Low power consumption, low noise and high linearity instrument trans-impedance amplifier

Abstract

The application relates to a low-power-consumption low-noise high-linearity instrument trans-impedance amplifier, which comprises a complementary input pair, an adaptive bias circuit and a bias current source; the complementary input pair is composed of a complementary input differential pair and a source negative feedback structure; the source negative feedback structure makes the equivalent source stage negative feedback resistance value of the complementary input differential pair be related to the size of the difference Vid between two input signals of the complementary input differential pair, improves the linearity of the complementary input pair when the Vid is small, and avoids current saturation of the complementary input pair when the Vid is large; the complementary input pair is biased by the adaptive bias circuit, can generate corresponding dynamic current when the input signal of the complementary input pair changes, and realizes low power consumption, low noise and high linearity; the bias current source is used for providing the bias current of the adaptive bias circuit. The beneficial effect is high linearity, support for rail-to-rail input, and satisfaction of low power consumption and low noise applications.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of analog integrated circuit technology, in particular to a low-power low-noise high-linearity instrumentation trans-impedance amplifier. BACKGROUND

[0002] In recent years, with the increasing demand for mobile medical health monitoring, wearable electronic devices are becoming more and more common in people's lives, and the performance of the sensing interface circuit as the entrance of signal sensing also determines the performance parameters of the entire sensing system to some extent. In order to improve the spatio-temporal resolution of signal sensing, realize effective diagnosis, and improve the endurance, it is an inevitable trend to develop ultra-low-power multi-channel wearable sensing interface circuit, and the current domain frequency division multiplexing wearable sensing interface circuit has broad application prospects because it can alleviate the trade-off between power consumption and channel number and the gain mismatch problem.

[0003] As one of the important modules in the current domain frequency division multiplexing wearable sensing interface circuit, the instrumentation trans-impedance amplifier not only needs to meet the basic requirements of low power consumption and low noise, but also needs to meet other performance requirements: 1. Wearable electronic devices generally work under low power supply voltage conditions, so the instrumentation trans-impedance amplifier needs to be able to work normally when the power supply reaches two rails, that is, it needs to support rail-to-rail (Rail-to-Rail full swing) input. Common rail-to-rail input structures include PMOS, NMOS complementary input pair structures with additional control circuits and single input pair structures with adaptive bias circuits such as flipped voltage followers (FVF). 2. The instrumentation trans-impedance amplifier has a flat transconductance curve within the input voltage range, but the large signal nonlinearity of the transistor itself will limit its linear input range and affect the signal quality of the entire interface circuit, so it needs to have high linearity. Common linearization techniques include source negative feedback, cross-coupled differential pairs, and body effect of MOS transistors. The existing instrumentation trans-impedance amplifier structure still suffers from nonlinearity problems, and it is difficult to simultaneously meet low power consumption, low noise and high linearity, and it is even less likely to achieve rail-to-rail input, making it difficult to apply to current domain frequency division multiplexing sensing interface applications.

[0004] The present application improves the instrumentation trans-impedance amplifier to solve the technical problem of the existing instrumentation trans-impedance amplifier structure suffering from nonlinearity problems. SUMMARY

[0005] The purpose of the present application is to provide an instrumentation trans-impedance amplifier with high linearity, supporting rail-to-rail input, and meeting low power consumption and low noise applications.

[0006] In order to achieve the above object, the technical scheme adopted by the present application is a low-power-consumption, low-noise and high-linearity instrument trans-impedance amplifier, comprising a complementary input pair, an adaptive biasing circuit and a biasing current source; the complementary input pair is composed of a metal oxide semiconductor field effect transistor-based complementary input differential pair and a source negative feedback structure based on a metal oxide semiconductor field effect transistor; the source negative feedback structure makes the equivalent source stage negative feedback resistance value of the complementary input differential pair related to the size of the difference Vid between the two input signals Vip and Vin of the complementary input differential pair, improves the linearity of the complementary input pair when Vid is small, and avoids the complementary input pair from generating current saturation when Vid is large; the complementary input pair is biased by the adaptive biasing circuit, which can generate corresponding dynamic current when the input signals Vip and Vin of the complementary input pair change, thereby realizing low power consumption, low noise and high linearity; the biasing current source is used to provide the biasing current of the adaptive biasing circuit.

[0007] Preferably, the complementary input differential pair is composed of two P-type metal oxide semiconductor field effect transistors M1 and M2 with the same channel length and width and two N-type metal oxide semiconductor field effect transistors M3 and M4 with the same channel length and width, the gates of M1 and M3 are connected to serve as a voltage signal Vip input end, the drains of M1 and M3 are connected to serve as a current signal Ion output end, the gates of M2 and M4 are connected to serve as a voltage signal Vin input end, and the drains of M2 and M4 are connected to serve as a current signal Iop output end; the source negative feedback structure is composed of two P-type metal oxide semiconductor field effect transistors M5 and M6 with the same channel length and width, two N-type metal oxide semiconductor field effect transistors M7 and M8 with the same channel length and width, and four resistors R1, R2, R3 and R4 with the same length and width, the drain and gate of M5 are connected to the source and gate of M1 respectively, one end of R1 is connected to the drain of M5 and the other end is connected to the source of M5, the drain and gate of M6 are connected to the source and gate of M2 respectively, one end of R2 is connected to the drain of M6 and the other end is connected to the source of M6, the drain and gate of M7 are connected to the source and gate of M3 respectively, one end of R3 is connected to the drain of M7 and the other end is connected to the source of M7, the drain and gate of M8 are connected to the source and gate of M4 respectively, and one end of R4 is connected to the drain of M8 and the other end is connected to the source of M8.

[0008] Preferably, the adaptive bias circuit consists of a common bias flip voltage follower and a balancing resistor; the adaptive bias circuit is used to provide an extremely low static current and generate a corresponding dynamic current when the input signals Vip and Vin change; the bias current of the common bias flip voltage follower is proportional to the current of the complementary input pair, and is used to improve the linearity of the complementary input pair when Vid is small; the balancing resistor has no current in static state, so that the instrument transconductance amplifier can better tolerate the impact of process fluctuations.

[0009] Preferably, the common bias flip voltage follower is composed of two P-type metal oxide semiconductor field effect transistors M with the same channel length and width. 1A 、M 2A , two P-type metal oxide semiconductor field effect transistors M with the same channel length and width 1B 、M 2B , two N-type metal oxide semiconductor field effect transistors M with the same channel length and width 3A 、M 4A , two N-type metal oxide semiconductor field effect transistors M with the same channel length and width 3B 、M 4B And four resistors R5, R6, R7, R8 of the same length and width; the ratio of the channel width to the channel length of M1 and M2 is the same as that of M 1A 、M 2A The ratio of the channel width to the channel length is X:1, and the ratio of the channel width to the channel length of M3 and M4 is X:1. 3A 、M 4A The ratio of the channel width to the channel length is X:1; the ratio of the length to the width of R5, R6, R7, and R8 to the length to the width of R1, R2, R3, and R4 is X:1; M 1A The drain and M 2A The drain of M 1A The gate of the M is connected to the voltage signal Vip, 1A The source of is connected to one end of R5, M 2A The gate of M is connected to the voltage signal Vin, 1A The source of M is connected to one end of R6; 1B The drain of is connected to the other end of R5, M 1B The gate and M 1A The drain of M 1B The source of M is connected to the positive power supply voltage Vdd, 2B The drain of is connected to the other end of R6, M 2B The gate and M 2A The drain of M 2B The source of M is connected to the positive power supply voltage Vdd;3A The drain and M 4A The drain of M 3A The gate of M is connected to the voltage signal Vip, 3A The source of is connected to one end of R7, M 4A The gate of M is connected to the voltage signal Vin, 4A The source of M is connected to one end of R8; 3B The drain of R7 is connected to the other end of M 3B The gate and M 3A The drain of M 3B The source of M is connected to the negative power supply voltage Vss. 4B The drain of R8 is connected to the other end, M 4B The gate and M 4A The drain of M 4B The source is connected to the negative power supply voltage Vss.

[0010] Preferably, the balancing resistor is composed of two resistors R9 and R 10 Composition; one end of R9 and M 1B The drain of R9 is connected to the source of M6, and the other end of R9 is connected to the source of M6. 2B The drain of M5 is connected to the source of R 10 One end and M 3B The drain of M8 is connected to the source of M8, R 10 The other end of M 4B The drain of M1 is connected to the drain of M2 and the source of M7.

[0011] Preferably, the bias current source is composed of two current sources I bp , I bn Composition; I bp The inflow end and M 1A The drain and M 2A The drain of the device is connected to the negative power supply voltage Vss; bn The inflow end is connected to the positive power supply voltage Vdd, and the outflow end is connected to M 3A The drain and M 4A The drain is connected.

[0012] Compared with the prior art, the low-power, low-noise, and high-linearity instrument transconductance amplifier of the present invention has the following beneficial effects: the instrument transconductance amplifier is designed by adopting a complementary input differential pair, an adaptive bias based on a novel flip voltage follower, and a novel source-level negative feedback technology, supports rail-to-rail input and can exhibit excellent linear performance under low power consumption conditions, while having low noise, and is suitable for applications in current domain frequency division multiplexing sensing interfaces.

Brief Description of the Drawings

[0013] Figure 1 It is a kind of low-power low-noise high linearity instrument trans-impedance amplifier overall structure frame schematic diagram.

[0014] Figure 2 It is a kind of low-power low-noise high linearity instrument trans-impedance amplifier complementary input pair schematic diagram.

[0015] Figure 3 It is a kind of low-power low-noise high linearity instrument trans-impedance amplifier adaptive bias circuit schematic diagram.

[0016] Figure 4 It is a kind of low-power low-noise high linearity instrument trans-impedance amplifier bias current source schematic diagram.

[0017] Figure 5 It is a kind of low-power low-noise high linearity instrument trans-impedance amplifier transmission characteristic curve when bias current source takes I1 and I2 (I1

[0018] Figure 6 It is a kind of low-power low-noise high linearity instrument trans-impedance amplifier equivalent trans-impedance curve when bias current source takes I1 and I2 (I1

[0019] Figure 7 It is a kind of low-power low-noise high linearity instrument trans-impedance amplifier output signal total harmonic distortion changes with input signal frequency and amplitude curve when bias current source is I1.

[0020] Figure 8 It is a kind of low-power low-noise high linearity instrument trans-impedance amplifier output signal total harmonic distortion changes with input signal frequency and amplitude curve when bias current source is I2.

[0021] The reference signs and components involved in the drawings are shown as follows: 1, complementary input pair, 11, complementary input differential pair, 12, source negative feedback structure, 2, adaptive bias circuit, 21, common bias flip voltage follower, 22, balanced resistance, 3, bias current source.

CONCRETE IMPLEMENTATION

[0022] The application will be further described below in conjunction with examples and with reference to the drawings.

[0023] Example

[0024] The embodiment realizes a kind of low-power low-noise high linearity instrument trans-impedance amplifier.

[0025] Figure 1 It is a kind of low-power low-noise high linearity instrument trans-impedance amplifier overall structure frame schematic diagram. As Figure 1As shown in the figure, the low-power low-noise high-linearity instrument trans-impedance amplifier of the embodiment comprises a complementary input pair 1, an adaptive bias circuit 2 and a bias current source 3.

[0026] Figure 2 As shown in the figure, the low-power low-noise high-linearity instrument trans-impedance amplifier of the embodiment comprises a complementary input pair 1, an adaptive bias circuit 2 and a bias current source 3. Figure 2 As shown in the figure, the low-power low-noise high-linearity instrument trans-impedance amplifier of the embodiment comprises a complementary input pair 1, an adaptive bias circuit 2 and a bias current source 3.

[0027] As shown in the figure, the low-power low-noise high-linearity instrument trans-impedance amplifier of the embodiment comprises a complementary input pair 1, an adaptive bias circuit 2 and a bias current source 3.

[0028] In this embodiment, the source negative feedback structure 12 makes the resistance value of the equivalent source negative feedback resistance related to the size of the difference Vid between the two input signals Vip and Vin. When Vid is small, the equivalent resistance of M5, M6 and M7, M8 is much larger than the resistance value of the resistors R1, R2, R3, R4, so the equivalent source negative feedback resistance is determined by the resistors R1, R2, R3, R4, which plays a role in improving linearity. When Vid is positive and large, M5 and M8 are in the cutoff region and are not considered, while the equivalent resistance of M6 and M7 is much smaller than the resistance value of the resistors R2, R3, so the equivalent source negative feedback resistance is determined by the equivalent resistance of M6 and M7, which avoids current saturation of the complementary input pair 1. When Vid is negative and large, the case is similar to the positive case, M6 and M7 are in the cutoff region and are not considered, while the equivalent resistance of M5 and M8 is much smaller than the resistance value of the resistors R1, R4, so the equivalent source negative feedback resistance is determined by the equivalent resistance of M5 and M8, which avoids current saturation of the complementary input pair 1.

[0029] Figure 3 A low-power low-noise high-linearity instrument transconductance amplifier adaptive bias circuit schematic diagram. As shown in Figure 3 the adaptive bias circuit of the low-power low-noise high-linearity instrument transconductance amplifier includes a common bias inverting voltage follower 21 and a balanced resistor 22. The common bias inverting voltage follower 21 is composed of two P-type metal oxide semiconductor field effect transistors (M 1A , M 2A ) with the same channel length and width, two P-type metal oxide semiconductor field effect transistors (M 1B , M 2B ) with the same channel length and width, two N-type metal oxide semiconductor field effect transistors (M 3A , M 4A ) with the same channel length and width, two N-type metal oxide semiconductor field effect transistors (M 3B , M 4B ) with the same channel length and width, and four resistors (R5, R6, R7, R8) with the same length and width. Among them, the ratio of the channel width to the channel length of M1 and M2 of the complementary input differential pair 11 to the ratio of the channel width to the channel length of M 1A , M 2A is X:1, and similarly, the ratio of the channel width to the channel length of M3 and M4 of the complementary input differential pair 11 to the ratio of the channel width to the channel length of M 3A , M 4A is X:1; the ratio of the length to the width of R5, R6, R7, R8 to the ratio of the length to the width of R1, R2, R3, R4 of the source negative feedback structure 12 is X:1; and the ratio of the length to the width of M1A the drain of M 2A is connected to the voltage signal Vip, the source is connected to one end of R5, and the gate of M 2A is connected to the voltage signal Vin, the source is connected to one end of R6; the drain of M 1B is connected to the other end of R5, the gate is connected to M 1A , the source is connected to the positive power voltage Vdd; the drain of M 2B is connected to the other end of R6, the gate is connected to M 2A , the source is connected to the positive power voltage Vdd; the drain of M 3A is connected to the drain of M 4A , the gate is connected to the voltage signal Vip, the source is connected to one end of R7, and the gate of M 4A is connected to the voltage signal Vin, the source is connected to one end of R8; the drain of M 3B is connected to the other end of R7, the gate is connected to M 3A , the source is connected to the negative power voltage Vss; the drain of M 4B is connected to the other end of R8, the gate is connected to M 4A , the source is connected to the negative power voltage Vss.

[0030] The balanced resistor 22 is composed of two resistors (R9, R 10 ) of the same length and the same width. One end of R9 is connected to the drain of M 1B of the common-bias inverting voltage follower 21, and simultaneously connected to the source of M6 of the source negative feedback structure 12, and the other end is connected to the drain of M 2B of the common-bias inverting voltage follower 21, and simultaneously connected to the source of M5 of the source negative feedback structure 12; one end of R 10 is connected to the drain of M 3B of the common-bias inverting voltage follower 21, and simultaneously connected to the source of M8 of the source negative feedback structure 12, and the other end is connected to the drain of M 4B of the common-bias inverting voltage follower 21, and simultaneously connected to the source of M7 of the source negative feedback structure 12.

[0031] In this embodiment, the principle of the adaptive bias circuit 2 is to provide extremely low static current for the instrument transconductance amplifier while generating corresponding dynamic current when the input signal changes. M 1A , M 2A , M 3A , M 4Aand R5, R6, R7, R8 and M1, M2, M3, M4 and R1, R2, R3, R4 in the complementary input pair 1 constitute a proportional relationship, so that the current of the complementary input pair 1 is proportional to the bias current of the common biasing inverting voltage follower 21, which improves the robustness of the whole instrument trans-impedance amplifier to process, voltage and temperature (PVT). The common biasing inverting voltage follower 21 also makes the V1, V4 voltage rise and the V2, V3 voltage drop when the Vid is positive and small, reduces the equivalent gate-source voltage variation range of the complementary input pair 1, thereby reducing the variation of the output current, and plays a linearization role; in the case that the Vid is negative and small, the V2, V3 voltage rises and the V1, V4 voltage drops, which reduces the equivalent gate-source voltage variation range of the complementary input pair 1, thereby reducing the variation of the output current, and plays a linearization role. The balancing resistor 22 has no current in the static state, and therefore does not affect the static power consumption, and its role is to make the whole structure better tolerate the influence of process fluctuations.

[0032] Figure 4 It is a schematic diagram of a low-power low-noise high-linearity instrument trans-impedance amplifier bias current source. As shown in Figure 4 , the low-power low-noise high-linearity instrument trans-impedance amplifier of the embodiment, the bias current source includes two current sources I bp , I bn with equal current; the inflow end of I bp is connected with the drain of M 1A and the drain of M 2A , and the outflow end is connected with the negative power supply voltage Vss; the inflow end of I bn is connected with the positive power supply voltage Vdd, and the outflow end is connected with the drain of M 3A and the drain of M 4A .

[0033] In the embodiment, the bias current source 3 provides a bias current for the adaptive biasing circuit.

[0034] Figure 5 It is a transmission characteristic curve of a low-power low-noise high-linearity instrument trans-impedance amplifier when the bias current source takes I1 and I2 (I1 Figure 5 , the differential output current and the Vid show a linear relationship when the absolute value of the Vid is small, and when the absolute value of the Vid further increases, although there is inevitably a non-linear problem, the differential output current still maintains a small amplitude increase, avoids the current from reaching the saturation value, and realizes rail-to-rail input.

[0035] Figure 6It is the equivalent transconductance curve of a low-power, low-noise, and high-linearity instrumentation transconductance amplifier when the bias current sources are I1 and I2 (I1 < I2) respectively. As Figure 6 shown, in an embodiment of a low-power, low-noise, and high-linearity instrumentation transconductance amplifier, when the absolute value of Vid is small, the equivalent transconductance fluctuates little and has high linearity. When the absolute value of Vid approaches the power supply voltage, the equivalent transconductance is greater than 0, alleviating the problem that the equivalent transconductance of the existing instrumentation transconductance amplifier approaches 0 at large swings.

[0036] Figure 7 It is the curve of the total harmonic distortion of the output signal of a low-power, low-noise, and high-linearity instrumentation transconductance amplifier varying with the frequency and amplitude of the input signal when the bias current source is I1. As Figure 7 shown, in an embodiment of a low-power, low-noise, and high-linearity instrumentation transconductance amplifier, the frequency of the input signal is not the main factor affecting the total harmonic distortion of the output signal. When the amplitude of the input signal is less than 565 mV pp the total harmonic distortion of the output signal is less than -60 dB; when the amplitude is less than 1.05 V pp the total harmonic distortion of the output signal is less than -40 dB; the total harmonic distortion of the output signal at full swing is less than -27 dB.

[0037] Figure 8 It is the curve of the total harmonic distortion of the output signal of a low-power, low-noise, and high-linearity instrumentation transconductance amplifier varying with the frequency and amplitude of the input signal when the bias current source is I2. As Figure 8 shown, in an embodiment of a low-power, low-noise, and high-linearity instrumentation transconductance amplifier, the frequency of the input signal is not the main factor affecting the total harmonic distortion of the output signal. When the amplitude of the input signal is less than 528 mV pp the total harmonic distortion of the output signal is less than -60 dB; when the amplitude is less than 1.35 V pp the total harmonic distortion of the output signal is less than -40 dB; the total harmonic distortion of the output signal at full swing is less than -26 dB.

[0038] In an embodiment of a low-power, low-noise, and high-linearity instrumentation transconductance amplifier, in addition to the characteristics of low power and low noise, it also realizes rail-to-rail input based on the complementary input differential pair 11 and the adaptive bias circuit 2, and uses the source negative feedback structure 12 and the common bias flip voltage follower 21 to improve linearity, which is applicable to multi-channel wearable sensing interface circuits with low power, low noise, and high linearity.

[0039] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and supplements can be made, and these improvements and supplements should also be regarded as the protection scope of the present invention.

Claims

1. A low power low noise high linearity instrumentation trans-impedance amplifier characterized by: The application relates to a complementary input pair (1), an adaptive bias circuit (2) and a bias current source (3); the complementary input pair (1) is composed of a metal oxide semiconductor field effect transistor-based complementary input differential pair (11) and a metal oxide semiconductor field effect transistor-based source negative feedback structure (12); the source negative feedback structure (12) makes the equivalent source stage negative feedback resistance value of the complementary input differential pair (11) related to the size of the difference Vid between two input signals Vip and Vin of the complementary input differential pair (11), improves the linearity of the complementary input pair (1) when Vid is small, and avoids current saturation of the complementary input pair (1) when Vid is large; the complementary input pair (1) is biased by the adaptive bias circuit (2), can generate corresponding dynamic current when input signals Vip and Vin of the complementary input pair (1) change, and realizes low power consumption, low noise and high linearity; the bias current source (3) is used for providing the bias current of the adaptive bias circuit (2); The complementary input differential pair (11) is composed of two P-type metal oxide semiconductor field effect transistors M1 and M2 with the same channel length and the same width and two N-type metal oxide semiconductor field effect transistors M3 and M4 with the same channel length and the same width, the gate of M1 is connected with the gate of M3 and used as a voltage signal Vip input end, the drain of M1 is connected with the drain of M3 and used as a current signal Ion output end, the gate of M2 is connected with the gate of M4 and used as a voltage signal Vin input end, and the drain of M2 is connected with the drain of M4 and used as a current signal Iop output end; the source negative feedback structure (12) is composed of two P-type metal oxide semiconductor field effect transistors M5 and M6 with the same channel length and the same width, two N-type metal oxide semiconductor field effect transistors M7 and M8 with the same channel length and the same width and four resistors R1, R2, R3 and R4 with the same length and the same width, the drain of M5 is connected with the source of M1, one end of R1 is connected with the drain of M5, the other end of R1 is connected with the source of M5, the drain of M6 is connected with the source of M2, one end of R2 is connected with the drain of M6, the other end of R2 is connected with the source of M6, the drain of M7 is connected with the source of M3, one end of R3 is connected with the drain of M7, the other end of R3 is connected with the source of M7, the drain of M8 is connected with the source of M4, and one end of R4 is connected with the drain of M8, the other end of R4 is connected with the source of M8; The adaptive bias circuit (2) is composed of a common bias inverting voltage follower (21) and a balanced resistance (22); the adaptive bias circuit (2) is used for providing extremely low static current and generating corresponding dynamic current when the input signal Vip, Vin changes; the bias current of the common bias inverting voltage follower (21) is proportional to the current of the complementary input pair (1), and is used for improving the linearity of the complementary input pair (1) when Vid is small; the balanced resistance (22) has no current in the static state, so that the instrument trans-impedance amplifier tolerates the influence of process fluctuations better.

2. The low power low noise high linearity instrumentation trans- impedance amplifier of claim 1, wherein: The co-biasing flip voltage follower (21) is composed of two P-type metal oxide semiconductor field effect transistors M 1A , 2A , two P-type metal oxide semiconductor field effect transistors M 1B , 2B , two N-type metal oxide semiconductor field effect transistors M 3A , 4A , two N-type metal oxide semiconductor field effect transistors M 3B , 4B and four resistors R5, R6, R7, R8 with the same length and width; the ratio of the channel width to the channel length of M 1A , 2A is X:1, the ratio of the channel width to the channel length of M 3A , 4A is X:1; the ratio of the length to the width of R5, R6, R7, R8 and the ratio of the length to the width of R1, R2, R3, R4 is X:1; the drain of M 1A is connected to the drain of M 2A , the gate of M 1A is connected to a voltage signal Vip, the source of M 1A is connected to one end of R5, the gate of M 2A is connected to a voltage signal Vin, the source of M 1A is connected to one end of R6; the drain of M 1B is connected to the other end of R5, the gate of M 1B is connected to the drain of M 1A , the source of M 1B is connected to a positive power voltage Vdd, the drain of M 2B is connected to the other end of R6, the gate of M 2B is connected to the drain of M 2A , the source of M 2B is connected to a positive power voltage Vdd; the drain of M 3A is connected to the drain of M 4A , the gate of M 3A is connected to a voltage signal Vip, the source of M 3A is connected to one end of R7, the gate of M 4A is connected to a voltage signal Vin, the source of M 4A is connected to one end of R8; the drain of M 3B is connected to the other end of R7, the gate of M 3B is connected to the drain of M 3A The drain of M 3B The source of M 4B The drain of M 4B The gate of M 4A The drain of M 4B The source of M 3. The low power low noise high linearity instrumentation trans- impedance amplifier of claim 2, wherein: The balancing resistor (22) is composed of two resistors R9, R 10 of the same length and width; one end of R9 is connected to the drain of M 1B and the source of M6, and the other end of R9 is connected to the drain of M 2B and the source of M5; one end of R 10 is connected to the drain of M 3B and the source of M8, and the other end of R 10 is connected to the drain of M 4B and the source of M7.

4. The low power low noise high linearity instrumentation trans- impedance amplifier of claim 3, wherein: The bias current source (3) is composed of two current sources I bp , bn with equal currents; the inflow end of I bp is connected with the drain of M 1A and the drain of M 2A , and the outflow end is connected with the negative power voltage Vss; the inflow end of I bn is connected with the positive power voltage Vdd, and the outflow end is connected with the drain of M 3A and the drain of M 4A .

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