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In the low cost laser tracking applications, the width of the laser echo pulses received by four-quadrant photodetector from an illuminated target are narrow, and are only a few hundred or dozens of nanoseconds. In order to obtain the peak of these narrow laser pulses of nS level, by using peak holding technique, a simplified transconductance peak holding circuit model is constructed, taking into account of low cost applications with large number of requirements. The key parameters of the transconductance peak holding circuit such as response time, droop rate and bandwidth are analyzed for narrow laser pulse signals. The transconductance peak holding circuit is designed using a low-cost integrated chip OPA615, then is simulated by the software PSpice tools. Finally, a circuit board is manufactured for further tests. The results show that: the bandwidth of the circuit is about 76.4 MHz, response time is about 7 ns, and droop rate is about 5.7 mV/μs. The peaks of narrow laser pulses are effectively acquired, meeting the needs for the subsequent low speed and low cost A/D converter.
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