Temperature compensated APD detector bias and transimpedance amplifier circuitry for laser range finders

摘要

Laser range finder circuitry (FIG. 1) including an avalanche photodiode detector (315), a capacitor (C1) for storing a detector bias voltage, and a transimpedance amplifier (317) for amplifying the detector signal. The capacitor (C1) is charged in response to a first control signal (IUP) by a circuit employing first and second field effect transistors (Qb1, Qb2) and is discharged in response to a second control signal (IDN) by a circuit employing a third field effect transistor (Qb4). An overload protection circuit including a single diode (CR3) is provided to accommodate excessive charge created by backscatter upon initial laser firing. A temperature sensor (319) is provided to develop a temperature signal which may be monitored to adjust the detector bias voltage and other parameters so as to permit use of an associated laser range finder over a wide range of temperatures. IMAGE