低纹波低功耗自动控制APD偏压电路

全站仪红外测距系统接收电路采用APD雪崩光电二极管作为接收器件,它的精度对后级的信号处理及测量精度起着决定性的影响,针对其高精度要求,提出两种APD偏压电路。前者采用交流反馈网络消除冲击电压,提高了开关管寿命,采用三级滤波网络极大的降低了电路纹波从而提高了测量精度;后者采用专用芯片控制电路电源,使储能电感处于非连续工作状态,大大降低了电路的功耗,同时采用4个变容二极管既升高了电压,又减小了纹波。两种电路均具有可自动控制,且能对APD的内部增益进行全范围补偿的优点。实践证明,电路工作性能理想,提高了测距精度。

APD bias voltage circuit of low ripple and low power automatic controll

The APD is used in the receive circuit of total station infrared distance measure system.Its accuracy have crucial influence on signal process and measure accuracy.In consideration of its high accuracy requirement,this paper presents two APD bias voltage circuits.the former adopts intercourse feedback network to slake the impact voltage,and the MOSFET's longevity is prolonged.It also adopts third class filter to depress the voltage ripple.The latter circuit introduces a special chip to control the power,the inductance works in discrete mode,it reduces power consumption,and the four variodes is used to impove the voltage and depress the ripple.These two circuits have the advantages of automatic control and the inner gain of APD can also be compensated for all range.The circuits are proved to perform well in practice and the measure accuracy is improved.