stage 84 has (1) an input coupled to the first input of the power amplifier 14, and (2) an output. Amplifier stage 86 has (1) an input coupled to the output of amplifier stage 84 of the first signal chain, and (2) an output. The power amplifier 14 further includes a second signal chain having amplifier stages 88 and 90. Amplifier stage 88 has (1) an input coupled to the second input of the power amplifier, and (2) an output. Amplifier stage 90 has (1) an input coupled to the output of the first amplifier stage 88 of the second signal chain, and (2) an output.

[0090] The power amplifier 14 further includes a selection circuit 92, which has (1) a first input coupled to the output of the amplifier stage 86 of the first signal chain, (2) a second input coupled to the output of the amplifier stage 90 of the second signal chain, and (3) an output that forms the output of the power amplifier 14. The selection circuit 92 has a control input coupled to the gain control A lead 114.

[0091] The amplifier stages 84, 86, 88, and 90 may be implemented with any combination of the amplifier stages described herein or with other types of amplifier stages. In some examples, the amplifier stages 84 and 88 may be implemented with the amplifier stages illustrated in Figure 13, and the amplifier stages 86 and 90 may be implemented with the amplifier stages illustrated in Figure 14.

[0092] In some examples, each of the amplifier stages 84, 86, 88, and 90 of the power amplifier 14 may include single-ended or differential self-bias amplifiers (e.g., self-bias inverters). Each of the amplifier stages 84, 86, 88, and 90 may further have independently adjustable power rail voltages provided by adjustable power supplies 94 and 96. By adjusting the power rail voltage for a particular amplifier stage, the self-bias amplifier of that stage may be biased with a different bias current, thereby adjusting the gain of the self-bias amplifier. Thus, by using independently adjustable power rail voltages for different self-bias amplifier stages, a multi-stage power amplifier with stage-independent gain adjustment can be achieved using a relatively small number of circuit components.

[0093] In some examples, gain control A signal may be coarse gain control, controlling the selection of which oscillator voltage to use to generate the power-amplified output signal. In such examples, gain control B signal and gain control C signal may collectively constitute fine gain control in the multistage power amplifier 14, controlling the gains of amplifier stages 84, 86, 88, and 90. Fine gain control may, in some examples, provide a continuous gain control function, but the range of gain values ​​over which the gain control function is linear may be relatively small. On the other hand, coarse gain control function may be linear over a relatively large range of gain values, but may be a discrete function with discrete gain steps.

[0094] By providing both coarse and fine gain control, it becomes possible to finely adjust the gain of a power amplifier over a wide range. In this way, a power amplifier with relatively high-precision gain control can be achieved over a relatively large range of output power settings.

[0095] Figure 6 is a schematic diagram illustrating an exemplary reactive component network 34 that may be used in an exemplary oscillator of this disclosure. In some examples, the reactive component network 34 may be used to implement the reactive component network 34 illustrated in Figure 3. The reactive component network 34 includes inductors L1, L2, L3, L4, and nodes 36, 38, 120, 122, and 124. Inductor L1 is coupled between node 36 and node 120. Inductor L2 is coupled between node 120 and node 122. Inductor L3 is coupled between node 122 and node 124. Inductor L4 is coupled between node 124 and node 38.

[0096] Tap 54 is connected to node 120, and tap 40 is connected to node 124. Nodes 36 and 38 may form a first differential output, and taps 54 and 40 may form a second differential output.

[0097] As shown in Figure 6, taps 54 and 40 are coupled to nodes 120 and 124 between nodes 36 and 38. Therefore, the inductance between nodes 36 and 38 is greater than the inductance between taps 54 and 40 of the reactive component network 34, thereby making the voltage between taps 54 and 40 proportional to the voltage between nodes 36 and 38, but less than the voltage between nodes 36 and 38.

[0098] Figure 7 is a schematic diagram illustrating an exemplary oscillator 12 incorporating the exemplary reactive component network 34 of Figure 6, in accordance with this disclosure. The oscillator 12 includes transistors 126 and 128, a ground rail 130, a high-voltage rail 132, and the reactive component network 34 shown in Figure 6. The source of transistor 126 is coupled to the ground rail 130. The drain of transistor 126 is coupled to node 36 and the gate of transistor 128. The gate of transistor 126 is coupled to node 38 and the drain of transistor 128. The source of transistor 128 is coupled to the ground rail 130. The drain of transistor 128 is coupled to node 38 and the gate of transistor 126. The gate of transistor 128 is coupled to node 36 and the drain of transistor 126. Node 122 of the reactive component network 34 is coupled to the high-voltage rail 132.

[0099] Transistors 126 and 128 may be examples of cross-coupled transistors, and the outputs of the cross-coupled transistors are coupled to nodes 36 and 38. Nodes 36 and 38 form a first differential output to oscillator 12, and taps 40 and 54 form a second differential output to oscillator 12. In Figure 7, inductors L1, L2, L3, and L4 are examples of configurations of one or more inductors coupled in series between nodes 36 and 38 of oscillator 12.

[0100] During operation, transistors 126 and 128 can each act as a common-source amplifier with a reactive load. Inductors L1, L2, L3, and L4 can form all or part of the reactive load for transistors 126 and 128. Specifically, transistor 126 can amplify the signal at the drain of transistor 128 and apply a 180-degree phase shift to the signal. Transistor 128 can amplify the signal at the drain of transistor 126 and apply a 180-degree phase shift to the signal. The feedback loop formed by the cross-coupled oscillators can collectively oscillate the signals at the two differential outputs at nodes 36 and 38. The inductances of inductors L1, L2, L3, and L4, along with one or more parasitic capacitances in transistors 126 and 128, can control the frequency of the oscillations with respect to oscillator 12.

[0101] The second differential output of oscillator 12, formed by taps 40 and 54, is proportional to, but may provide, a smaller oscillating output signal than, the output signal provided by the first differential output of oscillator 12, formed by nodes 36 and 38. By selecting which of these voltages to amplify, it may be possible to change the gain of the power amplifier. By using one or more taps of the network of reactive components included in oscillator 12 (e.g., inductors L1, L2, L3, L4) to output voltage levels of different voltages, it may be possible to change the gain of the power amplifier without requiring additional reactive components in the power amplifier or outside the integrated circuit. In this way, a variable-gain, relatively low-power amplifier can be obtained using a relatively small number of components.

[0102] Figure 8 is a schematic diagram illustrating another exemplary reactive component network 34 that may be used in an exemplary oscillator of this disclosure. The reactive component network 34 includes inductors L5, L6, L7, L8, L9, L10, nodes 134, 136, 138, 140, 142, 144, 146, and taps 148, 150, 152, 154. Inductor L5 is coupled between node 134 and node 136. Inductor L6 is coupled between node 136 and node 138. Inductor L7 is coupled between node 138 and node 140. Inductor L8 is coupled between node 140 and node 142. Inductor L9 is coupled between node 142 and node 144. Inductor L10 is coupled between node 144 and node 146. In Figure 8, inductors L5, L6, L7, L8, L9, and L10 are examples of configurations in which one or more inductors are connected in series between nodes 134 and 146 of oscillator 12.

[0103] Tap 148 is joined to node 136. Tap 150 is joined to node 138. Tap 152 is joined to node 142. Tap 154 ​​is joined to node 144.

[0104] Nodes 134 and 146 may form a first differential output, taps 136 and 144 may form a second differential output, and taps 138 and 142 may form a third differential output. The second differential output may output an oscillatory signal proportional to, but smaller than, the signal output by the first differential output. The third differential output may output an oscillatory signal proportional to, but smaller than, the signals output by the first and second differential outputs. In general, any number of taps can be arranged in a series of inductors connected in series to form any number of differential outputs and thereby to provide any number of gain steps to a power amplifier according to this disclosure.

[0105] Figure 9 is a schematic diagram of an exemplary reactive component and switching circuit 156 that may be used in an exemplary transmitter of this disclosure. In some examples, a reactive component network 34 may be used to implement the reactive component network 34 shown in Figure 3 and / or the selection circuit 60 shown in Figure 4. The reactive component and switching circuit 156 includes inductors L11, L12, L13, switches S1, S2, S3, S4, and nodes 158, 160, 162, 164, 166, 168.

[0106] Inductor L11 is coupled between node 158 and node 160. Inductor L12 is coupled between node 160 and node 162. Inductor L13 is coupled between node 162 and node 164. Switch S1 is coupled between node 158 and node 166. Switch S2 is coupled between node 160 and node 166. Switch S3 is coupled between node 162 and node 168. Switch S4 is coupled between node 164 and node 168.

[0107] Nodes 158 and 164 can form a differential input. Nodes 166 and 168 can form a differential output.

[0108] In some examples, inductors Lll, L12, L13 and nodes 158, 160, 162, 164 may be included in the reactive component network 34 of oscillator 12 (e.g., Figure 3), and switches S1, S2, S3, S4 may be included in the selection circuit 60 of power amplifier 14 (e.g., Figure 4). In such examples, nodes 158, 164 may correspond to nodes 36, 38, respectively, and nodes 166, 168 may correspond to the outputs of the selection circuit 60. In such examples, the control inputs of switches S1, S2, S3, S4 may be coupled to gain control lead A 78.

[0109] During operation, the control circuit can selectively open and close switches S1, S2, S3, and S4 based on a gain control signal. During the first operating state, switches S1 and S4 may be closed, and switches S2 and S3 may be open, thereby outputting voltages between nodes 158 and 164 at nodes 166 and 168. During the second operating state, switches S2 and S3 may be closed, and switches S1 and S4 may be open, thereby outputting voltages between nodes 160 and 162 at nodes 166 and 168.

[0110] In some examples, inductors L11, L12, and L13 can form tapped inductors. Tapped inductors, along with switches S1, S2, S3, and S4, can provide a gain step between the VCO and the PA. In some examples, inductors L11, L12, and L13 can be implemented as inductors inside the VCO core, and switches S1, S2, S3, and S4 can provide an attenuator step.

[0111] Figure 10 is a schematic diagram illustrating another exemplary reactive component network 34 that may be used in an exemplary oscillator of this disclosure. The reactive component network 34 includes capacitors C1, C2, C3, C4, C5, C6, C7, C8, switches S5, S6, nodes 170, 172, 174, 176, 178, 180, 182, 184, 186, 188, and taps 190, 192, 194, 196. Capacitor C1 is coupled between node 170 and node 172. Capacitor C2 is coupled between node 172 and node 174. Capacitor C3 is coupled between node 178 and node 180. Capacitor C4 is coupled between node 176 and node 178. Capacitor C5 is coupled between node 172 and node 182. Capacitor C6 is coupled between node 178 and node 186. Capacitor C7 is coupled between node 174 and node 184. Capacitor C8 is coupled between node 176 and node 188. Switch S5 is coupled between node 182 and node 186. Switch S6 is coupled between node 184 and node 188. Tap 190 is coupled to node 172, tap 192 is coupled to node 174, tap 194 is coupled to node 176, and tap 196 is coupled to node 178.

[0112] Nodes 170 and 180 may form the ends of the reactive component network 34 and may correspond to the first differential output of the reactive component network 34. Taps 190 and 196 may form the second differential output of the reactive component network 34, and taps 192 and 194 may form the third differential output of the reactive component network 34.

[0113] As shown in Figure 10, taps 192 and 194 are coupled to the reactive component network 34 between taps 190 and 196, and between nodes 170 and 180. Similarly, taps 190 and 196 are coupled to the reactive component network 34 between nodes 170 and 180. Therefore, the capacitance between nodes 170 and 180 is greater than the capacitance between taps 190 and 196 (when one of switches S5 and S6 is closed), and thereafter the voltage between taps 190 and 196 is proportional to, but less than, the voltage between nodes 170 and 180. Similarly, the capacitance between node 170 and node 180 is greater than the capacitance between tap 190 and tap 196 (when switch S6 is closed), and the capacitance between tap 190 and tap 196 is greater than the capacitance between tap 192 and tap 194 (when switch S6 is closed), so that the voltage between tap 192 and tap 194 is proportional to, but less than, the voltage between tap 190 and tap 196 and the voltage between node 170 and node 180.

[0114] Figure 11 is a schematic diagram illustrating an exemplary oscillator 12 incorporating the exemplary reactive component network 34 of Figure 10, in accordance with this disclosure. The oscillator 12 includes transistors 198, 200, inductors L14, L15, a ground rail 202, a high-voltage rail 204, a node 206, and the reactive component network 34 shown in Figure 10. The source of transistor 198 is coupled to the ground rail 202. The drain of transistor 198 is coupled to node 170 and the gate of transistor 200. The gate of transistor 198 is coupled to node 180 and the drain of transistor 200. The source of transistor 200 is coupled to the ground rail 202. The drain of transistor 200 is coupled to node 180 and the gate of transistor 198. The gate of transistor 200 is coupled to node 170 and the drain of transistor 198. Inductor L14 is coupled between node 170 and node 206. Inductor L15 is coupled between node 206 and node 180. Node 206 is coupled to high-voltage rail 204.

[0115] Transistors 198 and 200 may be examples of cross-coupled transistors, the outputs of which are coupled to nodes 36 and 38. Switches S5 and S6 include control inputs that are coupled to the control circuit. In Figure 11, when one of switches S5 or S6 is closed, the capacitance between nodes 170 and 180 may be an example of a configuration of one or more capacitors coupled in series between nodes 170 and 180 of oscillator 12.

[0116] During operation, transistors 198 and 200 can each act as a common-source amplifier with a reactive load. Capacitors C1, C2, C3, C4, C5, C6, C7, C8, and inductors L14 and L15 can form all or part of the reactive load for transistors 198 and 200. Specifically, transistor 198 can amplify the signal at the drain of transistor 200 and apply a 180-degree phase shift to this signal. Transistor 200 can amplify the signal at the drain of transistor 198 and apply a 180-degree phase shift to this signal. The feedback loop formed by the cross-coupled oscillators can collectively oscillate the signals at the two differential outputs at nodes 170 and 180. The inductances of inductors L14 and L15, together with the capacitances of one or more capacitors C1, C2, C3, C4, C5, C6, C7, and C8 (and, in some examples, one or more parasitic capacitances in transistors 198 and 200), can control the frequency of oscillations with respect to oscillator 12.

[0117] Switches S5 and S6 can be selectively opened and closed to program the oscillation frequency of oscillator 12. Any combination of open and closed states for switches S5 and S6 can correspond to different oscillation frequencies.

[0118] The third differential output of oscillator 12, formed by taps 192 and 194, may provide an oscillating output signal that is proportional to, but smaller than, the output signal provided by the second differential output of oscillator 12, formed by taps 190 and 196, and the output signal provided by the second differential output of oscillator 12, formed by taps 190 and 196, is proportional to, but smaller than, the output signal provided by the first differential output of oscillator 12, formed by nodes 170 and 180. It may be possible to change the gain of the power amplifier by selecting which voltage to amplify. The gain of the power amplifier can be changed without requiring additional reactive components in the power amplifier or outside the integrated circuit by using one or more taps (e.g., capacitors C1, C2, C3, C4, C5, C6, C7, C8) of the network of reactive components included in oscillator 12 to output voltage levels of different voltages. In this way, a variable-gain, relatively low-power amplifier can be obtained using a relatively small number of components.

[0119] Figure 12 is a schematic diagram illustrating another exemplary reactive component network 208 that may be used in an exemplary oscillator of this disclosure. The reactive component network 208 includes capacitors C9, C10, C11, C12, C13, C14, switches S7, S8, S9, S10, and nodes 210, 212, 214, 216, 218, 220. Capacitor C9 is coupled between nodes 210 and 212. Capacitor C10 is coupled between nodes 212 and 214. Capacitor C11 is coupled between nodes 216 and 218. Capacitor C12 is coupled between nodes 218 and 220. Capacitor C13 is coupled between switches S7 and S8. Capacitor C14 is coupled between switches S9 and S10. Switch S7 is coupled between capacitor C13 and node 212. Switch S8 is coupled between capacitor C13 and node 218. Switch S9 is coupled between capacitor C14 and node 212. Switch S10 is coupled between capacitor C14 and node 218.

[0120] In some examples, the reactive component network 208 in Figure 12 may implement a capacitive attenuation circuit that can be used in the coarse gain control circuit of the present disclosure. The capacitive attenuation circuit may provide gain between the VCO and the power amplifier in the transmitter. In some examples, the reactive component network 208 may be combined with capacitors inside the VCO core, and switches S7, S8, S9, and S10 may provide attenuation steps.

[0121] Figure 13 is a schematic diagram illustrating an exemplary amplifier stage 230 that may be used in a power amplifier of the present disclosure. The amplifier stage 230 includes transistors 232, 234, 236, 238, an adjustable LDO 240, resistors 242, 244, 246, 248, bias resistors 250, 252, adjustable resistors 254, 256, capacitors 258, 260, a ground rail 262, and nodes 264, 266, 268, 270, 272, 274, 276, 278.

[0122] Transistor 232 is coupled between resistor 242 and node 268. Specifically, the source of transistor 232 is coupled to resistor 242, and the drain of transistor 232 is coupled to node 268. The gate of transistor 232 is coupled to node 276. Transistor 234 is coupled between resistor 246 and node 268. Specifically, the source of transistor 234 is coupled to resistor 246, and the drain of transistor 234 is coupled to node 268. The gate of transistor 234 is coupled to node 276.

[0123] Transistor 236 is coupled between resistor 244 and node 270. Specifically, the source of transistor 236 is coupled to resistor 244, and the drain of transistor 236 is coupled to node 270. The gate of transistor 236 is coupled to node 278. Transistor 238 is coupled between resistor 248 and node 270. Specifically, the source of transistor 238 is coupled to resistor 248, and the drain of transistor 238 is coupled to node 270. The gate of transistor 238 is coupled to node 278.

[0124] Resistor 242 is coupled between transistor 232 and node 272. Resistor 244 is coupled between transistor 236 and node 272. Resistor 246 is coupled between transistor 234 and node 274. Resistor 248 is coupled between transistor 238 and node 274. Bias resistor 250 is coupled between node 268 and node 276. Bias resistor 252 is coupled between node 270 and node 278.

[0125] Adjustable resistor 254 is coupled between the output of adjustable LDO 240 and node 272. Adjustable resistor 256 is coupled between node 274 and ground rail 262. Capacitor 258 is coupled between node 264 and node 276. Capacitor 260 is coupled between node 266 and node 278.

[0126] Transistors 232, 234 and bias resistor 250 form a first self-bias amplifier (e.g., a self-bias inverter). Transistors 236, 238 and bias resistor 252 form a second self-bias amplifier (e.g., a self-bias inverter). Transistors 232, 234, 236, 238 and bias resistors 250, 252 together form a differential self-bias amplifier (e.g., a differential self-bias inverter).

[0127] Nodes 264 and 266 can form differential inputs to the amplifier stage 230, and nodes 268 and 270 can form differential outputs to the amplifier stage 230. Specifically, node 264 can form a non-inverting input, and node 266 can form an inverting input. Similarly, node 268 can form a non-inverting output, and node 270 can form an inverting output.

[0128] As shown in Figure 13, the amplifier stage 230 includes (1) a power rail (e.g., a lead coupled to the output of an adjustable LDO 240), an adjustable resistor 254, (2) a first self-bias inverter (e.g., transistors 232, 234, and resistor 250) coupled to the power rail via the adjustable resistor 254, and (3) a second self-bias inverter (e.g., transistors 236, 238, and resistor 252) coupled to the power rail (e.g., the output of an adjustable LDO 240) via the adjustable resistor 254. The power rail is coupled to an adjustable power supply, such as an adjustable LDO 240. The amplifier stage 230 further includes an adjustable resistor 256. A first self-bias inverter (e.g., transistors 232, 234, and resistor 250) is coupled to the ground rail 262 via an adjustable resistor 256, and a second self-bias inverter (e.g., transistors 236, 238, and resistor 252) is coupled to the ground rail 262 via an adjustable resistor 256.

[0129] The first self-bias inverter includes an input (e.g., node 276), an output (e.g., node 268), and a bias resistor 250 coupled between the input and output of the first self-bias inverter. The second self-bias inverter includes an input (e.g., node 278), an output (e.g., node 270), and a bias resistor 252 coupled between the input and output of the second self-bias inverter.

[0130] During operation, bias resistors 250 and 252 bias the self-bias inverter with a voltage that is approximately midway between the voltage output by the adjustable LDO 240 and ground. Capacitors 258 and 260 filter out DC and other low-frequency signal components received at nodes 264 and 266. The amplifier formed by transistors 232, 234, 236, and 238 amplifies the filtered input signal received from capacitors 258 and 260, and outputs the amplified signal at nodes 268 and 270.

[0131] In some examples, the amplifier stage 230 may implement a self-biased Class AB PA stage. Adjustable resistors 254 and 256 may control the current consumption of the PA stage and provide rejection of second harmonics from the VCO, while resistors 242, 244, 246, and 248 may provide linearity to the stage so that no additional harmonics are substantially generated.

[0132] In some examples, coarse gain control may be coupled to adjustable resistors 254 and 256, and fine gain control may be coupled to the adjustable LDO 240. In additional examples, the adjustable LDO 240 may be a fixed power supply that is not variable.

[0133] Increasing the resistance of the adjustable resistors 254 and 256 may increase the even-harmonic suppression of the amplifier stage 230, but may decrease the gain of the amplifier stage 230. Decreasing the resistance of the adjustable resistors 254 and 256 may have the opposite effect. Therefore, by placing the adjustable resistors 254 and 256 at the locations shown in Figure 13, the trade-off between even-harmonic suppression and amplifier gain can be dynamically adjusted and balanced in the amplifier stage 230.

[0134] Figure 14 is a schematic diagram illustrating another exemplary amplifier stage 280 that may be used in the power amplifier of the present disclosure. The amplifier stage 280 includes transistors 282, 284, an adjustable LDO 286, switches 288, 290, 292, 294, 296, bias resistors 298, 300, 302, capacitors 304, 306, a ground rail 308, and nodes 310, 312, 314, 316, 318, 320, 322, 324, 326, 328.

[0135] Transistor 282 is coupled between the adjustable LDO 286 and node 320. Specifically, the source of transistor 282 is coupled to the output of the adjustable LDO 286, and the drain of transistor 282 is coupled to node 320. The gate of transistor 282 is coupled to node 312. Transistor 284 is coupled between node 320 and the ground rail 308. Specifically, the source of transistor 284 is coupled to the ground rail 308, and the drain of transistor 284 is coupled to node 320. The gate of transistor 284 is coupled to node 314.

[0136] Switch 288 is coupled between node 312 and node 324. Switch 290 is coupled between node 312 and node 316. Switch 292 is coupled between node 316 and node 318. Switch 294 is coupled between node 316 and node 314. Switch 296 is coupled between node 314 and node 326. Bias resistor 298 is coupled between node 318 and node 320. Bias resistor 300 is coupled between node 322 and node 324. Bias resistor 302 is coupled between node 326 and node 328. Capacitor 304 is coupled between node 310 and node 312. Capacitor 306 is coupled between node 310 and node 314. Node 322 is connected to the first bias voltage source (V_BIAS_P), and node 328 is connected to the second bias voltage source (V_BIAS_N).

[0137] When switches 290, 292, and 294 are closed, transistors 282, 284, and bias resistor 298 form a self-bias amplifier (e.g., a self-bias inverter). Node 310 may form an input to amplifier stage 280, and node 320 may form an output to amplifier stage 280.

[0138] As shown in Figure 14, the amplifier stage 280 includes (1) an inverter having transistors 282 and 284, (2) a bias resistor 298 coupled to the output of the inverter (e.g., node 320), (3) a first bias voltage source (V_BIAS_P), (4) a second bias voltage source (V_BIAS_N), (5) a switch 290 coupled between the bias resistor 298 and the gate of transistor 282, (6) a switch 288 coupled between the first bias voltage source (V_BIAS_P) and the gate of transistor 282, (7) a switch 294 coupled between the bias resistor 298 and the gate of transistor 284, and (8) a switch 296 coupled between the second bias voltage source (V_BIAS_N) and the gate of transistor 284. The amplifier stage 280 may include a control unit (not shown) coupled to switches 288, 290, 292, 294, and 296, and configured to switch the amplifier stage 280 between a self-biased operating mode and a nonlinear operating mode.

[0139] During self-bias operation mode, switches 290, 292, and 294 are closed, and switches 288 and 296 are open. Bias resistor 298 biases the inverter formed by transistors 282 and 284 with a voltage approximately midway between the voltage output by the adjustable LDO 286 and ground. Capacitors 304 and 306 filter out DC and other frequency signal components received at node 310. The amplifier formed by transistors 282 and 284 amplifies the filtered input signal received at nodes 312 and 314, and outputs the amplified signal at node 320.

[0140] During the nonlinear operating mode, switches 290, 292, and 294 are open, and switches 288 and 296 are closed. A first bias voltage source (V_BIAS_P) biases transistor 282 via bias resistor 300. A second bias voltage source (V_BIAS_N) biases transistor 284 via bias resistor 302. Capacitors 304 and 306 filter out DC and other frequency signal components received at node 310. The amplifier formed by transistors 282 and 284 amplifies the filtered input signal received at nodes 312 and 314, and outputs the amplified signal at node 320.

[0141] As described above, the amplifier stage 280 can operate in self-bias mode or nonlinear mode depending on the configuration of switches 288, 290, 292, 294, and 296. The self-bias mode may provide a greater degree of linearity than the nonlinear mode, but the power efficiency may be lower. On the other hand, the nonlinear mode may provide a greater power efficiency, but the linearity may be lower. By providing an amplifier stage that can be configured to operate in self-bias mode and nonlinear mode, the trade-off between linearity and power efficiency can be dynamically adjusted and balanced in the amplifier.

[0142] Figure 15 is a schematic diagram illustrating another exemplary amplifier stage 330 that may be used in the power amplifier of the present disclosure. Amplifier stage 330 is similar to amplifier stage 230 illustrated in Figure 13, except that (1) resistors 242, 244, 246, 248 and adjustable resistors 254, 256 are omitted, and (2) transistors 232, 234 and transistors 236, 238 are coupled to separately adjustable LDOs 240. The same or similar components are given the same reference numerals between Figure 13 and Figure 15. As shown in Figure 15, the source of transistor 232 is directly coupled to the first output of the adjustable LDO 240 without intervening resistors, and the source of transistor 236 is directly coupled to the second output of the adjustable LDO 240 without intervening resistors.

[0143] Figure 16 is a block diagram illustrating another exemplary transmitter 340 in accordance with this disclosure. Transmitter 340 is similar to transmitter 10 shown in Figure 4, except that transmitter 340 in Figure 16 includes a coarse gain control circuit 342 instead of a selection circuit 60. The same or similar components are given the same reference numerals between Figure 4 and Figure 16.

[0144] The first input of the Coarse gain control circuit 342 is coupled to the first output of the oscillator 12 via connection 20. The second input of the Coarse gain control circuit 342 is coupled to the second output of the oscillator 12 via connection 22. The output of the Coarse gain control circuit 342 is coupled to the input of the amplifier stage 62 via connection 70. The control input of the Coarse gain control circuit 342 is coupled to the gain control A lead 78.

[0145] The coarse gain control circuit 342 may include one or more passive attenuation circuits (e.g., reactive components) configured to attenuate signals received through connections 20, 22. The passive attenuation circuits may include capacitive attenuation circuits and / or inductive attenuation circuits. The passive attenuation circuits may be variable gain passive attenuation circuits (e.g., a network of reactive components with multiple taps) in which the level of gain or attenuation of the circuit can be varied (e.g., by selecting different combinations of taps to produce an output signal). Exemplary capacitive attenuation circuits are illustrated in Figures 10 and 12. Exemplary inductive attenuation circuits are illustrated in Figures 6, 8, and 9.

[0146] The Coarse gain control circuit 342 may select one of the signals received via connections 20 and 22 and attenuate the signal using one or more passive attenuation circuits to generate an attenuated signal at connection 70. The Coarse gain control circuit 342 may decide which signal to select based on a gain control A signal. If the passive attenuation circuit is a variable gain passive attenuation circuit, the Coarse gain control circuit 342 may decide, based on the gain control A signal, how much the passive attenuation circuit should attenuate the signal. In some examples, the gain control A signal may include a first component that determines which signal to select and a second component that determines the amount by which the passive attenuator attenuates the signal.

[0147] Figure 17 is a block diagram illustrating another exemplary transmitter 350 in accordance with the present disclosure. Transmitter 350 may be similar to transmitter 340 shown in Figure 16, except that (1) the transmitter 350 in Figure 17 includes a single-input coarse gain control circuit 352 instead of the dual-input coarse gain control circuit 342 shown in Figure 16, and (2) the oscillator 12 is a single-output oscillator 12. The same or similar components are given the same reference numerals between Figure 16 and Figure 17.

[0148] The input of the Coarse gain control circuit 352 is coupled to the output of the oscillator 12 via connection 354. The output of the Coarse gain control circuit 352 is coupled to the input of the amplifier stage 62 via connection 70. The control input of the Coarse gain control circuit 352 is coupled to the gain control A lead 78.

[0149] The coarse gain control circuit 352 may include one or more passive attenuation circuits (e.g., reactive components) configured to attenuate the signal received via connection 354. The passive attenuation circuits may include any of the passive attenuation circuits described above in relation to the coarse gain control circuit 342 in Figure 16.

[0150] The Coarse gain control circuit 352 may attenuate the signal received via connection 354 using one or more passive attenuation circuits in order to generate an attenuated signal at connection 70. If the passive attenuation circuit is a variable gain passive attenuation circuit, the Coarse gain control circuit 352 may determine how much the passive attenuation circuit should attenuate the signal based on the gain control A signal.

[0151] Figure 17 illustrates the overall transmitter architecture. The Coarse gain control circuit 352 may be a tapped inductor, a capacitive attenuator, or a bypass. In some examples, the elements of the Coarse gain control circuit 352 may not provide any degradation of VCO phase noise. In some examples, the amplifier stages 62 and 64 may use self-biased amplifiers to engage substantially all of the current consumption for signal processing and amplification. The control circuit may program the output signal swing of the amplifier stages 62 and 64 by varying the power supply from LDOs (e.g., adjustable power supplies 66 and 68). The control circuit may program each stage of the amplifier stages 62 and 64 with the corresponding LDOs so that the control circuit covers a wide programming range for output power. Power savings may be achieved by programming the LDOs to relatively desirable operating points to improve power consumption. For example, the Coarse gain control circuit 352 may provide attenuation to the VCO signal, and then the LDO setting may be further reduced to process signals with significantly smaller amplitudes. Each LDO may, in some examples, utilize a replica circuit to obtain a reference voltage for the PA structure. Similar principles may be applied to other amplifier architectures of this disclosure.

[0152] In some examples, the coarse gain control circuit 352 can be implemented at least partially by using (a) capacitive attenuation from the VCO capacitor array, (b) tapped inductors by using symmetric tapping points from the VCO inductors, or (c) a simple bypass.

[0153] Figure 18 is a block diagram illustrating another exemplary transmitter 360 in accordance with this disclosure. Transmitter 360 may be similar to transmitter 10 shown in Figure 5, except that transmitter 360 in Figure 18 further includes coarse gain control circuits 362, 364 and gain control leads 366, 368. The same or similar components are given the same reference numerals between Figure 5 and Figure 18.

[0154] The input of the Coarse gain control circuit 362 is coupled to the first output of the oscillator 12 via connection 20. The input of the Coarse gain control circuit 364 is coupled to the second output of the oscillator 12 via connection 22. The output of the Coarse gain control circuit 362 is coupled to the input of the amplifier stage 84 via lead 370. The output of the Coarse gain control circuit 364 is coupled to the input of the amplifier stage 88 via lead 372. The control input of the Coarse gain control circuit 362 is coupled to the gain control lead D366. The control input of the Coarse gain control circuit 364 is coupled to the gain control lead E368.

[0155] The coarse gain control circuits 362, 364 may include one or more passive attenuation circuits (e.g., reactive components) configured to attenuate signals received via connections 20, 22. The passive attenuation circuits may include any of the passive attenuation circuits described above with respect to the coarse gain control circuit 342 in Figure 16.

[0156] The Coarse gain control circuit 362 may attenuate the signal received via connection 20 using one or more passive attenuation circuits and output the attenuated signal at lead 370. If the passive attenuation circuit is a variable gain passive attenuation circuit, the Coarse gain control circuit 362 may determine how much the passive attenuation circuit should attenuate the signal based on a gain control signal received via gain control lead D366.

[0157] The Coarse gain control circuit 364 may attenuate the signal received via connection 22 using one or more passive attenuation circuits and output the attenuated signal at lead 372. If the passive attenuation circuit is a variable gain passive attenuation circuit, the Coarse gain control circuit 364 may determine how much the passive attenuation circuit should attenuate the signal based on a gain control signal received via gain control lead E368.

[0158] Figure 19 is a block diagram illustrating another exemplary transmitter 380 in accordance with this disclosure. Transmitter 380 may be similar to transmitter 360 shown in Figure 18, except that (1) transmitter 380 in Figure 19 includes a single input power amplifier 14 instead of the dual input power amplifier 14 shown in Figure 18, (2) oscillator 12 is a single output oscillator 12, and (3) both inputs of coarse gain control circuits 362, 364 are coupled to a single output of oscillator 12 via connection 382. The same or similar components are given the same reference numerals between Figure 18 and Figure 19.

[0159] Figure 20 is a block diagram illustrating another exemplary transmitter 390 in accordance with this disclosure. Transmitter 390 may be similar to transmitter 10 shown in Figure 4, except that (1) the selection circuit 60 and gain control A lead 78 are omitted from the power amplifier 14 in Figure 20, and (2) the input of the amplifier stage 62 is directly coupled to the output of the oscillator 12 via connection 392. The same or similar components are given the same reference numerals between Figure 4 and Figure 20.

[0160] For example, as shown in Figures 4 and 20, the power amplifier 14 includes (1) an amplifier stage 62 having inputs and outputs, (2) an amplifier stage 64 having an input coupled to the output of amplifier stage 62, and (3) an output. The power amplifier 14 further includes (1) a first adjustable power supply (e.g., an adjustable power supply 66) coupled to amplifier stage 62, and (2) a second adjustable power supply (e.g., an adjustable power supply 68) coupled to amplifier stage 64. In some examples, the first and second adjustable power supplies may be programmable LDOs and / or adjustable LDOs.

[0161] In some examples, the integrated circuit includes a voltage-controlled oscillator (VCO) (e.g., oscillator 12) having one or more reactive components (e.g., a reactive component network 34). The integrated circuit further includes a programmable passive attenuation circuit (e.g., a reactive component network 34, a selection circuit 60, a reactive component and switching circuit 156, a coarse gain control circuit 342, a coarse gain control circuit 352, a coarse gain control circuit 362, 364) coupled to the VCO. The programmable passive attenuation circuit includes at least some of the one or more reactive components (e.g., a reactive component network 34) included in the VCO. The integrated circuit further includes a power amplifier (e.g., a power amplifier 14) coupled to the programmable passive attenuation circuit.

[0162] In some examples, the programmable passive attenuation circuit is an inductive attenuator. In such examples, one or more reactive components may include one or more tapped inductors. In further examples, the programmable passive attenuation circuit forms a capacitive attenuator. In such examples, one or more reactive components may include one or more capacitors.

[0163] In some examples, the power amplifier includes a first power source, a second power source, a first amplifier stage coupled to the first power source, and a second amplifier stage coupled to the second power source. In such examples, the first and second power sources may be programmable power sources, such as programmable LDOs.

[0164] Figure 21 is a flowchart illustrating an exemplary method for amplifying the power of a signal according to this disclosure. The method shown in Figure 21 can be implemented in many of the circuits described in this disclosure. For the purposes of this explanation, the method will be described with respect to the transmitter 10 shown in Figure 3.

[0165] The oscillator 12 generates a first oscillatory signal (400) using the reactive component network 34 included in the oscillator 12 and outputs the first oscillatory signal via leads 42 and 56. The oscillator 12 outputs a second oscillatory signal (402) via one or more taps (e.g., taps 40 and 54) included in the reactive component network 34. The second oscillatory signal is proportional to the first oscillatory signal and has a smaller magnitude than the first oscillatory signal.

[0166] The power amplifier 14 selects one of the first and second oscillator signals based on gain control for use in generating a power-amplified output signal (404). The power amplifier 14 generates a power-amplified output signal based on the selected one of the first and second oscillator signals (406).

[0167] In some examples (e.g., Figure 4), the power amplifier 14 may select one of a first and a second vibration signal to generate a selected vibration signal, and may amplify the selected vibration signal to generate a power-amplified output signal. In such examples, the power amplifier 14 may amplify the selected vibration signal using a gain determined by an adjustable low-dropout regulator (LDO).

[0168] In a further example (e.g., Figure 5), the power amplifier 14 may amplify a first oscillatory signal to generate a first power-amplified signal, amplify a second oscillatory signal to generate a second power-amplified signal, select one of the first or second power-amplified signals to generate a selected power-amplified signal, and output the selected power-amplified signal as a power-amplified output signal. In such an example, the power amplifier 14 may, in some cases, amplify a first oscillatory signal using a gain determined by an adjustable low-dropout regulator (LDO), and amplify a second oscillatory signal using a gain determined by an adjustable LDO.

[0169] This disclosure describes various power amplifier configurations that can be used to implement low-power power amplifier (PA) architectures for low-power radio. The methods of this disclosure can provide architectures that realize low-power, high-efficiency power amplifiers with a reduced number of external components to save on the external bill of materials. The low-power PAs described in this disclosure may, in some examples, have (a) high efficiency, (b) low out-of-band harmonic content, and (c) gain control. These characteristics can, in some examples, be achieved with relatively low current consumption. This disclosure provides various self-biased transmit PA (TXPA) configurations. The PA architectures described in this disclosure may, in some examples, provide a relatively low-area implementation scheme for gain control.

[0170] In some examples, the architecture of the power amplifier 14 may be a multi-stage architecture. In some examples, the first stage of the multi-stage architecture (e.g., amplifier stage 62) may correspond to amplifier stage 230 shown in Figure 13. In such examples, the architecture used for the second stage (e.g., amplifier stage 64) may use the same configuration as in Figure 13, but without resistors 242, 244, 246, 248 and adjustable resistors 254, 256 (i.e., the resistance of those resistors is equal to 0). In this way, the second amplifier stage may be configured as either a single-ended or differential amplifier, depending on the properties of the external components (single-ended or differential, respectively).

[0171] To further increase efficiency, the second amplifier stage may include a programmable gate bias in addition to an adjustable LDO to enhance efficiency, as shown in Figure 14. The switch can be implemented in some examples by using the smallest possible size metal oxide semiconductor (MOS) transistors. The amplifier stage 280 in Figure 14 can be configured in two different modes: (a) a self-biased Class AB architecture mode, and (b) a nonlinear type amplifier mode.

[0172] To configure the amplifier stage 280 in a self-biased Class AB architecture mode, the control circuit can close switches 290, 292, and 294 and open switches 288 and 296. In this case, self-biasing is made possible via bias resistor 298, and the adjustable LDO 286 can be programmed to provide increased efficiency and linearity as desired.

[0173] To configure amplifier stage 280 in a self-biased Class AB architecture mode, the control circuit can open switches 290, 292, and 294, close switches 288 and 296, and individually bias each transistor via separate bias voltage sources (V_BIAS_P, V_BIAS_N). The output of amplifier stage 280 can be monitored using built-in calibration to ensure that the DC level at the output is approximately in the middle of the voltage range.

[0174] Figure 22 is a schematic diagram illustrating an exemplary reactive component network 410 that may be used in an exemplary oscillator of this disclosure. The reactive component network 410 includes inductors L16, L17, L18, L19, L20, L21, and nodes 412, 414, 416, 418, 420, 422, 424, and 426.

[0175] Inductor L16 is coupled between node 412 and node 414. Inductor L17 is coupled between node 414 and node 416. Inductor L18 is coupled between node 416 and node 418. Inductor L19 is coupled between node 420 and node 422. Inductor L20 is coupled between node 422 and node 424. Inductor L21 is coupled between node 424 and node 426. Taps may be coupled to one or more nodes 412, 414, 416, 418, 420, 422, 424, and 426.

[0176] Inductor L16 is magnetically coupled to inductor L19. Inductor L17 is magnetically coupled to inductor L20. Inductor L18 is magnetically coupled to inductor L21. In some examples, inductors L16 and L19 may be transformers, inductors L17 and L20 may be transformers, and / or inductors L18 and L21 may be transformers.

[0177] Taps coupled to nodes 412 and 414 may form a first differential output (VCO+, VCO-). Taps coupled to nodes 414 and 416 may form a second differential output (PA1+, PA1-). Taps coupled to nodes 420 and 426 may form a third differential output (PA2+, PA2-). Taps coupled to nodes 422 and 424 may form a fourth differential output (PA3+, PA3-). One or more of these differential outputs may be coupled to the corresponding inputs of a power amplifier.

[0178] In some examples, nodes 420 and 426 may correspond to nodes 36 and 38 in Figures 2 and 3, respectively. In further examples, nodes 412 and 414 may correspond to nodes 36 and 38 in Figures 2 and 3, respectively.

[0179] In some examples, the reactive component network 410 may correspond to the reactive component network 34 shown in Figures 2 and 3. In such examples, the reactive component network 410 may include at least two chains of one or more reactive components, each chain of reactive components including one or more reactive components coupled in series (e.g., a first chain formed by inductors L16, L17, L18, and a second chain formed by inductors L19, L20, L21). The at least two chains of reactive components may be inductively (or magnetically) coupled to one another. For example, one or more reactive components in the first chain of reactive components may be inductively (or magnetically) coupled to one or more reactive components in the second chain of reactive components. One or more taps may be coupled to the first chain of reactive components and / or the second chain of reactive components so as to form one or more differential outputs.

[0180] In some examples, a first chain of reactive components may be electrically coupled to an active circuit element of an oscillator, and a second chain of reactive components may be inductively coupled to the first chain of reactive components. In some implementations of this example, a first differential output may be formed via a tap coupled to the first chain of reactive components, and a second differential output may be formed via a tap coupled to the second chain of reactive components. In further implementations of this example, at least two differential outputs may be formed via taps coupled to the first chain of reactive components. In an additional implementation of the first example, at least two differential outputs may be formed via taps coupled to the second chain of reactive components.

[0181] In some examples, the inductances of inductors L162 and L18 may be equal to each other, and the inductances of inductors L19, L20, and L21 may be equal to each other. In additional examples, the inductance of inductor L17 may be equal to a first inductance value, the inductances of inductors L16 and L18 may each be equal to a second inductance value, and the inductances of inductors L19, L20, and L21 may each be equal to a third inductance value.

[0182] A reactive component network can be formed using one or both of tapped inductors (with direct electrical coupling) and magnetic coupling (DC isolation). The reactive component network may use tapping from one or more coils (inductors) to produce different outputs with different levels of attenuation. Magnetic coupling may implement a fixed (coarse) step attenuator.

[0183] In some examples, coarse-step attenuation in the reactive components of this disclosure can be process-invariant, given that the amount of attenuation may correspond to a ratio between two similar quantities that are process-invariant. In further examples, coarse-step attenuation may provide frequency-independent signal scaling. For example, if a VCO oscillates between 2.4 GHz and 3.0 GHz, the coarse-gain control technique of this disclosure provides the same signal attenuation in such an example.

[0184] Figure 23 is a schematic diagram illustrating an exemplary reactive component network 430 that may be used in an exemplary oscillator of this disclosure. The reactive component network 430 includes capacitors C15, C16, C17, and nodes 432, 434, 436, and 438.

[0185] Capacitor C15 is coupled between node 432 and node 434. Capacitor C16 is coupled between node 434 and node 436. Capacitor C17 is coupled between node 436 and node 438. Taps may be coupled to one or more of nodes 432, 434, 436, and 438.

[0186] Taps coupled to nodes 432 and 438 may form a first differential output (VCO+, VCO-). Taps coupled to nodes 434 and 436 may form a second differential output (PA+, PA-). Figure 23 illustrates a configuration in which tapping can be performed using multiple capacitors connected in series, and signals can be symmetrically extracted from the reactive component network to interface with a power amplifier.

[0187] In the example configuration shown in Figure 23, capacitors C15, C16, and C17 are all variable capacitances. In another example, all of capacitors C15, C16, and C17 may be fixed capacitances. Alternatively, some of capacitors C15, C16, and C17 may be variable capacitances, and some may be fixed capacitances. In some examples, the variable capacitances may be voltage-controlled. In some examples, the capacitances of capacitors C15 and C17 may be equal to each other, and the capacitance of capacitor C16 may be different from the capacitances of capacitors C15 and C17.

[0188] In an example where capacitors C15, C16, and C17 have fixed capacitances, the reactive component network 430 can provide a constant attenuation factor. In some implementations where capacitors C15, C16, and C17 are voltage-controlled variable capacitances, all of capacitors C15, C16, and C17 can be programmed by the same control voltage, in which case a constant attenuation can be achieved, and the center frequency of the VCO can be varied by the same set of capacitors. In an additional implementation where capacitors C15, C16, and C17 are voltage-controlled variable capacitances, capacitors C15, C16, and C17 can be programmed for different voltages. For example, the capacitance (C0) of capacitors C15 and C17 can be programmed by a first voltage (V0), and the capacitance (C1) of capacitor C16 can be programmed by a second voltage (V1). In such an implementation, both C0 and C1 may be involved in frequency control, and by changing V0 in a manner different from V1, a variable attenuator step (fine control in addition to coarse gain control) can be achieved.

[0189] Ultra-low power transceivers may utilize low-power PAs with multiple gain steps to reduce overall system power. It is desirable to implement such receivers using a minimum number of external components.

[0190] This disclosure describes various techniques for achieving low-power PAs in several examples. According to the first technique, a two-stage PA architecture in the Class AB style may be used for power amplification, with each stage being independently programmed via separate LDOs. According to the second technique, a coarse gain step may be obtained using a capacitive attenuator, and a fine gain step may be provided via an LDO. This technique may simplify the design of the gain steps. According to the third technique, a coarse gain step may be obtained using a tapped inductor (e.g., an automatic transformer). In some cases, a tapped inductor may consume no additional power or area. A fine gain step may be performed using an LDO.

[0191] In some cases, due to the coarse gain step provided by tapped inductors and / or capacitive attenuators, the LDO may not need to cover the entire range of the gain step. This can reduce power consumption and the resulting amplifier area. In some examples, on-chip calibration techniques for frequency drift may be used to compensate for the finite isolation provided to the VCO by a two-stage PA.

[0192] In some examples, coarse gain control and fine gain control can be provided by programmable LDOs. In further examples, coarse gain control can be provided using capacitive attenuators, and fine gain control can be provided using LDOs. In additional examples, coarse gain control can be provided using automatic transformers, and fine gain control can be provided using LDOs.

[0193] In some examples, the methods of this disclosure may utilize a Class AB PA architecture. This may enable operation using only one radio frequency (RF) pin and fewer external components in some examples. In some examples, degeneration is not used, thereby reducing current consumption and improving power efficiency. In further examples, various stages may be self-biased using a relatively simple design, and the gain may be fully controlled by an LDO. In additional examples, the gain step may be achieved by one or more of the following: (1) fully by LDO control (both coarse and fine), (2) partially by a capacitive attenuator (coarse step using a capacitive attenuator, fine step using an LDO), and (3) partially by inductor tapping (coarse step using an automatic transformer, fine step using an LDO).

[0194] In some examples, the amplifier stage may be self-biased, thereby enabling biasing without any additional overhead in terms of bias current. In further examples, the gain step may be implemented using (1) LDOs only, (2) LDOs and capacitive attenuators, or (3) LDOs and tapped inductors. In additional examples, the method of this disclosure may use two stages with independent LDOs, thereby allowing the architecture to be reconfigured in terms of efficiency and harmonic performance. In further examples, the method of this disclosure may use a relatively small number of amplifier stages for even lower power consumption. If a VCO frequency shift occurs as a result of the gain change, a calibration engine may be enabled.

[0195] The techniques and circuit elements described herein may, in some examples, be implemented on any combination of one or more integrated circuits and other devices. Modifications are possible within the described embodiments within the scope of the claims of the present invention, and other embodiments are also possible.

Claims

1. It is an integrated circuit, A first coarse gain control circuit having a first coarse gain input, a first coarse gain output, and a first coarse gain control input, the first coarse gain control circuit including a set of first passive devices, A second coarse gain control circuit having a second coarse gain input, a second coarse gain output, and a second coarse gain control input, the second coarse gain control circuit comprising a set of second passive devices, The first amplifier stage, A first amplifier having a first amplifier gain control input, a first amplifier input coupled to the first coarse gain output, and a first amplifier output, A second amplifier having a second amplifier gain control input, a second amplifier input coupled to the second coarse gain output, and a second amplifier output, The first amplifier stage includes, The second amplifier stage, A third amplifier having a third amplifier gain control input, a third amplifier input coupled to the output of the first amplifier, and a third amplifier output, A fourth amplifier having a fourth amplifier gain control input, a fourth amplifier input coupled to the second amplifier output, and a fourth amplifier output, The second amplifier stage includes, An oscillator configured to provide a first oscillation signal to the first coarse-gain control circuit and a second oscillation signal to the second coarse-gain control circuit, Includes, An integrated circuit in which the first set of passive devices includes either a network of multiple inductors and capacitors coupled in series.

2. The integrated circuit according to claim 1, The first amplifier stage further includes a first power supply having a first power input and a first power output coupled to the first amplifier gain control input and the second amplifier gain control input, An integrated circuit further comprising a second power supply having a second power supply input and a second power supply output coupled to the third amplifier gain control input and the fourth amplifier gain control input.

3. The integrated circuit according to claim 2, An integrated circuit in which the first power supply and the second power supply are each low-dropout regulators.

4. The integrated circuit according to claim 1, An integrated circuit further comprising an oscillator configured to provide a single output signal to the first coarse-gain input and the second coarse-gain input.

5. The integrated circuit according to claim 1, The first set of passive devices includes a plurality of inductors coupled in series, The aforementioned multiple inductors A first inductor having a first terminal and a second terminal, A second inductor having a third terminal connected to the second terminal and a fourth terminal, A third inductor having a fifth terminal connected to the fourth terminal and a sixth terminal, A fourth inductor having a seventh terminal connected to the sixth terminal and an eighth terminal, A fifth inductor having a ninth terminal connected to the eighth terminal and a tenth terminal, A sixth inductor having an eleventh terminal and a twelfth terminal coupled to the tenth terminal, An integrated circuit, including

6. The integrated circuit according to claim 5, An integrated circuit in which, based on a coarse gain control signal received on the first coarse gain control input, one of the second, fourth, sixth, eighth, tenth, and twelfth terminals is coupled to the first coarse gain output.

7. The integrated circuit according to claim 6, The coarse gain control signal includes a plurality of components, and the plurality of components include a first component that indicates the amount of attenuation. An integrated circuit in which, based on the first component, the first coarse-gain control circuit is configured to select one of the second, fourth, sixth, eighth, and twelfth terminals to couple to the first coarse-gain output.

8. The integrated circuit according to claim 3, The first set of passive devices includes the network of capacitors, The capacitor network described above A first capacitor having a first terminal and a second terminal, A second capacitor having a third terminal connected to the second terminal and a fourth terminal, A third capacitor having a fifth terminal and a sixth terminal, A fourth capacitor having a seventh terminal connected to the sixth terminal and an eighth terminal, A fifth capacitor having a ninth terminal connected to the second terminal and the third terminal, and a tenth terminal connected to the first switch terminal of the first switch, A sixth capacitor having an eleventh terminal connected to the second switch terminal of the first switch, and a twelfth terminal connected to the sixth terminal and the seventh terminal, A seventh capacitor having a thirteenth terminal connected to the fourth terminal and a fourteenth terminal connected to the third switch terminal of the second switch, An eighth capacitor having a 15th terminal connected to the fourth switch terminal of the second switch and a 16th terminal connected to the eighth terminal, An integrated circuit, including

9. The integrated circuit according to claim 8, The system further includes an oscillator configured to provide a single output signal to the first terminal, An integrated circuit in which, based on a first coarse-gain control signal received on the first coarse-gain control input, one of the second, third, fourth, sixth, and eighth terminals is coupled to the first coarse-gain output.

10. The integrated circuit according to claim 9, The first coarse-gain control signal includes a plurality of components, and the plurality of components include a first component that indicates the amount of attenuation. An integrated circuit in which, based on the first component, the first coarse-gain control circuit is configured to select one of the second, third, fourth, sixth, and eighth terminals to couple to the first coarse-gain output.

11. The integrated circuit according to claim 1, An integrated circuit further comprising a harmonic network of transmitters coupled to the second amplifier stage.

12. A transmitter circuit, An oscillator having first and second oscillator outputs, configured to output a first oscillation signal to the first oscillator output and a second oscillation signal to the second oscillator output, A first coarse gain control circuit having a first coarse gain circuit input coupled to the output of the first oscillator, a first gain control input configured to receive a first gain control signal, and a first coarse gain circuit output configured to output a first output signal, the first coarse gain control circuit comprising a set of first passive devices, configured to adjust the first oscillation signal based on the first gain control signal, A second coarse gain control circuit having a second coarse gain circuit input coupled to the second oscillator output, a second gain control input configured to receive a second gain control signal, and a second coarse gain circuit output configured to output a second output signal, the second coarse gain control circuit comprising a set of second passive devices configured to adjust the second oscillation signal based on the second gain control signal, The first amplifier stage, A first amplifier having a first amplifier input coupled to the output of the first coarse-gain circuit, a first amplifier output, and a third gain control input, A second amplifier having a second amplifier input coupled to the output of the second coarse-gain circuit, a second amplifier output, and a fourth gain control input, A first voltage source having a first voltage input configured to receive a third gain control signal, and a first voltage output coupled to the third gain control input and the fourth gain control input, The first amplifier stage includes, Includes, A transmitter circuit in which the first set of passive devices includes a plurality of inductors coupled in series, and the first set of passive devices is configured to regulate the first oscillation signal to generate the first output signal.

13. A transmitter circuit according to claim 12, The second amplifier stage, A third amplifier having a third amplifier input coupled to the output of the first amplifier, a third amplifier output, and a fifth gain control input, A fourth amplifier having a fourth amplifier input coupled to the second amplifier output, a fourth amplifier output, and a sixth gain control input, A second voltage source having a second voltage input configured to receive a fourth gain control signal, and a second voltage output coupled to the fifth gain control input and the sixth gain control input, A transmitter circuit further comprising the second amplifier stage, which includes the following.

14. A transmitter circuit according to claim 12, The oscillator, A first transistor having a first control input, a first current terminal, and a second current terminal, A second transistor having a second control input connected to the first current terminal, a third current terminal connected to the first control input, and a fourth current terminal connected to the second current terminal, A transmitter circuit, including the transmitter circuit.

15. A transmitter circuit according to claim 12, The first gain control signal indicates the amount of attenuation. A transmitter circuit in which the first coarse-gain control circuit is further configured to attenuate the first oscillation signal based on the amount of attenuation.

16. A transmitter circuit according to claim 12, The set of the second passive devices is A first capacitor having a first terminal and a second terminal, A second capacitor having a third terminal connected to the second terminal and a fourth terminal, A third capacitor having a fifth terminal and a sixth terminal, A fourth capacitor having a seventh terminal connected to the sixth terminal and an eighth terminal, A fifth capacitor having a ninth terminal connected to the second terminal and the third terminal, and a tenth terminal connected to the first switch terminal of the first switch, A sixth capacitor having an eleventh terminal connected to the second switch terminal of the first switch, and a twelfth terminal connected to the sixth terminal and the seventh terminal, A seventh capacitor having a thirteenth terminal connected to the fourth terminal and a fourteenth terminal connected to the third switch terminal of the second switch, An eighth capacitor having a 15th terminal connected to the fourth switch terminal of the second switch and a 16th terminal connected to the eighth terminal, A transmitter circuit, including the transmitter circuit.

17. A transmitter circuit according to claim 12, The set of the first passive devices is A first inductor having a first terminal and a second terminal, A second inductor having a third terminal connected to the second terminal and a fourth terminal, A third inductor having a fifth terminal connected to the fourth terminal and a sixth terminal, A fourth inductor having a seventh terminal connected to the sixth terminal and an eighth terminal, A fifth inductor having a ninth terminal connected to the eighth terminal and a tenth terminal, A sixth inductor having an eleventh terminal and a twelfth terminal coupled to the tenth terminal, A transmitter circuit, including the transmitter circuit.

18. A transmitter circuit, An oscillator configured to output a first oscillation signal to the output of a first oscillator and a second oscillation signal to the output of a second oscillator, A first coarse gain control circuit having a first coarse gain circuit input coupled to the output of the first oscillator, a first gain control input configured to receive a first gain control signal, and a first coarse gain circuit output configured to output a first output signal, the first coarse gain control circuit comprising a set of first passive devices, configured to adjust the first oscillation signal based on the first gain control signal, A second coarse gain control circuit having a second coarse gain circuit input coupled to the second oscillator output, a second coarse gain control input configured to receive a second gain control signal, and a second coarse gain circuit output configured to output a second output signal, the second coarse gain control circuit comprising a set of second passive devices configured to adjust the second oscillation signal based on the second gain control signal, The first amplifier stage, A first amplifier having a first amplifier input coupled to the output of the first coarse-gain circuit, a first amplifier output, and a first gain control input, A second amplifier having a second amplifier input coupled to the output of the second coarse-gain circuit, a second amplifier output, and a second gain control input, A first voltage source having a first voltage input configured to receive a third gain control signal, and a first voltage output coupled to the first gain control input and the second gain control input, The first amplifier stage includes, Includes, A transmitter circuit comprising a first set of passive devices configured to regulate the first oscillation signal to generate the first output signal, and a second set of passive devices comprising a plurality of capacitors.

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