CN104283519A

CN104283519A - Current multiplexing type feed-forward compensation fully differential operational amplifier

Info

Publication number: CN104283519A
Application number: CN201410573839.4A
Authority: CN
Inventors: 王帅; 叶向阳; 高博; 曲韩宾; 吴兰
Original assignee: CETC 13 Research Institute
Current assignee: CETC 13 Research Institute
Priority date: 2014-10-24
Filing date: 2014-10-24
Publication date: 2015-01-14
Anticipated expiration: 2034-10-24
Also published as: CN104283519B

Abstract

The invention discloses a current multiplexing type feed-forward compensation fully differential operational amplifier, belonging to the technical field of fully differential operational amplifiers. The current multiplexing type feed-forward compensation fully differential operational amplifier comprises a first gain stage, a second gain stage, a feed-forward stage and a common mode feedback circuit, wherein the feed-forward stage and the second gain stage are loads for each other and current is multiplexed. According to the current multiplexing type feed-forward compensation fully differential operational amplifier, the power consumption of the whole operational amplifier can be remarkably reduced; meanwhile, high low-frequency open-loop gain is realized and the bandwidth of the operational amplifier is extremely expanded; and the current multiplexing type feed-forward compensation fully differential operational amplifier can be widely applied to a trans-impedance amplifier, a programmable gain amplifier or a filter at the analog front end of a wireless radio frequency chip, and has good application prospects.

Description

Current multiplexing type feedforward compensation Full differential operational amplifier

Technical field

The present invention relates to Full differential operational amplifier technical field.

Background technology

In the AFE (analog front end) of radio frequency chip, in order to process large bandwidth signal accurately, trans-impedance amplifier (TIA), programmable gain amplifier (PGA) and filter need the Full differential operational amplifier (abbreviation Differential OPAMP) of higher gain and large gain bandwidth product (GBW).

Traditional two-stage Differential OPAMP, owing to adopting the miller-compensated raising directly constraining bandwidth of electric capacity, makes the limited bandwidth of trans-impedance amplifier, programmable gain amplifier and filter.Differential OPAMP based on feedforward compensation comprises the first gain stage, the second gain stage, feedforward level and common mode feedback circuit four part, it by introducing feedforward level between two gain stages, thus a zero point is produced in forward path, time limit can be compensated this zero point approx.Owing to not using miller capacitance, this structure greatly extends the bandwidth of amplifier, but because the second gain stage and feedforward level independently exist, the electric current that this structure consumes is relatively large, this adds increased the power consumption of integrated circuit.

Summary of the invention

The technical problem to be solved in the present invention there is provided a kind of current multiplexing type feedforward compensation Full differential operational amplifier, it makes the second gain stage with feedforward level load each other thus achieves current multiplexing, avoid the drawback that when the second gain stage independently exists with feedforward level, current sinking is larger, significantly reduce the power consumption of integrated circuit.

For solving the problems of the technologies described above, the technical solution used in the present invention is: a kind of current multiplexing type feedforward compensation Full differential operational amplifier, it comprises the first gain stage, the second gain stage, feedforward level and common mode feedback circuit, and the level that wherein feedovers and the second gain stage have the syndeton of load each other and current multiplexing.

As preferably, the first gain stage is the fully-differential amplifier of local common-mode feedback.

As preferably, common mode feedback circuit is the common mode testing circuit based on voltage comparator.

The beneficial effect adopting technique scheme to produce is: the second level and the load each other of feedforward level in the present invention, achieve the multiplexing of electric current, significantly reduce the power consumption of whole amplifier, achieve high low frequency open-loop gain simultaneously, and greatly extend the bandwidth of amplifier, can be widely used in, in the trans-impedance amplifier of radio frequency chip AFE (analog front end), programmable gain amplifier or filter, having a good application prospect.

Accompanying drawing explanation

Fig. 1 is electrical block diagram of the present invention.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is further detailed explanation.

As shown in Figure 1, a kind of current multiplexing type feedforward compensation Full differential operational amplifier, it comprises the first gain stage, the second gain stage, feedforward level and common mode feedback circuit, wherein feedover level and the load each other of the second gain stage and current multiplexing, first gain stage is the fully-differential amplifier of local common-mode feedback, and common mode feedback circuit is the common mode testing circuit based on voltage comparator.

The outside port of whole amplifier has in-phase input end VIP, inverting input VIN, in-phase output end VOP, reversed-phase output VON, common-mode voltage reference edge CMREF, and biased electrical pressure side Vbias/Vbias1.

First gain stage is by NMOS(N type Metal-oxide-semicondutor) pipe M1, M2, M3, M4, M17 and PMOS(P type Metal-oxide-semicondutor) pipe M5, M6 and resistance R1, R2 form, wherein R1, R2 are the local common-mode feedback resistor of the first order, and resistance is equal.

The grid end of NMOS tube M1, M2 is connected with inverting input VIN, the in-phase input end VIP of amplifier respectively; The source of NMOS tube M1, M2 is all connected to the drain terminal of NMOS tube M17; The drain terminal of NMOS tube M1, M2 is connected with the source of NMOS tube M3, M4 respectively; The drain terminal of NMOS tube M3, M4 is connected with output OUT2, OUT1 of the first order respectively; The grid end of NMOS tube M3, M4 is all connected with biased electrical pressure side Vbias1; The drain terminal of PMOS M5, M6 is connected with output OUT2, OUT1 of the first order respectively; The source of PMOS M5, M6 is all connected with power end VDD; The grid end of PMOS M5, M6 is connected to the anode of R1, R2; The negative terminal of R1, R2 is connected with output OUT2, OUT1 of the first order respectively; The grid of NMOS tube M17, source respectively with biased electrical pressure side Vbias, GND be connected.

Second gain stage is made up of PMOS M9, M10, M21.

The drain terminal of PMOS M9, M10 is connected with reversed-phase output VON, the in-phase output end VOP of amplifier respectively; The grid end of PMOS M9, M10 respectively with the first order output OUT2, OUT1 be connected; The source of PMOS M9, M10 is all connected to the drain terminal of PMOS M21; Grid, the source of PMOS M21 are held with common-mode feedback CMFB respectively, power vd D is connected.

Feedforward level is made up of NMOS tube M7, M8, M18.

The grid end of NMOS tube M7, M8 is connected with in-phase input end VIP, the inverting input VIN of amplifier respectively; The drain terminal of NMOS tube M7, M8 is connected with reversed-phase output VON, the in-phase output end VOP of amplifier respectively; The source of NMOS tube M7, M8 is all connected to the drain terminal of NMOS tube M18; The grid of NMOS tube M18, source respectively with biased electrical pressure side Vbias, GND be connected.

Common mode feedback circuit is made up of NMOS tube M11, M12, M13, M14, M19, M20 and PMOS M15, M16, produces feedback voltage CMFB control PMOS M21 the common mode of output VOP, VON is stabilized near CMREF by the output of amplifier compared with common-mode reference CMREF.

The grid end of NMOS tube M11, M12 is held with reversed-phase output VON, the common-mode reference CMREF of amplifier respectively and is connected; The drain terminal of NMOS tube M11, M12 is held be connected with the drain terminal of PMOS M15, common-mode feedback CMFB respectively; The source of NMOS tube M11, M12 is all connected to NMOS tube M19 drain terminal; The grid end of NMOS tube M13, M14 is held with common-mode reference CMREF respectively, the in-phase output end VOP of amplifier is connected; The drain terminal of NMOS tube M13, M14 is held with common-mode feedback CMFB respectively, the drain terminal of PMOS M15 is connected; The source of NMOS tube M13, M14 is all connected to the drain terminal of NMOS tube M20; The grid of NMOS tube M19, M20, source respectively with biased electrical pressure side Vbias, GND be connected; Grid, the source of PMOS M15 are connected with its drain terminal, power vd D respectively; The grid of PMOS M16, source and drain terminal are held be connected with the grid end of PMOS M15, power vd D, common-mode feedback CMFB respectively.

In this Full differential operational amplifier, consider that the impact of parasitic capacitance in high frequency response limits the increase of bandwidth, in amplifier, each pipe sizing can not be too large to reduce parasitic capacitance.Embody rule is as follows:

The gain A 1=g of the first order _m1(g _m3ro3ro1∥ r _o5∥ R1),

The gain A 2=g of the second level _m9(r _o9∥ r _o7),

The gain A 3=g of feedforward level _m7(r _o7∥ r _o9),

Total gain A=A1 A2+A3,

Wherein g _m1, g _m3, g _m7, g _m9for corresponding MOS(Metal-oxide-semicondutor) mutual conductance of pipe, r _o1, r _o3, r _o7, r _o9for the output resistance of corresponding metal-oxide-semiconductor.

The limit p1=1 ∕ C1 (g of the first order _m3ro3ro1∥ r _o5∥ R1),

The limit p2=1 ∕ C2 (r of the second level _o9∥ r _o7),

The theoretical value at Left half-plane zero point of being introduced by feedforward level is z=p1 (1+A1 A2 ∕ A3),

Wherein C1 is the electric capacity summation of first order output node OUT1/OUT2 to ground; C2 is the electric capacity summation (comprise load capacitance) of second level output node VOP/VON to ground.

The circuit parameter of adjustment feedforward level makes z=p2, thus balances out the impact of time limit, extends the bandwidth of amplifier.

For avoiding common-mode oscillation, the compensation of common mode loop in actual design of the present invention, also should be done according to actual conditions.

Based on circuit structure of the present invention, Differential OPAMP designed by application TSMC0.18um RF CMOS technology is presented at power supply 1.8V through the interchange post-simulation of domain, electric current 1.3mA, temperature is 27 DEG C, TT process corner, open loop low-frequency gain during load capacitance 2pF is 60dB, three dB bandwidth is at more than 9MHz, gain bandwidth product (GBW) is at more than 9G, open loop phase nargin is 15 ° (the open loop phase nargin of Differential OPAMP generally can not affect the adjustment of the phase margin of differential mode loop in closed loop application), and similar result to be reached based on existing second gain stage and feedforward level self-existent feedforward compensation Differential OPAMP, need electric current about 2mA, visible the present invention reduces the overall power of circuit really.

In a word, second gain stage and the load each other of feedforward level in the present invention, achieve the multiplexing of electric current, reach the power consumption that large bandwidth sum is relatively low simultaneously, its structure is simple, it can be widely used in processing in the trans-impedance amplifier of radio frequency chip AFE (analog front end) of broadband signal, programmable gain amplifier or filter, thus reduces the power consumption of whole chip, has a good application prospect.

For a person skilled in the art, according to technical scheme described above and design, other various corresponding change and distortion can be made, and all these change and are out of shape all within the protection range of patent claims.

Claims

1. a current multiplexing type feedforward compensation Full differential operational amplifier, it comprises the first gain stage, the second gain stage, feedforward level and common mode feedback circuit, it is characterized in that: feedforward level and the second gain stage have the syndeton of load each other and current multiplexing.

2. current multiplexing type feedforward compensation Full differential operational amplifier according to claim 1, is characterized in that described first gain stage is the fully-differential amplifier of local common-mode feedback.

3. current multiplexing type feedforward compensation Full differential operational amplifier according to claim 1, is characterized in that described common mode feedback circuit is the common mode testing circuit based on voltage comparator.