CN103095231B - A kind of common mode feedback circuit - Google Patents
A kind of common mode feedback circuit Download PDFInfo
- Publication number
- CN103095231B CN103095231B CN201110346696.XA CN201110346696A CN103095231B CN 103095231 B CN103095231 B CN 103095231B CN 201110346696 A CN201110346696 A CN 201110346696A CN 103095231 B CN103095231 B CN 103095231B
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- Prior art keywords
- common mode
- output
- pmos
- input
- circuit
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Abstract
The present invention relates to a kind of novel common mode feedback circuit, comprise output common mode current detection circuit, error amplifier and reference current generating circuit.When the differential input end of this circuit is connected with the output of Full differential operational amplifier, output common mode current detection circuit will produce an electric current relevant to the output common mode level of Full differential operational amplifier, by error amplifier and negative feedback, make this electric current equal with the reference current that reference current generating circuit produces, thus make the output common mode level of Full differential operational amplifier equal a certain reference voltage.Adopt the present invention when realizing common-mode feedback, do not need timing to refresh, can not reduce the open-loop gain of Full differential operational amplifier, output voltage swing and input common-mode range etc. to circuit; There is the advantages such as less area and ghost effect simultaneously.
Description
Technical field
The present invention relates to Full differential operational amplifier technical field, particularly relate to a kind of novel common mode feedback circuit.
Background technology
Prior art discloses operational amplifier is an important module in analog integrated circuit.Compared with the operational amplifier of Single-end output, Full differential operational amplifier has larger output voltage swing and stronger antijamming capability, is widely used in the circuit such as analog to digital converter, filter.
Research display, because the output common mode level of high-gain fully-differential operational amplifier is very responsive to the mismatch of device, so must stablize its output common mode level by increasing common mode feedback circuit.Common mode feedback circuit will realize following functions usually: detect output common mode level, testing result and a certain reference voltage are compared, produce error voltage or error current, for a certain road bias current of resonance-amplifier, be this reference voltage by negative feedback by output common mode level equalization.
The existing circuit for output common mode level detection has following a few class, one class is by resistance detection, but must be more much larger than the output impedance of operational amplifier for the resistance detected, otherwise the open-loop gain of meeting step-down amplifier, and the resistance of high value can take large chip area and bring large ghost effect; One class detects with the metal-oxide-semiconductor being operated in dark linear zone, but there is following two problems in this method, a problem is output voltage swing or the input common-mode range that can reduce amplifier, and another problem is value output common mode voltage stabilization can not determined at; Also have a class to be by capacitance detecting, but this kind of circuit need periodically to refresh.
Summary of the invention
Main purpose of the present invention is the defect overcoming prior art existence, provides a kind of novel common mode feedback circuit.
In order to achieve the above object, technical scheme of the present invention is: provide a kind of novel common mode feedback circuit (as shown in Figure 1), is made up of output common mode current detection circuit (1), error amplifier (2) and reference current generating circuit (3); There are four inputs, wherein V
inpand V
innbe two differential input ends, V
bpfor bias voltage input, V
reffor reference voltage input terminal; There is an output V
cmfb;
Described output common mode current detection circuit (1) is made up of four metal-oxide-semiconductors, wherein PMOS M
1and M
2grid respectively with input V
inpand V
innbe connected; PMOS M
1and M
2drain electrode concurrent, and with NMOS tube M
3drain and gate be connected; NMOS tube M
3source electrode be connected with ground GND; PMOS M
4grid and input V
bpbe connected; M
4source electrode be connected with power vd D; PMOS M
1and M
2source electrode concurrent, and with PMOS M
4drain electrode, V
in_cman input of end and error amplifier is connected;
Described reference current generating circuit (3) is made up of four metal-oxide-semiconductors, wherein PMOS M
6and M
7grid respectively with input V
refbe connected; PMOS M
6and M
7drain electrode concurrent, and with NMOS tube M
5drain and gate be connected; NMOS tube M
5source electrode be connected with ground GND; PMOS M
8grid and input V
bpbe connected; M
8source electrode be connected with power vd D; PMOS M
6and M
7source electrode concurrent, and with PMOS M
8drain electrode, V
ref_cman input of end and error amplifier is connected;
The output of described error amplifier (2) and output V
cmfbbe connected.
When realizing common-mode feedback function, differential input end V
inpand V
innrespectively with the output V of Full differential operational amplifier
outpand V
outnbe connected, output V
cmfbfor controlling a certain road bias current of Full differential operational amplifier, forming negative feedback loop, making the output common mode level of operational amplifier equal reference voltage V
ref.
When the output common mode level of Full differential operational amplifier changes, as worked as output common mode level higher than reference voltage V
reftime, the V of output common mode current detection circuit (1)
in_cmterminal voltage rises, by the V of error amplifier (2) by itself and reference current generating circuit (3)
ref_cmterminal voltage compares, and is amplified by error voltage, passes through V
cmfbthe a certain road bias current of output control algorithm amplifier, makes output common mode level decline, and finally makes it equal reference voltage V
ref.Equally, when output common mode level is lower than reference voltage V
reftime, the V of output common mode current detection circuit (1)
in_cmterminal voltage declines, by the V of error amplifier (2) by itself and reference current generating circuit (3)
ref_cmterminal voltage compares, and is amplified by error voltage, passes through V
cmfbthe a certain road bias current of output control algorithm amplifier, makes output common mode level rise by negative feedback, finally makes it equal reference voltage V
ref.
Common mode feedback circuit of the present invention has the following advantages:
1, the common mode feedback circuit utilizing the present invention to realize, does not need timing to refresh, can not reduce the open-loop gain of operational amplifier, output voltage swing and input common-mode range etc. to circuit;
2, there is the advantages such as less area and ghost effect simultaneously.
Accompanying drawing explanation
Fig. 1 is the circuit diagram of common mode feedback circuit of the present invention.
Embodiment
Below in conjunction with accompanying drawing, the present invention is described in more detail.
Figure 1 shows that the circuit diagram of a kind of novel common mode feedback circuit provided by the invention, be made up of output common mode current detection circuit (1), error amplifier (2) and reference current generating circuit (3).PMOS M
1, M
2, M
6and M
7identical, PMOS M
4and M
8identical, NMOS tube M
3and M
5identical.
When the present invention is used for common-mode feedback, differential input end V
inpand V
innrespectively with the output V of Full differential operational amplifier
outpand V
outnbe connected.Differential Input in common mode current testing circuit (1) is to M
1and M
2the common mode incoming level of pipe, i.e. the output common mode level V of Full differential operational amplifier
cmfor:
V
cm＝0.5*(V
outp+V
outn)(1)
PMOS M
4electric current be:
μ in formula (2)
p, C
ox, V
thwith
be respectively M
1/ M
2the carrier mobility of pipe, the gate oxide capacitance of unit are, threshold voltage and breadth length ratio.
Differential pair M in reference current generating circuit (3)
6and M
7the common mode incoming level of pipe is V
ref, flow through metal-oxide-semiconductor M
8electric current be:
μ in formula (3)
p, C
ox, V
thwith
be respectively M
6/ M
7the carrier mobility of pipe, the gate oxide capacitance of unit are, threshold voltage and breadth length ratio.
Due to degenerative effect, make two input terminal voltages of error amplifier (2) equal, i.e. V
ref_cm=V
in_cm.Because metal-oxide-semiconductor M
4and M
8there is identical size and identical grid voltage, drain voltage and source voltage, so there is I
m8=I
m4, namely formula (2) equals formula (3).Due to metal-oxide-semiconductor M
1, M
2, M
6and M
7be all PMOS, and there is identical width and length, therefore can be obtained by formula (2)=formula (3):
V
cm＝V
ref(4)
Like this, be just reference voltage V the output common mode level equalization of Full differential operational amplifier
ref.
Compared with existing common-mode feedback technology, a kind of novel common mode feedback circuit of the present invention does not need timing to refresh, can not reduce the open-loop gain of operational amplifier, output voltage swing and input common-mode range etc. to circuit; There is the advantages such as less area and ghost effect simultaneously.
Claims (4)
1. a common mode feedback circuit, is characterized in that, this circuit is made up of output common mode current detection circuit (1), error amplifier (2) and reference current generating circuit (3); Have four inputs, wherein Vinp and Vinn is two differential input ends, and Vbp is bias voltage input, and Vref is reference voltage input terminal; There is an output Vcmfb;
Described output common mode current detection circuit (1) is made up of four metal-oxide-semiconductors, and wherein PMOS M1 is connected with input Vinp with Vinn respectively with the grid of M2; The drain electrode concurrent of PMOS M1 and M2, and be connected with the drain and gate of NMOS tube M3;
The source electrode of NMOS tube M3 is connected with ground GND; The grid of PMOS M4 is connected with input Vbp; The source electrode of M4 is connected with power vd D; The source electrode concurrent of PMOS M1 and M2, and with the drain electrode of PMOS M4, Vin_cm holds and an input of error amplifier is connected;
Described reference current generating circuit (3) is made up of four metal-oxide-semiconductors, and wherein PMOS M6 is connected with input Vref respectively with the grid of M7; The drain electrode concurrent of PMOS M6 and M7, and be connected with the drain and gate of NMOS tube M5; The source electrode of NMOS tube M5 is connected with ground GND; The grid of PMOS M8 is connected with input Vbp; The source electrode of M8 is connected with power vd D; The source electrode concurrent of PMOS M6 and M7, and with the drain electrode of PMOS M8, Vref_cm holds and an input of error amplifier is connected;
The output of described error amplifier (2) is connected with output Vcmfb.
2. by common mode feedback circuit according to claim 1, it is characterized in that, when realizing common-mode feedback function, described differential input end Vinp with Vinn is connected with output end vo utp with Voutn of Full differential operational amplifier respectively, output Vcmfb is for controlling a certain road bias current of Full differential operational amplifier, form negative feedback loop, make the output common mode level of operational amplifier equal reference voltage Vref.
3. by common mode feedback circuit according to claim 1, it is characterized in that, when the output common mode level of Full differential operational amplifier changes, wherein, when output common mode level is higher than reference voltage Vref, the Vin_cm terminal voltage of output common mode current detection circuit (1) rises, compared by the Vref_cm terminal voltage of error amplifier (2) with reference current generating circuit (3), and error voltage is amplified, by a certain road bias current of Vcmfb output control algorithm amplifier, output common mode level is declined, it is finally made to equal reference voltage Vref.
4. by common mode feedback circuit according to claim 1, it is characterized in that, when the output common mode level of Full differential operational amplifier changes, wherein, when output common mode level is lower than reference voltage Vref, the Vin_cm terminal voltage of output common mode current detection circuit (1) declines, compared by the Vref_cm terminal voltage of error amplifier (2) with reference current generating circuit (3), and error voltage is amplified, by a certain road bias current of Vcmfb output control algorithm amplifier, output common mode level is made to increase by negative feedback, it is finally made to equal reference voltage Vref.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110346696.XA CN103095231B (en) | 2011-11-06 | 2011-11-06 | A kind of common mode feedback circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110346696.XA CN103095231B (en) | 2011-11-06 | 2011-11-06 | A kind of common mode feedback circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN103095231A CN103095231A (en) | 2013-05-08 |
| CN103095231B true CN103095231B (en) | 2016-03-30 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201110346696.XA Expired - Fee Related CN103095231B (en) | 2011-11-06 | 2011-11-06 | A kind of common mode feedback circuit |
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| Country | Link |
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| CN (1) | CN103095231B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6321411B2 (en) * | 2014-03-13 | 2018-05-09 | エイブリック株式会社 | Voltage detection circuit |
| CN105334378A (en) * | 2014-08-07 | 2016-02-17 | 苏州普源精电科技有限公司 | Prepositioned difference measuring circuit and measuring device with circuit |
| CN107315149B (en) * | 2016-04-26 | 2021-03-30 | 德昌电机(深圳)有限公司 | Magnetic sensor integrated circuit, motor assembly and application equipment |
| CN108880495A (en) * | 2018-07-11 | 2018-11-23 | 电子科技大学 | A kind of dynamic residual amplifier circuit of high-gain high linearity |
| CN110763922B (en) * | 2019-11-01 | 2021-12-31 | 龙迅半导体（合肥）股份有限公司 | Differential reference voltage generation circuit, peak signal detection circuit, and electronic device |
| CN112730957B (en) * | 2020-12-21 | 2021-11-19 | 华中科技大学 | Current detection circuit |
| CN115118237A (en) * | 2021-03-23 | 2022-09-27 | 圣邦微电子（北京）股份有限公司 | Fully differential operational amplifier and fully differential operational amplifier circuit |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5381114A (en) * | 1994-04-04 | 1995-01-10 | Motorola, Inc. | Continuous time common mode feedback amplifier |
| CN1783706A (en) * | 2004-11-11 | 2006-06-07 | 三星电子株式会社 | Transconductance amplifier having common mode feedback circuit and method of operating the same |
| CN101355346A (en) * | 2008-09-17 | 2009-01-28 | 清华大学 | Method for compensating frequency of wideband common mode feedback loop of two-stage operational amplifier |
| CN102158180A (en) * | 2011-03-28 | 2011-08-17 | 浙江大学 | Switch-type operation amplifier with low power consumption |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01126811A (en) * | 1987-11-12 | 1989-05-18 | Toshiba Corp | Common mode feedback circuit for full differential amplifier |
-
2011
- 2011-11-06 CN CN201110346696.XA patent/CN103095231B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5381114A (en) * | 1994-04-04 | 1995-01-10 | Motorola, Inc. | Continuous time common mode feedback amplifier |
| CN1783706A (en) * | 2004-11-11 | 2006-06-07 | 三星电子株式会社 | Transconductance amplifier having common mode feedback circuit and method of operating the same |
| CN101355346A (en) * | 2008-09-17 | 2009-01-28 | 清华大学 | Method for compensating frequency of wideband common mode feedback loop of two-stage operational amplifier |
| CN102158180A (en) * | 2011-03-28 | 2011-08-17 | 浙江大学 | Switch-type operation amplifier with low power consumption |
Non-Patent Citations (2)
| Title |
|---|
| 一种改进跨导运放的采样保持电路;王静，邬齐荣，龚敏，陈畅;《四川大学学报(自然科学版)》;20100331;第47卷(第2期);311-316 * |
| 一种高增益带宽积高压摆率的输入AB类全差分运算放大器;陈润，刘力源，朱颖佳，李冬梅;《中国电子学会第二十届电路与系统学术年会》;20071231;686-689 * |
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|---|---|
| CN103095231A (en) | 2013-05-08 |
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