CN104765399A - CMOS low-temperature small-noise operation amplifying circuit - Google Patents

Abstract

The invention discloses a CMOS low-temperature small-noise operation amplifying circuit. The CMOS low-temperature small-noise operation amplifying circuit is that a biasing circuit is in a form of a multi-stage current mirror set; reference current datum is generated by two MOS tube active resistors connected through a diodes; the reference current of an amplifier is high in temperature characteristic; the amplifying part is of a differential input folding cascade structure; the open ring gain of the amplifier is more than 80dB under first-stage amplifier, so that the shortage that oscillating easily occurs at the temperature of 77K while using miller compensation capacitor in second-stage amplification in the traditional process is overcome; a differential input pair transistor is large tube of which the width-to-length ratio is more than 100, which can improve the noise performance of a CMOS amplifier; the differential operation amplifier can normally work between the normal temperature and the low temperature of 77K and can be used as a standard amplifier module designed for the low-temperature CMOS circuit; the amplifier can be applied to a photovoltaic infrared detector circuit and a long-wave infrared light guide detector circuit.

Description

CMOS low temperature low noise discharge circuit

Technical field

The present invention relates to a kind of CMOS discharge circuit, be specifically related to a kind of discharge circuit of CMOS low temperature low noise.

Background technology

In spacer remote sensing field, most infrared eye works all at low temperatures, and for improving the performance of system, reduce the extraneous interference introduced, require that detector is closely connected with circuit, the circuit namely designed also needs to work at low temperatures.At present, business-like circuit product all for normal temperature design, possibly cannot normally work at low temperatures.In order to improve the performance of system, the CMOS sensing circuit that can normally work under must designing low temperature, wherein in sensing circuit, nucleus module is CMOS differential operational amplifier, if have ripe low temperature CMOS differential operational amplifier module, will advantageously in the design of low temperature cmos circuit in future.

The Chinese patent CN 1588794A of the Cao Bisong that on March 2nd, 2005 authorizes etc., disclose a kind of radio frequency band low temperature low noise amplifier, this amplifier is the amplifier belonging to radio frequency arts, be mainly used in CDMA frequency range, what adopt is bipolar technology, do not adopt present stand CMOS, cannot be applied in the design of present main stream of CMOS circuit.

Summary of the invention

The object of the present invention is to provide a kind of CMOS differential operational amplifier standard module that can be applied in the design of low temperature cmos circuit, improve the design level of low temperature CMOS special IC.As shown in Figure 1, it comprises amplification circuit module and biasing circuit module to the amplifier section of this low temperature CMOS differential operational amplifier, wherein:

Described amplification circuit module adopts the amplifying circuit of the folded cascode configuration of Differential Input, wherein the Differential Input PMOS that adopts breadth length ratio to equal 100 to pipe;

Differential Input in described amplification circuit module is that 1500 μm/1.5 μm PMOS are formed by two breadth length ratios, with the pipe composition inputs of 72 41.7 μm/1.5 μm to pipe PM7, PM8, adopt interdigital transistor, ensure up and down with symmetrical, and in input, protection ring is used to the outside of pipe;

In described amplification circuit module, PM7, PM8, NM4, NM5 form the cascode structure of Differential Input, PM4, PM5 are the active load of difference output, NM6, NM7 provide current source to cascade, Bias1, Bias2, Bias3 are bias voltage port, its voltage is supplied by biasing circuit module, and In-, In+ are the positive-negative input end of differential operational amplifier;

Described biasing circuit module adopts multistage current mirror to overlap structure mode, and its reference current part adopts the active pull-up composition of diode connected mode; Described biasing circuit is made up of eight pipes, and NM3 and NM0 forms first order current mirror, and PM0 and PM1 forms second level current mirror, and NM6, NM7 of NM1 and amplifier section form current mirror, and the PM3 of PM0 and amplifier section forms current mirror; PM2, NM3 of adopting diode to connect form reference current source, be mirrored to NM0 produce a road electric current by NM3, then are mirrored to the other road electric current of PM1 generation by PM0.

PM7 and PM8 in the one-level folded cascode configuration of Differential Input is adopted to be that input is to pipe, PM7, PM8, NM4, NM5 form the cascode structure of Differential Input, PM4, PM5 are the active load of difference output, NM6, NM7 provide current source to cascade, Bias1, Bias2, Bias3 are bias voltage, and In-, In+ are the positive-negative input end of differential operational amplifier.The bias circuit portion of this low temperature CMOS differential operational amplifier as shown in Figure 2, wherein NM3 and NM0 forms first order current mirror, PM0 and PM1 forms second level current mirror, and NM6, NM7 of NM1 and amplifier section form current mirror, and the PM3 of PM0 and amplifier section forms current mirror.

The input pipe of this CMOS low temperature low noise differential operational amplifier adopts the large pipe of 1500 μm/1.5 μm, greatly reduces the equivalent input noise of amplifier; Circuit topological structure adopts one-level folded cascode configuration, without the need to using miller-compensated electric capacity, overcoming the miller-compensated at low temperatures capacitance variations of common two-stage amplifier and easily causing the shortcoming of circuit oscillation; The biasing circuit of cryogenic low noise amplifier adopts the mode of three class mirror-images, does not use polysilicon resistance to generate reference current, overcomes polysilicon resistance and varies with temperature the shortcoming causing circuit static operating point drift.This CMOS differential operational amplifier can normally work between normal temperature and low temperature 77K.This method for designing is suitable for the microelectronic technique of most micron order or submicron order.The reference amplifier module that this amplifier can be used as cmos circuit design uses, and namely can be applied in photovoltaic infrared detector circuit, also can be applicable to long-wave light-guide infrared eye circuit.

Advantage of the present invention is as follows:

1. this CMOS low temperature low noise amplifier module employs cascode structure, and one-level amplifies the enlargement factor that just can reach more than 80dB, and supply-voltage rejection ratio is also higher, reduces the noise that power supply ripple is introduced.

2. this CMOS low temperature low noise amplifier module is less than 0.03pA/Hz for its equivalent inpnt current noise during infrared photovoltage detector circuit ^1/2@1KHz.

3. this CMOS low temperature low noise amplifier module can normally work from normal temperature 300K to low temperature 77K, and the signal that not only can be applicable to photovoltaic and photoconduction infrared eye amplifies, and can also use as the standard operational amplifier module of other low temperature cmos circuit.

4. this CMOS low temperature low noise amplifier module adopts the micron of standard or sub-micron CMOS technology manufacture to form, and ensure that the repeatability of chip manufacturing.

5. this CMOS low temperature low noise amplifier module is without the need to using compensation electric capacity, overcomes common two-stage amplifier building-out capacitor and changes at low temperatures and easily cause the shortcoming of circuit oscillation.

Accompanying drawing explanation

Fig. 1 is CMOS low temperature low noise amplifier module amplification circuits structural drawing.

Fig. 2 is CMOS low temperature low noise amplifier module bias circuit portion structural drawing.

Fig. 3 is the symmetrical domain of CMOS low temperature low noise amplifier module input to pipe.

Fig. 4 is the simulation result figure of CMOS low temperature low noise amplifier open-loop gain.

Fig. 5 is that CMOS low temperature low noise amplifier module amplifying circuit is always schemed.

Embodiment

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in further detail:

Embodiment 1

The total noise of this circuit determines primarily of input pipe PM7, PM8 pipe, and its equivalent input noise voltage computing formula is:

$S_{v_e}\left(f\right)=\frac{8}{3}\frac{\mathrm{kT}}{g_m}+\frac{K_f}{C_{\mathrm{ox}}^2\mathrm{WL}}\frac{1}{f}$ (wherein $g_m=\sqrt{{2K}_p\frac{W}{L}{I}_{\mathrm{ds}}}$ )

Section 1 is channel noise, and Section 2 is 1/f noise.

G _mfor the mutual conductance of input pipe, be reduce overall noise, the size of input pipe W/L and the design of bias current extremely important.From above formula known increase g _mcan channel noise be reduced, under the condition of area license, increase the W/L of input pipe, adopt 1500 μm/1.5 μm and increase g _m, when drawing domain with the input of the pipe of 72 41.7 μm/1.5 μm composition to pipe PM7, PM8, and in input, protection ring is employed to the outside of pipe, is conducive to reducing inputting and the imbalance of pipe and extraneous crosstalk are come in noise.PMOS is less than the 1/f noise of NMOS, so input pipe PM7, PM8 select PMOS to reduce 1/f noise.Increase W × L in addition and also can reduce 1/f noise, under the condition that power consumption and area are permitted, other pipes also consider that low noise standard designs as far as possible.Electric current strengthens and threshold voltage V when the temperature decreases _tincrease may make device work, so will take into full account when designing the W/L of each pipe.

The amplifier section of this low temperature low noise CMOS differential operational amplifier as shown in Figure 1, adopts the one-level folded cascode configuration of Differential Input.Wherein PM7 and PM8 is that input is to pipe, PM7, PM8, NM4, NM5 form the cascode structure of Differential Input, PM4, PM5 are the active load of difference output, NM6, NM7 provide current source to cascade, Bias1, Bias2, Bias3 are bias voltage, and In-, In+ are the positive-negative input end of differential operational amplifier.The pipe reference dimension of amplifier section is as shown in the table (unit is micron).

Pipe	PM7、PM8	NM4、NM5	NM6、NM7	PM4、PM5	PM3
						W/L	1500/1.5	120/10	120/10	10/10	200/10

Embodiment 2

The bias circuit portion of this low temperature low noise CMOS differential operational amplifier as shown in Figure 2, wherein NM3 and NM0 forms first order current mirror, PM0 and PM1 forms second level current mirror, and NM6, NM7 of NM1 and amplifier section form current mirror, and the PM3 of PM0 and amplifier section forms current mirror.

Biased part is made up of eight pipes altogether, PM2, NM3 of adopting diode to connect form reference current source, be mirrored to NM0 by NM3 and produce a road electric current, be mirrored to PM1 by PM0 again and produce an other road electric current, this current source does not use the passive resistance to very temperature sensitive, so this current source can normally work under normal temperature and low temperature, it is very strong that test result shows this current source temperature rejection ability, so whole low temperature CMOS differential operational amplifier chip operating temperature scope is very wide, can normally work from normal temperature 300K to low temperature 77K.

The pipe reference dimension of bias circuit portion is as shown in the table (unit is micron).

Pipe	PM1、PM0、NM1	NM0、NM3、PM2	NM2	PM6
					W/L	10/10	10/50	100/10	40/10

Embodiment 3

When drawing amplifier domain, all all adopts interdigital transistor to pipe, ensure up and down with symmetrical as far as possible, the input end imbalance at low temperatures of CMOS differential operational amplifier can be reduced like this, the particularly input pipe of differential amplifier, particularly important, in this circuit, because Differential Input to have employed the large pipe of 1500 μm/1.5 μm to pipe, in order to realize up and down with symmetrical, input pipe with the pipe composition of 72 41.7 μm/1.5 μm when drawing domain, as shown in Figure 3, this reduces the input imbalance of whole differential operational amplifier to a great extent, test result shows that the input offset voltage of this low temperature low noise CMOS differential operational amplifier is very little, be less than 1mV.

Embodiment 4

What this low temperature low noise CMOS differential operational amplifier module adopted is the Foldable cascade structure of Differential Input, one-level amplifies open-loop gain just more than 80dB, reach the enlargement factor that conventional secondary amplifies, as shown in Figure 4, its open-loop gain reaches 88dB to the gain simulation result of this differential operational amplifier.Conventional amplifiers uses secondary to amplify, and miller-compensated electric capacity need be used to increase phase margin, but causes amplifier oscillate, so conventional amplifiers easily vibrates at low temperatures because the change of miller-compensated electric capacity may cause the change of phase margin at low temperatures.What low temperature low noise CMOS amplifier of the present invention adopted is that one-level is amplified, and do not use miller-compensated circuit, this structure overcomes the shortcoming that conventional two-stage amplifier easily causes vibration at low temperatures.Fig. 5 is total figure of CMOS low temperature low noise discharge circuit, and Bias1, Bias2, Bias3 of bias circuit portion are connected with Bias1, Bias2, Bias3 of amplification circuits, and In+, In-are positive and negative two input ends of discharge circuit.

This CMOS low temperature low noise discharge circuit can be used as amplifier module application at photovoltaic infrared detector cmos circuit and photoconduction infrared eye cmos circuit, through test, this CMOS low temperature low noise amplifier module is very low for its equivalent inpnt current noise during infrared photovoltage detector circuit, is less than 0.03pA/HZ ^1/2@1KHz.

Because this low temperature low noise CMOS differential operational amplifier have employed folded cascode configuration, operating voltage range is comparatively large, normally can work, but need consider that the difference of operating voltage result in the difference of cell power consumption between ± 2.5 volts and ± 1.2 volts.

Described the present invention by specific embodiment above, but the present invention is not limited to these specific embodiments.It will be understood by those skilled in the art that and can also make various amendment, equivalent replacement, change etc. to the present invention, as long as these conversion do not deviate from spirit of the present invention, all should within protection scope of the present invention.

Claims (1)

1. a CMOS low temperature low noise discharge circuit, comprises amplification circuit module and biasing circuit module, it is characterized in that:

Described amplification circuit module adopts the amplifying circuit of the folded cascode configuration of Differential Input, wherein the Differential Input PMOS that adopts breadth length ratio to equal 100 to pipe;

Differential Input in described amplification circuit module is that 1500 μm/1.5 μm PMOS are formed by two breadth length ratios, with the pipe composition inputs of 72 41.7 μm/1.5 μm to pipe PM7, PM8, adopt interdigital transistor, ensure up and down with symmetrical, and in input, protection ring is used to the outside of pipe;

In described amplification circuit module, PM7, PM8, NM4, NM5 form the cascode structure of Differential Input, PM4, PM5 are the active load of difference output, NM6, NM7 provide current source to cascade, Bias1, Bias2, Bias3 are bias voltage port, its voltage is supplied by biasing circuit module, and In-, In+ are the positive-negative input end of differential operational amplifier;

Described biasing circuit module adopts multistage current mirror to overlap structure mode, and its reference current part adopts the active pull-up composition of diode connected mode; Described biasing circuit is made up of eight pipes, and NM3 and NM0 forms first order current mirror, and PM0 and PM1 forms second level current mirror, and NM6, NM7 of NM1 and amplifier section form current mirror, and the PM3 of PM0 and amplifier section forms current mirror; PM2, NM3 of adopting diode to connect form reference current source, be mirrored to NM0 produce a road electric current by NM3, then are mirrored to the other road electric current of PM1 generation by PM0.