CN114978072A - Instrument amplifier based on current multiplexing DDA structure - Google Patents

Instrument amplifier based on current multiplexing DDA structure Download PDF

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Publication number
CN114978072A
CN114978072A CN202210662622.5A CN202210662622A CN114978072A CN 114978072 A CN114978072 A CN 114978072A CN 202210662622 A CN202210662622 A CN 202210662622A CN 114978072 A CN114978072 A CN 114978072A
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China
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amplifier
dda
switch
current
pmos tube
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张磊
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Bourne Semiconductor Wuxi Co ltd
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Bourne Semiconductor Wuxi Co ltd
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Priority to CN202210662622.5A priority Critical patent/CN114978072A/en
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/38—DC amplifiers with modulator at input and demodulator at output; Modulators or demodulators specially adapted for use in such amplifiers
    • H03F3/387—DC amplifiers with modulator at input and demodulator at output; Modulators or demodulators specially adapted for use in such amplifiers with semiconductor devices only
    • H03F3/393—DC amplifiers with modulator at input and demodulator at output; Modulators or demodulators specially adapted for use in such amplifiers with semiconductor devices only with field-effect devices
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/26—Modifications of amplifiers to reduce influence of noise generated by amplifying elements
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/56—Modifications of input or output impedances, not otherwise provided for
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/45—Differential amplifiers
    • H03F3/45071—Differential amplifiers with semiconductor devices only
    • H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
    • H03F3/45179—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using MOSFET transistors as the active amplifying circuit
    • H03F3/45197—Pl types
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/294—Indexing scheme relating to amplifiers the amplifier being a low noise amplifier [LNA]
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/372—Noise reduction and elimination in amplifier

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Amplifiers (AREA)

Abstract

The invention relates to an instrument amplifier based on a current multiplexing DDA structure, which comprises: the circuit comprises a first chopping modulator, a current multiplexing DDA amplifier, a closed loop gain feedback circuit and a second chopping modulator; the input end of the first chopping modulator is used as the signal input end of the instrumentation amplifier and is used for separating the effective signal from the noise and the maladjusted frequency spectrum in the differential signal; the current multiplexing DDA amplifier is used for providing open loop gain; a closed-loop gain feedback circuit which adjusts the amplified signal output via the current multiplexing DDA amplifier by negative feedback and controls the output amplitude of the amplified signal; and the second chopping modulator is used for carrying out frequency spectrum recovery on the adjusted amplified signal, and the output end of the second chopping modulator is used as the signal output end of the instrument amplifier. The invention realizes the low noise performance of the instrumentation amplifier, avoids using an impedance boosting circuit, simplifies the design of the instrumentation amplifier, and realizes the low power consumption performance by adopting the current multiplexing technology for the DDA amplifier.

Description

Instrument amplifier based on current multiplexing DDA structure
Technical Field
The invention belongs to the field of integrated circuit design, and particularly relates to an instrument amplifier based on a current multiplexing DDA structure.
Background
The instrumentation amplifier has the characteristics of low power consumption, low noise, high input impedance, high common mode rejection ratio and the like, can amplify a very weak electric signal of the sensor without distortion so as to facilitate signal acquisition, and is particularly widely applied to wearable or implantable medical equipment.
As shown in fig. 1, a conventional instrumentation amplifier based on a chopper-stabilized capacitive coupling structure uses a transconductance amplifier OTA as a core amplifier. Because the input capacitor is directly connected to the input of the OTA, the differential signal can be regarded as being connected to the alternating-current ground at the input end of the transconductance amplifier, at the moment, a chopping switch in the chopping modulator and the input capacitor form two switched capacitors at the input end of the OTA, the two switched capacitors are connected in parallel, an equivalent resistor is further formed between the differential input signals, and at the moment, the equivalent input impedance is inversely proportional to the product of the chopping switch frequency and the input capacitor. A higher chopping switching frequency means lower equivalent input noise but at the same time brings a reduction in the equivalent input impedance. A larger input capacitance means better closed loop gain stability, again with a reduction in the equivalent input impedance. Therefore, an impedance boosting circuit needs to be designed separately in the traditional instrumentation amplifier based on a chopper-stabilized capacitive coupling structure, and the complexity of the circuit is increased.
A conventional DDA amplifier is shown in fig. 2. The difference from the transconductance amplifier OTA is that the DDA amplifier has four input transistors, two output terminals, which are combined in pairs to form two new differential input pairs in a cross-connected manner. The two groups of differential input pairs can be used separately, but an additive relation exists between the two groups of differential input pairs, and two paths of bias current are needed for the two groups of differential input pairs, so that the power consumption of the DDA amplifier is limited.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides an instrument amplifier based on a current multiplexing DDA structure. The technical problem to be solved by the invention is realized by the following technical scheme:
the invention provides an instrument amplifier based on a current multiplexing DDA structure, which comprises: the circuit comprises a first chopping modulator, a current multiplexing DDA amplifier, a closed loop gain feedback circuit and a second chopping modulator.
The input end of the first chopping modulator is used as the signal input end of the instrumentation amplifier, differential signals are input, and the output end of the first chopping modulator is connected with the first differential input end of the current multiplexing DDA amplifier and is used for separating effective signals from noise and maladjustment frequency spectrums in the differential signals.
The second differential input end of the current multiplexing DDA amplifier is connected to the output end of the closed-loop gain feedback circuit, and the differential output ends of the current multiplexing DDA amplifier are respectively connected to the input end of the closed-loop gain feedback circuit and the input end of the second chopping modulator, and are used for providing open-loop gain.
The closed-loop gain feedback circuit is used for realizing the amplification of the closed-loop fixed gain of the current multiplexing DDA amplifier, adjusting the amplified signal output by the current multiplexing DDA amplifier through negative feedback, and controlling the output amplitude of the amplified signal.
And the second chopping modulator is used for recovering the frequency spectrum of the amplified signal adjusted by the closed-loop gain feedback circuit, separating an effective signal from noise and a maladjusted frequency spectrum in the adjusted amplified signal to obtain an effective amplified signal, and the output end of the effective amplified signal is used as the signal output end of the instrumentation amplifier.
In one embodiment of the present invention, the first chopping modulator includes a first switch, a second switch, a third switch, and a fourth switch.
The first switch is arranged between the positive-phase signal input end of the instrumentation amplifier and a first differential positive-phase input end of the current multiplexing amplifier; the second switch is arranged between the positive phase signal input end of the instrumentation amplifier and the first differential inverted input end of the current multiplexing amplifier.
The third switch is arranged between the instrumentation amplifier inverting signal input end and the first differential inverting input end of the current multiplexing amplifier; the fourth switch is arranged between the instrumentation amplifier inverting signal input and the first differential non-inverting input of the current multiplexing amplifier.
The first switch, the third switch, the second switch and the fourth switch are switched on or off according to a chopping switch clock CLK generated by an external clock circuit.
In an embodiment of the present invention, the current multiplexing DDA amplifier includes a first PMOS transistor, a second PMOS transistor, a third PMOS transistor, a fourth PMOS transistor, a fifth PMOS transistor, a first NMOS transistor, a second NMOS transistor, a third NMOS transistor, a fourth NMOS transistor, a fifth NMOS transistor, a first resistor, a second resistor, a first capacitor, a second capacitor, a first parasitic capacitor, a second parasitic capacitor, and a common mode feedback circuit.
And the source electrode of the first PMOS tube, the source electrode of the fourth PMOS tube and the source electrode of the fifth PMOS tube are connected with a power supply voltage end.
The grid electrode of the first PMOS tube is connected with an external bias voltage, and the drain electrode of the first PMOS tube is respectively connected with the source electrode of the second PMOS tube and the source electrode of the third PMOS tube; the grid electrode of the second PMOS tube is connected with the lower pole plate of the first parasitic capacitor and serves as a first differential non-inverting input end of the current multiplexing DDA amplifier, and the drain electrode of the second PMOS tube is respectively connected with the grid electrode of the fourth PMOS tube, the lower pole plate of the first capacitor and the drain electrode of the first NMOS tube.
The upper pole plate of the first parasitic capacitor is connected with a grounding end, the upper pole plate of the first capacitor is connected with the second end of the first resistor, and the first end of the first resistor is connected with the drain electrode of the fourth PMOS tube.
The grid electrode of the third PMOS tube is connected with the lower pole plate of the second parasitic capacitor and serves as a first differential inverting input end of the current multiplexing DDA amplifier, and the drain electrode of the third PMOS tube is respectively connected with the grid electrode of the fifth PMOS tube, the upper pole plate of the second capacitor and the drain electrode of the second NMOS tube.
The upper pole plate of the second parasitic capacitor is connected with the grounding terminal, the lower pole plate of the second parasitic capacitor is connected with the first end of the second resistor, and the second end of the second resistor is connected with the drain electrode of the fifth PMOS tube.
The drain electrode of the fourth PMOS tube is connected with the drain electrode of the fourth NMOS tube and is used as the in-phase differential output end of the current multiplexing DDA amplifier; and the drain electrode of the fifth PMOS tube is connected with the drain electrode of the fifth NMOS tube and is used as the inverted differential output end of the current multiplexing DDA amplifier.
And the grid electrode of the first NMOS tube is used as a second differential non-inverting input end of the current multiplexing DDA amplifier, and the source electrode of the first NMOS tube is respectively connected with the source electrode of the second NMOS tube and the drain electrode of the third NMOS tube.
The grid electrode of the second NMOS tube is used as a second differential inverting input end of the current multiplexing DDA amplifier; the source electrode of the third NMOS tube, the source electrode of the fourth NMOS tube and the source electrode of the fifth NMOS tube are all connected with the grounding terminal; and the grid electrode of the fourth NMOS tube is connected with the grid electrode of the fifth NMOS tube.
The drain electrode of the fourth PMOS tube and the drain electrode of the fifth PMOS tube are both connected with the input end of the common mode feedback circuit, and the grid electrode of the third NMOS tube is connected with the output end of the common mode feedback circuit.
In an embodiment of the invention, the common mode feedback circuit includes a sixth PMOS transistor, a seventh PMOS transistor, an eighth PMOS transistor, a ninth PMOS transistor, a tenth PMOS transistor, an eleventh PMOS transistor, a sixth NMOS transistor, and a seventh NMOS transistor.
And the source electrode of the sixth PMOS tube and the source electrode of the ninth PMOS tube are both connected with the power supply voltage end. And the grid electrode of the sixth PMOS tube and the grid electrode of the ninth PMOS tube are both connected with the external bias voltage.
The drain electrode of the sixth PMOS tube is respectively connected with the source electrode of the seventh PMOS tube and the source electrode of the eighth PMOS tube; and the grid electrode of the seventh PMOS tube is connected with the drain electrode of the fourth PMOS tube, and the drain electrode of the seventh PMOS tube is respectively connected with the drain electrode and the grid electrode of the sixth NMOS tube and is connected with the grid electrode of the third NMOS tube.
The grid electrode of the eighth PMOS tube is connected with the grid electrode of the tenth PMOS tube, and the drain electrode of the eighth PMOS tube is respectively connected with the drain electrode and the grid electrode of the seventh NMOS tube; and the drain electrode of the ninth PMOS tube is respectively connected with the source electrode of the tenth PMOS tube and the source electrode of the eleventh PMOS tube.
The drain electrode of the tenth PMOS tube is connected with the drain electrode of the eighth PMOS tube; the grid electrode of the eleventh PMOS tube is connected with the drain electrode of the fifth PMOS tube, and the drain electrode of the eleventh PMOS tube is connected with the drain electrode of the seventh PMOS tube.
And the source electrode of the sixth NMOS tube and the source electrode of the seventh NMOS tube are both connected with the grounding terminal.
In one embodiment of the present invention, the closed-loop gain feedback circuit includes a first feedback capacitor, a second feedback capacitor, a first input resistor, a second input resistor, a first input capacitor, and a second input capacitor.
And the lower polar plates of the first input capacitor and the second input capacitor are both connected with the grounding terminal.
The upper pole plate of the first input capacitor is connected with the upper pole plate of the first feedback capacitor and the first end of the first input resistor respectively, and the lower pole plate of the first feedback capacitor is connected with the second end of the first input resistor.
The upper pole plate of the second input capacitor is connected with the upper pole plate of the second feedback capacitor and the first end of the second input resistor respectively, and the lower pole plate of the second feedback capacitor is connected with the second end of the second input resistor.
The first end of the first resistor is connected with a second differential non-inverting input end of the current multiplexing DDA amplifier, and the second end of the first resistor is connected with a non-inverting differential output end of the current multiplexing DDA amplifier.
And the first end of the second resistor is connected with the second differential inverting input end of the current multiplexing DDA amplifier, and the second end of the second resistor is connected with the inverting differential output end of the current multiplexing DDA amplifier.
In one embodiment of the present invention, the second chopping modulator includes a fifth switch, a sixth switch, a seventh switch, and an eighth switch.
Wherein the fifth switch is arranged between the positive phase signal output end of the instrumentation amplifier and the in-phase differential output end of the current multiplexing amplifier; the sixth switch is arranged between the instrument amplifier inverted signal output end and the in-phase differential output end of the current multiplexing amplifier.
The seventh switch is arranged between the instrument amplifier inverted signal output end and the inverted differential output end of the current multiplexing amplifier; the eighth switch is arranged between the in-phase signal output end of the instrumentation amplifier and the inverted differential output end of the current multiplexing amplifier.
The fifth switch, the sixth switch, the seventh switch and the eighth switch are turned on or off according to a chopping switch clock CLK generated by the external clock circuit.
Compared with the prior art, the invention has the beneficial effects that:
1. the instrument amplifier based on the current multiplexing DDA structure realizes the frequency spectrum separation of effective signals, noise and maladjustment in differential signals through the first chopping modulator and the second chopping modulator so as to realize the low-noise performance of the instrument amplifier.
2. According to the instrumentation amplifier based on the current multiplexing DDA amplifier structure, when micro-volt to millivolt magnitude weak electric signal acquisition is carried out, the input signal path and the feedback path formed by the closed-loop gain feedback circuit are separated, the input impedance depends on the parasitic capacitance of the input end of the DDA amplifier at the moment and is not the input capacitance any more, the equivalent input impedance of the analog front-end circuit is ensured, the impedance boosting circuit is avoided, and the design of the instrumentation amplifier is simplified.
3. According to the instrument amplifier based on the current multiplexing DDA structure, the DDA amplifier adopts a current multiplexing technology, so that the total power consumption of the instrument amplifier can be reduced, and the low power consumption performance is realized.
The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical means of the present invention more clearly understood, the present invention may be implemented in accordance with the content of the description, and in order to make the above and other objects, features, and advantages of the present invention more clearly understood, the following preferred embodiments are described in detail with reference to the accompanying drawings.
Drawings
FIG. 1 is a schematic diagram of a conventional instrumentation amplifier based on a chopper-stabilized capacitive coupling structure;
FIG. 2 is a schematic circuit diagram of a conventional DDA amplifier;
fig. 3 is a block diagram of an instrumentation amplifier based on a current multiplexing DDA structure according to an embodiment of the present invention;
fig. 4 is a schematic circuit diagram of a first chopping modulator of an instrumentation amplifier based on a current multiplexing DDA architecture according to an embodiment of the present invention;
fig. 5 is a schematic circuit diagram of a current multiplexing DDA amplifier of an instrumentation amplifier based on a current multiplexing DDA structure according to an embodiment of the present invention;
fig. 6 is a schematic circuit structure diagram of a closed-loop gain feedback circuit of an instrumentation amplifier based on a current multiplexing DDA structure according to an embodiment of the present invention;
fig. 7 is a schematic circuit diagram of a second chopping modulator of an instrumentation amplifier based on a current multiplexing DDA architecture according to an embodiment of the present invention;
fig. 8 is a noise simulation diagram of an instrumentation amplifier based on a current multiplexing DDA structure according to an embodiment of the present invention, where (a) in fig. 8 is a noise simulation diagram of an instrumentation amplifier without adding a chopping technique, and (b) in fig. 8 is a noise simulation diagram of an instrumentation amplifier after adding a chopping technique;
fig. 9 is a transient simulation diagram of an instrumentation amplifier based on a current multiplexing DDA structure according to an embodiment of the present invention.
Detailed Description
To further illustrate the technical means and effects of the present invention adopted to achieve the predetermined objects, the following detailed description is provided for an instrumentation amplifier based on current multiplexing DDA structure according to the present invention with reference to the accompanying drawings and the detailed description.
The foregoing and other technical matters, features and effects of the present invention will be apparent from the following detailed description of the embodiments, which is to be read in connection with the accompanying drawings. While the present invention has been described in connection with the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
Example one
Referring to fig. 3, fig. 3 is a block diagram of an instrumentation amplifier based on a current multiplexing DDA structure according to an embodiment of the present invention.
As shown, an instrumentation amplifier based on a current multiplexing DDA architecture includes: a first chopping modulator 10, a current multiplexing DDA amplifier 20, a closed loop gain feedback circuit 30, and a second chopping modulator 40.
The input end of the first chopping modulator 10 is used as the signal input end of the instrumentation amplifier, differential signals are input, and the output end is connected with the first differential input end of the current multiplexing DDA amplifier 20, so as to separate the effective signals from the noise and the offset frequency spectrum in the differential signals.
In a specific embodiment, the second differential input of the current multiplexing DDA amplifier 20 is connected to the output of the closed-loop gain feedback circuit 30, and the differential outputs thereof are respectively connected to the input of the closed-loop gain feedback circuit 30 and the input of the second chopping modulator 40 for providing the open-loop gain.
In a specific embodiment, the closed-loop gain feedback circuit 30 is configured to implement amplification of the current-multiplexing DDA amplifier 20 by a closed-loop fixed gain, adjust the amplified signal output via the current-multiplexing DDA amplifier 20 through negative feedback, and control the output amplitude of the amplified signal.
In a specific embodiment, the second chopping modulator 40 is configured to perform spectrum recovery on the amplified signal adjusted by the closed-loop gain feedback circuit 30, separate the effective signal from the noise and the offset spectrum in the adjusted amplified signal, and obtain an effective amplified signal, where an output end of the effective amplified signal is used as a signal output end of the instrumentation amplifier.
Specifically, the first chopping modulator 10 chops the effective signal in the differential signal to a high-frequency position, but since the spectrum of the noise and offset generated by the current-multiplexing DDA amplifier 20 is mainly at a low-frequency position, the effective signal is restored to the low-frequency position by the secondary chopping by the second chopping modulator 40 again, and the spectrum of the noise and offset from the current-multiplexing DDA amplifier 20 is chopped to a high-frequency. The active signal is always kept spectrally separated from the noise and detuning from the current-multiplexed DDA amplifier 20 by the two chopping modulators.
Referring to fig. 4, fig. 4 is a schematic circuit diagram of a first chopping modulator of an instrumentation amplifier based on a current multiplexing DDA structure according to an embodiment of the present invention.
As shown, the first chopping modulator 10 includes a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4.
Wherein, the first switch S1 is arranged at the positive phase signal input end V of the instrumentation amplifier IN+ And a first differential non-inverting input terminal V of the current-multiplexing amplifier 20 IN1+ To (c) to (d); the second switch S2 is arranged at the positive phase signal input end V of the instrumentation amplifier IN+ And a first differential inverting input terminal V of the current-multiplexing amplifier 20 IN1- In the meantime.
In a specific embodiment, the third switch S3 is disposed at the instrumentation amplifier inverting signal input V IN- And a first differential inverting input terminal V of the current-multiplexing amplifier 20 IN1- To (c) to (d); a fourth switch S4 is provided at the inverting signal input V of the instrumentation amplifier IN- And a first differential non-inverting input terminal V of the current-multiplexing amplifier 20 IN1- In the meantime.
In a specific embodiment, the first switch S1, the third switch S3, the second switch S2, and the fourth switch S4 are turned on or off according to a chopping switch clock CLK generated by an external clock circuit.
Specifically, when the chopper switch clock CLK generated by the external clock circuit is high, the first switch S1 and the third switch S3 are closed, and the second switch S2 and the fourth switch S4 are opened; when the chopping switch clock CLK is low, the second switch S2 and the fourth switch S4 are closed, and the first switch S1 and the third switch S3 are opened.
Further, when the first switch S1 and the third switch S3 are closed, the first differential input terminal V of the current-multiplexing amplifier 20 IN1 Differential signal V input by instrument amplifier IN The phases are the same; the first differential input V of the current-multiplexing amplifier 20 is closed when the second switch S2 and the fourth switch S4 are closed IN1 Differential signal V input to instrumentation amplifier IN The phases are opposite. After the differential signal has passed through the first chopping modulator 10, the active signal is chopped to a high frequency position, at which time,the spectrum of noise and detuning of the current multiplexed DDA amplifier 20 is located at low frequency locations.
Referring to fig. 5, fig. 5 is a schematic circuit structure diagram of a current multiplexing DDA amplifier of an instrumentation amplifier based on a current multiplexing DDA structure according to an embodiment of the present invention.
In a specific embodiment, the current multiplexing DDA amplifier 20 includes a first PMOS transistor MP1, a second PMOS transistor MP2, a third PMOS transistor MP3, a fourth PMOS transistor MP4, a fifth PMOS transistor MP5, a first NMOS transistor MN1, a second NMOS transistor MN2, a third NMOS transistor MN3, a fourth NMOS transistor MN4, a fifth NMOS transistor MN5, a first resistor R Z1 A second resistor R Z2 A first capacitor C M1 A second capacitor C M2 A first parasitic capacitor C P1 A second parasitic capacitor C P2 And a common mode feedback circuit.
The source electrode of the first PMOS transistor MP1, the source electrode of the fourth PMOS transistor MP4, and the source electrode of the fifth PMOS transistor MP5 are all connected to the power voltage terminal VDD.
In an embodiment, the gate of the first PMOS transistor MP1 is connected to the external bias voltage VB0, and the drain thereof is connected to the source of the second PMOS transistor MP2 and the source of the third PMOS transistor MP3, respectively.
In an embodiment, the gate of the second PMOS transistor MP2 is connected to the first parasitic capacitor C P1 And serves as a first differential non-inverting input terminal V of the current multiplexing DDA amplifier 20 IN1+ The drain of the second PMOS transistor MP4 is connected to the gate of the fourth PMOS transistor MP4 and the first capacitor C M1 And the drain of the first NMOS transistor MN 1.
In a specific embodiment, the first parasitic capacitance C P1 The upper electrode plate is connected with a ground end GND and a first capacitor C M1 The upper polar plate is connected with a first resistor R Z1 Second terminal of (1), first resistor R Z1 Is connected to the drain of the fourth PMOS transistor MP 4.
In an embodiment, the gate of the third PMOS transistor MP3 is connected to the second parasitic capacitor C P2 And serves as a first differential inverting input terminal V of the current-multiplexing DDA amplifier 20 IN1- The drain of the second PMOS transistor is connected to the gate of the fifth PMOS transistor MP5 and the second capacitor C M2 Upper polar plate and second NMOS tubeThe drain of MN 2.
In a specific embodiment, the second parasitic capacitance C P2 The upper electrode plate is connected with a ground end GND and a second capacitor C M2 The lower polar plate is connected with a second resistor R Z2 A first terminal of (1), a second resistor R Z2 And the second end of the second PMOS transistor MP5 is connected to the drain of the fifth PMOS transistor MP 5.
In a specific embodiment, the drain of the fourth PMOS transistor MP4 is connected to the drain of the fourth NMOS transistor MN4 and serves as the non-inverting differential output V of the current-multiplexing DDA amplifier 20 OP (ii) a The drain of the fifth PMOS transistor MP5 is connected to the drain of the fifth NMOS transistor MN5 and serves as the inverted differential output terminal V of the current-multiplexing DDA amplifier 20 ON 。
In a specific embodiment, the gate of the first NMOS transistor MN1 serves as the second differential non-inverting input V of the current-multiplexing DDA amplifier 20 F+ The source electrode of the NMOS transistor is respectively connected with the source electrode of the second NMOS transistor MN2 and the drain electrode of the third NMOS transistor MN 3; the gate of the second NMOS transistor MN2 is used as the second differential inverting input terminal V of the current multiplexing DDA amplifier 20 F- 。
In a specific embodiment, the source of the third NMOS transistor MN3, the source of the fourth NMOS transistor MN4, and the source of the fifth NMOS transistor MN5 are all connected to the ground GND; the grid electrode of the fourth NMOS transistor MN4 is connected with the grid electrode of the fifth NMOS transistor MN 5; the drain of the fourth PMOS transistor MP4 and the drain of the fifth PMOS transistor MP5 are both connected to the input terminal of the common mode feedback circuit, and the gate of the third NMOS transistor MN3 is connected to the output terminal of the common mode feedback circuit.
Specifically, the first NMOS transistor MN1, the second NMOS transistor MN2, the first PMOS transistor MP2, and the third PMOS transistor MP3 serve as input pair transistors of the current multiplexing DDA amplifier, share one path of bias current, and reduce power consumption of the current multiplexing DDA amplifier 20.
Further, a first parasitic capacitance C P1 And a second parasitic capacitance C P2 For the first differential non-inverting input V of the current-multiplexing amplifier 20 IN1+ And an inverting input terminal V IN1- The size of the parasitic capacitance of the input terminal group of (1) is determined by the area of the input pair of transistors, the second PMOS transistor MP2 and the third PMOS transistor MP 3.
It is worth noting that the first resistor R Z1 A second resistor R Z2 The first stepA capacitor C M1 And a second capacitor C M2 The method is used for realizing the Miller compensation effect of the control zero point and ensuring the stability of the current multiplexing DDA amplifier 20.
In a specific embodiment, the common mode feedback circuit includes a sixth PMOS transistor MP6, a seventh PMOS transistor MP7, an eighth PMOS transistor MP8, a ninth PMOS transistor MP9, a tenth PMOS transistor MP10, an eleventh PMOS transistor MP11, a sixth NMOS transistor MN6, and a seventh NMOS transistor MN 7;
the source electrode of the sixth PMOS transistor MP6 and the source electrode of the ninth PMOS transistor MP9 are both connected to the power supply voltage terminal VDD; the grid electrode of the sixth PMOS transistor MP6 and the grid electrode of the ninth PMOS transistor MP9 are both connected with an external bias voltage V B0 。
In a specific embodiment, the drain of the sixth PMOS transistor MP6 is connected to the source of the seventh PMOS transistor MP7 and the source of the eighth PMOS transistor MP8, respectively; the gate of the seventh PMOS transistor MP7 is connected to the drain of the fourth PMOS transistor MP4, and the drains are respectively connected to the drain and the gate of the sixth NMOS transistor MN6 and to the gate of the third NMOS transistor MN 3.
In a specific embodiment, the gate of the eighth PMOS transistor MP8 is connected to the gate of the tenth PMOS transistor MP10, and the drains thereof are respectively connected to the drain and the gate of the seventh NMOS transistor MN 7; the drain of the ninth PMOS transistor MP9 is connected to the source of the tenth PMOS transistor MP10 and the source of the eleventh PMOS transistor MP11, respectively.
In a specific embodiment, the drain of the tenth PMOS transistor MP10 is connected to the drain of the eighth PMOS transistor MP 8; the gate of the eleventh PMOS transistor MP11 is connected to the drain of the fifth PMOS transistor MP5, and the drain thereof is connected to the drain of the seventh PMOS transistor MP 7; the source of the sixth NMOS transistor MN6 and the source of the seventh NMOS transistor MN7 are both connected to the ground GND.
It is noted that the output signal of the common mode feedback circuit is V CMFB The output is output by the drain electrode of a seventh PMOS tube, and the grid electrode of a third NMOS tube MN3 is connected with the output signal V of the common mode feedback circuit CMFB (ii) a Common mode feedback circuit output signal V CMFB By adjusting the gate-source voltage of the third NMOS transistor MN3, the bias current of the current-multiplexing DDA amplifier 20 is adjusted, and finally the output common-mode level of the current-multiplexing DDA amplifier 20 is stabilized, i.e., the dc operating point of the current-multiplexing DDA amplifier 20 is stabilized.
Referring to fig. 6, fig. 6 is a schematic circuit structure diagram of a closed-loop gain feedback circuit of an instrumentation amplifier based on a current multiplexing DDA structure according to an embodiment of the present invention.
As shown, the closed-loop gain feedback circuit 30 includes a first feedback capacitor C F1 A second feedback capacitor C F2 A first input resistor R F1 A second input resistor R F2 A first input capacitor C IN1 And a second input capacitance C IN2 。
Wherein the first input capacitor C IN1 And a second input capacitance C IN2 The lower polar plates are all connected with a ground terminal GND.
In a specific embodiment, the first input capacitance C IN1 The upper pole plates are respectively connected with a first feedback capacitor C F1 And a first input resistor R F1 A first terminal of a first feedback capacitor C F1 The lower polar plate is connected with a first input resistor R F1 A second end of (a); second input capacitance C IN2 The upper pole plates are respectively connected with second feedback capacitors C F1 And a second input resistor R F2 A first terminal of a second feedback capacitor C F2 The lower polar plate is connected with a second input resistor R F2 The second end of (a).
In a specific embodiment, the first resistor R F1 Is connected to a second differential non-inverting input V of the current-multiplexed DDA amplifier 20 F+ First resistance R F1 Is connected to the in-phase differential output terminal V of the current-multiplexed DDA amplifier 20 OP (ii) a A second resistor R F2 Is connected to a second differential inverting input terminal V of the current-multiplexed DDA amplifier 20 F- A second resistance R F2 Is connected to the inverting differential output V of the current multiplexing DDA amplifier 20 ON 。
In particular, a first input capacitance C IN1 A second input capacitor C IN2 A first feedback capacitor C F1 And a second feedback capacitor C F2 Together, form a capacitively coupled feedback loop that determines the closed loop gain of the current-multiplexed amplifier 20. First feedback resistor R F1 And a second feedback resistor R F2 For the DC path, the output is determinedThe modulus level.
Further, through negative feedback, the closed-loop gain feedback circuit 30 and the current multiplexing DDA amplifier 20 together realize a fixed closed-loop gain of the instrumentation amplifier, the closed-loop gain a CL Can be expressed as:
Figure BDA0003691474520000141
wherein A is CL For closed loop gain, C IN Is an input capacitor C IN Capacitance value of C F Is the capacitance value of the feedback capacitor.
It can be seen that the first chopping modulator 10 is now in phase with the first non-inverting input V of the current-multiplexing DDA amplifier 20 IN1 + and a first inverting input V IN1 Connected directly and no longer to the input capacitance C IN . Equivalent input impedance of instrumentation amplifier and parasitic capacitance C of chopping switching frequency and current multiplexed DDA amplifier 20 P The product of (a) is inversely proportional. In general, the parasitic capacitance C P Much smaller than the input capacitance C IN Therefore, the input impedance can be ensured without designing an additional impedance boosting circuit.
Referring to fig. 7, fig. 7 is a schematic circuit diagram of a second chopping modulator of an instrumentation amplifier based on a current multiplexing DDA architecture according to an embodiment of the present invention.
As shown, in the specific embodiment, the second chopping modulator 40 includes a fifth switch S5, a sixth switch S6, a seventh switch S7, and an eighth switch S8.
Wherein, the fifth switch S5 is arranged at the positive phase signal output end V of the instrumentation amplifier OUT+ In-phase differential output terminal V of sum current multiplexing amplifier 20 OP In the middle of; the sixth switch S6 is arranged at the inverting signal output end V of the instrumentation amplifier OUT- In-phase differential output terminal V of sum current multiplexing amplifier 20 OP In the meantime.
In a specific embodiment, the seventh switch S7 is disposed at the instrumentation amplifier inverting signal output terminal V OUT- And an inverting differential output terminal V of the current-multiplexing amplifier 20 ON Between(ii) a An eighth switch S8 is arranged at the in-phase signal output end V of the instrumentation amplifier OUT+ And an inverting differential output terminal V of the current-multiplexing amplifier 20 ON In the meantime.
Specifically, the fifth switch S5, the sixth switch S6, the seventh switch S7, and the eighth switch S8 are turned on or off in accordance with a chopper switch clock CLK generated by an external clock circuit.
Specifically, similar to the operation principle of the first chopping modulator 10, when the chopping switch clock CLK generated by the external clock circuit is high, the fifth switch S5 and the seventh switch S7 are closed, and the sixth switch S6 and the eighth switch S7 are open; when the chopping switch clock CLK is low, the sixth switch S6 and the eighth switch S8 are closed, and the fifth switch S5 and the seventh switch S7 are opened.
Further, when the fifth switch S5 and the seventh switch S7 are closed, the differential output terminal V of the current-multiplexing amplifier 20 O And the output differential signal V of the instrument amplifier OUT The phases are the same; when the sixth switch S6 and the eighth switch S8 are closed, the differential output terminal V of the current-multiplexing amplifier 20 O And the output differential signal V of the instrument amplifier OUT The phases are opposite.
It should be noted that the effective signal chopped to high frequency by the first chopping modulator 10 is amplified by the closed loop system formed by the closed loop gain feedback circuit 30 and the current multiplexing DDA amplifier 20, the effective signal is chopped by the second chopping modulator 40 again and then returns to the original low frequency position, but the noise and the offset originally at the low frequency position are modulated to high frequency by the second chopping modulator 40, so as to realize the separation of the signal, the noise and the offset again, and if the noise and the offset chopped to high frequency are filtered by a low-pass filter at this time, the low noise performance of the instrumentation amplifier can be realized.
Referring to fig. 8, fig. 8 is a noise simulation diagram of an instrumentation amplifier based on a current multiplexing DDA structure according to an embodiment of the present invention.
Fig. 8 (a) is a noise simulation diagram of an instrumentation amplifier without adding chopping technology, and the equivalent input integral noise is about 4.64 μ Vrms in the bandwidth range of 0.5-200 Hz.
Fig. 8 (b) is a noise simulation diagram of the instrumentation amplifier after the chopper technique is added, the in-band input noise spectral density is 91.467nV/√ Hz, and the equivalent input integral noise within the bandwidth range of 0.5-200Hz is 1.82 μ Vrms, so that the chopper switching technique can be seen to effectively realize the low-noise performance of the instrumentation amplifier.
Referring to fig. 9, fig. 9 is a transient simulation diagram of an instrumentation amplifier based on a current multiplexing DDA structure according to an embodiment of the present invention.
Wherein CLK, V OP 、IA、V OUT The chopper switch clock frequency, the output waveform of the DDA amplifier when passing through the first stage chopper modulator but not the second stage chopper modulator, the output waveform of the instrumentation amplifier (not passed through the low pass filter), and the output waveform of the instrumentation amplifier (passed through the low pass filter) are shown, respectively. In fig. 9, the power supply voltage is 1V, the input signal is two paths of sine waves with a phase difference of 180 °, the amplitude of the sine waves is 100 μ V, the frequency of the sine waves is 100Hz, and when the chopping switching frequency is set to 4kHz, the amplitude of the output signal of the instrumentation amplifier is 9.92mV, which is approximately amplified by 100 times.
In the instrumentation amplifier based on the current multiplexing DDA amplifier structure of the present embodiment, the first chopping modulator and the second chopping modulator implement spectral separation of effective signals from noise and detuning in the differential signals, so as to implement low noise performance of the instrumentation amplifier.
In the instrumentation amplifier based on the current multiplexing DDA amplifier structure, when acquiring a microvolt-millivolt level weak electrical signal, the input signal path and the feedback path formed by the closed-loop gain feedback circuit are separated, and the input impedance depends on the parasitic capacitance of the input end of the DDA amplifier at the moment and is not the input capacitance any more, so that the equivalent input impedance of the analog front-end circuit is ensured, an impedance boosting circuit is avoided, and the design of the instrumentation amplifier is simplified.
In the instrumentation amplifier based on the current multiplexing DDA amplifier structure of this embodiment, the DDA amplifier employs a current multiplexing technique, which can reduce the total power consumption of the instrumentation amplifier, thereby achieving low power consumption performance.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or device that comprises a list of elements does not include only those elements but may include other elements not expressly listed. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of additional like elements in the article or device comprising the element. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The directional or positional relationships indicated by "upper", "lower", "left", "right", etc., are based on the directional or positional relationships shown in the drawings, and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.
The foregoing is a further detailed description of the invention in connection with specific preferred embodiments and it is not intended to limit the invention to the specific embodiments described. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.

Claims (6)

1. An instrumentation amplifier based on a current multiplexed DDA architecture, comprising: a first chopping modulator (10), a current multiplexing DDA amplifier (20), a closed-loop gain feedback circuit (30) and a second chopping modulator (40);
wherein the input end of the first chopping modulator (10) is used as the signal input end of the instrumentation amplifier, differential signals are input, and the output end of the first chopping modulator is connected with the first differential input end of the current multiplexing DDA amplifier (20) and is used for separating effective signals from noise and maladjustment frequency spectrums in the differential signals;
a second differential input terminal of the current multiplexing DDA amplifier (20) is connected to the output terminal of the closed-loop gain feedback circuit (30), and differential output terminals thereof are respectively connected to the input terminal of the closed-loop gain feedback circuit (30) and the input terminal of the second chopping modulator (40) for providing an open-loop gain;
the closed-loop gain feedback circuit (30) is used for realizing the amplification of the closed-loop fixed gain of the current multiplexing DDA amplifier (20), adjusting the amplified signal output by the current multiplexing DDA amplifier (20) through negative feedback, and controlling the output amplitude of the amplified signal;
and the second chopping modulator (40) is used for recovering the frequency spectrum of the amplified signal adjusted by the closed-loop gain feedback circuit (30), separating an effective signal from noise and maladjustment frequency spectrum in the adjusted amplified signal to obtain an effective amplified signal, and the output end of the effective amplified signal is used as the signal output end of the instrumentation amplifier.
2. The instrumentation amplifier according to claim 1, wherein the first chopping modulator (10) comprises a first switch (S1), a second switch (S2), a third switch (S3), a fourth switch (S4);
wherein the first switch (S1) is provided at the instrumentation amplifier non-inverting signal input terminal (V) IN+ ) And a first differential non-inverting input (V) of said current-multiplexing amplifier (20) IN1+ ) To (c) to (d);
the second switch (S2) is arranged at the positive phase signal input end (V) of the instrumentation amplifier IN+ ) And a first differential inverting input (V) of said current-multiplexing amplifier (20) IN1- ) To (c) to (d);
the third switch (S3) is disposed at the instrumentation amplifier inverting signal input terminal (V) IN- ) And a first differential inverting input (V) of said current-multiplexing amplifier (20) IN1- ) To (c) to (d);
the fourth switch (S4) is arranged at the instrumentation amplifierInverted signal input terminal (V) IN- ) And a first differential non-inverting input (V) of said current-multiplexing amplifier (20) IN1- ) To (c) to (d);
the first switch (S1), the third switch (S3), the second switch (S2), and the fourth switch (S4) are turned on or off according to a chopper switch clock CLK generated by an external clock circuit.
3. A current multiplexing DDA architecture based instrumentation amplifier according to claim 2, wherein said current multiplexing DDA amplifier (20) comprises,
the transistor comprises a first PMOS (P-channel metal oxide semiconductor) tube (MP1), a second PMOS tube (MP2), a third PMOS tube (MP3), a fourth PMOS tube (MP4), a fifth PMOS tube (MP5), a first NMOS tube (MN1), a second NMOS tube (MN2), a third NMOS tube (MN3), a fourth NMOS tube (MN4), a fifth NMOS tube (MN5) and a first resistor (R5) Z1 ) A second resistor (R) Z2 ) A first capacitor (C) M1 ) A second capacitor (C) M2 ) A first parasitic capacitance (C) P1 ) A second parasitic capacitance (C) P2 ) And a common mode feedback circuit;
the source electrode of the first PMOS tube (MP1), the source electrode of the fourth PMOS tube (MP4) and the source electrode of the fifth PMOS tube (MP5) are all connected with a power supply voltage end (VDD);
the grid electrode of the first PMOS pipe (MP1) is connected with an external bias voltage (V) B0 ) The drain electrode of the PMOS transistor is respectively connected with the source electrode of the second PMOS transistor (MP2) and the source electrode of the third PMOS transistor (MP 3);
the grid electrode of the second PMOS tube (MP2) is connected with the first parasitic capacitor (C) P1 ) And as a first differential non-inverting input (V) of said current-multiplexed DDA amplifier (20) IN1+ ) The drain electrode of the first capacitor is respectively connected with the grid electrode of the fourth PMOS tube (MP4) and the first capacitor (C) M1 ) And the drain electrode of the first NMOS tube (MN 1);
the first parasitic capacitance (C) P1 ) Is connected to Ground (GND), the first capacitor (C) M1 ) Is connected with the first resistor (R) Z1 ) The first resistor (R), the second terminal of (C), the first resistor (R) Z1 ) Is connected with the drain of the fourth PMOS tube (MP4)A pole;
the grid electrode of the third PMOS tube (MP3) is connected with the second parasitic capacitor (C) P2 ) And as a first differential inverting input (V) of said current-multiplexed DDA amplifier (20) IN1- ) The drain electrode of the second PMOS tube is respectively connected with the grid electrode of the fifth PMOS tube (MP5) and the second capacitor (C) M2 ) And a drain of the second NMOS transistor (MN 2);
the second parasitic capacitance (C) P2 ) Is connected to the Ground (GND), the second capacitor (C) M2 ) Is connected with the second resistor (R) Z2 ) The second resistor (R), the second resistor (R) Z2 ) The second end of the second PMOS tube (MP5) is connected with the drain electrode of the fifth PMOS tube (MP 5);
the drain electrode of the fourth PMOS tube (MP4) is connected with the drain electrode of the fourth NMOS tube (MN4) and is used as the in-phase differential output end (V) of the current multiplexing DDA amplifier (20) OP )；
The drain electrode of the fifth PMOS tube (MP5) is connected with the drain electrode of the fifth NMOS tube (MN5) and is used as the inverted differential output end (V) of the current multiplexing DDA amplifier (20) ON )；
The grid electrode of the first NMOS tube (MN1) is used as a second differential non-inverting input end (V) of the current multiplexing DDA amplifier (20) F+ ) The source electrodes of the NMOS transistors are respectively connected with the source electrode of the second NMOS transistor (MN2) and the drain electrode of the third NMOS transistor (MN 3);
the gate of the second NMOS transistor (MN2) is used as a second differential inverting input terminal (V) of the current multiplexing DDA amplifier (20) F- )；
The source electrode of the third NMOS transistor (MN3), the source electrode of the fourth NMOS transistor (MN4) and the source electrode of the fifth NMOS transistor (MN5) are all connected with the ground terminal (GND);
the gate of the fourth NMOS transistor (MN4) is connected with the gate of the fifth NMOS transistor (MN 5);
the drain electrode of the fourth PMOS tube (MP4) and the drain electrode of the fifth PMOS tube (MP5) are both connected with the input end of the common mode feedback circuit, and the grid electrode of the third NMOS tube (MN3) is connected with the output end of the common mode feedback circuit.
4. The instrumentation amplifier according to claim 3, wherein said common mode feedback circuit comprises a sixth PMOS transistor (MP6), a seventh PMOS transistor (MP7), an eighth PMOS transistor (MP8), a ninth PMOS transistor (MP9), a tenth PMOS transistor (MP10), an eleventh PMOS transistor (MP11), a sixth NMOS transistor (MN6), and a seventh NMOS transistor (MN 7);
the source electrode of the sixth PMOS tube (MP6) and the source electrode of the ninth PMOS tube (MP9) are both connected with the power supply voltage end (VDD); the grid electrode of the sixth PMOS tube (MP6) and the grid electrode of the ninth PMOS tube (MP9) are both connected with the external bias voltage (V) B0 )；
The drain electrode of the sixth PMOS tube (MP6) is respectively connected with the source electrode of the seventh PMOS tube (MP7) and the source electrode of the eighth PMOS tube (MP 8);
the grid electrode of the seventh PMOS tube (MP7) is connected with the drain electrode of the fourth PMOS tube (MP4), and the drain electrodes of the seventh PMOS tube (MP7) are respectively connected with the drain electrode and the grid electrode of the sixth NMOS tube (MN6) and the grid electrode of the third NMOS tube (MN 3);
the gate of the eighth PMOS transistor (MP8) is connected to the gate of the tenth PMOS transistor (MP10), and the drains thereof are respectively connected to the drain and the gate of the seventh NMOS transistor (MN 7);
the drain electrode of the ninth PMOS tube (MP9) is respectively connected with the source electrode of the tenth PMOS tube (MP10) and the source electrode of the eleventh PMOS tube (MP 11);
the drain electrode of the tenth PMOS tube (MP10) is connected with the drain electrode of the eighth PMOS tube (MP 8);
the grid electrode of the eleventh PMOS tube (MP11) is connected with the drain electrode of the fifth PMOS tube (MP5), and the drain electrode of the eleventh PMOS tube (MP11) is connected with the drain electrode of the seventh PMOS tube (MP 7);
the source electrode of the sixth NMOS transistor (MN6) and the source electrode of the seventh NMOS transistor (MN7) are both connected with the ground terminal (GND).
5. An instrumentation amplifier according to a current multiplexing DDA architecture of claim 4 wherein said closed loop gain feedback circuit (30) comprises,
a first feedback capacitor (C) F1 ) A second feedback capacitor (C) F2 ) A first input resistor (R) F1 ) A second input resistor (R) F2 ) A first input capacitor (C) IN1 ) And a second input capacitance (C) IN2 )；
Wherein the first input capacitance (C) IN1 ) And said second input capacitance (C) IN2 ) The lower polar plates are all connected with the grounding end (GND);
the first input capacitance (C) IN1 ) Are respectively connected with the first feedback capacitors (C) F1 ) And said first input resistance (R) F1 ) Said first feedback capacitance (C) F1 ) The lower polar plate is connected with the first input resistor (R) F1 ) A second end of (a);
the second input capacitance (C) IN2 ) Are respectively connected with the second feedback capacitors (C) F2 ) And said second input resistance (R) F2 ) Said second feedback capacitance (C) F2 ) Is connected with the second input resistor (R) F2 ) A second end of (a);
the first resistor (R) F1 ) Is connected to a second differential non-inverting input (V) of said current-multiplexed DDA amplifier (20) F+ ) The first resistance (R) F1 ) Is connected to the in-phase differential output terminal (V) of said current-multiplexed DDA amplifier (20) OP )；
The second resistor (R) F2 ) Is connected to a second differential inverting input terminal (V) of said current-multiplexed DDA amplifier (20) F- ) Said second resistance (R) F2 ) Is connected to the inverting differential output (V) of said current-multiplexed DDA amplifier (20) ON )。
6. The instrumentation amplifier according to the current multiplexing DDA architecture of claim 1, wherein the second chopping modulator (40) comprises a fifth switch (S5), a sixth switch (S6), a seventh switch (S7), and an eighth switch (S8);
wherein the fifth switch (S5) is provided at the instrumentation amplifier positive phase signal output terminal (V) OUT+ ) And the in-phase differential output (V) of the current-multiplexing amplifier (20) OP ) To (c) to (d);
the sixth switch (S6) is arranged at the instrumentation amplifier inverting signal output end (V) OUT- ) And the in-phase differential output (V) of the current-multiplexing amplifier (20) OP ) To (c) to (d);
the seventh switch (S7) is arranged at the instrumentation amplifier inverting signal output end (V) OUT- ) And an inverting differential output (V) of said current-multiplexing amplifier (20) ON ) To (c) to (d);
the eighth switch (S8) is arranged at the in-phase signal output end (V) of the instrumentation amplifier OUT+ ) And an inverting differential output (V) of said current-multiplexing amplifier (20) ON ) In the middle of;
the fifth switch (S5), the sixth switch (S6), the seventh switch (S7), and the eighth switch (S8) are turned on or off according to a chopping switch clock CLK generated by the external clock current.
CN202210662622.5A 2022-06-13 2022-06-13 Instrument amplifier based on current multiplexing DDA structure Pending CN114978072A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116942169A (en) * 2023-09-21 2023-10-27 之江实验室 Miniaturized brain-computer signal amplifier and brain-computer interface chip system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116942169A (en) * 2023-09-21 2023-10-27 之江实验室 Miniaturized brain-computer signal amplifier and brain-computer interface chip system
CN116942169B (en) * 2023-09-21 2024-02-02 之江实验室 Miniaturized brain-computer signal amplifier and brain-computer interface chip system

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