CN212459821U - Integral modulation type micro-current measuring circuit - Google Patents
Integral modulation type micro-current measuring circuit Download PDFInfo
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- CN212459821U CN212459821U CN202020663549.XU CN202020663549U CN212459821U CN 212459821 U CN212459821 U CN 212459821U CN 202020663549 U CN202020663549 U CN 202020663549U CN 212459821 U CN212459821 U CN 212459821U
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Abstract
The utility model discloses an integral modulation type micro-current measuring circuit, including sequential logic circuit, integrating circuit, sample holder and differential circuit, the output of integrating circuit is connected the sample holder input, the sample holder is connected differential circuit, sequential logic circuit all with integrating circuit the sample holder with differential circuit links to each other, sequential logic circuit and DC voltage establish ties, sequential logic circuit links to each other with the output. The utility model adopts the above structure a little current measurement circuit of integral modulation type guarantees low noise, high linearity, wide linear range, wide dynamic range and the low drift of electric current-voltage conversion result.
Description
Technical Field
The utility model relates to a little current measurement amplifier technical field especially relates to an integral modulation type little current measurement circuit.
Background
In general, the current-voltage conversion uses a high feedback resistor R connected in parallel to the negative feedback and output terminals of the amplifier, as shown in fig. 1, and performs current-voltage conversion by using the current negative feedback of the amplifier. Since the amplifier is in the first stage, the noise caused by the amplifier itself has a large influence on the measurement result, and in order to reduce the noise, an integrating capacitor C is connected in parallel to the feedback resistor, but this capacitor affects the linear range of the current-voltage conversion, and when the input current is gaussian-shaped, the converted output has a "tailing" phenomenon.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing an integral modulation type micro current measuring circuit guarantees low noise, high linearity, wide linear range, wide dynamic range and the low drift of electric current-voltage conversion result.
In order to achieve the above object, the utility model provides an integral modulation type micro current measuring circuit, including sequential logic circuit, integrating circuit, sample holder and differential circuit, integrating circuit's output is connected the sample holder input, the sample holder is connected differential circuit, sequential logic circuit all with integrating circuit the sample holder with differential circuit links to each other, sequential logic circuit and direct current voltage establish ties, sequential logic circuit links to each other with the output.
Preferably, the integrating circuit includes a switch K2, a switch K3, an operational amplifier U1, a capacitor C1 and a capacitor C2, the capacitor C1 and the capacitor C2 are connected in parallel to the negative input end and the output end of the operational amplifier U1, the capacitor C2 is connected in series with a switch K2, the operational amplifier U1 is connected in series with a protection resistor R3, and the capacitor C1 is also connected in parallel with a switch K3.
Preferably, the integration circuit is connected in series with the direct-current voltage through a zero setting resistor R2 and a zero setting resistor R1 in sequence, and the input end of the integration circuit is short-circuited to the ground through a switch K1.
Preferably, the sample holder includes a switch K4, a switch K5, a capacitor C3, a capacitor C4, a resistor R4 and a resistor R5, an input terminal of the switch K5 is connected to the operational amplifier U1, the switch K4 is connected to an input terminal of the capacitor C1, the switch K4 is sequentially connected in series to the resistor R4 and the capacitor C3, and the switch K5 is sequentially connected in series to the resistor R5 and the capacitor C4.
Preferably, the differential circuit comprises a differential amplifier U2, a switch K6, a resistor R6, a capacitor C5 and an operational amplifier U3, output ends of the resistor R4 and the resistor R5 are respectively connected to a negative input end and an output end of the differential amplifier U2, the differential amplifier U2 is sequentially connected with the switch K6, the resistor R6 and the operational amplifier U3, and the capacitor C5 connected to the ground is connected between the resistor R6 and the operational amplifier U3.
Preferably, the control end F of the switch K1, the switch K2, the switch K3, the switch K4, the switch K5 and the switch K6 which are connected in parallel are connected with the input end of an operational amplifier U4 of the sequential logic circuit.
Therefore, the utility model adopts the above structure an integral modulation type micro current measurement circuit, the micro current passes through integrating circuit, convert the voltage into, sequential logic circuit control integration time, switch according to the chronogenesis, the sample hold circuit keeps the integral voltage of sampling and the integral voltage of zero input respectively, differential circuit subtracts the sampling voltage after the conversion and the zero input voltage difference, accomplish current-voltage conversion promptly, thereby realize reducing the drift noise of amplifier circuit itself effectively, also can insert and carry out the difference to the modulation output signal after the sensor modulation and subtract, in order to further reduce the detection noise that brings because sensor self noise.
The technical solution of the present invention is further described in detail by the accompanying drawings and examples.
Drawings
FIG. 1 is a circuit schematic of the prior art;
FIG. 2 is a schematic circuit diagram of an embodiment of an integral modulation type micro-current measuring circuit according to the present invention;
fig. 3 is a schematic diagram of the operation principle of the integral modulation type micro-current measuring circuit of the present invention.
Detailed Description
The following describes embodiments of the present invention with reference to the accompanying drawings.
Fig. 1 is a circuit schematic diagram of prior art, fig. 2 is the utility model relates to a circuit schematic diagram of little current measurement circuit of integral modulation type embodiment, fig. 3 is the utility model relates to a little current measurement circuit of integral modulation type's theory of operation schematic diagram, a little current measurement circuit of integral modulation type, including sequential logic circuit, integrating circuit, sample holder and difference circuit, the sample holder input is connected to integrating circuit's output, and the difference circuit is connected to the sample holder, and sequential logic circuit all links to each other with integrating circuit, sample holder and difference circuit, and sequential logic circuit and direct current voltage establish ties, and sequential logic circuit links to each other with the output.
The integrating circuit comprises a switch K2, a switch K3, an operational amplifier U1, a capacitor C1 and a capacitor C2, wherein the capacitor C1 and the capacitor C2 are connected in parallel to the negative input end and the output end of the operational amplifier U1, the capacitor C2 is connected in series with a switch K2, the operational amplifier U1 is connected in series with a protective resistor R3, and the capacitor C1 is also connected in parallel with a switch K3. The integrating circuit is connected with the direct-current voltage in series through a zero setting resistor R2 and a zero setting resistor R1. The input end of the integrating circuit is short-circuited and grounded through a switch K1, and the integrating circuit outputs zero input signal conversion voltage.
The sampling holder comprises a switch K4, a switch K5, a capacitor C3, a capacitor C4, a resistor R4 and a resistor R5, wherein the input end of the switch K5 is connected with an operational amplifier U1, the switch K4 is connected with the input end of a capacitor C1, the switch K4 is sequentially connected with a resistor R4 and a capacitor C3 in series, and the switch K5 is sequentially connected with a resistor R5 and a capacitor C4 in series.
The differential circuit comprises a differential amplifier U2, a switch K6, a resistor R6, a capacitor C5 and an operational amplifier U3, wherein the output ends of the resistor R4 and the resistor R5 are respectively connected to the negative input end and the output end of the differential amplifier U2, the differential amplifier U2 is sequentially connected with a switch K6, the resistor R6 and the operational amplifier U3, and the capacitor C5 which is connected to the ground is connected between the resistor R6 and the operational amplifier U3.
And the control end F of the switch K1, the switch K2, the switch K3, the switch K4, the switch K5 and the switch K6 which are connected in parallel are connected with the input end of an operational amplifier U4 of the sequential logic circuit.
The working principle of the utility model is as follows:
an integrating circuit:
wherein:
U0-current-voltage converted voltage
I1------------------sensor input current
In-total noise current
T-integration time
In the formula, the first term is the current I to be measured1The second term is the total noise InThe effect on the output. The longer the integration time, the less noise impact.
For convenient analysis, only the input current I to be measured1And (6) carrying out analysis. And the noise term is considered to be equal in probability of positive and negative noise in the integration process, and the positive and negative noise are mutually counteracted and tend to be zero.
The circuit works as follows, in continuous sampling time, the input of the operational amplifier U1 is modulated into two parts I by K1 under the modulation of the control terminal F111And I10Thus, there are two voltage outputs, U1 and U0, one containing valid signal and drift slow noise and the other containing only circuit drift noise.
Under the control of F4 and F5, signals between U1 and U0 are sampled and held as two paths of voltage signals which are independently output, and difference subtraction calculation is carried out by a difference unit. The output signal is a voltage signal only containing effective signals, and the slowly-varying drift noise is subtracted. The output signal is sampled and held again by the sample holder under the drive of the sampling pulse of F6, and the final voltage is output.
The sampling signal and the zero input signal are respectively connected to an integrating circuit under the control of a sequential logic circuit, the sampling capacitor of the integrating circuit carries out current-voltage conversion on the sensor signal, a sampling retainer respectively holds the sampled input and the zero sampled input, and finally a difference circuit carries out difference subtraction on the sampled input and the zero sampled input. The sampling input signal comprises a signal true value, signal transmission noise, self noise and drift of an amplifier and a zero input signal. After operation in the differential circuit, only the true value of the signal and the transmission noise are amplified. In the integration circuit, there is a variable integration time controlled by a logic circuit to match the different magnitudes of the input current. The switch of the integrating circuit can also switch another integrating capacitor to enlarge the detection range of the circuit.
Therefore, the utility model adopts the above structure an integral modulation type micro current measuring circuit, low noise, high linearity, wide linear range, wide dynamic range and the low drift of assurance current-voltage conversion result.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that modifications can be made by those skilled in the art without departing from the principle of the present invention, and these modifications should also be construed as the protection scope of the present invention.
Claims (6)
1. An integral modulation type micro-current measuring circuit is characterized in that: the sampling circuit comprises a sequential logic circuit, an integrating circuit, a sampling retainer and a differential circuit, wherein the output end of the integrating circuit is connected with the input end of the sampling retainer, the sampling retainer is connected with the differential circuit, the sequential logic circuit is connected with the integrating circuit, the sampling retainer and the differential circuit, the integrating circuit is connected with a direct-current voltage in series, and the sequential logic circuit is connected with the output end.
2. An integrating modulation type micro-current measuring circuit according to claim 1, characterized in that: the integrating circuit comprises a switch K2, a switch K3, an operational amplifier U1, a capacitor C1 and a capacitor C2, wherein the capacitor C1 and the capacitor C2 are connected in parallel to the negative input end and the output end of the operational amplifier U1, the capacitor C2 is connected in series with a switch K2, the operational amplifier U1 is connected in series with a protective resistor R3, and the capacitor C1 is also connected in parallel with a switch K3.
3. An integrating modulation type micro-current measuring circuit according to claim 2, characterized in that: the integration circuit is connected with the direct-current voltage in series through a zero setting resistor R2 and a zero setting resistor R1 in sequence, and the input end of the integration circuit is short-circuited and grounded through a switch K1.
4. An integrating modulation type micro-current measuring circuit according to claim 3, characterized in that: the sampling holder comprises a switch K4, a switch K5, a capacitor C3, a capacitor C4, a resistor R4 and a resistor R5, wherein the input end of the switch K5 is connected with the operational amplifier U1, the switch K4 is connected with the input end of the capacitor C1, the switch K4 is sequentially connected with the resistor R4 and the capacitor C3 in series, and the switch K5 is sequentially connected with the resistor R5 and the capacitor C4 in series.
5. An integrating modulation type micro-current measuring circuit according to claim 4, characterized in that: the differential circuit comprises a differential amplifier U2, a switch K6, a resistor R6, a capacitor C5 and an operational amplifier U3, wherein the output ends of the resistor R4 and the resistor R5 are respectively connected to the negative input end and the output end of the differential amplifier U2, the differential amplifier U2 is sequentially connected with a switch K6, the resistor R6 and the operational amplifier U3, and the capacitor C5 connected to the ground is connected between the resistor R6 and the operational amplifier U3.
6. An integrating modulation type micro-current measuring circuit according to claim 5, characterized in that: and the control end F of the switch K1, the switch K2, the switch K3, the switch K4, the switch K5 and the switch K6 which are connected in parallel are connected with the input end of an operational amplifier U4 of the sequential logic circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020663549.XU CN212459821U (en) | 2020-04-27 | 2020-04-27 | Integral modulation type micro-current measuring circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020663549.XU CN212459821U (en) | 2020-04-27 | 2020-04-27 | Integral modulation type micro-current measuring circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN212459821U true CN212459821U (en) | 2021-02-02 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202020663549.XU Active CN212459821U (en) | 2020-04-27 | 2020-04-27 | Integral modulation type micro-current measuring circuit |
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| CN (1) | CN212459821U (en) |
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2020
- 2020-04-27 CN CN202020663549.XU patent/CN212459821U/en active Active
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