CN102522696A - Closed-loop digital liquid diode (LD) laser driving circuit - Google Patents
Closed-loop digital liquid diode (LD) laser driving circuit Download PDFInfo
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- CN102522696A CN102522696A CN2011103898268A CN201110389826A CN102522696A CN 102522696 A CN102522696 A CN 102522696A CN 2011103898268 A CN2011103898268 A CN 2011103898268A CN 201110389826 A CN201110389826 A CN 201110389826A CN 102522696 A CN102522696 A CN 102522696A
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Abstract
The invention relates to a precision photoelectric detection technology, in particular to a closed-loop digital liquid diode (LD) laser driving circuit comprising a partial discharge (PD) monitoring module which can obtain diode monitoring current to be monitored, and the PD monitoring module passes through a differential amplifier module and an analog/digital (A/D) conversion circuit and is accessed to a single-chip microcomputer; the single-chip microcomputer can compare the voltage which is converted from the diode monitoring current with the reference value of the monitoring voltage and generates a voltage deviation signal, and proportional-integral-derivative (PID) operation is carried out to the deviation signal; and after passing through a digital/analog (D/A) conversion circuit and a voltage/current conversion module, the operation result data of the single-chip microcomputer is output to an LD driving circuit. According to the circuit, a typical PID control theory is integrated into laser diode power control, a digital regulation method is adopted, initial driving current can be set, the adjustable amount of the minimum current is small, the regulation precision is high, and the maximum driving current is variable. The driving circuit is matched with a temperature control circuit, so that the output power of a laser diode is highly stable and adjustable.
Description
Technical field
This invention relates to accurate photoelectric detecting technology, is specifically related to a kind of closed-loop digital formula LD drive circuit for laser.
Background technology
In precise light electro-detection field, the minor fluctuations of light source can cause measured bigger skew, thereby produces bigger measure error.As in the Atomic Absorption Characteristics Detection, usually need detect the luminous power front and back contrast of light wave after absorbing of specific wavelength.In this case, very high for the requirement of light source stability, reach 0.1%.Stabilized light source in optical fiber measurement during as electronic circuit test with swinging device as signal source, require to send high stable, light signal that luminous power is adjustable.Stabilized light source is a kind of important infrastructure device in the anxious fibre system tester leaved for development.More domestic scholars have done some researchs to the stabilized lasers light source.The method for designing that has makes the laser injection current stable, and is used temperature control circuit.Though this method improves to stability, other influencing factor is lacked consideration, not a kind of control system of closed loop.The adjusting to luminous power that has only uses the integration of simulation to regulate, because integral control is to lean on the accumulation to error to produce to the elimination effect of steady-state error, so reflection is insensitive, and the system stability allowance is descended, and overshoot increases, generally use separately.
Summary of the invention
The technical problem that will solve of the present invention is to provide a kind of control precision high, low in energy consumption closed-loop digital formula LD drive circuit for laser.
Closed-loop digital formula LD drive circuit for laser of the present invention includes the PD monitoring modular that can obtain diode monitoring current to be measured, and the PD monitoring modular inserts single-chip microcomputer behind difference amplification module and A/D change-over circuit; Single-chip microcomputer can compare and produce voltage deviation signal to the voltage and the monitoring voltage reference value of diode monitoring current conversion, again deviation signal is carried out the PID computing; Behind the operation result data process D/A change-over circuit and voltage/current modular converter of single-chip microcomputer, output to the LD drive circuit.
The present invention's employing Single-chip Controlling; The monitoring current of photodiode, difference is become a voltage after amplifying; Behind the high-precision a/d converter sample quantization, send into single-chip microcomputer, after the single-chip microcomputer calculation process, single-chip microcomputer directly drives the programmable current source output current and drives LD work.This circuit incorporates the classical PID control theory in the laser diode power control, adopts digital regulated mode, and initial driving electric current (LD power output) can be provided with, and the minimum current controlled variable is little, and degree of regulation is high, and maximum drive current is variable.This drive circuit and temperature-control circuit are used (threshold current of LD and power output receive the influence of working temperature bigger), can make output power of laser diode highly stable and adjustable.
Description of drawings
Fig. 1 is a system principle diagram of the present invention;
Fig. 2 is the circuit diagram of difference amplification module of the present invention.
Embodiment
One, design of drive circuit
1 laser diode package and parameter
Common laser diode package has two kinds of forms: be total to anode cathode type together.LD and monitoring the laser PIN photodiode of Output optical power dorsad are packaged together.Here, LD adopts SANYO655nm red laser diode, and packing forms is for being total to anode (negative pole of the positive pole of LD and PD (photodiode) links together).The maximum Output optical power of LD is 30mW, and threshold current is 40mA (25 ℃), and operating current is 110mA to the maximum.The monitoring current Im of PD and the power output P0 of laser are linear under temperature-resistant situation, and this design for the back control circuit provides foundation.
2 circuit theories
The monitoring current of photodiode becomes a voltage after difference is amplified; Behind the high-precision a/d converter sample quantization, send into single-chip microcomputer; With monitoring voltage reference value in the single-chip microcomputer (under the setting power condition; The numeral of the voltage that monitoring current becomes after difference is amplified) poor between, produce voltage deviation signal; Again deviation signal is carried out the PID computing, operation result becomes the drive circuit of LD after D/A conversion and voltage-to-current (V-I) conversion.It is in order to make output power of laser diode stable that PID regulates.This single-chip microcomputer closed-loop control system block diagram is as shown in Figure 1.
3 circuit module type selecting and calculating
3.1 difference amplification module
Visible by Fig. 2, its circuit monitoring electric current is very little, especially when laser output power＜10mW.Ultralow the bias current (≤75fA that this circuit adopts Texas Instruments to produce; The monolithic operational amplifier OPA128 of fA=10～15A); Because input stage adopts the FET of dielectric isolation to form, and has improved the geometric figure of input transistors, makes it have unique electric property.OPA128 is because its particular performances; Thereby be very suitable for adopting traditionally the application of the electrometer level operational amplifier aspect that vacuum static electricity meter pipe formed, like
mistakes such as electrometer, mass spectrometer, chromatograph, charge amplifier, measuring ion, Photoelectric Detection, high-energy ray instruments! Do not find Reference source.。The special character of these application is that they have the characteristic of high source impedance, low noise and ultralow bias current, can find out from OPA128 technical indicator given below, and it can satisfy the specific (special) requirements of this respect fully.
The key technical indexes of OPA128:
Input bias current＜± 75fA
Input offset voltage＜± 500 μ V
Differential-mode input impedance 1013//1pF
Common mode input impedance 1015//2pF
Open-loop voltage gain＞110dB
Because photodetector is operated under the zero offset, therefore produce electric current with light intensity has good linear relationship, through the I/V conversion, can obtain the voltage signal that supplies A/D to change.
Can know input Vo and output I in the circuit by Fig. 2
iRelation suc as formula:
V
0＝I
i×R
1
3.2 A/D converter
A/D converter is selected the MAX12557 of U.S. letter company for use; Be 14 high speed A devices of new a kind of low-power consumption, small size and the high dynamic characteristic of releasing of Maxim company, can be widely used in fields such as the data acquisition that requires low-power consumption, digital receiver, portable apparatus.The chip selection signal of transducer, clock line and data wire directly directly link to each other with the I/O mouth of single-chip microcomputer.The figure place of transducer has determined to detect the resolution of control circuit.14 bit pads can change into 214 parts to the voltage of 4.096V range; So the gain of adjustment differential amplifier makes its output voltage maximum reach the full scale voltage of A/D converter; Then all can detect for optical power change 1/1214 in theory; Promptly this drive circuit can detect＜0.01% laser optical variable power, and then can in single-chip microcomputer, regulate.
3.3 programmable current source
The LD drive current source adopts the Linear programmable current source chip LT3092 of company.
LT3092 has 1% initial accuracy and low-down temperature coefficient.Output current is programmable from 0.5mA to 200mA, and Current Regulation is superior to 10ppm/V in 1.5V to 40V scope.Satisfy the driving demand of LD laser fully.Different with other analog integrated circuit, LT3092 adopts the particular design method, realizing high DC and AC impedance, thereby guarantees steady operation, and need not the electrical power by-pass capacitor.Because LT3092 need not capacitor, thereby be very suitable for " essential safety " application, in this type of is used, the short circuit of output possibility, and can not allow any spark.Reverse electrical source tolerance limit and hot stoppage protection this IC and load.
In addition, single-chip microcomputer and intercomputer communicate through the USB mouth in the circuit, and the USB transceiver of employing is a single-chip microcomputer self-carried USB interface.Computer through the USB mouth can be to the initial driving electric current of LD, be provided with reference to monitoring voltage, can also set the parameter of the adjuster of can adjusting out quickly and easily like this to ratio, integration, the differential coefficient of pid number adjuster.Deposit the intermediate object program of some setup parameters and temporary PID computing in the memory.
Two, digital PID is regulated
PID adjuster control structure is simple, and parameter is adjusted easily, and the mathematical model that needn't obtain controlled device is scalable just.Relation between its input e (t) and output u (t) is:
In order to realize programming, write following formula as discretization, the output that can write out the k time sampling type PID is expressed as:
In the formula, E (k) is the deviate of the k time sampling type.If the monitoring voltage set point is VOset, the sampled value of the k time output of differential amplifier is Vo (k), then:
E(k)＝Voset-Vo(k) (5)
Convenient for programming, formula (4) to be done further to improve, the ratio of establishing is output as: Up (k)=KpE (k), integral is output as: Ui (k)=K1E (k)+P1 (k-1), differential term is output as: UD (k)=Kd [E (k)-E (k-1)], formula (4) can be write as so:
U(k)＝Up(k)+Ui(k)+UD(k) (6)
Formula (6) is the position type PID programming mode of discretization, generally adopts floating-point operation.
Three kinds of PID on, proportional action can be made timely response to deviation; Integral action mainly is used for eliminating static difference, improves the static characteristic of system; The status effect mainly is used for reducing overshoot, overcomes vibration, makes system's trend stable, accelerates the responsiveness of system, reduces the overshoot time, improves the dynamic characteristic of system.If can the intensity of three kinds of effects be cooperated suitably, can make controller fast, steadily, accurately, thereby obtain satisfied control effect.The parameter tuning of PID adjuster can use expanding critical proportion degree method.
Three, temperature-control circuit
The ADN8830 chip that the embodiment of the invention adopts is the single-chip TEC controller of switching mode; It is a closed-loop control system; Invest the laser die temperature on the TEC and be converted into magnitude of voltage through the negative tempperature coefficient thermistor detection; With analog input temperature voltage is set and compares, produce an error signal and come the stabilized lasers diode to get temperature via PWM controller drives TEC from DAC.The feedback control loop of system is through high stability, and low noise PID compensating network constitutes, and can change the system responses characteristic through the adjustment pid parameter.
The major advantage of ADN8830 single-chip TEC controller: 1. control precision is high, and have self-correcting, from characteristic steady zero, low drift, maximum drift voltage is lower than 250 μ V, in application, target temperature is lower than ± 0.01 ℃.2. system power dissipation is low.In the linear model controller, generally adopt push-pull circuit as output stage, its power efficiency is low; Mode switching controller adopts the switch mosfet pipe, and resistance is very little during conducting, greatly reduces system power dissipation.
Claims (1)
1. closed-loop digital formula LD drive circuit for laser, it is characterized in that: it includes the PD monitoring modular that can obtain diode monitoring current to be measured, and the PD monitoring modular inserts single-chip microcomputer behind difference amplification module and A/D change-over circuit; Single-chip microcomputer can compare and produce voltage deviation signal to the voltage and the monitoring voltage reference value of diode monitoring current conversion, again deviation signal is carried out the PID computing; Behind the operation result data process D/A change-over circuit and voltage/current modular converter of single-chip microcomputer, output to the LD drive circuit.
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| CN2011103898268A CN102522696A (en) | 2011-11-30 | 2011-11-30 | Closed-loop digital liquid diode (LD) laser driving circuit |
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| CN2011103898268A CN102522696A (en) | 2011-11-30 | 2011-11-30 | Closed-loop digital liquid diode (LD) laser driving circuit |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102999076A (en) * | 2012-11-22 | 2013-03-27 | 江苏飞格光电有限公司 | Numerical control direct current constant current source for LD (Laser Diode) driving |
| CN103730831A (en) * | 2013-12-20 | 2014-04-16 | 重庆南方数控设备有限责任公司 | Constant power laser output control system and method |
| CN105444879A (en) * | 2015-12-16 | 2016-03-30 | 天津津芯微电子科技有限公司 | Laser energy acquisition method and laser energy acquisition device |
| CN105912067A (en) * | 2016-06-15 | 2016-08-31 | 凌云天博光电科技股份有限公司 | Control method and device for pump laser input currents |
| CN106058629A (en) * | 2016-07-22 | 2016-10-26 | 中国电子科技集团公司第三十四研究所 | Closed-ring feedback control fiber amplifier and feedback control method thereof |
| CN109041385A (en) * | 2018-09-03 | 2018-12-18 | 武汉光迅科技股份有限公司 | A kind of control method and device of optical module inner drive |
| CN116435865A (en) * | 2023-04-24 | 2023-07-14 | 深圳市芯波微电子有限公司 | Laser diode driving control circuit |
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| CN2831538Y (en) * | 2005-01-21 | 2006-10-25 | 南昌航空工业学院 | Digital semiconductor laser driving power source |
| CN1862900A (en) * | 2006-05-19 | 2006-11-15 | 北京航空航天大学 | Stable light source light power output apparatus with full optical fiber structure |
| CN101141049A (en) * | 2007-05-23 | 2008-03-12 | 中兴通讯股份有限公司 | Laser automatic optical power control circuit |
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Patent Citations (3)
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| CN2831538Y (en) * | 2005-01-21 | 2006-10-25 | 南昌航空工业学院 | Digital semiconductor laser driving power source |
| CN1862900A (en) * | 2006-05-19 | 2006-11-15 | 北京航空航天大学 | Stable light source light power output apparatus with full optical fiber structure |
| CN101141049A (en) * | 2007-05-23 | 2008-03-12 | 中兴通讯股份有限公司 | Laser automatic optical power control circuit |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102999076A (en) * | 2012-11-22 | 2013-03-27 | 江苏飞格光电有限公司 | Numerical control direct current constant current source for LD (Laser Diode) driving |
| CN103730831A (en) * | 2013-12-20 | 2014-04-16 | 重庆南方数控设备有限责任公司 | Constant power laser output control system and method |
| CN105444879A (en) * | 2015-12-16 | 2016-03-30 | 天津津芯微电子科技有限公司 | Laser energy acquisition method and laser energy acquisition device |
| CN105912067A (en) * | 2016-06-15 | 2016-08-31 | 凌云天博光电科技股份有限公司 | Control method and device for pump laser input currents |
| CN105912067B (en) * | 2016-06-15 | 2017-05-24 | 凌云天博光电科技股份有限公司 | Control method and device for pump laser input currents |
| CN106058629A (en) * | 2016-07-22 | 2016-10-26 | 中国电子科技集团公司第三十四研究所 | Closed-ring feedback control fiber amplifier and feedback control method thereof |
| CN109041385A (en) * | 2018-09-03 | 2018-12-18 | 武汉光迅科技股份有限公司 | A kind of control method and device of optical module inner drive |
| CN109041385B (en) * | 2018-09-03 | 2020-01-21 | 武汉光迅科技股份有限公司 | Control method and device for optical module internal driver |
| CN116435865A (en) * | 2023-04-24 | 2023-07-14 | 深圳市芯波微电子有限公司 | Laser diode driving control circuit |
| CN116435865B (en) * | 2023-04-24 | 2024-06-11 | 深圳市芯波微电子有限公司 | Laser diode driving control circuit |
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Application publication date: 20120627 |