A precision low-side bidirectional current sense amplifier with power ground as output center

Abstract

The present application belongs to current detection device, and relates to a precision low-side bidirectional current detection amplifier with power ground as output flip center, which comprises a common mode level lifter, a chopping stabilized offset compensation circuit, a bidirectional amplification circuit and an output stage. IN The common mode level lifter amplifies the near ground differential signal V sensor according to the ratio of resistance R1 and input resistance R sensor The chopping stabilized offset compensation circuit samples the offset and noise of the common mode level lifter and compensates them. sensor The bidirectional amplification circuit further amplifies V OUT , suppresses its own offset and noise through chopping modulation technology, and controls the output stage switching according to the polarity of V OUT , so as to realize bidirectional current detection with power ground as output flip center. The current detection amplifier uses chopping stabilized technology and chopping modulation technology to reduce circuit offset and noise, and adopts bidirectional amplification circuit to make the output level independent of external reference voltage, so that the output voltage V IN has power ground as output flip center and depends on the absolute value of the precision amplified input voltage V sensor .

Description

Technical Field

[0001] This invention relates to a precision low-side bidirectional current sensing amplifier with power ground as the output switching center, belonging to the field of current sensing devices. Background Technology

[0002] In many electronic systems such as current monitoring / overcurrent protection devices, current loop systems, programmable current sources, or battery current meters, monitoring circuits detect the magnitude and direction of current to monitor system activity in real time, thereby achieving corresponding dynamic control and safety protection. Therefore, a current sense amplifier capable of accurately detecting current signals and converting them into input differential signals for amplification is crucial in system control. Resistance sensing is currently the most accurate current sensing technique, offering greater operability compared to combining different techniques for bidirectional current sensing. However, existing bidirectional current sense amplifiers implemented using resistance sensing methods heavily rely on external reference voltages for their output level and cannot achieve near-ground output. This invention focuses on developing a precision low-side bidirectional current sense amplifier with power ground as the output switching center. Summary of the Invention

[0003] This invention proposes a precision low-side bidirectional current sense amplifier with power supply ground as the output switching center. The aim is to effectively reduce the input noise and offset voltage of the current sense amplifier, improve common-mode rejection capability, and achieve precise current amplification by employing chopper stabilization and chopper modulation techniques, through modulation, demodulation, and dynamic offset compensation. The first stage of the current sense amplifier includes a common-mode level booster and a chopper stabilization and offset compensation circuit. The chopper stabilization technique significantly reduces the interference of external noise and the impact of internal offset and drift. The second stage is a bidirectional amplification circuit, employing a parallel structure of two unidirectional detection branches. Chopper modulation technology is used to reduce the circuit offset voltage and achieve bidirectional detection. The third stage is the output stage, connected to the bidirectional amplification circuit via two PMOS transistors, realizing bidirectional current detection with power supply ground as the output switching center.

[0004] The core idea of ​​this invention is to employ a parallel structure of two unidirectional detection branches, connected and switched through an output stage, to achieve bidirectional current detection with the power supply ground as the output switching center; and to utilize both chopper stabilization and chopper modulation techniques to effectively reduce the input noise and offset voltage of the current sensing amplifier; the current signal I... load Through resistor R sensor Converted to the input differential voltage V of the current sense amplifier sensor V sensorAfter being amplified and level-lifted by a common-mode level booster, the amplified difference signal is input to a bidirectional amplifier circuit. The outputs of the bidirectional amplifier circuit are connected to the gate terminals of transistors M1 and M2 in the output stage, respectively, controlling transistors M1 and M2 to follow the voltage V. sensor The common-mode level riser alternates between positive and negative switching to achieve bidirectional current detection with the power supply ground as the output switching center. The common-mode level riser includes a PMOS input stage OPA. G11 and two-stage AB class drive amplifier stage OPA G2 The chopper-stabilized offset compensation circuit consists of the modulator CH. 11 PMOS type input stage OTA1 G11 and OTA1 G12 OTA1 folded cascode structure G2 High-pass filter (HPF), demodulator (CH) 12 Integrator OTA2 and PMOS input stage OPA G12 It consists of components whose output is connected to the common-mode level booster (OPA). G2 The input terminal compensates for the offset and noise of the common-mode level booster; the bidirectional amplifier circuit consists of two parallel unidirectional detection branches using chopper modulation technology, each including a modulator CH. 21 OTA3, a folded Cascode structure for NMOS input transistors, and a demodulator CH. 22 The low-pass filter LPF and the active filter OTA4 are connected to the output through the drain terminals of the output stage M1 and M2 transistors, and form a negative feedback loop with the input terminal of the bidirectional amplifier circuit through the source terminals of the output stage M1 and M2 transistors.

[0005] The technical solution adopted in this invention is as follows:

[0006] The precision low-side bidirectional current sensing amplifier with power supply ground as the output switching center includes a first stage consisting of a common-mode level booster and a chopper-stabilized offset compensation circuit, a second stage consisting of a bidirectional amplification circuit, and a third stage consisting of an output stage (M1 and M2 transistors).

[0007] The common-mode level booster is implemented based on a fully differential operational amplifier, including a PMOS input stage OPA. G11 and two-stage AB class drive amplifier stage OPA G2 ;

[0008] The chopper stability offset compensation circuit consists of a modulator CH 11 PMOS type input stage OTA1 G11 and OTA1 G12 OTA1 folded Cascode structure G2 High-pass filter (HPF), demodulator (CH) 12Integrator OTA2 and PMOS input stage OPA G12 Composition; the modulator and demodulator consist of four switches, which are controlled to alternately turn on and off by an external non-overlapping clock signal;

[0009] The bidirectional amplifier circuit consists of two parallel unidirectional detection branches employing chopper modulation technology; the two unidirectional detection branches share a single modulator CH. 21 ; Unidirectional detection branch except modulator CH 21 In addition, it also includes the folded Cascode structure OTA3 of the NMOS input transistor and the demodulator CH. 22 Low-pass filter (LPF), active filter (OTA4);

[0010] The output stage consists of two PMOS transistors M1 and M2 connected at their drain terminals;

[0011] The connection relationships of each module in the bidirectional current sense amplifier are as follows: The input terminal of the common-mode level booster is connected to an external input resistor R. IN Resistor R1 is connected between the input and output of the common-mode level riser; the input of the chopper-stabilized offset compensation circuit is connected to the input of the common-mode level riser, and the output of the chopper-stabilized offset compensation circuit is connected to the OPA of the common-mode level riser. G11 The output is connected in parallel and connected to the OPA of the common-mode level booster. G2 Input: Two unidirectional detection branches are connected in parallel to form a bidirectional amplifier circuit, and share a modulator CH. 21 The input terminal of the bidirectional amplifier circuit is connected to the output terminal of the common-mode level booster through resistor R2. The output terminal of the bidirectional amplifier circuit is connected to the gate terminals of transistors M1 and M2 in the output stage. The drain terminals of transistors M1 and M2 in the output stage are connected to the output resistor R. OUT The source terminals of the output stage transistors M1 and M2 are connected to the input terminal of the bidirectional amplifier circuit.

[0012] The common-mode level booster is based on resistor R1 and input resistor R IN Ratio amplification of differential signal V sensor It also achieves level boosting at the output of the common-mode level booster, ensuring the normal operation of the subsequent bidirectional amplifier circuit;

[0013] The chopper-stabilized offset compensation circuit samples the offset and noise of the common-mode level riser, compensates the common-mode level riser in the form of current, and suppresses its own offset and noise through chopper modulation technology.

[0014] The bidirectional amplifier circuit further amplifies the input difference and controls the output stage switching to achieve the amplification function with the power supply ground as the output switching center; and it suppresses the offset and noise of the bidirectional amplifier circuit itself through chopper modulation technology.

[0015] The output stage, under the control of the bidirectional amplifier circuit, according to V sensor The polarity can be switched autonomously to achieve bidirectional current detection with the power supply ground as the switching center.

[0016] The working process of the bidirectional current detection includes:

[0017] S1: Set the input voltage, amplification factor, output voltage, and load current parameters, which includes the following sub-steps:

[0018] S11: The input voltage supplies power to the common-mode level booster, chopper stabilization offset compensation circuit, bidirectional amplifier circuit, and output stage of the current sensing amplifier.

[0019] S12: The magnitude of the amplification factor is determined by the input resistance R. IN and output resistance R OUT set up;

[0020] S13: The magnitude of the output voltage is determined by the differential signal V. sensor And the magnification factor determines it;

[0021] S14: The magnitude of the load current is determined by the output voltage V. OUT and output resistance R OUT Decide;

[0022] S2: Common-mode level booster amplifies and boosts the differential voltage V sensor The chopper-stabilized offset compensation circuit compensates for the offset of the common-mode level booster, and the chopper-stabilized offset compensation circuit suppresses its own offset. Specifically, it includes the following sub-steps:

[0023] S21: Common-mode level booster based on resistor R1 and input resistor R IN The ratio of the amplified differential signal V sensor At the same time, it converts the common-mode voltage at the input terminal centered on the power supply ground into a high-level common-mode voltage at the output terminal;

[0024] S22: The chopper-stabilized offset compensation circuit samples the offset and noise of the common-mode level booster, and transmits the signal via OPA. G12 The common-mode level booster is compensated in the form of current.

[0025] S23: The chopper-stabilized offset compensation circuit uses chopper modulation technology to suppress its own offset and noise, and specifically includes the following sub-steps:

[0026] S231: The chopper-stabilized offset compensation circuit uses the modulator CH 11 CH demodulator 12The input signal is modulated and demodulated. The offset and noise of the chopper stabilization offset compensation circuit are eliminated by the high-pass filter HPF and the integrator OTA2, while the input signal of the chopper stabilization offset compensation circuit is unaffected.

[0027] S232: OTA1 of the chopper-stabilized offset compensation circuit G12 Used to suppress the ripple generated by the DC offset of OTA1 in the chopper stability offset compensation circuit, thereby achieving high ripple suppression;

[0028] S3: The bidirectional amplifier circuit suppresses its own offset and controls the turn-off and turn-on of output stage transistors M1-M2 to achieve a voltage output with the power supply ground as the switching center. Specifically, it includes the following sub-steps:

[0029] S31: The bidirectional amplifier circuit uses a modulator CH 21 CH demodulator 22 The input signal is modulated and demodulated. The offset and noise of the bidirectional amplifier circuit are modulated to a high frequency and then eliminated by a low-pass filter LPF and an active filter OTA4, while the input signal of the bidirectional amplifier circuit remains unaffected.

[0030] S32: The bidirectional amplifier circuit connects to the gate terminals of the output stage transistors M1 and M2, controlling the turn-on and turn-off of the corresponding output stage PMOS transistors to achieve voltage output with the power supply ground as the switching center.

[0031] S4: The PMOS transistor in the output stage, together with the bidirectional amplifier circuit, forms a negative feedback loop, causing the output voltage V to... OUT With power supply ground as the reference level, the differential voltage V sensor The absolute value is linearly amplified.

[0032] Beneficial effects

[0033] The precision low-side bidirectional current sensing amplifier with power supply ground as the output switching center proposed in this invention has the following advantages compared with the prior art:

[0034] 1. The precision low-side bidirectional current sensing amplifier adopts a two-way unidirectional sensing branch parallel structure, controls the output stage switching, and uses the power supply ground as the output switching center to achieve near-ground bidirectional current sensing, and detects differential voltage V. sensor The absolute value is linearly amplified;

[0035] 2. The precision low-side bidirectional current sensing amplifier uses a common-mode level booster to boost the input common-mode voltage near ground, thereby achieving bidirectional current sensing with near-ground input and near-ground output, and the output level does not depend on any external reference voltage;

[0036] 3. The precision low-side bidirectional current sensing amplifier uses two offset suppression techniques, chopper stabilization and chopper modulation, to reduce circuit offset and noise, thereby achieving high-precision current sensing and amplification.

[0037] 4. The precision low-side bidirectional current sense amplifier uses an external input resistor R. IN and external output resistor R OUT It allows for flexible configuration of amplification factors, enabling a wide dynamic range for current detection. Attached Figure Description

[0038] Figure 1 This is an overall block diagram of a precision low-side bidirectional current sensing amplifier with power ground as the output switching center according to the present invention.

[0039] Figure 2 This is a circuit diagram of a common-mode level booster in a precision low-side bidirectional current sense amplifier with power supply ground as the output switching center, including an OPA. G11 and OPA G2 ;

[0040] Figure 3 This is a schematic diagram of the modulator and demodulator in a precision low-side bidirectional current detection amplifier with power ground as the output switching center according to the present invention;

[0041] Figure 4 This is a circuit diagram of OTA1, a chopper-stabilized offset compensation circuit in a precision low-side bidirectional current-sensing amplifier with power supply ground as the output switching center, according to the present invention. It includes OTA1. G12 OTA1 G11 and OTA1 G2 ;

[0042] Figure 5 This invention relates to the OTA2 and OPA components of a chopper-stabilized offset compensation circuit in a precision low-side bidirectional current-sensing amplifier with power supply ground as the output switching center. G12 Circuit diagram;

[0043] Figure 6 This is the OTA3 and OTA4 circuit diagram of the bidirectional amplification circuit in a precision low-side bidirectional current detection amplifier with power supply ground as the output switching center according to the present invention.

[0044] Figure 7 This invention relates to a common-mode feedback circuit used in the chopper-stabilized offset compensation circuit and the bidirectional amplification circuit of a precision low-side bidirectional current detection amplifier with power supply ground as the output switching center.

[0045] Figure 8This invention relates to a common-mode feedback circuit used in a common-mode level booster of a precision low-side bidirectional current sense amplifier with power supply ground as the output switching center.

[0046] Figure 9 This is a transient simulation comparison diagram of the offset suppression of a precision low-side bidirectional current sense amplifier with power supply ground as the output switching center under near-ground input and output conditions, according to the present invention.

[0047] Figure 10 This is a simulation result of the equivalent input noise of a precision low-side bidirectional current sense amplifier with power ground as the output switching center according to the present invention. Detailed Implementation

[0048] The following description, in conjunction with embodiments and accompanying drawings, further illustrates and details the circuit modules and working process of a precision low-side bidirectional current detection amplifier with power ground as the output switching center according to the present invention.

[0049] Example 1

[0050] This invention employs chopper stabilization and chopper modulation techniques, using a parallel structure of two unidirectional detection branches to achieve low-noise, low-offset, high-precision, low-side bidirectional current detection with power supply ground as the output switching center. This embodiment illustrates that this invention is applicable to the acquisition and amplification of weak current signals. Since weak current signals are often distributed in the lower frequency band, and the main sources of noise in traditional CMOS amplifiers are flicker noise in the low-frequency band and thermal noise across the entire frequency band, it is necessary to reduce the low-frequency flicker noise of the amplifier to meet the requirements of weak current signal detection. Traditional current sensing amplifiers oscillate up and down around an externally applied reference level, heavily relying on the external reference voltage, and cannot achieve near-ground output. To overcome these shortcomings, a precision low-side bidirectional current sensing amplifier with power supply ground as the output switching center is needed. The bidirectional current sensing amplifier described in this invention is perfectly suited for weak current signal detection.

[0051] The overall block diagram of the precision low-side bidirectional current sense amplifier with power supply ground as the output switching center is as follows: Figure 1 As shown, it includes a common-mode level booster, a chopper-stabilized offset compensation circuit, a bidirectional amplifier circuit, and an output stage. The input terminal of the common-mode level booster is connected to an external input resistor R. IN Resistor R1 is connected between the input and output of the common-mode level riser; the input of the chopper-stabilized offset compensation circuit is connected to the input of the common-mode level riser, and the output of the chopper-stabilized offset compensation circuit is connected to the OPA of the common-mode level riser. G11 The output is connected in parallel and connected to the OPA of the common-mode level booster. G2 Input: Two unidirectional detection branches are connected in parallel to form a bidirectional amplifier circuit, and share a modulator CH.21 The input terminal of the bidirectional amplifier circuit is connected to the output terminal of the common-mode level booster through resistor R2. The output terminal of the bidirectional amplifier circuit is connected to the gate terminals of transistors M1 and M2 in the output stage. The drain terminals of transistors M1 and M2 in the output stage are connected to the output resistor R. OUT The source terminals of the output stage transistors M1 and M2 are connected to the input terminal of the bidirectional amplifier circuit.

[0052] The common-mode level booster includes a PMOS input stage OPA. G11 and two-stage AB class drive amplifier stage OPA G2 The common-mode level booster is based on resistor R1 and input resistor R. IN Ratio amplification of differential signal V sensor It also achieves level boosting at the output of the common-mode level booster, ensuring the normal operation of the subsequent bidirectional amplifier circuit;

[0053] The chopper stability offset compensation circuit consists of a modulator CH 11 PMOS type input stage OTA1 G11 and OTA1 G12 OTA1 folded Cascode structure G2 High-pass filter (HPF), demodulator (CH) 12 Integrator OTA2 and PMOS input stage OPA G12 Composition: The modulator and demodulator consist of four switches, which are alternately turned on and off by an external non-overlapping clock signal; the chopper-stabilized offset compensation circuit samples the offset and noise of the common-mode level riser, compensates the common-mode level riser in the form of current, and suppresses its own offset and noise through chopper modulation technology;

[0054] The bidirectional amplifier circuit consists of two parallel unidirectional detection branches employing chopper modulation technology; the two unidirectional detection branches share a single modulator CH. 21 ; Unidirectional detection branch except modulator CH 21 In addition, it also includes the folded Cascode structure OTA3 of the NMOS input transistor and the demodulator CH. 22 Low-pass filter LPF, active filter OTA4; bidirectional amplifier circuit further amplifies the input difference, controls the output stage switching, and realizes the amplification function with the power supply ground as the output switching center; and suppresses the offset and noise of the bidirectional amplifier circuit itself through chopper modulation technology;

[0055] The output stage consists of two PMOS transistors M1 and M2 connected at their drain terminals. Under the control of the bidirectional amplifier circuit, it outputs power according to V. sensor The polarity can be switched autonomously to achieve bidirectional current detection with the power supply ground as the switching center.

[0056] The operation of the precision low-side bidirectional current-sensing amplifier with power supply ground as the output switching center includes the following steps:

[0057] A: Set the input voltage, amplification factor, output voltage, and load current parameters, which includes the following sub-steps:

[0058] A1. Set the input voltage V DD ;

[0059] The input voltage V DD The current sense amplifier is powered by the common-mode level booster, chopper-stabilized offset compensation circuit, bidirectional amplifier circuit, and output stage. In this example, V... DD It is 1.2V.

[0060] A2. Set the magnification factor;

[0061] The amplification factor is determined by the input resistance R. IN and output resistance R OUT In this example, the maximum magnification is limited to 100, and the minimum is 10.

[0062] A3. Set the output voltage V OUT ;

[0063] The output voltage V OUT The magnitude is determined by the differential signal V sensor The maximum output voltage is determined by the amplification factor; in this example, the maximum output voltage is 0.5V and the minimum is 0V.

[0064] A4. Set the load current I OUT ;

[0065] The load current I OUT The magnitude is determined by the output voltage V OUT and output resistance R OUT In this example, the load current range is determined to be 0–25 μA.

[0066] B: Common-mode level booster amplifies and boosts the differential voltage V sensor The chopper-stabilized offset compensation circuit compensates for the offset of the common-mode level booster, and the chopper-stabilized offset compensation circuit suppresses its own offset. Specifically, it includes the following sub-steps:

[0067] B1. Common-mode level booster amplifies and boosts the differential voltage V. sensor ;

[0068] The common-mode level booster is based on a fully differential operational amplifier, depending on the relationship between resistor R1 and input resistor R. IN The ratio of the amplified differential signal V sensorAt the same time, it converts the common-mode voltage at the input terminal centered on the power supply ground into a high-level common-mode voltage at the output terminal;

[0069] B2. The chopper-stabilized offset compensation circuit compensates for the offset of the common-mode level booster.

[0070] The chopper-stabilized offset compensation circuit samples the offset and noise of the common-mode level booster and passes it through the OPA. G12 Offset compensation for the common-mode level booster is performed in the form of current.

[0071] B3. The chopper-stabilized offset compensation circuit suppresses its own offset, which specifically includes the following sub-steps:

[0072] B31, The chopper-stabilized offset compensation circuit uses the modulator CH 11 CH demodulator 12 The input signal is modulated and demodulated. The offset and noise of the chopper stabilization offset compensation circuit are eliminated by the high-pass filter HPF and the integrator OTA2, while the input signal of the chopper stabilization offset compensation circuit is unaffected.

[0073] B32, OTA1 of the chopper-stabilized offset compensation circuit G12 Used to suppress the ripple generated by the DC offset of OTA1 in the chopper stability offset compensation circuit, thereby achieving high ripple suppression;

[0074] C: The bidirectional amplifier circuit suppresses its own offset and controls the turn-off and turn-on of the output stage transistors M1-M2 to achieve an output voltage with the power supply ground as the switching center. This includes the following sub-steps:

[0075] C1. The bidirectional amplifier circuit suppresses its own offset;

[0076] The bidirectional amplifier circuit uses a modulator CH 21 CH demodulator 22 The input signal is modulated and demodulated. The offset and noise of the bidirectional amplifier circuit are modulated to a high frequency and then eliminated by a low-pass filter LPF and an active filter OTA4, while the input signal of the bidirectional amplifier circuit remains unaffected.

[0077] C2, controls the output stage to turn off and on;

[0078] The bidirectional amplifier circuit connects to the gate terminals of the output stage transistors M1 and M2, controlling the on and off states of the corresponding output stage PMOS transistors to achieve an output voltage with the power supply ground as the switching center.

[0079] D: The PMOS transistor conducting in the output stage, together with the bidirectional amplifier circuit, forms a negative feedback loop, causing the output voltage V to... OUT With power supply ground as the reference level, the differential voltage V sensor The absolute value is linearly amplified.

[0080] Example 2

[0081] This embodiment illustrates that the current sense amplifier uses a common-mode level booster based on a fully differential operational amplifier to sample and amplify the near-ground level signal at the input terminal; it also illustrates that the current sense amplifier uses a bidirectional amplifier circuit composed of two parallel unidirectional sensing branches, and achieves amplification with the power supply ground as the output switching center by controlling the switching of the output stage; and it further illustrates that the current sense amplifier uses two offset suppression techniques, chopper stabilization and chopper modulation, to achieve low offset, high precision, and low noise current sense amplification.

[0082] The precision low-side bidirectional current-sensing amplifier with power supply ground as the output switching center includes a common-mode level booster, a chopper-stabilized offset compensation circuit, a bidirectional amplification circuit, and an output stage; in this embodiment, the input resistor R is selected. IN The output resistance is 200–2000Ω. OUT The circuit has a 20kΩ resistor, a gain of 10–100, and an output voltage of V. sensor ×R OUT / R IN The maximum output voltage is 0.5V, and the minimum output voltage is 0.

[0083] The common-mode level booster, such as Figure 2 As shown, it consists of a PMOS type input stage OPA. G11 and the two-level Class-AB structure OPA G2 The required common-mode feedback circuit is as follows: Figure 8 As shown; in this example, M P11 M P12 For PMOS type input pair transistors, VB1 to VB6 provide bias voltages, and CMFB is M. P1 M P2 Provides common-mode feedback voltage; M N5 M N6 and M P5 M P6 It is a floating current source structure, with two pairs of transistors conducting synchronously, pulling up and pushing down together to drive M. P7 M P8 and M N7 M N8 It provides a large current drive capability; capacitors C1 and C2 provide frequency compensation for the common-mode level booster to ensure circuit stability; the input terminal V of the common-mode level booster... INP_OPAG11 and V INN_OPAG11 The output of the common-mode level booster is connected via resistor R1; the input of the common-mode level booster is V. INP_OPAG11 and V INN_OPAG11 Through resistor R INConnect an external sensing resistor R sensor The two ends; the common-mode level booster is based on the resistor R1 and the input resistor R IN The ratio amplification of the near-ground differential signal V sensor This enables level boosting, ensuring the normal operation of the subsequent bidirectional amplifier circuit.

[0084] The chopper-stabilized offset compensation circuit consists of the modulator CH 11 PMOS type input stage OTA1 G11 and OTA1 G12 OTA1 folded Cascode structure G2 High-pass filter (HPF), demodulator (CH) 12 Integrator OTA2 and PMOS input stage OPA G12 Composition; in this example, the modulator and demodulator are as follows: Figure 3 As shown, it consists of four switches, which are controlled to alternately turn on and off by external non-overlapping clock signals CH1 and CH2; the OTA1 G11 OTA1 G12 and OTA1 G2 like Figure 4 As shown, the required common-mode feedback circuit is as follows: Figure 7 As shown, M P9 M P10 and M P11 M P12 For the two sets of PMOS input pairs, VB1 to VB4 provide bias voltages, and CMFB is M. P1 M P2 Provides common-mode feedback voltage; OTA1 G11 With OTA1 G2 The folded cascode amplifier that constitutes the PMOS input pair is OTA1, and OTA1 G12 This constitutes a ripple suppression circuit, attenuating the ripple generated by the DC offset of OTA1, thereby achieving high ripple suppression; the OTA2 and OPA... G12 like Figure 5 As shown, the common-mode feedback circuit required for OTA2 is as follows: Figure 7 As shown, M P6 M P7 and M P8 M P9 For the two sets of PMOS input pairs, VB1 to VB4 provide bias voltages, and CMFB is M. P1 M P2 Provides common-mode feedback voltage; the chopper-stabilized offset compensation circuit uses the modulator CH 11 CH demodulator 12The input signal is modulated and demodulated. The offset and noise of the chopper-stabilized offset compensation circuit are eliminated by a high-pass filter (HPF) and an integrator (OTA2), while the input signal of the chopper-stabilized offset compensation circuit remains unaffected. The chopper-stabilized offset compensation circuit samples the offset and noise at the input of the common-mode level booster and passes it through an OPA. G12 Connect to OPA G2 Offset compensation for the common-mode level booster is performed in the form of current.

[0085] The bidirectional amplifier circuit consists of two unidirectional detection branches connected in parallel; the two unidirectional detection branches share a single modulator CH. 21 ; Unidirectional detection branch except modulator CH 21 In addition, it also includes the folded Cascode type OTA3 of the NMOS input transistor and the demodulator CH. 22 Low-pass filter LPF, active filter OTA4; OTA3 and OTA4 are as follows Figure 6 As shown, the common-mode feedback circuit required for OTA3 is as follows: Figure 7 As shown; M N5 M N6 M is an NMOS input pair transistor. P6 M P7 For PMOS type input pair transistors, VB1 to VB4 provide bias voltages, and CMFB is M. P1 M P2 It provides common-mode feedback voltage; the bidirectional amplifier circuit further amplifies the input difference and controls the output stage switching to achieve the amplification function with the power supply ground as the output switching center; through chopper modulation technology, the bidirectional amplifier circuit can suppress its own offset and noise.

[0086] Figure 9 The transient simulation verification of this invention under typical conditions using a 65nm CMOS process is presented. The input resistance R is selected. IN The output resistance is 200Ω. OUT The transient simulation output voltage triangular wave waveform with a resistance of 20kΩ and a circuit gain of 100; and the selection of the input resistance R. IN The output resistance is 2kΩ, and the output resistance R is 2kΩ. OUT The transient simulation output voltage triangular wave waveform is shown when the Ω is 20kΩ and the circuit gain is 10. It can be seen that the output voltage triangular wave waveform under offset conditions (three offset conditions correspond to three line types) almost overlaps with the output voltage triangular wave waveform under no offset conditions (no ripple), and the ripple is less than 1.6mV.

[0087] Figure 10 Noise simulation verification of this invention under typical conditions using a 65nm CMOS process is presented. The input resistance R is selected. INThe output resistance is 200Ω. OUT Simulation results of equivalent input noise with a 20kΩ resistor and a circuit gain of 100 are presented. It can be seen that when both offset suppression techniques are in operation, the system's equivalent input root-mean-square noise voltage decreases from 429μV. RMS Reduced to 230nV RMS At 1 kHz, the input-related noise spectral density is 27 nV / √Hz. Compared with the circuit without offset suppression, the equivalent input noise of the system is significantly reduced.

[0088] The above description is merely a preferred embodiment of the present invention, and the present invention should not be limited to the content disclosed in this embodiment and the accompanying drawings. Any equivalent or modified embodiments made without departing from the spirit of the present invention fall within the scope of protection of the present invention.

Claims

1. A precision low-side bidirectional current-sensing amplifier with power supply ground as the output switching center, comprising a first stage consisting of a common-mode level booster and a chopper-stabilized offset compensation circuit, a second stage consisting of a bidirectional amplification circuit, and a third stage consisting of an output stage (transistors M1 and M2); The input terminal of the common-mode level booster is connected to an external input resistor R. IN Resistor R1 is connected between the input and output terminals of the common-mode level booster; The input end of the chopper stability imbalance compensation circuit is connected with the input end of the common mode level lifter, the output end of the chopper stability imbalance compensation circuit is connected with the OP G11 A output end of the common mode level lifter in parallel, and the OP G2 A output end of the common mode level lifter is connected; two one-way detection branches are connected in parallel to form a bidirectional amplification circuit, and share a modulator CH 21 The input end of the bidirectional amplification circuit is connected with the output end of the common mode level lifter through a resistor R2, and the output end of the bidirectional amplification circuit is connected with the gate end of output stage M1 and M2 tubes; the drain end of the output stage M1 and M2 tubes is connected with an output resistor R OUT The source end of the output stage M1 and M2 tubes is connected with the input end of the bidirectional amplification circuit; The common-mode level lifter amplifies the near-earth differential signal V IN according to the ratio of resistance R1 to input resistance R sensor , and realizes the level lifting of the output end of the common-mode level lifter, and ensures the normal work of the later-stage bidirectional amplification circuit. The chopper-stabilized offset compensation circuit samples the offset and noise of the common-mode level riser, compensates the common-mode level riser in the form of current, and suppresses its own offset and noise through chopper modulation technology. The bidirectional amplifier circuit further amplifies the input difference and controls the output stage switching to achieve the amplification function with the power supply ground as the output switching center; and it suppresses the offset and noise of the bidirectional amplifier circuit itself through chopper modulation technology. The output stage autonomously switches according to the polarity of V sensor to realize bidirectional current detection with the power ground as the output flip center. The working process of the bidirectional current detection includes: S1: Set the input voltage, amplification factor, output voltage, and load current parameters; S2: Common-mode level booster amplifies and boosts the differential voltage V sensor The chopper-stabilized offset compensation circuit compensates for the offset of the common-mode level booster; the chopper-stabilized offset compensation circuit suppresses its own offset. S3: The bidirectional amplifier circuit suppresses its own offset and controls the turn-off and turn-on of the output stage transistors M1-M2 to achieve a voltage output with the power supply ground as the switching center. S4: The PMOS transistor in the output stage, together with the bidirectional amplifier circuit, forms a negative feedback loop, causing the output voltage V to... OUT With power supply ground as the reference level, the differential voltage V sensor The absolute value is linearly amplified.

2. The current sensing amplifier according to claim 1, characterized in that, The common-mode level booster is implemented based on a fully differential operational amplifier, including a PMOS input stage OPA. G11 and two-stage AB class drive amplifier stage OPA G2 .

3. The current sensing amplifier according to claim 1, characterized in that, The chopper stability offset compensation circuit consists of a modulator CH 11 PMOS type input stage OTA1 G11 and OTA1 G12 OTA1 folded Cascode structure G2 High-pass filter (HPF), demodulator (CH) 12 Integrator OTA2 and PMOS input stage OPA G12 The modulator and demodulator consist of four switches, which are controlled to alternately turn on and off by an external non-overlapping clock signal.

4. The current sensing amplifier according to claim 1, characterized in that, The bidirectional amplifier circuit consists of two parallel unidirectional detection branches employing chopper modulation technology; the two unidirectional detection branches share a single modulator CH. 21 ; Unidirectional detection branch except modulator CH 21 In addition, it also includes the folded Cascode structure OTA3 of the NMOS input transistor and the demodulator CH. 22 Low-pass filter (LPF) and active filter (OTA4).

5. The current sensing amplifier according to claim 1, characterized in that, The output stage consists of two PMOS transistors, M1 and M2, connected at their drain terminals.

6. The current sensing amplifier according to claim 1, characterized in that, Employing both chopper stabilization and chopper modulation techniques to suppress offset, and through modulation, demodulation, and dynamic offset compensation, the input noise and offset voltage of the current sense amplifier are effectively reduced. A parallel structure with two unidirectional detection branches is used to achieve accurate detection of the near-ground differential signal V. sensor It features bidirectional detection and precise amplification with the power supply ground as the output switching center. Furthermore, the output resistance R can be adjusted to achieve this. OUT and input resistance R IN The ratio is used to determine the magnification.

7. The current sensing amplifier according to claim 1, characterized in that, S2 specifically includes the following sub-steps: S21, Common-mode level booster amplifies and boosts the differential voltage V sensor ; The common-mode level booster is based on resistor R1 and input resistor R IN The ratio of the amplified differential signal V sensor At the same time, it converts the common-mode voltage at the input terminal centered on the power supply ground into a high-level common-mode voltage at the output terminal; S22, The chopper-stabilized offset compensation circuit compensates for the offset of the common-mode level booster; The chopper-stabilized offset compensation circuit samples the offset and noise of the common-mode level booster and passes it through the OPA. G12 The common-mode level booster is compensated in the form of current. S23. The chopper-stabilized offset compensation circuit uses chopper modulation technology to suppress its own offset and noise, specifically including the following sub-steps: S231, the chopper-stabilized offset compensation circuit uses the modulator CH 11 CH demodulator 12 The input signal is modulated and demodulated. The offset and noise of the chopper stabilization offset compensation circuit are eliminated by the high-pass filter HPF and the integrator OTA2, while the input signal of the chopper stabilization offset compensation circuit is unaffected. S232, OTA1 of the chopper-stabilized offset compensation circuit G12 This is used to suppress the ripple generated by the DC offset of OTA1 in the chopper stabilization offset compensation circuit, thereby achieving high ripple suppression.

8. The current sensing amplifier according to claim 1, characterized in that, S3 specifically includes the following sub-steps: S31. Bidirectional amplifier circuit suppresses its own offset; The bidirectional amplifier circuit uses a modulator CH 21 CH demodulator 22 The input signal is modulated and demodulated. The offset and noise of the bidirectional amplifier circuit are modulated to a high frequency and then eliminated by a low-pass filter LPF and an active filter OTA4, while the input signal of the bidirectional amplifier circuit remains unaffected. S32 controls the turn-off and turn-on of output stage transistors M1-M2 to achieve voltage output with power supply ground as the switching center; The bidirectional amplifier circuit connects to the gate terminals of the output stage transistors M1 and M2, controlling the on and off states of the corresponding output stage PMOS transistors to achieve an output voltage with the power supply ground as the switching center.

9. The current sensing amplifier according to claim 1, characterized in that, Step S4 involves the PMOS transistor in the output stage being turned on, forming a negative feedback loop with the bidirectional amplifier circuit, causing the output voltage V to... OUT With power supply ground as the reference level, the differential voltage V sensor The absolute value is linearly amplified.

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