CN103107780A - Chopping amplifier - Google Patents
Chopping amplifier Download PDFInfo
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- CN103107780A CN103107780A CN2012105739241A CN201210573924A CN103107780A CN 103107780 A CN103107780 A CN 103107780A CN 2012105739241 A CN2012105739241 A CN 2012105739241A CN 201210573924 A CN201210573924 A CN 201210573924A CN 103107780 A CN103107780 A CN 103107780A
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- amplifying circuit
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Abstract
The invention discloses a chopping amplifier which comprises a first level chopping switch, a first level amplifying circuit, a second level chopping switch and a second level amplifying circuit. The first level amplifying circuit is a band-pass amplifying circuit. Pass-band frequency of the band-pass amplifying circuit is distributed at two sides of chopping frequency of the first level chopping switch and covers a frequency range where an input signal located and the input signal is chopped to high frequency, while a frequency range where equivalent input imbalanced voltage of the first level chopping switch located is not included. Compared with the prior art, the chopping amplifier has the advantages of being capable of reducing imbalanced voltage of the chopping amplifier and remaining rippled waves caused by low frequency noise.
Description
Technical field
The invention belongs to the Analog Circuit Design field, particularly relate to a kind of chopper amplification circuit.
Background technology
In order to amplify the faint input signal of low frequency, usually need to carry out copped wave to amplifier.Its operation principle as shown in Figure 1.Input signal vin is modulated onto chopping frequency fch through first order chopping switch 100, then amplify through first order amplifying circuit 200, then through 300 modulated times low frequencies of second level chopping switch, after amplifying, second level amplifying circuit 400 obtains output signal vout finally by crossing.The purpose of copped wave is to avoid input signal vin to be subject to the offset voltage of first order amplifying circuit and the interference of low-frequency noise.
Input signal vin in the variation of chopper amplifier amplification process intermediate frequency spectrum as shown in Figure 2, in figure, each icon implication is: V: input signal; Vo1: the equivalent input noise voltage of first order amplifying circuit and low-frequency noise; V1: copped wave is to the input signal of high frequency; Vo1 ＇: equivalence output offset voltage and the low-frequency noise of first order amplifying circuit: V1 ＇: the signal after amplifying through first order amplifying circuit; V2: the signal of getting back to for the second time low frequency after copped wave; Vo2: the equivalent input noise voltage of second level amplifying circuit and low-frequency noise; Vo1 ＇ ＇: the offset voltage and the noise that are converted to for the second time the first order amplifier of high frequency after copped wave; Fch: chopping frequency.As seen from the figure, through twice copped wave and amplification thereafter, final output signal vout is positioned at low frequency, and first order offset voltage and noise are modulated onto high frequency.And this residual interference that is positioned at high frequency will become the remaining ripple that is superimposed upon on output signal vout.Offset voltage and the low-frequency noise of first order amplifying circuit are larger, and the residual High-frequency Interference of chopper amplifier output is larger, and namely remaining ripple is larger.Remaining ripple will affect the precision of output signal, and therefore remaining ripple is the smaller the better.
As shown in Figure 3, input signal vin through copped wave for the first time after the spectrum diagram of input first order amplifying circuit.Be distributed in different frequencies by noise and the imbalance of copped wave to the signal of fch frequency and the equivalence of first order amplifying circuit to input.
And prior art to the understanding of chopper amplifier amplifying circuit frequency responses at different levels is: the bandwidth of the amplifying circuit of first order high-gain and low bandwidth is easy to contain the whole signals after copped wave, also is conducive to the stability of whole chopper amplifier under closed loop use state simultaneously.In fact first order amplifying circuit has high-gain and low bandwidth usually, take Fig. 3 as example, the offset voltage and the noise that are positioned at low frequency will be by magnification at high multiples, the multiplication factor of signal that is positioned at high frequency is lower, like this at the output of first order amplifying circuit, imbalance and low-frequency noise will become larger with respect to signal, cause the ripple of final chopper amplifier output signal also larger.
The general thinking that addresses the above problem is: make chopping frequency low, the frequency band after signal copped wave is still in amplifier bandwidth or make chopping frequency high, and the bandwidth of amplifier is also large, can comprise signal frequency.But the signal frequency of above-mentioned the first thinking after due to copped wave be more near the low-frequency noise frequency, both easier aliasings, and the second thinking needs the amplifier of a high-gain that is difficult to realize, high bandwidth.
Summary of the invention
Technical problem to be solved by this invention is, a kind of chopper amplifier is provided, and makes the output of whole chopper amplifier have lower remaining ripple.
Technical problem of the present invention is solved by following technological means:
A kind of chopper amplifier, comprise first order chopping switch, first order amplifying circuit, second level chopping switch, second level amplifying circuit, described first order amplifying circuit is the logical amplifying circuit of band, the band connection frequency of the logical amplifying circuit of described band is distributed in the chopping frequency both sides of described first order chopping switch, covering is by the frequency range of copped wave to the input signal place of high frequency, and do not comprise the frequency range at the equivalent input noise voltage place of described first order amplifying circuit.
Preferably: the logical amplifying circuit of described band comprise bias current sources, as the first metal-oxide-semiconductor MN1 and the second metal-oxide-semiconductor MN2 of difference input pipe, be connected to the 3rd metal-oxide-semiconductor MN3 between power vd D and the first metal-oxide-semiconductor MN2 and be connected to power vd D and the second metal-oxide-semiconductor MN3 between the 4th metal-oxide-semiconductor MN4; The load capacitance CL that also comprises grid and the second resistance R 2 between the first resistance R 1, the grid that is connected to the 4th metal-oxide-semiconductor and power vd D between power vd D that is connected to the 3rd metal-oxide-semiconductor and be connected to the logical amplification circuit output end of band.
Preferably: the minimum of the band connection frequency of the logical amplifying circuit of described band is higher than the flicker noise of described first order amplifying circuit and the break frequency of thermal noise.
Compared with prior art, the present invention uses the first order amplifying circuit with the logical function of band, and the equivalent input noise voltage of the amplitude-frequency response of amplifying circuit, input signal, amplifying circuit and the spectrum distribution of noise are as shown in Figure 4.The passband of the logical amplifying circuit of band is distributed in chopping frequency fch both sides, comprise by the signal bandwidth of copped wave to high frequency, thereby high-frequency signal is amplified, suppressed simultaneously offset voltage and the noise of low frequency, thereby can reduce the remaining ripple of chopper amplifier output.Therefore, the beneficial effect that has the remaining ripple that the offset voltage that can reduce chopper amplifier and low-frequency noise cause.
Description of drawings
Fig. 1 is the theory diagram of existing chopper amplifier;
Fig. 2 is that the input signal vin of chopper amplifier of Fig. 1 is at the variation diagram of amplification process intermediate frequency spectrum;
Fig. 3 be the input signal vin of chopper amplifier of Fig. 1 through copped wave for the first time after the spectrum diagram of first order amplifying circuit of input low-pass characteristic;
Fig. 4 is the theory diagram of the chopper amplifier of the logical first order amplifying circuit of employing band of the present invention;
Fig. 5 be the input signal vin of amplifier of Fig. 4 through copped wave for the first time after the spectrum diagram of first order amplifying circuit of input bandpass characteristics;
Fig. 6 is the schematic diagram of the logical amplifying circuit of band of the present invention.
Embodiment
Preferred embodiment the invention will be further described for the below's contrast accompanying drawing and combination.
As shown in Figure 4, the chopper amplifier of the present embodiment, comprise first order chopping switch 100, first order amplifying circuit 201, second level chopping switch 300, second level amplifying circuit 400, wherein first order amplifying circuit 201 is the logical amplifying circuit of band, the band connection frequency of the logical amplifying circuit 201 of this band is distributed in the chopping frequency both sides of described first order chopping switch, covering is by the frequency range of copped wave to the input signal place of high frequency, and do not comprise the equivalent input noise voltage of first order amplifying circuit 201 and the frequency range at low-frequency noise place.It is main frequency range that this patent Middle and low frequency noise refers in particular to the amplifier flicker noise, and the highest frequency of this low-frequency noise is the break frequency between amplifier flicker noise and thermal noise.
As shown in Figure 6, the circuit diagram of the logical amplifying circuit of the band that adopts for the present embodiment, it comprises bias current sources IB, the difference input is to pipe metal-oxide-semiconductor MN1 and MN2, be connected to the metal-oxide-semiconductor MN3 between power vd D and metal-oxide-semiconductor MN1, be connected to the 4th metal-oxide-semiconductor MN4 between power vd D and metal-oxide-semiconductor MN2, the load capacitance CL that also comprises grid and the resistance R 2 between the resistance R 1 between power vd D, the grid that is connected to metal-oxide-semiconductor MN4 and power vd D that is connected to metal-oxide-semiconductor MN3 and be connected to logical amplification circuit output end Vout1, Vout2 of band.The metal-oxide-semiconductor MN3 of the logical amplifying circuit of this band and resistance R 1, the R2 between metal-oxide-semiconductor MN4 and their grids and power vd D consist of active inductance, and this active inductance and load capacitance CL form has the load of bandpass characteristics, thereby has consisted of the amplifying circuit of bandpass characteristics.
As shown in Figure 5, the passband of the passband amplifying circuit of the present embodiment is distributed in the chopping frequency fch both sides of first order chopping switch, comprises by the bandwidth of copped wave to the signal V1 of high frequency, and offset voltage and low-frequency noise are positioned at outside free transmission range.
Outside the logical amplifying circuit of band shown in Figure 6, the present invention also can adopt the logical amplifying circuit of the band of other types, for example the also replaceable logical amplifying circuit of band that consists of another kind of form for passive inductance of the active inductance in Fig. 6.
Above content is in conjunction with concrete preferred implementation further description made for the present invention, can not assert that concrete enforcement of the present invention is confined to these explanations.For those skilled in the art, without departing from the inventive concept of the premise, can also make some being equal to substitute or obvious modification, and performance or purposes identical, all should be considered as belonging to protection scope of the present invention.
Claims (3)
1. a chopper amplifier, comprise first order chopping switch, first order amplifying circuit, second level chopping switch, second level amplifying circuit, it is characterized in that:
Described first order amplifying circuit is the logical amplifying circuit of band, the band connection frequency of the logical amplifying circuit of described band is distributed in the chopping frequency both sides of described first order chopping switch, covering is by the frequency range of copped wave to the input signal place of high frequency, and do not comprise the frequency range at the equivalent input noise voltage place of described first order amplifying circuit.
2. chopper amplification circuit according to claim 1 is characterized in that: the logical amplifying circuit of described band comprise bias current sources, as the first metal-oxide-semiconductor (MN1) and second metal-oxide-semiconductor (MN2) of difference input pipe, be connected to the 3rd metal-oxide-semiconductor (MN3) between power supply (VDD) and the first metal-oxide-semiconductor (MN1) and be connected to power supply (VDD) and the second metal-oxide-semiconductor (MN2) between the 4th metal-oxide-semiconductor (MN4); The load capacitance (CL) that also comprises grid and the second resistance (R2) between the first resistance (R1) between power supply (VDD), the grid that is connected to the 4th metal-oxide-semiconductor and power supply (VDD) that is connected to the 3rd metal-oxide-semiconductor and be connected to the logical amplification circuit output end of band.
3. chopper amplifier according to claim 1 and 2 is characterized in that: the minimum of the band connection frequency of the logical amplifying circuit of described band is higher than the flicker noise of described first order amplifying circuit and the break frequency of thermal noise.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210573924.1A CN103107780B (en) | 2012-12-26 | 2012-12-26 | A kind of chopper amplifier |
| HK13107637.9A HK1180461A1 (en) | 2012-12-26 | 2013-06-28 | Chopping amplifier |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210573924.1A CN103107780B (en) | 2012-12-26 | 2012-12-26 | A kind of chopper amplifier |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN103107780A true CN103107780A (en) | 2013-05-15 |
| CN103107780B CN103107780B (en) | 2015-10-14 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201210573924.1A Expired - Fee Related CN103107780B (en) | 2012-12-26 | 2012-12-26 | A kind of chopper amplifier |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN103107780B (en) |
| HK (1) | HK1180461A1 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104950165A (en) * | 2015-06-19 | 2015-09-30 | 杭州士兰微电子股份有限公司 | Detecting circuit and detecting method |
| CN108494370A (en) * | 2018-05-31 | 2018-09-04 | 福州大学 | Chopper-stabilized instrumentation amplifier |
| CN109541990A (en) * | 2018-10-26 | 2019-03-29 | 中国科学院长春光学精密机械与物理研究所 | A kind of resonant electromagnetism tuning fork chopper auto gain control method |
| CN109541991A (en) * | 2018-10-26 | 2019-03-29 | 中国科学院长春光学精密机械与物理研究所 | A kind of resonant electromagnetism tuning fork chopper AGC system |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20070216477A1 (en) * | 2005-12-22 | 2007-09-20 | Sirf Technology, Inc. | Baseband noise reduction |
| CN101373980A (en) * | 2007-08-24 | 2009-02-25 | 锐迪科创微电子（北京）有限公司 | Wireless receiver and method for eliminating DC offset voltage |
| CN102109360A (en) * | 2009-12-24 | 2011-06-29 | 上海华虹Nec电子有限公司 | Signal processing circuit of linear Hall sensor |
-
2012
- 2012-12-26 CN CN201210573924.1A patent/CN103107780B/en not_active Expired - Fee Related
-
2013
- 2013-06-28 HK HK13107637.9A patent/HK1180461A1/en not_active IP Right Cessation
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20070216477A1 (en) * | 2005-12-22 | 2007-09-20 | Sirf Technology, Inc. | Baseband noise reduction |
| CN101373980A (en) * | 2007-08-24 | 2009-02-25 | 锐迪科创微电子（北京）有限公司 | Wireless receiver and method for eliminating DC offset voltage |
| CN102109360A (en) * | 2009-12-24 | 2011-06-29 | 上海华虹Nec电子有限公司 | Signal processing circuit of linear Hall sensor |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104950165A (en) * | 2015-06-19 | 2015-09-30 | 杭州士兰微电子股份有限公司 | Detecting circuit and detecting method |
| CN108494370A (en) * | 2018-05-31 | 2018-09-04 | 福州大学 | Chopper-stabilized instrumentation amplifier |
| CN108494370B (en) * | 2018-05-31 | 2023-12-29 | 福州大学 | Chopper stabilized instrumentation amplifier |
| CN109541990A (en) * | 2018-10-26 | 2019-03-29 | 中国科学院长春光学精密机械与物理研究所 | A kind of resonant electromagnetism tuning fork chopper auto gain control method |
| CN109541991A (en) * | 2018-10-26 | 2019-03-29 | 中国科学院长春光学精密机械与物理研究所 | A kind of resonant electromagnetism tuning fork chopper AGC system |
Also Published As
| Publication number | Publication date |
|---|---|
| CN103107780B (en) | 2015-10-14 |
| HK1180461A1 (en) | 2013-10-18 |
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