Open-loop digital pwm envelope tracking system with dynamic boost function

Abstract

The present disclosure is an open-loop digital PWM envelope tracking system with dynamic boost function. Systems, apparatuses, and methods are described for dynamically boosting (increasing) the supply voltage of an envelope tracking (ET) modulator in a transmitter system when the target / desired PA supply voltage exceeds a pre-determined threshold (e.g., the pre-determined threshold is equal to the available supply voltage of the system, such as the battery voltage). By boosting the supply voltage input to the ET modulator, the modulated supply provided to the power amplifier (PA) is also increased. As such, voltage clipping, which typically occurs when the target / desired PA supply voltage is higher than the available supply voltage, is mitigated or avoided, and the distortion of the transmitted signal is reduced.

Description

[0001] Related applications cross-application

[0002] This application claims priority to U.S. Nonprovisional Patent Application No. 14 / 677,288, filed April 2, 2015, entitled "Open Loop Digital PWM Envelope Tracking System with Dynamic Boosting," the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to wireless communication, and more particularly, to a wireless transmitter having a power amplifier and an envelope tracking modulator. Background Technology

[0004] In wireless communication terminals such as mobile phones, modulating the power amplifier (PA) voltage by tracking the envelope of the transmitted signal can make the PA operate more efficiently, thereby reducing power consumption. This technique is called envelope tracking (ET). The circuit / component that modulates the power supply voltage of the input PA in such a system is called an ET modulator.

[0005] In most mobile applications (e.g., mobile phones), the operating power supply voltage is provided by the battery and modulated by an ET modulator. The modulated power supply voltage is then input to the power amplifier (PA). In some applications, the required PA power supply voltage may be higher than the available battery voltage. Typically, the transmitter's output power is at its maximum when the required PA power supply voltage is higher than the available battery voltage. During this period, the ET modulator may only output the modulated power supply voltage, which is equal to (or less than) the battery voltage. This results in the PA power supply voltage being truncated. This truncation leads to significant distortion, degrading the transmitted signal as adjacent channel power rejection (ACPR) attenuation and error vector magnitude (EVM) degradation.

[0006] Therefore, circuits, systems, and methods are needed to mitigate the cutoff of the power supply voltage at the input PA of the ET modulator, thereby improving the performance of the transmitter. Summary of the Invention

[0007] According to the present application, a transmitter having an envelope generator for receiving a data signal to be transmitted and generating an envelope signal based on the received data signal is provided. A pulse width modulation (PWM) generator is coupled to the envelope generator for outputting a PWM signal to an envelope tracking (ET) modulator coupled to the PWM generator. The ET modulator is configured to receive the PWM signal and output a power amplifier (PA) switching power supply, and to receive a first supply voltage or a second supply voltage in response to an ET modulator boost enable signal, wherein the second supply voltage is higher than the first supply voltage.

[0008] In another embodiment, a method for dynamically boosting a supply voltage of a power amplifier (PA) in an input transmitter is provided, the transmitter comprising an envelope signal generator and an envelope tracking (ET) modulator. The method comprises receiving a first signal indicative of a voltage level of an available supply voltage of the transmitter; receiving an envelope signal output by the envelope signal generator, the envelope signal being generated in response to a data signal to be transmitted; comparing the envelope signal and the first signal; (1) when the envelope signal is less than a preset threshold based on the first signal, inputting the available supply voltage to the ET modulator; (2) when the envelope signal is greater than the preset threshold based on the first signal, inputting a boosted supply voltage to the ET modulator.

[0009] In yet another embodiment, a transmitter comprising a power supply terminal for providing an available supply voltage from an available power supply for use by the transmitter is provided. A boost circuit is coupled to the power supply terminal for generating a boosted supply voltage, the boosted supply voltage being higher than the available supply voltage. An envelope generator is configured to receive a data signal to be transmitted by the transmitter and generate an envelope signal for input to a pulse width modulation (PWM) generator, the PWM generator being configured to output a PWM signal. The transmitter further comprises an envelope tracking (ET) modulator coupled to the PWM generator, the ET modulator being configured to modulate an ET modulator input supply voltage. A controller is configured to receive the envelope signal and a signal indicative of the available supply voltage and generate a dynamic boost enable / disable signal therefrom. A switching circuit is coupled to the available supply voltage and the boosted supply voltage for selecting the available supply voltage or the boosted supply voltage to be input as the ET modulator input supply voltage. BRIEF DESCRIPTION OF DRAWINGS

[0010] For a more complete understanding of the present application, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings in which like numbers designate like objects, in which:

[0011] Figure 1 is a diagram illustrating part of the circuitry / components of a prior art transmitter system in a wireless communication terminal / device, the transmitter system comprising an envelope tracking (ET) system;

[0012] Figure 2 is a signal waveform illustrating a static primary supply voltage of an input ET modulator and a time-varying example supply voltage of a required power amplifier;

[0013] Figure 3 is a diagram illustrating relevant parts of a transmitter system according to the present application;

[0014] Figure 4 is a signal waveform illustrating a supply voltage of an input dynamic boost type ET modulator and a time-varying example supply voltage of a required power amplifier;

[0015] Figure 5 and Figure 6 shows a PWM generator and a V supply embodiment of voltage generation;

[0016] Figure 7 is a diagram illustrating the concept of pre-charging a boost supply voltage according to the present application;

[0017] Figure 8 shows different alternative embodiments of an ET modulator and an APT modulator according to the present application;

[0018] Figure 9 shows an exemplary wireless communication network comprising communication devices comprising transmitter systems according to the present application;

[0019] Figure 10 is another embodiment of an exemplary wireless communication network comprising communication devices comprising transmitter systems according to the present application;

[0020] Figure 11A and Figure 11B shows a block diagram of an exemplary device which can be used to implement transmitter systems and methods according to the present application;

[0021] Figure 12 shows a process 1400 of boosting the ET modulator supply voltage of a transmitter system in Figure 3 according to the present application. DETAILED DESCRIPTION

[0022] Envelop tracking power amplifiers and compensation systems for use with transmitters of wireless communication devices / terminals are described. Such wireless communication systems can operate in accordance with any protocol, standard or specification, including, for example, Global System for Mobile Communication (GSM), Code Division Multiple Access (CDMA), Universal Mobile Telecommunication System (UMTS), Worldwide Interoperability for Microwave Access (WiMAX), WiFi, and others well known to those skilled in the art.

[0023] For the sake of brevity, certain portions of communication devices / terminals and their transmitter systems, or aspects thereof, are omitted in this description, being understood to exist solely for the purposes of providing an enabling and full understanding of the present application.

[0024] Systems, apparatuses, and methods are described and disclosed for dynamically boosting (increasing) the supply voltage of an input ET modulator when the target / desired power amplifier (PA) supply voltage exceeds a predetermined threshold (e.g., is equal to the available supply voltage, such as a battery voltage). By boosting the supply voltage of the input ET modulator, the supply provided to the PA is also increased. In this way, voltage clipping, which typically occurs when the target / desired PA supply voltage is higher than the available supply voltage, is mitigated or avoided, and distortion of the transmitted signal is reduced.

[0025] In general, various circuits and methods are described for sensing / measuring / determining the available supply voltage powering the ET modulator and the target / desired PA supply voltage. When the target / desired PA supply voltage exceeds a predetermined threshold based on the available supply voltage, a boosted supply voltage is input to the ET modulator. In other words, the magnitude of the supply voltage input to the ET modulator is increased or boosted to a higher level. This is also referred to as dynamic boosting. In one embodiment, dynamic boosting is achieved by switching between the available supply voltage and a boosted supply voltage, where the boosted supply voltage is generated by a boost circuit based on the available supply voltage.

[0026] The mode controller receives two voltage values and determines whether the ET modulator receives an available supply voltage or a boosted supply voltage as an input voltage. The ET modulator operates in one of two modes: (1) a normal mode of operation: the available supply voltage is input to the ET modulator; and (2) a boosted mode of operation: the boosted supply voltage is input to the ET modulator. It is to be understood that the ET modulator (and various embodiments thereof) and related components described herein are part of a cellular terminal, device, or base station.

[0027] Reference is made to Figure 1 , Figure 1 FIG. 1 shows a block diagram of partial circuitry / components of a prior art transmitter system 100 in a wireless communication terminal / device. Although other circuitry / components can also be included in the transmitter system 100, only the portions necessary or relevant to understanding the present application are shown herein.

[0028] Figure 1 The main components shown include a digital baseband circuit 110, a transceiver 120, a power amplifier (PA) 130, and an envelope tracking (ET) and average power tracking (APT) modulator 140. The ET and APT modulator 140 includes an ET modulator 142 having a switch core for implementing the envelope tracking function, and an APT modulator 144 having a buck / boost circuit providing a switch core for implementing the APT function.

[0029] Within the digital baseband circuit 110, an IQ supply 111 provides an input signal (e.g., digital in-phase (ID) and quadrature (QD) components of a baseband signal, not shown separately) to a digital gain control circuit 112, which in turn provides a signal to a digital-to-analog converter (DAC) 113. The DAC 113 converts the ID and QD components into analog in-phase and quadrature signals for input to the transceiver 120. Figure 1

[0030] The transceiver 120 (which can include a receiver) converts the analog in-phase and quadrature signals into a radio frequency (RF) signal X. The RF signal X is input to the power amplifier (PA) 130 for amplification to generate an RF signal Y at a desired power level for transmission from an antenna (not shown) of the transmitter system 100.

[0031] ​The signals ID and QD (after gain control) are also input to an envelope generator 114 that generates an envelope waveform E of the transmission signal. The E signal is processed by a pre-distortion circuit 115 to apply pre-distortion. For a non-ideal ET modulator, the waveform E can be adjusted (pre-distorted) to compensate for the frequency response and non-linearity of the ET modulator 142 so that V CC is more closely matched to the waveform E. In other words, for a particular power amplifier (PA) impedance characteristic, the frequency response and non-linearity of the ET modulator 142 can be compensated for by adjusting (pre-distorting) the input waveform E. The above is well known in the art.

[0032] The waveform E is input to a pulse width modulation (PWM) generator 116 that drives the switching circuit of the ET modulator 142 (within the ET and APT modulator 140) with non-overlapping (break-before-make) high-side and low-side waveforms PWMH and PWML. The pulse width is a function of time and corresponds to the envelope waveform E. Thus, the PWM generator 116 receives the waveform E and generates appropriate switching signals to input to the ET modulator 142, which generates the PA supply voltage V CC (derived from the primary supply voltage V bat from the device).

[0033] The PWM generator 116 also includes a V supply generation circuit 117 that receives a signal indicative of the primary supply voltage V bat (i.e. the ET modulator supply voltage). The V supply generation circuit 117 is used to scale the PWM signal duty cycle accordingly.

[0034] At the output switching stage of the ET modulator 142, a low pass inductor-capacitor (LC) filter circuit 155 formed by LI, L2, CI, L3 and C2 removes the high frequency components of the output voltage, resulting in the desired PA supply voltage waveform V CC It is to be understood that different configurations of the filter circuit 155 can be used as desired.

[0035] The APT modulator 144 includes a buck / boost converter circuit 146, an APT switch 147, and a second LC circuit 148. The average power tracking (APT) modulator 144 can be used in different operating scenarios where average power tracking is required. It is to be understood that the available supply voltage can be any voltage source / supply. In the embodiments described herein, the available supply voltage is provided by a rechargeable battery.

[0036] In one embodiment, the system 100 includes components that allow the system to accommodate batteries with different voltages. A low-speed V bat The sense circuit 170 measures or senses the primary supply voltage V bat (analog) and outputs an analog signal. An analog-to-digital converter (ADC) 171 is used to convert the analog signal to a digital signal, which is input to the PWM generator 116 of the V supply generation circuit 117 to scale the PWM output signal duty cycle.

[0037] In Figure 1 the transmitter system 100 shown, the PA input signal peak (peak of the digitally modulated signal) is high enough such that the required PA input supply voltage V CC (to maintain acceptable ACPR performance) is higher than the available supply voltage (V bat ) of the battery. This scenario is shown in Figure 2 .

[0038] Figure 2 is a graph showing a relatively static primary supply voltage V bat (approximately equal to 3.4 volts) 210 and a time-varying required PA example supply voltage V CC 220. The primary supply voltage V bat input to the ET modulator 142 is limited, so the maximum PA supply voltage V CC output by the ET modulator 142 is also limited. Thus, when the required PA supply voltage 220 is higher than the supply voltage V bat 210, a limitation is required, and the PA 130 only receives a supply voltage that is (approximately) equal to the supply voltage V bat . This results in a voltage clipping phenomenon, which in turn results in ACPR degradation and EVM degradation.

[0039] The following Table 1 shows the analog power amplifier output spectrum and ACPR performance under the following conditions: signal type: LTE, wideband = all RBs of 20 megahertz signal, output power = 26.5 decibel-milliwatts, battery voltage = 3.4 volts.

[0040] Table 1

[0041] 'EUTRA' 'EUTRA1' 'EUTRA2' left 33.8016 39.6309 39.4673 right 34.1496 38.468 40.3632

[0042] The above simulation results show the ACPR performance of the system 100 shown in Figure 1 without reference to the teachings of the present invention.

[0043] Reference is made to Figure 3 , Figure 3shown is a block diagram of some of the circuitry / components of a transmitter system 300 in accordance with the present application and teachings. The system 300 includes a plurality of components that are the same or similar to those in the transmitter system 100 shown in FIG. 1. For brevity and ease of reference, these same / similar components are not described again, but are referenced by the same reference numbers as those in the transmitter system 100 shown in FIG. 1. Figure 1 The components in the transmitter system 100 shown are the same or similar to those in the transmitter system 300 shown in FIG. 3. For brevity and ease of reference, these same / similar components are not described again, but are referenced by the same reference numbers as those in the transmitter system 300 shown in FIG. 3. Figure 1 The components shown have the same reference numbers as those described in the transmitter system 300 shown in FIG. 3, and have the same / similar functionality as those described in the transmitter system 300 shown in FIG. 3. Figure 1

[0044] The transmitter system 300 also includes a system / circuit / method for dynamically boosting the supply voltage provided to the ET modulator 142 to a level higher than the primary supply voltage (e.g., V bat ) of the device. The supply voltage of the ET modulator is boosted when the required PA supply voltage V cc (based on the envelope of the transmission signal) is equal to or higher than a pre-set voltage threshold. The threshold is generally set to a voltage level equal to or close to the primary supply voltage (e.g., V bat ).

[0045] As shown, the system 300 includes the digital baseband circuit 110a with an ET boost mode controller or control circuit 310, the ET and APT modulator 140a with an ET boost selection circuit 320, and optionally, a line control circuit 330. In general, the ET boost mode controller 310 receives signals indicative of the primary supply voltage (e.g., V bat ) and the required PA supply voltage V cc (e.g., signal E, target voltage), and generates a boost enable / disable signal. For example, when the waveform signal E (input to the PWM generator 116) is equal to or greater than V bat , the controller 310 determines to use the ET boost enable / disable signal to cause the selection circuit 320 to select the first supply voltage (e.g., the boosted voltage output from the buck / boost converter 146) as the supply voltage to the ET modulator 142. Similarly, when the waveform signal E (input to the PWM generator 116) is less than V bat , the controller 310 disables the ET boost enable / disable signal, and the selection circuit 320 selects the second supply voltage (e.g., V bat ) as the supply voltage to the ET modulator 142. By monitoring the required PA supply voltage V cc (e.g., signal E) and the available primary supply voltage (e.g., V bat ), the digital baseband circuit 110a can determine whether boosting is needed.

[0046] ​In one embodiment, the ET boost selection circuit 320 includes a first switch 322 and a second switch 324. It is to be understood that various suitable circuits, structures or components can be used to provide the desired switching functionality described herein. Fast switching between the two supply voltages is desirable, and thus the switches used should have fast on / off times. For envelope tracking mode operation, the existing APT boost converter circuit can be reused to generate the desired ET modulator boost supply voltage (Vout_boost). The Vout_boost signal can be routed to the ET modulator 142 by appropriately configuring the positions of switches 322, 324 and 147. When switch 322 is off and switches 324 and 147 are on, the ET modulator operates in the normal mode, in which it is powered by the supply voltage V bat from the battery. When switch 324 is off and switches 322 and 147 are on, the ET modulator operates in the boost mode, in which it is powered by the boost supply voltage Vout_boost. When switch 147 is off and switches 322 and 324 are on, the normal APT mode is active. In one example, the amplitude of Vout_boost can be 4 volts, while the amplitude of the supply voltage V bat from the battery is generally less than 4 volts.

[0047] In Figure 3 the transmitter system 300 shown, the PA input signal peak (peak of the digitally modulated signal) is high enough so that the required PA input supply voltage V CC (to maintain acceptable ACPR performance) is higher than the available supply voltage V bat from the battery. However, when V CC is higher than V bat , the ET boost mode controller 310 selects the supply voltage higher than V bat through the selection circuit 320. This scenario is shown in Figure 4 .

[0048] Figure 4 is a graph showing the relatively static primary supply voltage V bat (approximately equal to 3.4 volts) 210 and the time-varying required PA example supply voltage V CC 220. When the required PA supply voltage V CC 220 is approximately equal to (or higher than) the primary supply voltage V bat , during which time the ET boost mode controller determines to use the boost enable signal to use the boost voltage as the supply voltage for the ET modulator 142. Each legend number 410 indicates the supply voltage for the ET modulator for a time period (not all time periods have a legend number 410).

[0049] In one example, the boosted voltage output from the buck / boost converter 146 is equal to 4 volts, and voltage clipping occurs when the required PA supply voltage 220 is higher than 4 volts. In the example shown, voltage clipping does not occur most of the time because the required voltage is typically 4 volts or less. Thus, the present application reduces the voltage clipping effect that occurs when the required voltage is higher than the power supply voltage of the device (e.g., V bat ) is greater than the measured available voltage (e.g., battery voltage).

[0050] It is understood that the boosted voltage can not be 4 volts (4 volts is just one example). The value of the boosted voltage is determined at design time based on the specification requirements of the system 300 (e.g., circuit configuration, power specifications, etc.), but is still required to be higher than the available power supply voltage.

[0051] PA input signal peaks only occur during burst transmissions. However, because some peaks are high, the linear degradation is also typically large, which results in deep voltage clipping. With the dynamic boosting architecture, the impact on efficiency is small (because the boosted voltage is rarely used), but the linear gain is greatly improved (eliminating light voltage clipping and mitigating deep voltage clipping).

[0052] Table 2 below shows simulated power amplifier output spectrum and ACPR performance under the following conditions: signal type: LTE, wideband = 20 MHz all RB signal, output power = 26.5 dBm, battery voltage = 3.4 volts.

[0053] Table 2

[0054] 'EUTRA' 'EUTRA1' 'EUTRA2' left 38.2796 44.5026 43.9509 right 38.7142 44.1211 44.8159

[0055] With real dynamic ET boosting, the ACPR is significantly increased by 4 to 5 dB.

[0056] In summary, the output voltage of the continuous comparative load predistortion circuit 115 (e.g., the required PA supply voltage V cc ) is continuously compared to the measured available voltage (e.g., battery voltage). If the required voltage is higher than the measured battery voltage, voltage clipping can occur. To mitigate voltage clipping, the boosted supply voltage is used to power the ET modulator 142. A preset threshold based on the available power supply voltage can be used. In one embodiment, the threshold can be equal to the value of the available power supply voltage, or some other larger (smaller) value. In most applications, the boosted supply voltage should be input to the ET modulator when the amplitude of the required PA supply voltage V cc is greater than the measured available voltage (e.g., battery voltage).

[0057] For example, when the required PA supply voltage V cc > Vbat X A, a boost power supply voltage setting threshold. A is a fixed or adjustable coefficient. Assume A is 1.05, V bat equals 3.4 volts. In this case, the required PA power supply voltage V cc is approximately 3.57 volts (3.4 x 1.05), i.e., the ET power supply voltage is boosted. The reason for using a threshold slightly greater than the available power supply voltage is to save power and to use the boosted power supply voltage only when a large voltage cut-off occurs. In other words, a slight voltage cut-off is tolerable because it does not cause severe distortion, and it is more important to mitigate / avoid severe / deep voltage cut-off phenomena.

[0058] It is to be understood that the power supply voltage to the ET modulator 142 should be quickly switched between the available power supply voltage and the boosted power supply voltage so that the boosted operation can be activated in a short time. To achieve this, the boost circuit 146 can be continuously operated (always on) and output the boosted voltage. Since the boost switch 324 is normally on, the current power consumption in the boost idle state is relatively low. In addition, an optional line control circuit 330 can be used. Compared with other control methods such as MIPI control, line control directly applies a control signal to the target circuit without the need to decode the signal, so that the reaction time is faster.

[0059] The PWM generator 116 uses the power supply voltage information of the ET modulator 142 to generate a PWM signal. The battery sensing circuit 170 and the ADC circuit 171 are generally designed to operate at low speed (to save current, and the battery voltage usually only changes at low speed). In the ET power supply voltage dynamic boosting technique described and taught herein, the ET voltage sensed by the circuits 170 and 171 changes quickly (the faster the better). Therefore, the power supply voltage information of the ET modulator used by the PWM generator 116 should also be adapted to the quick switching of the power supply voltage.

[0060] One of the methods adapted to the low speed of the circuits 170 and 171 is to set the boosted power supply voltage to a fixed value (4 volts in this example), and to select (1) the voltage V bat sensed by the battery sensing ADC 171 (better tracking of the battery voltage) or (2) to set a fixed signal voltage equal to the boosted power supply voltage. Figure 5 A possible implementation of this function is shown.

[0061] As Figure 5 shown, V supplyThe generator 117a receives digital values representing the continuously sensed battery voltage (from the ADC 171) that need to be processed (by the battery sense circuit 520) to clean up and up-sample the continuously monitored battery voltage before inputting the sensed signal to the PWM generator 116. Digital values representing a fixed voltage are stored in the circuit 510, which is a register or other storage circuit. In one embodiment, the fixed value is equal to (or approximately equal to) the boosted supply voltage value output from the boost circuit 146. The multiplexer 530 selects either the fixed voltage value (e.g., the boosted supply voltage value) or the value of V bat as V supply information, used by the PWM generator 116 to generate the PWM signal.

[0062] It is to be understood that using the ET boost enable signal to control the multiplexer 530 to select which voltage to use for high efficiency is an analog to the analog circuit function of the ET modulator. This means that the switching done by the multiplexer 530 matches the position of the switches 322 and 324 in the ET and APT modulators.

[0063] In another embodiment (not shown), the supply voltage sense ADC 171 can also be used to increase the sampling rate of the supply voltage sense ADC 171 when it is determined to use the ET boost signal (or when the required PA supply voltage V cc is higher than a voltage that is slightly less than the sensed V bat ). This avoids the need for the additional circuitry shown in Figure 5 .

[0064] Referring to Figure 6 , Figure 6 another embodiment of the V supply generation circuit 117a in the PWM generator 116 is shown. A low pass filter (LPF) 600 is placed in the line between the fixed voltage circuit 510 and the multiplexer 530 to model the setup of the analog circuit (the bandwidth of the analog circuit is limited, so there is always a setup time). The analog circuit here refers to the ET_Boost_En terminal / signal and the actual ET modulator supply voltage both have the same bandwidth limitations, such as the limited speed of the switches 322 and 324, the parasitic capacitance between the digital baseband of the printed circuit board (PCB) and the ET and APT modulators, and the limited speed of the line control circuit 330. The coefficients of the LPF 600 are pre-set based on laboratory measurements to match the design of the analog circuit to improve the performance of the system.

[0065] In another embodiment, the boost circuit can be pre-charged when a large signal peak is required. This can reduce the stand-by time of the boost voltage. Figure 7 The concept involved in this method is shown. The exact time of pre-charging the boost voltage capacitor (t2-t1 in Figure 7 ) is determined by the settling time of the analog circuit, which is variable in value. The settling time of the analog circuit refers to the limited on-speed of the boost converter within the APT modulator 144. The shorter the stand-by time of the boost voltage, the more power can be saved (less current).

[0066] As shown in the figure, at time t1, the output stage of the buck / boost converter 144 starts pre-charging. At time t2, the pre-charging is completed, and the voltage input to the ET modulator 142 is switched from V bat to the boost voltage (when it is determined to use ET boost enable signal). At time t3, the voltage input to the ET modulator 142 is switched from the boost voltage to V bat (not to use ET boost enable signal). Times t4, t5 and t6 show another cycle, which respectively represent starting pre-charging, switching the ET supply voltage from V bat to the boost voltage, and switching back to V bat .

[0067] Reference is made to Figure 8 , Figure 8 A detailed diagram showing another embodiment of the ET and APT modulator 140 (identified as 140b) provided according to the present application is provided.

[0068] In an embodiment, the ET modulator 142 (identified as 142b) includes a first set of switch circuits 143 (identified as 800a in Figure 8 ) and a second set of switch circuits 800b. In Figure 3 , only the first set of switch circuits is included, while Figure 8 shows two sets of switch circuits of the switch core of the ET modulator. As shown in the figure, the supply voltage of the first switch circuit 800a is V bat , while the supply voltage of the second switch circuit 800b is the boost voltage. The line control circuit 330a controls based on the ET boost enable signal using the two sets of switch circuits 800a and 800b. When in the boost mode, the switch circuit 800b is in the active state, while the switch circuit 800a is in the inactive state. When in the regular mode, the switch circuit 800a is in the active state, while the switch circuit 800b is in the inactive state. In the implementation process, the on-resistance (Ron) loss of the series switches 322 and 324 (see Figure 3 ) can be avoided, which can improve the overall efficiency.

[0069] In another embodiment, a boost capacitor 810 is used instead of a boost converter 146 to output a boosted voltage. The boost capacitor 810 is charged using the boosted voltage already provided in the boost converter 146 by a low drop out (LDO) regulator 820. This embodiment can simplify the design of the buck / boost converter 146 while saving power. A large boost capacitor 810 does not need to turn on the boost converter quickly because the short burst of current needed for a signal peak can be provided by the capacitor itself.

[0070] It is to be understood that Figure 8 the two embodiments described in the Background section can be used in combination, or each embodiment can be incorporated separately Figure 3 in the main embodiment shown in the Background section.

[0071] Operation

[0072] Reference Figure 12 , Figure 12 Figure 14 shows a process 1400 for boosting the ET modulator supply voltage of a transmitter system 300 according to the present application. It is to be understood that only the relevant steps / functions necessary to understand the present application are described herein.

[0073] During operation, the ET boost mode controller 310 receives a signal indicative of a target or desired PA input supply voltage V CC (e.g., signal E), which is referred to as V target (step 1410a). The controller 310 also receives a signal indicative of an available supply voltage (e.g., V bat ). This voltage is referred to as V available (step 1410b).

[0074] The controller 310 determines whether to boost or increase the supply voltage of the ET modulator 142 based on the two input signals (step 1420). The determination is made based on a comparison of V target and V available associated with a predetermined threshold. In one embodiment, the ET modulator boost is activated when V target is equal to or higher than V available . In another embodiment, the ET modulator boost operation is activated when V target > V available x A.

[0075] When activated, the boosted supply voltage is selectively input to provide power to the ET modulator 142 (step 1430). When not activated (or deactivated), the available supply voltage is selectively input to provide power to the ET modulator 142 (step 1440). In other words, the voltage of the ET modulator 142 is selectively switched between the available supply voltage (e.g., normal operation) and the boosted supply voltage (e.g., boosted operation). It is to be appreciated that the boosted supply voltage has a magnitude greater than that of the available supply voltage. In an embodiment, the boosted supply voltage is generated from the available supply voltage by a boost circuit (not shown in FIG. 1). Figure 12

[0076] Additionally, when activated, the boosted supply voltage signal is selectively input to the PWM generator 116, which is used to generate the PWM signal input to the ET modulator 142. When not activated (or deactivated), the available supply signal is selectively input to the PWM generator 116, which is used to generate the PWM signal input to the ET modulator 142.

[0077] Thus, a first supply voltage is input to the ET modulator 142 and provides power to the ET modulator 142 in a first mode (normal operation). A second supply voltage is input to the ET modulator 142 and provides power to the ET modulator 142 in a second mode (boosted operation). In the present disclosure, when the target / desired PA input supply voltage V CC meets or exceeds a predetermined threshold, the second supply voltage (higher than the first supply voltage) is input to the ET modulator 142.

[0078] Regardless of whether in normal operation or boosted operation, the ET boost mode controller 310 receives the envelope tracking signal E (or pre-distorts the same signal) as V target , V target to the data input to the envelope generator 114. It is to be appreciated that the input data is the data to be transmitted by the transmitter system 300.

[0079] It is to be appreciated that the above description of the flow 1400 is equally applicable to all embodiments described herein.

[0080] Various circuits and methods are described herein, including selecting one of two supply voltages (e.g., battery voltage, boosted voltage) to input to the ET modulator 142. In an embodiment, the signal / value of the target or desired PA input supply voltage V cc and the signal / value of the available battery voltage are continuously compared to the signal / value in the digital baseband circuit 110. It is to be appreciated that the signal in the baseband circuit 110 is in digital form.

[0081] ​In one embodiment, the digital baseband circuit 110 determines to switch between two signals / values, thus, no analog signal is needed for comparison / determination. In this way, power is saved relative to analog-based approaches. In the PWM generator 116, two Vs are provided supply The two paths generate a path. The two paths can enable fast switching, solving the problem in conventional low-speed battery-aware circuits.

[0082] RF communication network

[0083] See Figure 9 , Figure 9 A block diagram of an exemplary wireless communication network 900 is shown. The wireless communication network 900 employs an inventive envelope tracking system having the functionality of dynamically boosting the supply voltage of the ET modulator as described herein. The wireless communication system 900 includes a first wireless communication device 1100 and a second wireless communication device 1104. The first wireless communication device 1100 includes the system 300 described above according to the present application. Similarly, the second wireless communication system 1104 also includes the system 300 described above according to the present application. It is understood that the devices 1100 and 1104 need not both include the transmitter system 300, where one contains the system 300 or both devices include the system 300.

[0084] The communication devices 1100 and 1104 communicate using RF signals through antennas 1102 and 1106, respectively, as shown.

[0085] The exemplary wireless communication network 900 can operate according to one or more wireless protocols or technologies, such as CDMA, TDMA, FDMA, UMTS, LTE, etc. (or various versions thereof). Moreover, the network 900 can support circuit- switched, packet- switched, or packet-data communications.

[0086] In Figure 9In the illustrated embodiment, the first communication device 1100 is shown as a mobile station or mobile terminal (or possibly fixed) such as a wireless telephone; the second communication device 1104 is shown as a base station. However, the illustrated embodiment is not limited in this regard. The devices 1100 and 1104 can be any devices having wireless communication functionality. As shown, the base station 1104 includes a base transceiver subsystem (BTS) 1108, which includes the system 300. The BTS 1108 is coupled to a base station controller (BSC) 1110. The BTS 1108 and the BSC 1110 are logically collectively referred to as the base station 1104. Sometimes multiple BTSs 1108 share a single BSC 1110, and the BSC 1110 manages resource allocation for the multiple BTSs. In general, the terms "base station" and "access network" refer to any entity (or series of entities) that wirelessly communicates with a mobile station to conduct a communication session (e.g., circuit-switched or packet-switched). The base station 1104 is coupled to a public switched telephone network (PSTN) or other data or switching network. This path can include additional elements, such as a mobile switching center (MSC) (not shown) coupled to the BSC 1110.

[0087] Although the devices 1100 and 1120 are shown in the illustrated embodiment as including the receiver 700 separate from the transmitter system 300, it is to be understood that the transmitter and receiver (or portions thereof) can be combined to form a transceiver, or can be configured as one or more elements, and that the features described herein do not limit the devices 1100 or 1120, or the transmitter 300 or receiver 700.

[0088] The methods / flows and devices described above can be incorporated into a wireless communication network and implemented by devices such as those described below or in the figures.

[0089] Figure 10Another example communication system 1200 is shown. The communication system 1200 applies the inventive envelope tracking system with the functionality of dynamically boosting the voltage of the ET modulator described herein. In general, the system 1200 allows multiple wireless users to transmit and receive data and other content. The system 1200 can implement one or more channel access methods, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), orthogonal FDMA (OFDMA), or single-carrier FDMA (SC-FDMA).

[0090] In this example, the communication system 1200 includes user equipment (UE) 1210a-1210c, radio access networks (RANs) 1220a-1220b, a core network 1230, a public switched telephone network (PSTN) 1240, the Internet 1250, and other networks 1260. While a few of each type of Figure 10 Any number of components or elements can be included in the system 1200.

[0091] The UEs 1210a-1210c are configured to operate and / or communicate in the system 1200. For example, the UEs 1210a-1210c are configured to transmit and / or receive wireless signals. Each of the UEs 1210a-1210c represents any suitable end user device and can include (or be referred to as) a user equipment (UE), a wireless transmit / receive unit (WTRU), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop computer, a computer, a touchpad, a wireless sensor, a consumer electronics device, or the like. It is to be understood that one or more of the UEs 1210a-1210c can include the transmitter system 300 according to the present application.

[0092] The RANs 1220a and 1220b here each include a base station 1270a and 1270b. Each of the base stations 1270a-1270b can wirelessly communicate with one or more of the UEs 1210a-1210c and thereby facilitate access to networks including the core network 1230, the PSTN 1240, the Internet 1250, and / or other networks 1260. The base stations 1270a-1270b can include (or be) one or more well-known devices, such as a base transceiver station (BTS), a base station (BS), a Node-B, an eNode-B (eNB), a Home Node-B, a Home eNode-B, a site controller, an access point (AP), or a wireless router, for example. It will be appreciated that one or more of the base stations 1270a-1270b can comprise a transmitter system 300 in accordance with the present application.

[0093] In the illustrated embodiment, the base station 1270a forms part of the RAN 1220a, which can include other base stations, elements, and / or devices. Further, the base station 1270b forms part of the RAN 1220b, which can include other base stations, elements, and / or devices. Each of the base stations 1270a-1270b transmits and / or receives wireless signals within a particular geographic area, sometimes referred to as a "cell", which can include a macro cell, a small cell, or other cell type. In some embodiments, multiple-input multiple output (MIMO) technology can be applied, with multiple transceivers within each cell. Figure 10 The base stations 1270a-1270b communicate with one or more of the UEs 1210a-1210c over one or more air interfaces 1290 using wireless communication links. The air interfaces 1290 can use any suitable wireless access technology.

[0094] It is contemplated that the system 1200 can use multiple channel access functionalities including the schemes described above. In particular embodiments, the base stations and UEs use LTE, LTE-A, and / or LTE-B. Of course, other multiple access schemes and wireless protocols can be utilized.

[0095]

[0096] ​The RANs 1220a-1220b are in communication with the core network 1230, which can provide the UEs 1210a-1210c with access to

[0097] Figure 10 One example of a communication system is shown, but Figure 10 various changes can be made. For example, the communication system 1200 can include any number of UEs, base stations, networks, or other components in any suitable arrangement.

[0098] Figure 11A and Figure 11B An example device is shown that implements methods and teachings in accordance with the present disclosure. In particular, Figure 11A An example UE 1210 is shown, Figure 11B An example base station 1270 is shown. These components can be used in the system 1200 or in other suitable systems.

[0099] As Figure 11A shown, the UE 1210 includes at least one processing unit 1300. The processing unit 1300 is capable of carrying out various processing operations for the UE 1210. For example, the processing unit 1300 can carry out signal coding, data processing, power control, input / output processing, or any other functionality enabling the UE 1210 to operate in the system 1200. The processing unit 1300 also supports the methods and teachings described in detail above. Each processing unit 1300 includes any suitable processing or computing device capable of carrying out operations. Each processing unit 1300 can include, for example, a microprocessor, microcontroller, digital signal processor, field programmable gate array, or application specific integrated circuit.

[0100] The UE 1210 also includes at least one transceiver 1302 that includes a transmitter system 300. The transceiver 1320 is used to modulate data or other content for transmission by at least one antenna 1304. The transceiver 1302 is also used to demodulate data or other content received by the at least one antenna 1304. Each transceiver 1302 includes any suitable structure for generating signals for wireless transmission and / or processing signals received wirelessly. Each antenna 1304 includes any suitable structure for transmitting and / or receiving wireless signals. One or multiple transceivers 1302 can be used in the UE 1210, and one or multiple antennas 1304 can be used in the UE 1210. The transceiver 1302 shown is a single functional unit, but can be implemented as at least one transmitter and at least one separate receiver.

[0101] The UE 1210 also includes one or more input / output devices 1306. The input / output devices 1306 facilitate interaction with a user. Each input / output device 1306 includes any suitable structure for providing information to or receiving information from a user, such as a speaker, microphone, keypad, display, touchscreen, etc.

[0102] In addition, the UE 1219 includes at least one memory 1308. The memory 1308 stores instructions and data used, generated, or collected by the UE 1210. For example, the memory 1308 could store software or firmware instructions executed by the processing unit 1300 and data used or generated by the software or firmware instructions. Each memory 1308 includes any suitable volatile and / or non-volatile storage and retrieval devices. Any suitable storage device(s) can be used, such as a random access memory (RAM), read only memory (ROM), hard disk, optical disk, subscriber identity module (SIM) card, memory stick, secure digital (SD) memory card, etc.

[0103] As Figure 11BAs shown, base station 1270 includes at least one processing unit 1350, at least one transmitter 1352, at least one receiver 1354, one or more antennas 1356, and at least one memory 1358. Processing unit(s) 1350 is / are for various processing operations, e.g., signal coding, data processing, power control, input / output processing, or other functions. Processing unit(s) 1350 can also support the methods and teachings described above in detail. Each processing unit 1350 includes any suitable processing or computing device and can be implemented as any type of hardware computer processor or circuitry, as the like, including but not limited to one that includes a baseband integrated circuit or applications- specific circuitry.

[0104] Each transmitter 1352 includes any suitable structure for generating signals for wireless transmission to one or more UEs or other devices, and includes transmitter system 300 described above. Each receiver 1354 includes any suitable structure for processing received signals from one or more UEs or other devices. Although at least one transmitter 1352 and at least one receiver 1354 (or components thereof) are shown as being separate components, they can be integrated into a transceiver. Each antenna 1356 includes any suitable structure for transmitting and / or receiving wireless signals. Although a common antenna 1356 is shown in the figure as being coupled to both transmitter 1352 and receiver 1354, one or more antennas 1356 can be coupled to transmitter 1352, or one or more separate antennas 1356 can be coupled to receiver 1354. Each memory 1358 includes any suitable volatile and / or non-volatile storage and retrieval devices.

[0105] The detailed description set forth above of the UE 1210 and base station 1270 are known to those skilled in the art. Therefore, the details are not set forth in greater detail herein.

[0106] In certain embodiments, one or more of the devices' functions or processes are implemented or supported by a computer program that is executed on computers or computer- readable program code embodied in computer-readable media for execution on computers. The phrases "computer-readable program code" include any type of computer code, including source code, object code, and executable code. The phrase "computer-readable media" includes any type of media capable of being accessed by a computer, such as read only memory (ROM), random access memory (RAM), a hard disk drive, a compact disc (CD), a digital video disc (DVD), or any other type of memory. A "processor" includes any hardware system, hardware or software module or component that processes data based on instructions, such as a central processing unit on a computer or the like. Although the computer-readable media is not limited to being tangible, the computer-readable media can include computer- readable storage media.

[0107] It is helpful to define certain terms and phrases used throughout this patent document. The terms "include" and "comprise," and derivatives thereof, mean "without limitation." The term "or" is inclusive, meaning and / or. The phrases "associated with" and "associated therewith," as well as derivatives thereof, mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, be proximate to, be bound to or with, have a property of, have, have a property of, or the like.

[0108] While the application has been described with respect to certain embodiments and generally associated methods, various alterations and modifications will become apparent to the skilled artisan. Therefore, the above description of certain examples is not meant to limit or restrict the application. Other modifications, substitutions, and alterations are possible. The scope of the application should be determined with reference to the following claims, along with the full scope of equivalents to which such claims are entitled.

Claims

1. A transmitter, characterized in that, include: An envelope generator is used to receive data signals to be transmitted and generate envelope signals based on the received data signals. A pulse width modulation (PWM) generator coupled to the envelope generator is used to output a PWM signal; An envelope tracking (ET) and average power tracking (APT) modulator coupled to the PWM generator, the ET and APT modulators comprising: an ET modulator, an APT modulator, and a buck / boost converter circuit; the ET modulator and the APT modulator sharing the buck / boost converter circuit; the buck / boost converter circuit for generating a second power supply voltage based on a first power supply voltage; the ET modulator for receiving the PWM signal and outputting a power amplifier (PA) switching power supply; the ET modulator for further receiving either the first power supply voltage or the second power supply voltage in response to an ET modulator boost enable signal, wherein the second power supply voltage is higher than the first power supply voltage; Sensing circuitry for sensing and generating a sensing signal representing the first power supply voltage; and A multiplexer is configured to receive the sensing signal and a boost signal representing the second power supply voltage, and selectively output the sensing signal or the boost signal to the PWM generator in response to the ET modulator boost enable signal.

2. The transmitter according to claim 1, characterized in that, Also includes: An ET boost mode controller is used to generate an ET modulator boost enable signal when the amplitude of the envelope signal is greater than a preset value.

3. The transmitter according to claim 1, characterized in that, Also includes: A switching circuit coupled to the first power supply voltage, the second power supply voltage, and the ET modulator is used to switch and output the first power supply voltage or the second power supply voltage to the ET modulator.

4. The transmitter according to claim 3, characterized in that, The switching circuit includes: A first switch coupled to the first power supply voltage; A second switch coupled to the second power supply voltage; The first switch and the second switch selectively output the first power supply voltage or the second power supply voltage to the ET modulator in response to the ET modulator boost enable signal.

5. The transmitter according to claim 1, characterized in that, The buck / boost converter circuit includes: A boost circuit is used to receive the first power supply voltage and generate the second power supply voltage.

6. The transmitter according to claim 1, characterized in that, The sensing circuit includes an analog-to-digital converter (ADC) for generating the sensed signal in digital form.

7. The transmitter according to claim 1, characterized in that, Also includes: An ET boost mode controller is used to generate an ET modulator boost enable signal when the amplitude of the envelope signal is greater than a preset value.

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