CN103163443A

CN103163443A - Instrument for automatically testing parameters of avalanche photo diode (APD)

Info

Publication number: CN103163443A
Application number: CN2013101063662A
Authority: CN
Inventors: 曾庆立; 陈善荣; 杨永东
Original assignee: Jishou University
Current assignee: Jishou University
Priority date: 2013-03-29
Filing date: 2013-03-29
Publication date: 2013-06-19

Abstract

The invention discloses an instrument for automatically testing parameters of an avalanche photo diode (APD) and belongs to the technical field of test and measurement instruments. An APD tube has obvious parameter discreteness, so that the debugging difficulty of equipment adopting the APD tube is increased. The invention provides a device for accurately measuring main parameters of the APD quickly and drawing a volt-ampere characteristics curve of the APD tube. The device comprises a power supply circuit, a control circuit, a measuring circuit and a display circuit; a single lithium battery is used for supplying power, and positive 5-V and negative 5-V direct current voltage is generated so as to supply power to an analogue small signal processing circuit; voltage of 6 to 75V is generated by a step of 2mV, so that voltage scanning can be realized, and bias voltage is provided for the APD tube; a biasing circuit has the overcurrent protection function of quick response, current of the APD tube under different bias voltage is measured by using a 10-bit alternating current/direct current A/D singlechip, the volt-ampere characteristics curve of the APD tube is drawn, and the APD parameters obtained through calculation are displayed on a thin film transistor-liquid crystal display (TFT-LCD); and the instrument is suitable to be carried.

Description

Photoelectricity avalanche diode (APD) Automatic parameter tester

Technical field

Patent of the present invention relates to a kind of photoelectricity avalanche diode (APD) testing apparatus, belongs to the surveying instrument technical field.

Background technology

Photoelectricity avalanche diode (APD) is a kind of electrooptical device that photoelectric field extensively adopts, and it has high opto-electronic conversion sensitivity and very short reaction time.But the parameter discrete of photoelectricity avalanche diode (APD) clearly, and its parameter difference of product of same batch is also larger, increased the debugging difficulty that adopts the equipment of APD pipe.How quick and precisely to measure the major parameter of APD and the volt-ampere characteristic of drafting APD pipe important theory and practice meaning is arranged.

Important parameter and the opto-electronic conversion curve of measuring photoelectricity electricity avalanche diode are faced with several key issues: 1, different photoelectricity avalanche diodes enter avalanche process required voltage wider range, most of communication is managed bias voltage from 30V to 80V left and right with APD, and it is very responsive to voltage noise, and how producing the bias voltage that satisfies condition is the first problem that faces in test.2, in a single day photoelectricity electricity avalanche diode enters avalanche condition its electric current in without the current-limiting circuit situation and increases sharply and damage, and its time must guarantee in measurement that only at Microsecond grade APD does not damage, and protects voltage to be absolutely necessary fast.3, the raw data that the major parameter that how to draw the photoelectricity avalanche diode from test process needs analysis-by-synthesis to measure.4, demonstrate measurement parameter and curve with form intuitively.5, traditional equipment can't adapt to the requirement of field test with mains-supplied.Above four problems has hindered the exploitation of photoelectricity avalanche diode automatically testing parameters instrument, and at present domestic do not have patent achievement open, and external APD parameter tester uses civil power can't adapt to the field test requirement.According to above analysis, preferably resolve these problems by studying our the portable APD automatically testing parameters instrument of design.

Summary of the invention

The purpose of patent of the present invention is a kind of measuring equipment of design, realizes that APD pipe major parameter measures and draw the volt-ampere characteristic of APD pipe, solves the practical problems of using parameter in the APD process to regulate the undesired and cause damage of equipment of improper work.The scheme that we propose preferably resolves above-mentioned main several problems, has has successfully researched and developed APD automatically testing parameters instrument instrument and has used single lithium battery power supply, possesses the field test ability.

To achieve the above object, the present invention adopts following technical scheme: photoelectricity avalanche diode (APD) Automatic parameter tester comprises power circuit, control circuit, metering circuit and display circuit; Described power circuit is by single 3V to 5V powered battery, is converted into positive 5V and negative 5V DC voltage is powered to the simulation small-signal treatment circuit by the low noise switching power circuit; By produced accurate control voltage under the 1.2V reference voltage by 12 D/A, control bias generating circuit, precision with 2mV boosts to 6V to 75V with described single 3V to 5V cell voltage, for APD provides suitable bias voltage, realize voltage scanning, the overcurrent protection function that this bias circuit has a quick response makes the APD pipe avoid damaging when abnormal; Described metering circuit use integrated 10 AD chip microcontroller the electric current of APD pipe under different bias voltages measured; Described display circuit will be drawn according to measured value the volt-ampere characteristic of APD pipe, and with the APD parameter display that calculates on the TFT-LCD screen.Described display circuit uses the TFT-LCD of bus interface, realizes abundant curve and parameter display.

Described power circuit, bias generating circuit and high-speed and low-noise amplifying circuit are an independently analog signal processing circuit plate, input end connects the lithium battery of a 3.6V, output terminal have output-5V ,+5V ,+12V～+ the 80V adjustable dc voltage adjusts input lead with five output leads measuring output and ground and voltage.Control circuit board and display circuit are an independently circuit board, comprise the MCU circuit with the interface of power supply circuit board, 12 D/A converter circuit that are used for adjusting the APD bias voltage, key circuit, integrated 10 A/D on it; Display circuit supports that by one the 320*240 LCD of MPU bus interface is that core consists of, and it is realized with the mode that is connected with 16 buses of MCU, has accelerated to draw the speed of APD volt-ampere characteristic and demonstration.

Description of drawings

Fig. 1 is general structure block diagram of the present invention;

Fig. 2 is power circuit of the present invention and low noise feeble signal amplifying circuit;

Fig. 3 is APD bias-voltage generating circuit of the present invention;

Fig. 4 is control survey of the present invention and display circuit schematic diagram.

Embodiment

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

In Fig. 1, (1) power circuit realizes by single lithium battery input 3.6V boost in voltage and stable output+5V, the voltage reversal stable output-the 5V power supply ,+5V one tunnel supplies the control display part for dual power supply amplifier another road through LDO output 3.3V.For extending service time of battery, require quiescent current little, conversion efficiency is high.(2) the small-signal amplifier section is responsible for amplifying the faint light electric current that APD produces, and photocurrent requires amplifying circuit to have very low electric noise density at microampere order, and very high response speed is arranged simultaneously.(3) change in 20 to 80V scopes because of different APD pipes should be able to fine adjustment for the required APD bias voltage that adds, and simultaneously perfect defencive function should be arranged.(4) control survey and display circuit are 320*240 by the microprocessor of integrated 10 A/D and 12 D/A and resolution TFT LCD consists of.

In Fig. 2, consist of booster circuit by U101, R100 arranges output current current limliting thresholding, and R101, R102 arrange output voltage, and the design is output as 5V.U101 is that core consists of voltage reversing circuit, and output voltage is-5V.U102 is that core consists of the feeble signal amplifying circuit, uses low noise to realize across the resistance amplifier at a high speed.The microampere order photocurrent is converted to the volt step voltage supplies with metering circuit.

In Fig. 3, U103 is that core consists of the APD bias circuit.When the control voltage of the control voltage of 6 pin 6 pin of output voltage and U103 during lower than 1.2V linear, realized the accurate control of output voltage, R112 and R113 arrange the maximal value of output voltage, and this programme is made as 75V, and output voltage can be adjustable in 6V to 75V linearity.10 pin of U103 are with the mirror-image monitoring electric current of 1:1 output APD.9 pin resistance R 106 arrange the transient protective electric current of APD pipe.Guarantee that at Microsecond grade the APD pipe is not damaged actuation time.

In Fig. 4, U200 is for measuring the voltage-stabilizing device of controlling with the display part, stable output 3.3V.U201 is the single-chip microcomputer of integrated 10 A/D, parallel port P00～P07 of U201 and P20～P27 connect 16 bit data ends of TFT display module, triode Q200 connects the backlight control end of TFT_LCD, realizes that software control backlight is to reach energy-conservation and to extend service time of battery.U201 is 12 D/A converters, and the bias voltage of the Control of Voltage APD pipe of its output changes.U202 arranges the reference voltage of A/D conversion, uses the accurate reference voltage integrated circuit of 1.25V.During test, single-chip microcomputer is measured the electric current of APD simultaneously indirectly by the low to high control voltage of D/A converter output by built-in 10 D/A.Record the parameters such as the avalanche voltage of APD pipe and leakage current, drawn out the volt-ampere characteristic of APD pipe by electric current corresponding under each voltage for designer's design reference.

The avalanche diode of patent of the present invention (APD) Automatic parameter tester has the function of measuring APD pipe parameter and drawing corresponding volt-ampere characteristic, by the dependence of the unmatchful mains-supplied of the monocell power supply strong adaptability to environment, it is intuitively convenient to be shown by TFT_LCD, has solved the difficulty of APD pipe parameter testing.

Claims

1. photoelectricity avalanche diode (APD) Automatic parameter tester, is characterized in that: comprise power circuit, control circuit, metering circuit and display circuit; Described power circuit is by single 3V to 5V powered battery, is converted into positive 5V and negative 5V DC voltage is powered to the simulation small-signal treatment circuit by the low noise switching power circuit; By produced accurate control voltage under the 1.2V reference voltage by 12 D/A, control bias generating circuit, precision with 2mV boosts to 6V to 75V with described single 3V to 5V cell voltage, for APD provides suitable bias voltage, realize voltage scanning, the overcurrent protection function that this bias circuit has a quick response makes the APD pipe avoid damaging when abnormal; Described metering circuit use integrated 10 AD chip microcontroller the electric current of APD pipe under different bias voltages measured; Described display circuit will be drawn according to measured value the volt-ampere characteristic of APD pipe, and with the APD parameter display that calculates on the TFT-LCD screen.

2. photoelectricity avalanche diode according to claim 1 (APD) Automatic parameter tester, is characterized in that, described display circuit uses the TFT-LCD of bus interface, realizes abundant curve and parameter display.