CN103166585A

CN103166585A - Complementary metal oxide semiconductor (CMOS) amplifying circuit matched with infrared low-impedance photoconductive detector

Info

Publication number: CN103166585A
Application number: CN2013101004448A
Authority: CN
Inventors: 袁红辉; 陈永平; 陈世军
Original assignee: Shanghai Institute of Technical Physics of CAS
Current assignee: Shanghai Institute of Technical Physics of CAS
Priority date: 2013-03-26
Filing date: 2013-03-26
Publication date: 2013-06-19

Abstract

The invention discloses a complementary metal oxide semiconductor (CMOS) amplifying circuit matched with an infrared low-impedance photoconductive detector. The amplifying circuit adopts a bridge circuit mode at an input end, is suitable for amplifying 20-200 ohm low-input-impedance infrared photoconductive detector signals, and can work at liquid nitrogen temperature. A first-level double-end input single-ended output differential amplifier adopts a positive-negative power source for power supply, and enables input quiescent voltage to be free of limitation of the threshold voltage of a metal oxide semiconductor (MOS) transistor. Another branch circuit corresponding to a biasing resistor and the detector adopts 10 kilohms to be connected with 50 ohms in series, the noise rejection ratio led in from another biasing input end is enabled to reach 200 times, and reduction of circuit overall noise is benefited. Under the requirement of a certain bandwidth, in order to increase pre-level gain and lower equivalent input noise, a 1megohm feedback resistor is adopted between a negative input end of the amplifier and output. A direct connection mode is respectively adopted among a bridge input mode, the first-level amplifier and a second-level amplifier, and the amplifiers can amplify both alternate current signals and direct current signals.

Description

The CMOS amplifying circuit of a kind of and infrared Low ESR optical waveguide detector coupling

Technical field

The present invention relates to a kind of cmos circuit method for designing, particularly a kind of can with the CMOS amplifying circuit of working under the low temperature of LONG WAVE INFRARED Low ESR optical waveguide detector coupling.

Background technology

At present, still take the HgCdTe photoconductive detectors as main, its resistance is very low, is 50 ohm of left and right at the detector of wavelength more than 12 microns for wavelength, is difficult to be complementary with the cmos circuit of high resistant.Certain applications even require wavelength to reach 15 microns, but no matter the scale of detector has much, nearly all optical waveguide detector is all the device of not being with RIOC, and reading and process all of signal completed by the peripheral electron circuit, and system applies is caused very large restriction.Present infrared focus plane ROIC is nearly all for photovoltaic detector.Why unrealized focal plane is integrated for the long-wave light-guide detector, and one of the main reasons is there is no suitable guide type focal plane ROIC.Integrated in order to realize the focal plane, reduce the overall system noise, need reading circuit closely to be connected with Infrared Detectors, namely the optical waveguide detector circuit also is operated in low temperature.Along with the development of IC technology, design and the working ability of cmos circuit are largely increased, and the ROIC circuit that development is applicable to HgCdTe guide type focal plane has become possibility.In fact, non-refrigeration micro-metering bolometer infrared focus plane (Bolometer UFPA) is exactly a kind of guide type focal plane device of normal temperature work, uses for reference the mentality of designing of its ROIC, can attempt developing the ROIC of HgCdTe long-wave light-guide focal plane.

Summary of the invention

The objective of the invention is to overcome the deficiency of existence conditions, designed a kind of cmos circuit, adopt the bridge-type input mode at front end, solved the problem with Low ESR detector coupling, this circuit can be applied to 20 ohm to the amplification of 200 ohm of Low ESR detector signals, and can work under liquid nitrogen temperature.

The technical problem that the present invention solves is to provide a kind of low temperature cmos circuit that can adapt to low input impedance photoconductive detectors.Described CMOS amplifying circuit adopts the bridge circuit mode at input, and wherein one is that detector is connected with the 10K Ohmic resistance; The resistance of another bridge circuit adopts ratio to connect higher than two resistance of 200 times; Its both-end input Single-end output amplifier adopts positive-negative power supply; Adopt resistance to realize first order amplification higher than the feedback resistance of 1M ohm between negative input end and output; The second level is amplified the employing anode and is amplified mode, and multiplication factor is higher than 10 times; All adopt direct-coupling between bridge-type input, the first order and the second level.

Characteristics of the present invention are: front end is the bridge-type mode, the minor variations of detector resistance can make the bridge disequilibrium, its voltage difference is directly inputted to the positive-negative input end of amplifier and realizes differential amplification, feedback resistance is designed to 1M ohm, is guaranteeing that enough large multiplication factor has guaranteed again the bandwidth of amplifier simultaneously.If it is too large to flow through the electric current of detector, can make detector heating aggravation, increase the cooling system requirement, but the voltage signal that too little electric current can make detector produce is too little, the high-performance that is unfavorable for signal is read, so biasing resistor is designed to 10K ohm, the electric current that flows through detector during ± 1.5 volts to ± 5 volts power supplies is 500 microamperes to 150 microamperes left and right.Because the bridge with detectors is designed to 10K ohm and 50 ohm, so the noise of introducing from offset side can reduce 200 times during to amplifier in, greatly reduced system noise.

Characteristics of the present invention are: the mode that this structure adopts two-stage to amplify, adopt direct-connected mode between two-stage, and prevented noise and bandwidth problem that capacitive coupling is brought.The first order has designed the resistive degeneration amplification, the second level adopts anode to amplify mode, enough large multiplication factor has reduced equivalent input noise effectively, the advantage that the amplification mode that two-stage is different has effectively utilized different amplification modes to bring has reduced the circuit oscillation phenomenon that the multistage connection of single amplification mode may bring.

The present invention has comprised following test result:

1 through test, and its equivalent input noise is less than 3 microvolts at normal temperatures in this system, and the voltage amplification factor of its normal temperature surpasses 10,000 times, and the 3DB band is wider than 10KHZ.

2 at low temperatures, this amplifier with can work after detector is connected, its multiplication factor is 2.5 times of normal temperature, its equivalent input noise is less than normal temperature, band is wider than 3KHZ.

Description of drawings

Fig. 1 bridge-type input mode and the Low ESR cmos amplifier first order.Optical waveguide detector, R4, R7, R8 consist of bridge circuit.

Fig. 2 Low ESR cmos amplifier second level.For anode amplifies mode, signal is inputted from anode, output and input same-phase.

Fig. 3 Low ESR amplifier full figure.Direct-coupling between the first order and the second level, without coupling capacitance, this mode can be amplified direct current and AC signal simultaneously.

Fig. 4 Low ESR amplifier simulation result figure.The left side is AC signal emulation, and the right is the transient signal simulation result.OUT1 is first order output signal, and OUT2 is second level output signal.

Embodiment

Embodiment 1

Fig. 1 is that bridge-type mode and the first order of amplifier amplified.R4 is connected with infrared photoconductive detector, and this circuit design is 10K ohm, if will strengthen or reduce to flow through the electric current of optical waveguide detector, can strengthen or reduce the resistance of R4.R7 is corresponding with R4, and its resistance should be designed to equate, this circuit also is designed to 10K ohm.R8 is corresponding with optical waveguide detector, and the resistance sizes of size design and detector is suitable, and this circuit design is 50 ohm of left and right.If the not of uniform size of the resistance of detector and R8 causes, can to make circuit its output voltage when the static state be the zero volt left and right by regulating Vbias.This amplifier is fit to the amplification of 20 ohm to 200 ohm low input impedance optical waveguide detector signals.After infrared optical waveguide detector was accepted infrared signal, its resistance generation minor variations caused that the voltage difference of IN and REF end changes, and its change amount reads infrared signal by the amplifier of back smoothly.

200 times of R8 due to R7, so when holding the noise of introducing to arrive amplifier in from Vbias, its noise is just suppressed 200 times, the difference of R7 and R8 is larger more beneficial to noise suppressed, but has reduced to mate by regulating Vbias voltage the scope of optical waveguide detector internal resistance.

In order to guarantee suitable multiplication factor, the feedback resistance of this circuit is designed to 1M ohm, if will increase the prime multiplication factor, can increase the feedback resistance size, but may cause diminishing of amplifier bandwidth.This circuit feedback capacity is designed to 2PF, and this capacitance size can be done suitable adjustment according to the concrete condition of CMOS technique, and purpose is to guarantee amplifier phase margin compensation when normal operation, eliminates the higher-order of oscillation, plays stabilizing circuit.

Embodiment 2

Fig. 2 is that anode amplifies mode, its output and input signal same-phase, and the ratio of R11 and R12 has determined the multiplication factor of the second level, and this circuit R11 is designed to 100K ohm, and R12 is designed to 10K ohm.Multiplication factor is 10 times.If increase the multiplication factor of the second level, can change the R11 resistance ratio different from R12.Feedback capacity between IN negative terminal and OUT is designed to 2PF, and this electric capacity plays the stabilization of second circuit, and different multiplication factors should adopt different feedback capacities to compensate.

Embodiment 3

Fig. 3 is total figure that the first order is connected with the second level, adopt direct-connected mode between dual-stage amplifier, also adopt direct connected mode between bridge-type input mode and first order amplifier, overcome capacity coupled shortcoming, the slow drift phenomenon of direct current static point that capacitive coupling is caused due to the small electric leakage of electric capacity.The mode that direct current connects makes circuit can amplify AC signal, also can amplify direct current signal.

Embodiment 4

Fig. 4 is the functional simulation figure as a result of circuit, this circuit can work under normal temperature and low temperature, 2.5 times of normal temperature due to the low temperature feedback resistance, the multiplication factor that causes low temperature is 2.5 times of normal temperature, the equivalent input noise of low temperature is less than normal temperature, and its low temperature equivalent input noise is less than 1.5 microvolts.

Claims

1. CMOS amplifying circuit with LONG WAVE INFRARED Low ESR optical waveguide detector coupling is characterized in that:

Described CMOS amplifying circuit adopts the bridge circuit mode at input, and wherein one is that detector is connected with the 10K Ohmic resistance; The resistance of another bridge circuit adopts ratio to connect higher than two resistance of 200 times; Its both-end input Single-end output amplifier adopts positive-negative power supply; Adopt resistance to realize first order amplification higher than the feedback resistance of 1M ohm between negative input end and output; The second level is amplified the employing anode and is amplified mode, and multiplication factor is higher than 10 times; All adopt direct-coupling between bridge-type input, the first order and the second level.