Desihn And Implementation Of The APD Test System

APD avalanche diode as a key device for high-speed optical system, and more important role with the development of photovoltaic technology. APD avalanche diode test equipment test parameters imperfect and price, can not meet the needs of APD tube production test, for which this paper developed APD avalanche diode test system. The system uses a highly integrated on-chip integration avalanche diode (APD) bias voltage control and optical current sensing devices, with good anti-interference performance, while the system increases the light source to make up for the existing system can not be directly APD tube response lack of measurement, the same test system fast the APD pipe a variety of characteristic parameters of the test. The system can APD tube breakdown voltage, dark current, response to the degree, and multiplier factor test.Based on the characteristics of the APD avalanche diode, determine the parameters of the system measured, the development program for APD test system, the APD test booster circuit and the weak current detection circuit, as well as the light source used to generate laser drive circuit. The system is able to dynamically output voltage of the APD test, with a weak current detection function, APD test booster circuit part of the Maxim MAX5026device is set up, the output voltage up to60V, covering the voltage range of the APD work; APD bias control and current sensing part to build the the ADI company ADL5317devices, integrated voltage control and current mirror, voltage and current of the APD can be measured indirectly, does not affect the work of the APD; measurement of the weak current IV transform the typical conversion circuit, an optional preamplifier OPA376is a low-noise, low bias current precision amplifier; In addition, unique to the light source LD backlight feedback structures, with good stability, making the APD test more perfect. System microcontroller to DSPIC33FJ64as the core processor, data acquisition and on-site control, and connected through the serial port and LCD, and software for processing the data in the output test results on the LCD.System debug results show this article APD avalanche diode test system solutions, with little interference, low cost, can be used for breakdown voltage, dark current, responsivity and the multiplication factor test, the output optical power of-20-Odbm to meet the APD response to the requirements of the degree of test-10dbm system is feasible, the APD avalanche diode test.