CN108964616A - A kind of capacitance detecting signal processing circuit reduction Noise Method - Google Patents
A kind of capacitance detecting signal processing circuit reduction Noise Method Download PDFInfo
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- CN108964616A CN108964616A CN201810583739.8A CN201810583739A CN108964616A CN 108964616 A CN108964616 A CN 108964616A CN 201810583739 A CN201810583739 A CN 201810583739A CN 108964616 A CN108964616 A CN 108964616A
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- offset voltage
- amplifier
- operational amplifier
- signal processing
- capacitance detecting
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- 238000000034 method Methods 0.000 title claims abstract description 23
- 238000012545 processing Methods 0.000 title claims abstract description 18
- 238000012937 correction Methods 0.000 claims description 3
- 238000005516 engineering process Methods 0.000 abstract description 13
- 238000013461 design Methods 0.000 description 3
- 238000005070 sampling Methods 0.000 description 3
- 238000001514 detection method Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 230000003321 amplification Effects 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000000593 degrading effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
Classifications
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- 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
- 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
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/68—Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics
-
- 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]
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Amplifiers (AREA)
Abstract
The invention discloses a kind of capacitance detecting signal processing circuits to reduce Noise Method, a main operational amplifier is connected in the output end of capacitance detecting signal processing circuit, an auxiliary operation amplifier in parallel on main operational amplifier, to reduce the input offset voltage Voffest for the integral operation amplifier that main operational amplifier and auxiliary operation amplifier are constituted.Method of the invention can reduce the noise of circuit itself, while anti-interference ability with higher.The volume of circuit can reduce using CMOS integrated circuit technology and reduce power consumption.
Description
Technical field
The invention belongs to semiconductor integrated circuit design fields more particularly to a kind of capacitance detecting signal processing circuit to reduce
The method of noise.
Background technique
Modern CMOS integrated circuit technique increasingly develops towards the direction for improving digital circuit performance, this makes digital rings
Analog signal processing in border has to face brought by supply voltage reduction and 1/f noise voltage, offset voltage increase
Challenge.
By taking typical 0.35 μm of CMOS technology as an example, operating voltage has already decreased to 3.3V, and typical sizes metal-oxide-semiconductor
1/f noise corner frequency be generally higher than 100kHz, input offset voltage is also in mV magnitude.It is rapid with integrated circuit technology
Development, an important trend of MEMS sensing technology are to realize the integrated of sensor interface circuitry, or even realize micro- biography
The Single-Chip Integration of sensor and sensor circuit.
For MEMS sensor, since its output signal is mainly in low frequency end, and signal amplitude very little, therefore CMOS
The increase of technique bring imbalance and low frequency 1/f noise, proposes huge choose to the design of MEMS microsensor interface circuit
War.
One important technology index of MEMS signal processing system is noise, and the background noise of system limits sensitivity
It improves, it is therefore desirable to which the functional structure of successive optimization capacitive detection circuit reduces system noise.
1, when the resolution ratio of MEMS sensor is higher, the circuit noise of the ports such as mainly CV is degrading MEMS sensor
The signal-to-noise ratio of final output signal, at this moment can be by changing the structure of circuit or selecting the background of better device reduction system
Noise improves the resolution ratio of system；
2, when the resolution ratio of MEMS sensor is lower, when being more than the background noise of the circuit at the ends such as CV, point of system
Resolution is mainly determined by the performance of MEMS sensor structure, at this moment by changing the structure of circuit or selecting better device drop
The background noise of low system helps the resolution ratio of the system of raising little.
In actual production, due to the non-integrity of the micrometer-nanometer processing technology of MEMS sensor, error can be brought to system,
Coupling error caused by mainly thering is detection capacitor to mismatch, temperature error etc..
Main Noise Sources: (1) CV element of noise；(2) filter and amplification unit noise；(3) synchronous demodulation module and low pass filtered
Wave unit.
Imbalance is reduced at present and the main method of 1/f noise is automatic balancing technology and wave chopping technology.
Automatic balancing technology is a kind of sampling technique, by sampling to low-frequency noise, imbalance, then in operation amplifier
The input of device or output end subtract them from the instant value of signal, the reduction to imbalance and 1/f noise are realized, due to it
It is a kind of lack sampling process to broadband white noise, will cause the aliasing of white noise, i.e., will increase again while reducing 1/f noise
The white noise of low frequency end is contributed, therefore automatic balancing technology is more suitable for the discrete signals circuit such as switching capacity.
Wave chopping technology is a kind of continuous time method, and the method that it uses modulation and demodulation modulates imbalance and 1/f noise
It is filtered out to front end, and with low-pass filter, and useful signal is after ovennodulation, and is demodulated to base band, this technology can disappear
Except amplifier is because non-linear caused by offset voltage, and device noise can be effectively inhibited；Lacking without white noise aliasing simultaneously
Point, therefore be highly suitable for using in continuous time MEMS sensor interface circuit.
Chopping process can generate many mixed products, including chopping frequency and input signal and poor item.These mixing produce
Object can cause very big distortion, especially particularly evident when signal frequency is close to chopping frequency.And low-pass filtering can reduce
The bandwidth of available signal.
Summary of the invention
Technical problem to be solved by the invention is to provide a kind of capacitance detecting signal processing circuits to reduce Noise Method, can
To inhibit noise and imbalance in the case where signal bandwidth does not reduce.
In order to solve the above technical problems, the technical solution adopted by the present invention are as follows:
A kind of capacitance detecting signal processing circuit reduction Noise Method, characterized in that in capacitance detecting signal processing circuit
Output end connect a main operational amplifier, an in parallel auxiliary operation amplifier on main operational amplifier, to reduce main operation
The input offset voltage Voffest for the integral operation amplifier that amplifier and auxiliary operation amplifier are constituted.
If the input offset voltage of integral operation amplifier is Voffest, then, output signal voltage Vout are as follows:
Vout=A* (Voffset-Vos)+A1* [Vos1+A2* (Voffset-Vos2)]
Wherein, the primary input end offset voltage of main operational amplifier gm is Vos, gain A；Main operational amplifier gm from
Input terminal offset voltage is Vos1, gain A1；The input offset voltage Vos2 of auxiliary operation amplifier, gain A2.
The input offset voltage Voffest of integral operation amplifier are as follows:
Voffset=(A*Vos+A1A2*Vos2-A1*Vos1)/(A+A1A2)
Wherein, the primary input end offset voltage of main operational amplifier gm is Vos, gain A；Main operational amplifier gm from
Input terminal offset voltage is Vos1, gain A1；The input offset voltage Vos2 of auxiliary operation amplifier, gain A2.
If A1*A2 > > A, and the offset voltage Vos2 of auxiliary operation amplifier tends to be smaller, then it is whole to calculate the defeated of amplifier
Enter offset voltage Voffest and tends to be very small.
Output signal Vout after integral operation amplifier modulation and demodulation is only to carry even order components correction just
String signal.
Auxiliary operation amplifier uses chopping operational amplifier.
Advantageous effects of the invention:
1, the noise of circuit itself, while anti-interference ability with higher can be reduced.
2, the volume of circuit can reduce using CMOS integrated circuit technology and reduces power consumption.
Detailed description of the invention
Fig. 1 is low noise chopper stabilized operational amplifier of the present invention.
Fig. 2 is the chopping modulation process and corresponding waveform diagram of low-frequency noise of the present invention.
Fig. 3 is the low frequency input noise frequency spectrum of chopper amplifier of the present invention.
Specific embodiment
The invention will be further described below in conjunction with the accompanying drawings.Following embodiment is only used for clearly illustrating the present invention
Technical solution, and not intended to limit the protection scope of the present invention.
As shown in Figure 1, to inhibit noise and imbalance, the solution of the design in the case where signal bandwidth does not reduce
It is stable operational amplifier of being lacked of proper care using copped wave.
If the input offset voltage of whole amplifier is Voffest, the primary input end offset voltage of main operational amplifier gm is
Vos, gain A；The slave input terminal offset voltage of main operational amplifier gm is Vos1, gain A1；Main operational amplifier gm is mentioned
For the gain and bandwidth of whole amplifier.
Auxiliary operation amplifier gmc is used to reduce noise, and chopping operational amplifier can be used in auxiliary operation amplifier gmc.
The input offset voltage Vos2 of auxiliary operation amplifier, gain A2.
Vout=A* (Voffset-Vos)+A1* [Vos1+A2* (Voffset-Vos2)]
Voffset=(A*Vos+A1A2*Vos2-A1*Vos1)/(A+A1A2)
If A1*A2 > > A, and the offset voltage Vos2 very little of auxiliary operation amplifier, the input of whole amplifier is lacked of proper care electric
Press Voffest can be very small.
Vin and Vout is input and output signal voltage respectively.Period is the modulation and demodulation signal of T=1/fchop,
Fchop is the frequency of chopping signal.The direct current input offset voltage and noise of Noise simulation amplifier.As it can be seen that through ovennodulation and solution
Output signal Vout after tune becomes the sinusoidal signal for only carrying even order components correction.Noise and offset voltage are transferred to
At the odd harmonic frequencies of chopping frequency, it can be filtered out through wave filter, as shown in Figures 2 and 3.
The above is only a preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
For member, without departing from the technical principles of the invention, several improvement and deformations can also be made, these improvement and deformations
Also it should be regarded as protection scope of the present invention.
Claims (6)
1. a kind of capacitance detecting signal processing circuit reduces Noise Method, characterized in that in capacitance detecting signal processing circuit
Output end connects a main operational amplifier, and an auxiliary operation amplifier in parallel, is put on main operational amplifier with reducing main operation
The input offset voltage Voffest for the integral operation amplifier that big device and auxiliary operation amplifier are constituted.
2. a kind of capacitance detecting signal processing circuit according to claim 1 reduces Noise Method, characterized in that
If the input offset voltage of integral operation amplifier is Voffest, then, output signal voltage Vout are as follows:
Vout=A* (Voffset-Vos)+A1* [Vos1+A2* (Voffset-Vos2)]
Wherein, the primary input end offset voltage of main operational amplifier gm is Vos, gain A；Main operational amplifier gm from input
End offset voltage is Vos1, gain A1；The input offset voltage Vos2 of auxiliary operation amplifier, gain A2.
3. a kind of capacitance detecting signal processing circuit according to claim 1 or 2 reduces Noise Method, characterized in that whole
The input offset voltage Voffest of body operational amplifier are as follows:
Voffset=(A*Vos+A1A2*Vos2-A1*Vos1)/(A+A1A2)
Wherein, the primary input end offset voltage of main operational amplifier gm is Vos, gain A；Main operational amplifier gm from input
End offset voltage is Vos1, gain A1；The input offset voltage Vos2 of auxiliary operation amplifier, gain A2.
4. a kind of capacitance detecting signal processing circuit according to claim 3 reduces Noise Method, characterized in that if A1*
A2 > > A, and the offset voltage Vos2 of auxiliary operation amplifier tends to be smaller, then entirety calculates the input offset voltage of amplifier
Voffest tends to be very small.
5. a kind of capacitance detecting signal processing circuit according to claim 1 reduces Noise Method, characterized in that by whole
Output signal Vout after body operational amplifier modulation and demodulation is the sinusoidal signal for only carrying even order components correction.
6. a kind of capacitance detecting signal processing circuit according to claim 1 reduces Noise Method, characterized in that auxiliary fortune
It calculates amplifier and uses chopping operational amplifier.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810583739.8A CN108964616A (en) | 2018-06-08 | 2018-06-08 | A kind of capacitance detecting signal processing circuit reduction Noise Method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810583739.8A CN108964616A (en) | 2018-06-08 | 2018-06-08 | A kind of capacitance detecting signal processing circuit reduction Noise Method |
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| CN108964616A true CN108964616A (en) | 2018-12-07 |
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| CN201810583739.8A Pending CN108964616A (en) | 2018-06-08 | 2018-06-08 | A kind of capacitance detecting signal processing circuit reduction Noise Method |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7965139B1 (en) * | 2010-03-05 | 2011-06-21 | Texas Instruments Incorporated | Amplifier offset and noise reduction in a multistage system |
| CN103414442A (en) * | 2013-08-26 | 2013-11-27 | 电子科技大学 | High-precision fully differential amplifier based on chopper technology |
-
2018
- 2018-06-08 CN CN201810583739.8A patent/CN108964616A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7965139B1 (en) * | 2010-03-05 | 2011-06-21 | Texas Instruments Incorporated | Amplifier offset and noise reduction in a multistage system |
| CN103414442A (en) * | 2013-08-26 | 2013-11-27 | 电子科技大学 | High-precision fully differential amplifier based on chopper technology |
Non-Patent Citations (1)
| Title |
|---|
| 张阳等: ""一种斩波失调稳定仪表放大器的研究与设计"", 《微型机与应用》 * |
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Application publication date: 20181207 |