CN206226386U - A kind of instrument amplifier that without coupled capacitor there is DC maladjustment to suppress function - Google Patents
A kind of instrument amplifier that without coupled capacitor there is DC maladjustment to suppress function Download PDFInfo
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- CN206226386U CN206226386U CN201621322140.1U CN201621322140U CN206226386U CN 206226386 U CN206226386 U CN 206226386U CN 201621322140 U CN201621322140 U CN 201621322140U CN 206226386 U CN206226386 U CN 206226386U
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- circuit
- amplifier
- input
- instrument amplifier
- transconductance circuit
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Abstract
The utility model is related to a kind of instrument amplifier that without coupled capacitor there is DC maladjustment to suppress function, including the first transconductance circuit Gm1, the second transconductance circuit Gm2, trans-impedance amplifier, charge pump circuit, feedback resistive network and imbalance to suppress feedback circuit.The utility model can be used in the cardiac electricity detecting system on portable set, effectively solve the problems, such as that offset voltage interference occurs output saturation and full amplitude of oscillation input and output.
Description
Technical field
The utility model is related to heart rate to guard front end field, particularly a kind of without coupled capacitor to there is DC maladjustment to suppress work(
The instrument amplifier of energy.
Background technology
The sports apparatus of demand more and more higher with portable set and to(for) heart rate detection, this kind of equipment requirement electrocardio prison
Survey chip power-consumption is low, and external device is as few as possible, and this demand causes to turn into work for the instrument amplifier of ECG signal sampling
The focus of industry research.
Instrument amplifier general utility functions are to amplify small-signal, and suppression is superimposed upon the big offset voltage on signal, electrocardio letter
Number can regard the signal being superimposed with weaker nearly DC voltage compared with strong dc voltage as, thus be accordingly used in the instrument of detection electrocardiosignal
The requirement of amplifier common mode rejection ratio is very high, simultaneously as electrocardiosignal can carry polarizing voltage and low frequency wonder, instrument is amplified
Easily there is saturation in device output end, so the suppression of offset voltage must be carried out to instrument amplifier while being also prevented from instrument
Amplifier exports saturation, and with a portable device, therefore power consumption requirements are small, outward element requirement is lacked, simultaneously because the heart
Signal frequency is relatively low, belongs to nearly direct current signal, and DC voltage cannot be separated using coupled capacitor based on this some reason, and this is just
Correspondence proposes new requirement used in the design of the instrument amplifier of cardioelectric monitor.So one kind without coupled capacitor there is direct current to press down
The key for being designed to cardioelectric monitor front-end chip of the instrument amplifier of function processed.
Cardioelectric monitor front-end chip system design can be divided mainly into traditional three amplifiers structure in the world at present, i.e., by two
Buffer is followed by a difference amplifier and offsets common-mode voltage (reference as differential input end：Spinelli E.M, " AC-
Coupled Front-End for Biopotential Measurement ", IEEE Trans.Biomedical
Engineering, SC-36 (11), Vol.50 Τ pp.391-395, March 2003) and dynamic offset canceling, that is, use
Dynamic offset cancellation circuit is inserted in instrument amplifier offset voltage is eliminated into (reference：J.F.Witte,“A current-
feedback instrumentation amplifier with 5V offset for bidirectional highside
Current-sensing ", IEEE J.Solid-State Circuits, vol.43, no.12, pp.2769-2775,
Dec.2008.), above instrument amplifier chip is widely applied in the signal detection of each electronic product.But tradition
The shortcoming of three amplifiers is small input common-mode range, it is impossible to comprising Voltage rails, and secondly output is easily saturated, and is especially needing low work(
In the case of consumption.It is that can suppress offset voltage that dynamic offset cancellation circuit advantage is inserted in instrument amplifier, common mode
Rejection ratio can reach very high.But circuit structure is complicated, and power consumption is larger, and can introduce the interference of chopping signal.Traditional
Three amplifier structures cause output offset excessive and export saturation down to chip in common mode input compared with conference.And electrocardiosignal is input into
In the case of it is very high for the requirement of common mode input scope.So this proposes challenge to the design of ECG detecting chip.
The content of the invention
In view of this, the purpose of this utility model is to provide a kind of instrument that without coupled capacitor there is DC maladjustment to suppress function
Table amplifier, can be used in the cardiac electricity detecting system on portable set, effectively solves offset voltage interference and exports
Saturation and the problem of full amplitude of oscillation input and output.
The utility model is realized using following scheme：It is a kind of without coupled capacitor to there is the instrument that DC maladjustment suppresses function to put
Big device, including the first transconductance circuit Gm1, the second transconductance circuit Gm2, trans-impedance amplifier, charge pump circuit, feedback resistive network with
And imbalance suppresses feedback circuit；
The first transconductance circuit Gm1 is connected and is connected to the output of the second transconductance circuit Gm2 and described put across resistance
The input of big device, as the main amplifier of the instrument amplifier；
The output end that the first input end of the second transconductance circuit Gm2 suppresses feedback circuit with the imbalance is connected, and uses
To provide DC offset voltage；The input that the imbalance suppresses feedback circuit is connected to the output end of the instrument amplifier,
To feedback loop output signal；Second input of the second transconductance circuit Gm2 is connected to the instrument and puts through resitstance voltage divider
The output end of big device, is used to set the overall gain of the instrument amplifier；
The first transconductance circuit Gm1 is connected to the electricity with the power voltage input terminal of the second transconductance circuit Gm2
Lotus pump circuit, is used to be lifted the input common-mode range of instrument amplifier；
Two inputs of the first transconductance circuit Gm1 as the instrument amplifier input；It is described to be put across resistance
The output end of big device as the instrument amplifier output end.
Further, it is the inverting integrator being made up of amplifier A, resistance R, electric capacity C that the imbalance suppresses feedback circuit.
Further, the first transconductance circuit Gm1 is identical structure with the second transconductance circuit Gm2, is served as reasons
The common-source amplifier of PMOS and equivalent resistance into the active damping resistance of band.
Further, the trans-impedance amplifier includes the electric current summing circuit and classAB of output stage cascade.
The cardiac electricity detecting system that the utility model can be used on portable set, it can be held in low-power consumption environment,
On the basis of the small high-gain of output voltage signal noise, feedback circuit, charge pump and classAB output electricity are suppressed using imbalance
Road, effectively solves the problems, such as that offset voltage interference occurs output saturation and full amplitude of oscillation input and output.
Brief description of the drawings
Fig. 1 without coupled capacitor there is the instrument amplifier circuit that DC maladjustment suppresses function to illustrate for the embodiment of the present invention
Figure.
Fig. 2 without coupled capacitor there is DC maladjustment to suppress the mistake of the instrument amplifier circuit of function for the embodiment of the present invention
Adjust and suppress feedback circuit.
Fig. 3 for the embodiment of the present invention without coupled capacitor have DC maladjustment suppress the instrument amplifier circuit of function across
Conductive path.
Fig. 4 for the embodiment of the present invention without coupled capacitor have DC maladjustment suppress the instrument amplifier circuit of function across
Impedance amplifier.
Specific embodiment
Below in conjunction with the accompanying drawings and embodiment is described further to the utility model.
Present embodiments provide a kind of instrument amplifier that without coupled capacitor there is DC maladjustment to suppress function, including first
Transconductance circuit Gm1, the second transconductance circuit Gm2, trans-impedance amplifier, charge pump circuit, feedback resistive network and imbalance suppress anti-
Current feed circuit；
The first transconductance circuit Gm1 is connected and is connected to the output of the second transconductance circuit Gm2 and described put across resistance
The input of big device, as the main amplifier of the instrument amplifier；
The output end that the first input end of the second transconductance circuit Gm2 suppresses feedback circuit with the imbalance is connected, and uses
To provide DC offset voltage；The input that the imbalance suppresses feedback circuit is connected to the output end of the instrument amplifier,
To feedback loop output signal；Second input of the second transconductance circuit Gm2 is connected to the instrument and puts through resitstance voltage divider
The output end of big device, is used to set the overall gain of the instrument amplifier；
The first transconductance circuit Gm1 is connected to the electricity with the power voltage input terminal of the second transconductance circuit Gm2
Lotus pump circuit, is used to be lifted the input common-mode range of instrument amplifier；
Two inputs of the first transconductance circuit Gm1 as the instrument amplifier input；It is described to be put across resistance
The output end of big device as the instrument amplifier output end.
In the present embodiment, it is the anti-phase integration being made up of amplifier A, resistance R, electric capacity C that the imbalance suppresses feedback circuit
Device.The DC maladjustment of the gain factor of instrument amplifier main amplifier output appears in the input that imbalance suppresses feedback circuit,
Imbalance suppresses feedback circuit as an inverting integrator, and it is equal with normal phase input end to order about inverting input, makes main amplifier
DC maladjustment eliminate.Lack of proper care simultaneously and suppress feedback circuit in systems as single pole high pass filter, be used to prevent instrument
Amplifier exports saturation, while keeping high-gain.
In the present embodiment, the first transconductance circuit Gm1 is identical structure with the second transconductance circuit Gm2, is
By PMOS and equivalent resistance into the active damping resistance of band common-source amplifier.PMOS is operated in sub-threshold region, is provided with to rear class
Signal code, acts on the output end of transconductance circuit Gm2, while exporting to trans-impedance amplifier, charge pump is used to improve mutual conductance electricity
The supply voltage on road is input into realizing the full amplitude of oscillation.
In the present embodiment, the trans-impedance amplifier includes the electric current summing circuit and classAB of output stage cascade.Difference
Current amplifier, floating current source composition electric current summing circuit, classAB efferent ducts, electric capacity C1, C2 and classAB control electricity
Road constitutes classAB output stages.To provide full swing signal and output current, act on resitstance voltage divider and imbalance suppresses feedback
Circuit.
(in Fig. 1,1 is the first transconductance circuit Gm1, and 2 is the second transconductance circuit Gm2, and 3 is trans-impedance amplifier, 4 as shown in Figure 1
For imbalance suppresses feedback circuit, 5 is charge pump circuit, and 6 is feedback resistive network), the present embodiment additionally provides a kind of based on upper
Without coupled capacitor there is DC maladjustment to suppress the implementation method of the instrument amplifier of function described in text, specially：Described first
Differential input signal Vin1, Vin2 are converted into the small-signal current proportional to differential input signal by transconductance circuit Gm1 (1)；
Two inputs of the second transconductance circuit Gm2 (2) suppress output and the feedback resistance net of feedback circuit 4 with imbalance respectively
Network 6 is connected for monitoring signal offset voltage；By the input of trans-impedance amplifier 3 respectively with the first transconductance circuit Gm1, second
The output of transconductance circuit Gm2 is connected, as output stage for rear class is provided treated signal voltage；Imbalance is suppressed into feedback
The input of circuit is connected with the output of trans-impedance amplifier, for any nearly direct current signal to be fed back into the second transconductance circuit Gm2, from
And offset voltage is eliminated, and baseline drift is filtered, prevent amplifier from exporting saturation；By the output of charge pump circuit 5 and the first mutual conductance
Circuit Gm1, the supply voltage of the second transconductance circuit Gm2 are connected, for lifting the first transconductance circuit Gm1, the second transconductance circuit
The input common-mode range of Gm2, so as to meet the demand of the full amplitude of oscillation input of circuit；One end of feedback resistive network is amplified with across resistance
The output connection of device, is used to monitor the output voltage of trans-impedance amplifier, and the second mutual conductance electricity is sent into after this voltage is carried out into partial pressure
Road Gm2 is converted into electric current, the offset voltage of offset input signal.
Amplitude can be mingled with as shown in Fig. 2 in the present embodiment, it is contemplated that input signal Vin1, in Vin2 much larger than required
The noise voltage of the offset voltage of signal, polarizing voltage, Hz noise and baseline drift, imbalance suppresses feedback circuit by amplifier
A, resistance R, the integrator of electric capacity C compositions, the output to trans-impedance amplifier is integrated, exported after comparing with reference level to across
Conductive path is used as voltage reference, it is contemplated that the influence of polarizing voltage and baseline drift, and imbalance suppresses feedback circuit to be had in circuit
There is high pass filter function, polarizing voltage and baseline drift etc. can be suppressed some very low frequencies effect of signals, the filter cutoff
Frequency is：
Wherein, A6It is the resistance ratio value of feedback resistive network, R, C are respectively imbalance and suppress what is connected on feedback circuit 4
Resistance value and capacitance.
As shown in figure 3, (in Fig. 3,1 is the first transconductance circuit Gm1, and 2 are power supply for the second transconductance circuit Gm2,3 and 4)
In the present embodiment, it is contemplated that the factor of input common-mode range, common-mode rejection ratio and power consumption, input signal Vin1, Vin2 are by
One transconductance circuit Gm1 (1) is converted into signal code proportional thereto, and it is poor that input signal Vin1, Vin2 are input into transconductance circuit 1
Point circuit Gm2 (2) is cross over to second is connected, and input difference is cross over circuit to the signal code outflow that will produce Iout with second
The output current of Gm2 (2) is sued for peace, and the transconductance value of the first transconductance circuit Gm1 (1) can be by input difference to the resistance of upper bridging
R determines that transconductance value is：
Wherein, R is the resistance value in the first transconductance circuit Gm1, and current source 3,4 is cross over circuit for input difference to second
Gm2 provides bias current, input difference is operated in suitable scope to the second transconductance circuit Gm2, and charge pump circuit makes first
VH is arrived in the supply voltage Vdd liftings of transconductance circuit Gm1, and input difference is cross over the input common-mode range lifting of circuit Gm2 to second
To Vdd before.
(in Fig. 4,1 and 3 are electric current summing circuit, and 2 is floating current source, and 4 is that classAB controls electricity as shown in Figure 4
Road), in the present embodiment, two output currents of transconductance circuit are used as the input current in trans-impedance amplifier, the first mutual conductance electricity
The output current of road Gm1 and the second transconductance circuit Gm2 is Iin, is the input current of the electric current summing circuit 3 of trans-impedance amplifier,
Two output currents of transconductance circuit are sued for peace in electric current summing circuit 3, when circuit stability, two electricity of transconductance circuit
Stream is matching, by the feedback of feedback resistive network the two electric currents can be made to match, the conduct of floating current source 2 in Fig. 4
The biasing circuit of electric current summing circuit 1 and electric current summing circuit 3, the outflow electric current of floating current source 2 summing circuit 1, inflow current
Summing circuit 3, stabilization is carried out by the direct current biasing of the two circuits, while electric current summing circuit 1 and electric current summing circuit 3 is defeated
Go out to connect classAB control circuits 4, the classAB controls structure of circuit 4 is identical with floating current source 2, classAB control circuits 4
Bias current also flows out electric current summing circuit 1, inflow current summing circuit 3, classAB control circuits produced about 4 one compared with
It is the bias voltage of stabilization, is connected with the grid of M1, M2 respectively, secures M1, the gate source voltage of M2, so that M1 is also secured,
The quiescent current of M2, maintains circuit stability.M1, M2 are common-source amplifier structures, constitute classAB efferent ducts.Electric capacity C1, C2
And classAB control circuits and classAB efferent ducts collectively constitute classAB output stages, realize rail-to-rail output.
It is noted that the utility model protection is hardware configuration, do not claimed as design Communication software.With
Upper is only a preferably embodiment in the utility model embodiment.But, the utility model is not limited to above-mentioned embodiment party
Case, all any impartial changes done by the utility model scheme and modification, produced function is without departing from this programme
During scope, protection domain of the present utility model is belonged to.
Claims (4)
1. it is a kind of without coupled capacitor have DC maladjustment suppress function instrument amplifier, it is characterised in that：Including the first mutual conductance
Circuit Gm1, the second transconductance circuit Gm2, trans-impedance amplifier, charge pump circuit, feedback resistive network and imbalance suppress feedback electricity
Road；
The first transconductance circuit Gm1 is connected with the output of the second transconductance circuit Gm2 and is connected to the trans-impedance amplifier
Input, as the main amplifier of the instrument amplifier；
The output end that the first input end of the second transconductance circuit Gm2 suppresses feedback circuit with the imbalance is connected, and is used to carry
For DC offset voltage；The input that the imbalance suppresses feedback circuit is connected to the output end of the instrument amplifier, is used to
Feedback loop output signal；Second input of the second transconductance circuit Gm2 is connected to the instrument amplifier through resitstance voltage divider
Output end, be used to set the overall gain of the instrument amplifier；
The first transconductance circuit Gm1 is connected to the charge pump with the power voltage input terminal of the second transconductance circuit Gm2
Circuit, is used to be lifted the input common-mode range of instrument amplifier；
Two inputs of the first transconductance circuit Gm1 as the instrument amplifier input；The trans-impedance amplifier
Output end as the instrument amplifier output end.
2. a kind of instrument amplifier that without coupled capacitor there is DC maladjustment to suppress function according to claim 1, it is special
Levy and be：It is the inverting integrator being made up of amplifier A, resistance R, electric capacity C that the imbalance suppresses feedback circuit.
3. a kind of instrument amplifier that without coupled capacitor there is DC maladjustment to suppress function according to claim 1, it is special
Levy and be：The first transconductance circuit Gm1 is identical structure with the second transconductance circuit Gm2, is by PMOS and resistance etc.
Imitate into the common-source amplifier of the active damping resistance of band.
4. a kind of instrument amplifier that without coupled capacitor there is DC maladjustment to suppress function according to claim 1, it is special
Levy and be：The trans-impedance amplifier includes the electric current summing circuit and classAB of output stage cascade.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201621322140.1U CN206226386U (en) | 2016-12-05 | 2016-12-05 | A kind of instrument amplifier that without coupled capacitor there is DC maladjustment to suppress function |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201621322140.1U CN206226386U (en) | 2016-12-05 | 2016-12-05 | A kind of instrument amplifier that without coupled capacitor there is DC maladjustment to suppress function |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN206226386U true CN206226386U (en) | 2017-06-06 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201621322140.1U Expired - Fee Related CN206226386U (en) | 2016-12-05 | 2016-12-05 | A kind of instrument amplifier that without coupled capacitor there is DC maladjustment to suppress function |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN206226386U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110638443A (en) * | 2019-11-07 | 2020-01-03 | 福州大学 | Electrocardiosignal reading circuit |
| CN116938176A (en) * | 2023-06-29 | 2023-10-24 | 华中科技大学 | Real-time direct current offset calibration circuit without coupling capacitor |
-
2016
- 2016-12-05 CN CN201621322140.1U patent/CN206226386U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110638443A (en) * | 2019-11-07 | 2020-01-03 | 福州大学 | Electrocardiosignal reading circuit |
| CN116938176A (en) * | 2023-06-29 | 2023-10-24 | 华中科技大学 | Real-time direct current offset calibration circuit without coupling capacitor |
| CN116938176B (en) * | 2023-06-29 | 2024-04-09 | 华中科技大学 | Real-time direct current offset calibration circuit without coupling capacitor |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20170606 Termination date: 20201205 |