Amplifier with temperature compensation and balanced circuit structure

Abstract

The utility model provides an amplifier with temperature compensation, and the amplifier comprises an amplifier which is provided with a signal input end and a signal output end; the resistance variable circuit is connected between the signal input end and the signal output end and is used for adjusting the resistance of the resistance variable circuit based on a control signal so as to adjust the output impedance of the amplifier; and the control signal generation circuit is used for generating the control signal changing along with the temperature and outputting the control signal to the resistance variable circuit. The utility model further relates to a balanced circuit structure for the amplifier.

Description

TECHNICAL FIELD

[0001] The present application relates to integrated circuits, and in particular, to an amplifier with temperature compensation and a balanced circuit structure. BACKGROUND

[0002] In a communication transceiver link, an amplifier is used to amplify a signal, but the gain of the amplifier will change at high and low temperatures, and the transistor threshold voltage will drift positively as the temperature rises, thereby causing the transconductance and gain of the amplifier to decrease. For radio frequency circuits, the temperature range during operation is usually required, that is, the performance change within a specific temperature range does not exceed the required value. In order to reduce the gain fluctuation of the amplifier over the whole temperature range, a gain temperature compensation module needs to be added to the circuit.

[0003] Traditionally, one method is to adjust the bias of the amplifier to change the operating current of the amplifier to adjust the gain, and the other is to add a voltage-controlled attenuator module to reduce the gain at low temperature to achieve the effect of temperature gain compensation. However, the compensation accuracy and compensation range of the traditional method are insufficient, or an additional compensation circuit module is required. Therefore, there is an urgent need for a new type of circuit for temperature compensation of the amplifier. CONTENT OF THE INVENTION

[0004] In order to improve the temperature compensation accuracy of the amplifier, the present application provides an amplifier with a feedback network for temperature compensation.

[0005] The amplifier with temperature compensation comprises an amplifier having a signal input end and a signal output end, a resistance variable circuit connected between the signal input end and the signal output end, for adjusting the resistance of the resistance variable circuit based on a control signal to adjust the load impedance of the amplifier, and a control signal generation circuit for generating the control signal varying with temperature and outputting the control signal to the resistance variable circuit.

[0006] In the above structure, the resistance variable circuit and the control signal generation circuit constitute a feedback network of the amplifier. Since the gain of the amplifier will change with the change of the output impedance, and the impedance of the amplifier itself cannot or is difficult to adjust, the equivalent load impedance of the output end of the amplifier can be controlled by controlling the resistance of the feedback network. Thus, at different ambient temperatures, the gain of the amplifier can be kept in a stable state, that is, the temperature compensation of the amplifier is achieved.

[0007] Optionally, the control signal is a digital switch signal, and the variable resistance circuit is a resistance array configured to receive the digital switch signal and adjust resistance in the resistance array to adjust the resistance value of the variable resistance circuit. By using a digital switch signal and a resistance array to adjust resistance, the resistance value can be more accurately controlled within the limits of circuit area and complexity, thereby improving the accuracy of temperature compensation, and the range of impedance adjustment can be adjusted by controlling the number of resistances in the resistance array, thereby allowing temperature compensation of the amplifier within each temperature range, thereby solving the problem of insufficient accuracy and range of temperature compensation in the prior art.

[0008] Optionally, the control signal generation circuit includes a temperature sensor configured to obtain real-time temperature information of an environment, an analog-to-digital converter connected to the temperature sensor and configured to convert the real-time temperature information into a digital temperature signal, a storage module storing a correspondence between the digital temperature signal and the digital switch signal, and a control module connected to the analog-to-digital converter and the storage module and configured to convert the digital temperature signal into the digital switch signal based on the digital temperature signal obtained from the analog-to-digital converter and the corresponding digital switch signal found in the storage module. When a digital switch signal and a resistance array are used, the circuit itself does not have temperature characteristics, so an additional temperature sensor is needed to obtain the real-time temperature of the working environment of the amplifier, and the corresponding correspondence is usually obtained from the memory to obtain an accurate digital switch signal. The correspondence can be obtained through prior experiments.

[0009] Optionally, the circuit further includes a variable capacitance circuit configured to receive the digital switch signal and adjust the capacitance value of the variable capacitance circuit to adjust the output impedance of the amplifier.

[0010] Optionally, the variable capacitance circuit is a capacitance array.

[0011] In addition to the variable resistance circuit, the feedback network usually includes a fixed capacitance to isolate the DC voltage, so that the feedback network forms an RC feedback circuit. However, when the output impedance of the amplifier is changed by the variable resistance circuit, the impedance of the amplifier output terminal may not be matched. Therefore, the capacitance in the feedback network can also be designed as a variable capacitance circuit, and a structure similar to the variable resistance circuit can be used to design a capacitance array.

[0012] Optionally, the control signal is a control voltage, and the variable resistance circuit is a voltage-controlled MOS transistor.

[0013] In another embodiment, the control voltage in the form of an analog signal can also be used to control the resistance variable circuit. Thus, the resistance variable circuit can also be designed as a voltage-controlled MOS transistor which has different on-resistances according to the size of the analog voltage. Thus, the resistance value controlled by the control voltage in the resistance variable circuit can be accurately controlled, so as to improve the accuracy of temperature compensation, and the range of impedance adjustment can be adjusted by controlling the size of the on-resistance value, so as to compensate the amplifier at various temperature ranges, thereby solving the problem of insufficient accuracy and range of temperature compensation in the prior art.

[0014] Optionally, the control signal generation circuit comprises:

[0015] a voltage generation unit configured to generate a first voltage related to temperature.

[0016] Optionally, when the first voltage is positively correlated with temperature, the control signal generation circuit further comprises:

[0017] a voltage inverting unit connected to an output end of the control signal generation circuit, configured to invert the voltage input into the voltage inverting unit to obtain the control voltage negatively correlated with temperature.

[0018] Since the control signal is a control voltage, an electronic circuit is used to realize the control signal generation circuit. The voltage inversion is to change the polarity of the slope of the voltage, for example, the slope of the first voltage curve is positive, and after inversion, it becomes negative.

[0019] Optionally, when the first voltage is negatively correlated with temperature, the first voltage is the control voltage.

[0020] Optionally, the voltage generation unit comprises:

[0021] a first operational amplifier, two transistors, four resistors, and two diodes, the two transistors comprising a first transistor and a second transistor, the four resistors comprising a first resistor, a second resistor, a third resistor, and a fourth resistor, and the two diodes comprising a first diode and a second diode,

[0022] The second resistor, the first resistor and the first diode are connected in series, and are connected in parallel with the third resistor and the second diode connected in series, the inverting input terminal of the first operational amplifier is connected between the third resistor and the second diode, the non-inverting input terminal of the first operational amplifier is connected between the second resistor and the first resistor, the output terminal of the first operational amplifier is connected to the gate of the first transistor, the drain of the first transistor is connected to one end of the second resistor and one end of the third resistor, the gate of the second transistor is connected to the gate of the first transistor, the drain of the second transistor is connected to one end of the fourth resistor and outputs the first voltage, the source of the first transistor and the source of the second transistor are connected to a power supply, the negative electrode of the first diode, the negative electrode of the second diode and the other end of the fourth resistor are grounded.

[0023] Optionally, the control signal generating circuit further comprises a voltage adjusting unit connected between the output terminal of the voltage generating unit and the input terminal of the voltage inverting unit, for adjusting the slope and intercept of the first voltage-temperature curve respectively, to obtain a second voltage; and the voltage inverting unit is used for inverting the second voltage to obtain the control voltage.

[0024] Since the voltage generating unit can only adjust the slope and intercept of the temperature-voltage curve simultaneously, the voltage adjusting unit can adjust the slope and intercept of the first voltage-temperature curve respectively.

[0025] Optionally, the voltage adjusting unit comprises a second operational amplifier, a fifth resistor and a sixth resistor.

[0026] The output terminal of the voltage generating unit is connected to the non-inverting input terminal of the second operational amplifier, the output terminal of the second operational amplifier is connected to one end of the fifth resistor, the inverting input terminal of the second operational amplifier is connected to the other end of the fifth resistor, the other end of the fifth resistor is connected to one end of the sixth resistor, and the other end of the sixth resistor inputs a reference voltage (VR).

[0027] Optionally, the voltage inverting unit comprises a third operational amplifier, a seventh resistor, an eighth resistor, a ninth resistor and a tenth resistor.

[0028] One end of the seventh resistor is connected to the output terminal of the voltage generating unit or the voltage adjusting unit, and the other end is connected to the inverting input terminal of the third operational amplifier and one end of the eighth resistor, one end of the ninth resistor inputs a threshold voltage, and the other end is connected to the non-inverting input terminal of the third operational amplifier and one end of the tenth resistor, the other end of the eighth resistor is connected to the output terminal of the third operational amplifier, and the other end of the tenth resistor is grounded.

[0029] Optionally, the threshold voltage is a maximum value of the second voltage.

[0030] In addition, in order to solve the influence of the feedback network on the impedance matching in the gain adjustment process, the application further provides a balanced circuit structure for an amplifier with a feedback network, comprising:

[0031] a first amplifier and a second amplifier; wherein the first amplifier and the second amplifier are the amplifier of any one of the preceding.

[0032] a first 90-degree coupler comprising a first through port and a first coupled port, wherein the first through port is connected to the input end of the first amplifier, and the first coupled port is connected to the input end of the second amplifier;

[0033] a second 90-degree coupler comprising a second through port and a second coupled port, wherein the second through port is connected to the output end of the second amplifier, and the second coupled port is connected to the output end of the first amplifier.

[0034] The balanced circuit structure only uses two 90-degree couplers to realize the impedance matching of the amplifier, and has good anti-mismatch characteristics. By combining the balanced circuit structure with the aforementioned amplifier, the gain temperature compensation of the amplifier is realized, and at the same time, it is guaranteed that the balanced circuit structure has good impedance matching characteristics regardless of how the input and output impedances of the first amplifier and the second amplifier change in the gain compensation process.

[0035] The above feedback circuit adjusts the gain of the amplifier by adjusting the load impedance, so that the amplifier gain tends to be close at different operating temperatures, thereby realizing temperature compensation of the amplifier. At the same time, two different ways are proposed to adjust the impedance of the amplifier, which improves the control accuracy of the variable resistance circuit, thereby further improving the accuracy of temperature compensation. In addition, while adjusting the output impedance for temperature compensation, impedance matching can also be achieved by adjusting the impedance, saving the cost and time cost of adjusting the impedance matching device. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a graph of the relationship between the gain of the amplifier without temperature compensation and the temperature and signal frequency.

[0037] Figure 2 is a graph of the relationship between the gain of the amplifier without temperature compensation and the temperature.

[0038] Figure 3 shows the structure principle schematic diagram of the amplifier with temperature compensation proposed by the application.

[0039] Figure 4 Fig. 1(a) and (b) show a simplified small signal model of the amplifier with temperature compensation according to the present application.

[0040] Figure 4 Fig. 1(c) and (d) show the single-ended and differential basic circuit structure of the amplifier according to the present application.

[0041] Figure 5 Fig. 2 shows the relationship between the gain of the amplifier with temperature compensation according to the present application and the resistance value of the feedback network.

[0042] Figure 6 Fig. 3 is a structure diagram of the amplifier with temperature compensation according to the first embodiment of the present application.

[0043] Figure 7 Fig. 4 is a control signal generation circuit structure diagram of the amplifier with temperature compensation according to the first embodiment of the present application.

[0044] Figure 8 Fig. 5(a)-(g) are the relationship diagrams between the various voltages, resistances and gains and the temperature according to the first embodiment of the present application.

[0045] Figure 9 Fig. 6 is a structure diagram of the amplifier with temperature compensation according to the second embodiment of the present application.

[0046] Figure 10 Fig. 7 is a resistance-temperature relationship diagram of the amplifier with temperature compensation according to the second embodiment of the present application.

[0047] Figure 11 Fig. 8 is a structure diagram of the amplifier with temperature compensation according to the third embodiment of the present application.

[0048] Figure 12 Fig. 9 is a structure diagram of the balanced circuit structure for the amplifier according to the fourth embodiment of the present application. DETAILED DESCRIPTION

[0049] Generally, in the case of inputting the same frequency signal, for example, frequency f1, the gain of the amplifier will decrease with the increase of the temperature, as shown in Fig. 1(a). As shown in Fig. 1(b), the corresponding relationship between the working temperature of the amplifier and the gain is a negative correlation, wherein, in some working conditions, -40°C and 105°C are the working temperature threshold of the amplifier. Since the difficulty of increasing the gain of the amplifier itself is much higher than that of decreasing the gain, the present application reduces the gain of the amplifier in the working temperature range to the gain close to the high temperature, thereby reducing the gain fluctuation of the amplifier, and the specific principle is described as follows. Figure 1 Figure 2 ​​

[0050] Figure 3 The schematic diagram of the principle structure of the amplifier with temperature compensation proposed in the present application. The amplifier mainly comprises a compensated amplifier 301, a resistance variable circuit 302 and a control signal generating circuit 303. Among them, the amplifier 301 has a signal input end RFin and a signal output end RFout; the resistance variable circuit 302 is connected between the signal input end and the signal output end; the control signal generating circuit 303 is used for generating a control signal changing with temperature. Among them, the resistance variable circuit is connected between the two ends of the amplifier 301 to form a feedback circuit, so that the load impedance of the amplifier can be changed by changing the resistance of the resistance variable circuit 302 through the control signal. It can be understood that the resistance variable circuit 302 is usually also connected in series with a capacitor to form an RC feedback circuit to isolate the direct current voltage, and in addition, if the capacitor is designed as a variable capacitor, it also has the function of adjusting the load impedance, so as to cooperate with the resistance variable circuit to better adjust the load impedance matching of the amplifier.

[0051] Next, the principle of the circuits in (a) and (b) will be explained in detail with reference to the circuit analysis diagrams in (a) and (b). Figure 4

[0052] Figure 4 (a) is a structural schematic diagram of the common source circuit of the amplifier, Figure 4 (b) is a simplified small signal model of the circuit structure. Among them, Rp is the resistance of the RC feedback circuit (i.e. the resistance variable circuit 302), Cp is the capacitance of the RC feedback circuit, Vi is the input voltage of the amplifier 301, Vo is the output voltage of the amplifier 301, and the remaining part of the structure of the amplifier 301 includes an input end resistance Ri, a power supply end resistance Rd and a transistor M1. In this circuit structure, the following formulas can be obtained according to the circuit law:

[0053]

[0054] Among them, Vx is the gate voltage of the transistor M1, g m is the transconductance of the transistor M1, and Zp is the impedance of the RC feedback circuit. Formula (1) is the impedance calculation formula of the RC feedback circuit, formula (2) is obtained according to the Kirchhoff's current law at node P, and formula (3) is obtained according to the principle that the series circuit current of Vi passing through the RC feedback circuit to Vo is the same.

[0055] Through formula (2), the following formula (4) can be obtained:

[0056]

[0057] By bringing formula (4) into formula (3), the gain of the amplifier can be obtained by solving the ratio of the output voltage Vo of the amplifier 301 to the input voltage Vi of the amplifier 301:​

[0058]

[0059] Here, Av represents the amplifier's gain. It can be seen that the impedance Zp of the RC feedback network affects the gain; when the impedance Zp decreases, the gain Av also decreases. Since this application primarily changes the overall output impedance of the amplifier with the feedback network (i.e., the amplifier's load impedance) by altering the resistance of the feedback network, the relationship between the amplifier's gain and the feedback network's resistance is shown in the curve below. Figure 5 As shown.

[0060] Furthermore, the compensated amplifier 301 can be various types of amplifiers, for example:

[0061] According to their working principle, amplifiers can be classified as follows: Bipolar Junction Transistor (BJT) amplifiers, Field Effect Transistor (FET) amplifiers, High Electron Mobility Transistor (HEMT) amplifiers, and Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) amplifiers.

[0062] Classified by power output: Low noise amplifier (LNA), power amplifier (PA), and driver amplifier.

[0063] Classified by operating frequency: low-frequency radio frequency amplifiers, high-frequency radio frequency amplifiers, microwave amplifiers, and millimeter-wave amplifiers.

[0064] Amplifiers are classified by power amplifier type: Class A amplifiers, Class B amplifiers, Class AB amplifiers, Class C amplifiers, and Class D amplifiers.

[0065] Classified by application field: wireless communication amplifiers, radar amplifiers, satellite communication amplifiers, etc.

[0066] For example, it could also be like... Figure 4 The single-ended amplifier shown in (c) and as shown in (c) Figure 4 The differential amplifier shown in (d) has gates for M1 and M2 that are the two differential inputs. Figure 4 As shown in (c), the radio frequency signal is input to the amplifier from the input terminal RFin and connected to the gate of transistor M1 via a capacitor. The gate of transistor M1 is also connected to the bias voltage VB1 via a resistor, its source is grounded, and its drain is connected to the source of transistor M2. The bias voltage VB2 is connected to the gate of transistor M2 via a resistor, and the gate of transistor M2 is also grounded via a capacitor. Its drain is connected to the power supply voltage VDD via an inductor and to the amplifier output terminal RFout via a capacitor. Figure 4As shown in (d), RFin is one end of a primary coil of a first transformer, and the other end of the primary coil of the first transformer is grounded. A bias voltage VB is connected to the middle of a secondary coil of the first transformer, one end of the secondary coil is connected to the gate of a transistor M1, and the other end of the secondary coil is connected to the gate of a transistor M2, and the gates of the transistors M1 and M2 are two differential input terminals. The sources of the transistors M1 and M2 are both grounded. The drain of the transistor M1 is connected to one end of a primary coil of a second transformer, the drain of the transistor M2 is connected to the other end of the primary coil of the second transformer, and the middle of the primary coil is connected to a power supply voltage VDD. One end of a secondary coil of the second transformer is connected to the output terminal RFout of the amplifier, and the other end of the secondary coil is grounded. The structure of the amplifier can also be a common source structure, a common source and common gate structure, a three-stack structure, etc., and the number and size of the transistors included in the amplifier can be determined according to actual needs.

[0067] Based on the above principles, the present application proposes a plurality of specific embodiments.

[0068] Embodiment one is as follows Figure 6As shown, the control signal generation circuit 601 generates a control voltage in the form of an analog signal, and thus the resistance variable circuit can employ a voltage-controlled MOS tube 602 whose on-resistance varies with voltage. The voltage-controlled MOS tube 602 can be an NMOS tube or a PMOS tube. The control principle of this embodiment is that the greater the gate voltage of the voltage-controlled MOS tube, the smaller the on-resistance in the feedback network, and thus the overall gain of the amplifier is reduced. It can be understood that the voltage-controlled MOS tube 602 is only a schematic structure, and any electronic device or circuit structure that can change resistance according to the control voltage can be applied, for example, a plurality of voltage-controlled MOS tubes in series, which are controlled by dividing the control voltage into multiple paths. Thus, the resistance value of the on-resistance in the resistance variable circuit controlled by the control voltage can accurately control the resistance value, thereby improving the accuracy of temperature compensation, and the range of impedance adjustment can be adjusted by controlling the size of the on-resistance value controlled by the control voltage, so that the amplifier can be temperature compensated in each temperature range, solving the problem of insufficient accuracy and range of temperature compensation in the prior art. The control signal generation circuit includes a voltage generation unit. The voltage generation unit is the front-end circuit of the control signal generation circuit, which has a temperature characteristic to generate a first voltage related to temperature. The first voltage and temperature can be positively correlated or negatively correlated. When the first voltage and temperature are positively correlated, the control signal generation circuit also needs to set a voltage flipping unit to receive the first voltage and flip it, so that the output voltage and temperature are negatively correlated. The voltage output by the voltage flipping unit is the control voltage, and thus the lower the temperature, the greater the control voltage, the smaller the on-resistance of the voltage-controlled MOS tube, and the smaller the output impedance of the amplifier, thereby reducing the gain and making the amplifier gain at low temperature close to that at high temperature. When the first voltage and temperature are negatively correlated, the first voltage can be directly used as the control voltage.

[0069] It can be understood that the voltage generation unit can adjust the first voltage by adjusting the internal device, but it can only adjust the slope and intercept of the first voltage curve (i.e., the relationship curve between the first voltage and temperature) at the same time. The circuit structure of the voltage generation unit is usually complex and difficult to adjust after being determined, and thus a voltage adjustment unit with a relatively simple structure can be set in the control signal generation circuit to adjust the slope and intercept of the first voltage curve at the same time. Thus, when the control signal generation circuit does not include a voltage adjustment unit, the voltage input to the voltage flipping unit is the first voltage; when the control signal generation circuit includes a voltage adjustment unit, the voltage input to the voltage flipping unit is the second voltage. The control signal generation circuit in this embodiment includes a voltage adjustment unit and a voltage flipping unit.

[0070] Figure 7A circuit diagram of a control signal generation circuit including a voltage generation unit 701, a voltage adjustment unit 702, and a voltage inversion unit 703.

[0071] As shown in Figure 7 The voltage generation unit 701 includes a first operational amplifier 71, two transistors, four resistors, and two diodes. The two transistors include a first transistor M71 and a second transistor M72. The four resistors include a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. The two diodes include a first diode D1 and a second diode D2. It can be understood that the first transistor M71 and the second transistor M72 are connected by a plurality of identical transistors. The first transistor M71 includes m1 transistors, and the second transistor M72 includes m2 transistors. Similarly, the first diode D1 includes n1 diodes, and the second diode D2 includes n2 diodes.

[0072] It can be understood that the above scheme uses a plurality of devices to ensure that the gate lengths of the first transistor M71 and the second transistor M72 are the same, the widths satisfy 1:M, and the area ratio of the first diode D1 and the second diode D2 is N. Therefore, the first transistor M71, the second transistor M72, the first diode D1, and the second diode D2 can also include one device that satisfies the above ratio relationship, respectively.

[0073] The second resistor R2, the first resistor R1, and the first diode D1 are connected in series, and are connected in parallel with the third resistor R3 and the second diode D2 connected in series. The inverting input terminal of the first operational amplifier 71 is connected between the third resistor R3 and the second diode D2. The non-inverting input terminal of the first operational amplifier 71 is connected between the second resistor R2 and the first resistor R1. The output terminal of the first operational amplifier 71 is connected to the gate of the first transistor M71. The drain of the first transistor M71 is connected to one end of the second resistor R2 and one end of the third resistor R3. The gate of the second transistor M72 is connected to the gate of the first transistor M71. The drain of the second transistor M72 is connected to one end of the fourth resistor R4 and outputs a first voltage. The source of the first transistor M71 and the source of the second transistor M72 are connected to a power supply VDD. The negative electrode of the first diode D1, the negative electrode of the second diode D2, and the other end of the fourth resistor R4 are grounded. Thus, the first voltage VTC output by the voltage generation unit 701 can be obtained by the following formula:

[0074]

[0075] Wherein, M=m2 / m1, N=n1 / n2, k is the Boltzmann constant, q is the unit charge, and T is the ambient temperature. It can be seen from the above formula that when the circuit structure of the voltage generating unit is determined, the first voltage VTC is only related to the ambient temperature T and is positively correlated. When adjusting the device parameters in the circuit structure, the slope and intercept of the first voltage VTC will change at the same time. It can be seen from the above formula that the voltage generating unit 701 can adjust the slope and intercept of the first voltage VTC by adjusting the resistance values of the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4, the ratio of the gate width of the second transistor M72 and the first transistor M71, and the area ratio of the first diode D1 and the second diode D2.

[0076] The voltage adjusting unit 702 includes a second operational amplifier 72, a fifth resistor R5, and a sixth resistor R6.

[0077] The output end of the voltage generating unit 701 is connected to the positive input end of the second operational amplifier 72, and the first voltage VTC is input to the voltage adjusting unit 702 to generate a second voltage V0. The output end of the second operational amplifier 72 is connected to one end of the fifth resistor R5, the inverting input end of the second operational amplifier 72 is connected to the other end of the fifth resistor R5, the other end of the fifth resistor R5 is connected to one end of the sixth resistor R6, and the other end of the sixth resistor R6 inputs a reference voltage VR. Thus, the second voltage V0 output by the voltage adjusting unit 702 can be obtained by the following formula:

[0078]

[0079] Wherein, the reference voltage VR is a voltage that does not change with temperature and can be generated by a bandgap reference circuit. As can be seen from the above formula (7), by adjusting the resistance values of the fifth resistor R5 and the sixth resistor R6, the slope and intercept of the second voltage V0 can be adjusted based on the first voltage VTC, and the intercept can be adjusted separately by adjusting the size of the reference voltage VR.

[0080] Then, the second voltage V0 is input to the voltage flipping unit 703. The voltage flipping unit 703 includes a third operational amplifier 73, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a tenth resistor R10.

[0081] One end of the seventh resistor R7 is connected to the output terminal of the voltage adjustment unit 702 (or the output terminal of the voltage generation unit 701 when there is no voltage adjustment unit 702), and the other end is connected to the inverting input terminal of the third operational amplifier 73 and one end of the eighth resistor R8. One end of the ninth resistor R9 is connected to the reference voltage V1, and the other end is connected to the non-inverting input terminal of the third operational amplifier 73 and one end of the tenth resistor R10. The other end of the eighth resistor R8 is connected to the output terminal of the third operational amplifier 73, and the other end of the tenth resistor R10 is grounded. The reference voltage V1 can be the maximum value of the second voltage V0, which is the threshold voltage used to limit the control voltage Vctrl. Therefore, the control voltage Vctrl output by the voltage inversion unit 703 can be obtained using the following formula:

[0082]

[0083] The values ​​of resistors R6, R7, R8, R9, and V1 must be set to ensure that Vctrl is greater than 0, so that the output control voltage Vctrl can control the transistor in the variable resistor circuit.

[0084] When R6 = R7 = R8 = R9, as shown in the following formula, the maximum value of the reference voltage V1 is the maximum value of Vo.

[0085] Vctrl = V1 - V0 (8).

[0086] Next reference Figure 8 The temperature compensation principle of this embodiment will be explained in sections (a)-(g).

[0087] Figure 8 (a) shows the amplifier gain as a function of temperature before temperature compensation.

[0088] Figure 8 Figure (b) shows the relationship between the first voltage VTC and temperature, combined with formula (6).

[0089]

[0090] The operating temperature Tmin is usually not 0, so the first voltage changes positively with temperature and still has a positive intercept at the minimum operating temperature.

[0091] Figure 8 (c) is a graph showing the relationship between the second voltage V0 and temperature, combined with formula (7). The intercept can be made zero by adjusting the resistance values ​​of the fifth resistor R5 and the sixth resistor R6 and / or the reference voltage VR. Since the resistance values ​​of the fifth resistor R5 and the sixth resistor R6 are scalars and do not affect their sign, the second voltage also changes positively with temperature, and its maximum value is the reference voltage V1.

[0092] Figure 8 Fig. 2 is a graph showing the relationship between the control voltage Vctrl and the temperature, wherein Figure 8 In Fig. 2, the reference V1 is a fixed voltage value, i.e. only as a parameter representing the maximum value of the second voltage V0, the second voltage V0 is a voltage value that positively correlates with the temperature, and is 0 at the minimum working temperature Tmin and the maximum value is V1, so that the intercept of the control voltage Vctrl at Tmin is V1, and the slope changes from positive to negative, so that the control voltage negatively correlates with the temperature.

[0093] Figure 8 Fig. 2 is a graph showing the relationship between the control voltage Vctrl and the temperature, wherein

[0094] Figure 8 Fig. 2 is a graph showing the relationship between the control voltage Vctrl and the temperature, wherein

[0095] In addition, in Figure 8 In Figs. 2(c)-(e), a saturation section with constant ordinate value is included when approaching the maximum temperature (Tmax), so that the output impedance of the amplifier is constant in a certain temperature range approaching the maximum temperature, resulting in the same amount of gain change caused by the output impedance, i.e. the compensation amount of the temperature compensation performed by the feedback circuit is constant. However, the amplifier itself will still be affected by the temperature, so that the gain of the amplifier will still be affected, resulting in a certain fluctuation of the gain of the amplifier in this temperature range. However, it can be understood that as long as the fluctuation meets the precision requirement of the use of the amplifier, i.e. the temperature compensation is considered to be accurate enough, for example, the gain value of the amplifier working at the maximum working temperature is 30dB, and the precision requirement is less than or equal to 2dB, then the maximum gain of the amplifier after temperature compensation is (30+2)dB, i.e. the temperature compensation is considered to be accurate enough, for example,Figure 9 As shown in (g).

[0096] In the case of circuit area and circuit complexity, the present application proposes a second embodiment of controlling resistance by digital signal. In this embodiment, the control signal can be a digital switch signal, and the resistance variable circuit can be a resistance array, which receives the digital switch signal to adjust the size of the resistance in the resistance variable circuit, thereby adjusting the resistance value of the resistance variable circuit.

[0097] Figure 9 For an example structure of the second embodiment, it includes an amplifier 901, a resistance variable circuit 902, and a control signal generation circuit 903. Among them, the control signal generation circuit 903 includes a temperature sensor 91, an analog-to-digital converter (ADC) 92, a storage module 93, and a control module 94, and the resistance variable circuit 902 includes a resistance array 95. In order to isolate the direct current voltage, the resistance variable circuit is connected in series with a capacitor structure to form an RC feedback circuit, and the output impedance can also be adjusted by adjusting the capacitance value, thereby adjusting the output matching effect.

[0098] In this embodiment, since the control signal in the form of digital signal is used, there is no device with temperature characteristics in the control signal generation circuit, so an additional temperature sensor 91 is needed to obtain the real-time temperature information of the working environment of the amplifier. It can be understood that the real-time temperature information is in the form of an analog signal, so an analog-to-digital converter 92 is also needed to receive the real-time temperature information in the form of an analog signal and convert it into a digital temperature signal in the form of a digital signal. The storage module 93 stores the corresponding relationship between the digital temperature signal and the digital switch signal. The control module 94 is connected with the analog-to-digital converter 92 and the storage module 93 at the same time to obtain the digital temperature signal from the analog-to-digital converter 92 and to obtain the digital switch signal corresponding to the digital temperature signal from the storage module 93, so as to convert the digital temperature signal into the digital switch signal. It can be understood that the corresponding relationship between the digital temperature signal and the digital switch signal can be obtained through a large number of prior experiments, or can be obtained through simulation.

[0099] After the control module 94 obtains the digital switch signal, it sends the digital switch signal to the resistance array 95 to control the size of the resistance connected by the resistance array 95. As a non-limiting embodiment, the resistance array 95 can be a plurality of parallel resistors with different / same resistance values, each of which is connected in series with a switch, and the digital switch signal can be used to control the disconnection of a certain resistor to control the connection of a certain resistor or multiple resistors, thereby realizing the control of the connected resistance value, such as Figure 10For example, if a high-level signal "1" represents a closed switch and a low-level signal "0" represents an open switch, a first resistance is 10 kΩ, a second resistance is 20 kΩ, a third resistance is 30 kΩ, and a fourth resistance is 40 kΩ, when the digital switch signal is 1000, the resistance value connected is 10 kΩ; when the digital switch signal is 0100, the resistance value connected is 20 kΩ, and so on. The resistance-temperature relationship curve is as shown in FIG. 4. Figure 11 In addition, the on-off of multiple switches can also be controlled simultaneously. For example, when the digital switch signal is 1001, the resistance value connected is 10*40 / (10+40) = 8 kΩ (parallel resistance value). In addition, the resistance array can also be a plurality of resistances connected in series, each of which is connected in parallel with a switch, and the short circuit of a certain resistance can be controlled through the digital switch signal, thereby realizing the control of the connected resistance value. For example, if a high-level signal "1" represents a closed switch and a low-level signal "0" represents an open switch, a first resistance is 10 kΩ, a second resistance is 20 kΩ, a third resistance is 30 kΩ, and a fourth resistance is 40 kΩ, when the digital switch signal is 1100, the resistance value connected is 30+40 = 70 kΩ; when the digital switch signal is 1001, the resistance value connected is 10+40 = 50 kΩ. As the temperature decreases, the large resistance path is gradually switched to the small resistance path, the output impedance of the amplifier decreases, the gain decreases, and the gain of the amplifier at high and low temperatures tends to be close, thereby realizing temperature compensation. In addition, the range of impedance adjustment can be adjusted by controlling the number of resistances turned on in the resistance array, thereby realizing temperature compensation of the amplifier in each temperature range and solving the problem of insufficient precision and range of temperature compensation in the prior art.

[0100] It can be understood that, in this embodiment, the digital switch signal is only used to control the on-off of a certain switch and is not associated with a specific resistance value.

[0101] When the resistance of the resistance variable circuit changes, the impedance of the RC feedback circuit composed of the resistance variable circuit and the capacitor changes, and the output impedance of the amplifier is affected, thereby affecting the output matching. Embodiment three can realize impedance matching during temperature compensation by setting a capacitance variable circuit in the feedback loop of the amplifier to adjust the capacitance. As shown in FIG. 5, based on the circuit shown in FIG. 4, the capacitance variable circuit can be designed as a capacitance array 111, and the digital switch signal is also used to control the connected capacitance of the capacitance variable circuit. The control logic is the same as that of the resistance array, and will not be described here. Preferably, the corresponding relationship between the appropriate digital switch signal and the digital temperature signal is obtained through simulation combined with experiments. Figure 9 Figure 12 As shown in FIG. 5, based on the circuit shown in FIG. 4, the capacitance variable circuit can be designed as a capacitance array 111, and the digital switch signal is also used to control the connected capacitance of the capacitance variable circuit. The control logic is the same as that of the resistance array, and will not be described here. Preferably, the corresponding relationship between the appropriate digital switch signal and the digital temperature signal is obtained through simulation combined with experiments.

[0102] ​For the case of using multiple amplifiers, the application also proposes a balanced circuit structure with simpler structure and lower cost, as shown in Embodiment Four. The balanced circuit structure mainly includes a first amplifier 121, a second amplifier 122, a first 90-degree coupler 123, and a second 90-degree coupler 124. ​

[0103] The first 90-degree coupler 123 includes a first input port IN, a first through port 1231, a first coupling port 1232, and a first isolation port. The first through port 1231 is connected to the input end of the first amplifier, the first coupling port 1232 is connected to the input end of the second amplifier, the first isolation port is connected to one end of a 50-ohm resistor, and the other end of the 50-ohm resistor is grounded. The second 90-degree coupler 124 includes a second input port OUT (the second input port OUT serving as the output port of the balanced structure), a second through port 1241, a second coupling port 1242, and a second isolation port. The second through port 1241 is connected to the output end of the second amplifier, the second coupling port 1242 is connected to the output end of the first amplifier, the second isolation port is connected to one end of a 50-ohm resistor, and the other end of the 50-ohm resistor is grounded.

[0104] An input signal enters the first coupling port 1232 of the balanced circuit structure from the input end IN and is phase-shifted by 90 degrees. After the reflected wave from the input end of the second amplifier 122, i.e., the first coupling port 1232, is reflected back to the input end IN of the balanced circuit structure, it is again phase-shifted by 90 degrees. Therefore, the reflected wave entering the first coupling port 1232 is phase-shifted by 180 degrees. The signal entering the first through port 1231 of the balanced circuit structure from the input end IN has the same phase as the input signal, and thus the two reflected waves cancel each other out after superposition at the input end IN of the balanced circuit structure, resulting in good impedance matching characteristics of the input end IN of the balanced circuit structure. The impedance matching principle of the output end OUT of the balanced circuit structure is the same as that of the input port IN, and thus is not described again.

[0105] The input and output of the balanced circuit structure both use 90-degree couplers, and the balanced circuit structure has good mismatch resistance characteristics due to the characteristic of the two reflected waves of the 90-degree couplers canceling each other out. By combining the balanced circuit structure with the amplifiers in the foregoing embodiments, the temperature compensation of the amplifiers is achieved while ensuring output matching.

[0106] ​The foregoing description of the exemplary embodiment of this application has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the precise form disclosed. Many modifications and variations are possible in light of this disclosure. It was noted above that any of the features of one embodiment can be utilized in any of the other embodiments, and vice versa. It is intended that the scope of the application be defined by the claims appended hereto rather than by the description presented hereinabove. While in accordance with the Patent Statutes, only the best mode and preferred embodiments have been presented and described in detail, it is to be understood that the application can be practiced otherwise than as specifically explained and illustrated without departing from the spirit and scope of the application.

[0107] Furthermore, various operations will be described as multiple discrete operations, in a manner that is most helpful in understanding the illustrative embodiments; however, the order of description should not be construed as to imply that these operations are necessarily order dependent. In particular, these operations need not be performed in the order of presentation.

[0108] The terms "comprise", "have" and "include" are synonymous, unless the context dictates otherwise. The phrase "A / B" means "A or B". The phrase "A and / or B" means "(A and B) or (A or B)".

[0109] As used herein, the terms "module" or "unit" can refer to, be part of, or include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor and / or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and / or other suitable components that provide the described functionality.

[0110] In the drawings, some of the structural or methodological acts are shown in a particular arrangement and / or order. It should be understood that such is merely an illustration and the specific arrangement and / or order of the acts can be varied. In some embodiments, the acts can be arranged at different times in a different order. Additionally, in some embodiments, intervening acts can be used, or not used, and not all acts can be used in every embodiment. Further, in some embodiments, one or more of the acts can be used in conjunction, at least partially, with one or more other acts. In some embodiments, the acts can be implemented by one or more components of the apparatuses described herein.

[0111] It should be understood that although terms hereof, such as "first" and "second", etc., can be used in describing various elements or data, these elements or data should not be limited by these terms. These terms are only used to distinguish one element or data from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element without departing from the scope of example embodiments.

[0112] It is noted that, in this document, like reference numerals and letters designate like items in the various drawings, and that changes and modifications can be made in the described embodiments, and their components, without departing from the scope of the application.

[0113] While the application has been illustrated and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details can be made therein without departing from the spirit and scope of the application.

Claims

1. An amplifier with temperature compensation, characterized by, The application relates to an amplifier, comprising: an amplifier having a signal input end and a signal output end; a resistance variable circuit connected between the signal input end and the signal output end, used for adjusting the resistance of the resistance variable circuit based on a control signal to adjust the load impedance of the amplifier; a control signal generation circuit used for generating the control signal varying with temperature and outputting the control signal to the resistance variable circuit.

2. The amplifier of claim 1, wherein, The control signal is a digital switch signal, and the resistance variable circuit is a resistance array used for receiving the digital switch signal and adjusting the resistance turned on in the resistance array to adjust the resistance value of the resistance variable circuit.

3. The amplifier of claim 2, wherein, The control signal generation circuit comprises: a temperature sensor used for acquiring real-time temperature information of an environment; an analog-to-digital converter connected with the temperature sensor and used for converting the real-time temperature information into a digital temperature signal; a storage module having a corresponding relationship between the digital temperature signal and the digital switch signal; a control module connected with the analog-to-digital converter and the storage module, used for converting the digital temperature signal into the digital switch signal based on the digital temperature signal acquired from the analog-to-digital converter and the corresponding digital switch signal found in the storage module.

4. The amplifier of claim 3, wherein, The amplifier further comprises a capacitance variable circuit used for receiving the digital switch signal and adjusting the capacitance value of the capacitance variable circuit to adjust the output impedance of the amplifier.

5. The amplifier of claim 4, wherein, The capacitance variable circuit is a capacitance array.

6. The amplifier of claim 1, wherein, The control signal is a control voltage, and the resistance variable circuit comprises at least one voltage-controlled MOS tube, and a plurality of voltage-controlled MOS tubes are connected in series or in parallel.

7. The amplifier of claim 6, wherein, The control signal generation circuit comprises: a voltage generation unit used for generating a first voltage varying with temperature.

8. The amplifier of claim 7, wherein, When the first voltage and temperature are positively correlated, the control signal generation circuit further comprises: a voltage flipping unit connected with the output end of the control signal generation circuit and used for flipping the voltage input into the voltage flipping unit to obtain the control voltage negatively correlated with temperature.

9. The amplifier of claim 7, wherein, When the first voltage and temperature are negatively correlated, the first voltage is the control voltage.

10. The amplifier of claim 7, wherein, The voltage generation unit comprises: a first operational amplifier, two transistors, four resistors and two diodes, the two transistors comprising a first transistor and a second transistor, the four resistors comprising a first resistor, a second resistor, a third resistor and a fourth resistor, and the two diodes comprising a first diode and a second diode, The second resistor, the first resistor, the first diode are connected in series, and are connected in parallel with the third resistor and the second diode connected in series, the inverting input terminal of the first operational amplifier is connected between the third resistor and the second diode, the non-inverting input terminal of the first operational amplifier is connected between the second resistor and the first resistor, the output terminal of the first operational amplifier is connected to the gate of the first transistor, the drain of the first transistor is connected to one end of the second resistor and one end of the third resistor, the gate of the second transistor is connected to the gate of the first transistor, the drain of the second transistor is connected to one end of the fourth resistor and outputs the first voltage, the source of the first transistor and the source of the second transistor are connected to a power supply, the negative electrode of the first diode, the negative electrode of the second diode and the other end of the fourth resistor are grounded.

11. The amplifier of claim 8, wherein, The control signal generation circuit further comprises a voltage adjustment unit connected between the output terminal of the voltage generation unit and the input terminal of the voltage flipping unit, for adjusting the slope and intercept of the first voltage-temperature relationship curve respectively to obtain a second voltage; and the voltage flipping unit is configured to flip the second voltage to obtain the control voltage.

12. The amplifier of claim 11, wherein, The voltage adjustment unit comprises a second operational amplifier, a fifth resistor, a sixth resistor; The output terminal of the voltage generation unit is connected to the non-inverting input terminal of the second operational amplifier, the output terminal of the second operational amplifier is connected to one end of the fifth resistor, the inverting input terminal of the second operational amplifier is connected to the other end of the fifth resistor, the other end of the fifth resistor is connected to one end of the sixth resistor, and the other end of the sixth resistor inputs a reference voltage (VR).

13. The amplifier of claim 12, wherein, The voltage flipping unit comprises a third operational amplifier, a seventh resistor, an eighth resistor, a ninth resistor and a tenth resistor, One end of the seventh resistor is connected to the output terminal of the voltage generation unit or the voltage adjustment unit, and the other end is connected to the inverting input terminal of the third operational amplifier and one end of the eighth resistor, one end of the ninth resistor inputs a threshold voltage, the other end is connected to the non-inverting input terminal of the third operational amplifier and one end of the tenth resistor, the other end of the eighth resistor is connected to the output terminal of the third operational amplifier, and the other end of the tenth resistor is grounded.

14. The amplifier of claim 13, wherein, The threshold voltage is the maximum value of the second voltage.

15. The amplifier of claim 1, wherein, The amplifier is a single-ended amplifier or a differential amplifier.

16. A balanced circuit structure for an amplifier, characterized by It comprises: a first amplifier and a second amplifier, wherein the first amplifier and the second amplifier are the amplifier of any one of claims 1-15; a first 90-degree coupler comprising a first through port and a first coupled port, wherein the first through port is connected to the input terminal of the first amplifier, and the first coupled port is connected to the input terminal of the second amplifier; a second 90-degree coupler comprising a second through port and a second coupled port, wherein the second through port is connected to the output terminal of the second amplifier, and the second coupled port is connected to the output terminal of the first amplifier.

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