Photodetector arrangement with current=carrying detector element in bridge - uses frequency modulation of bridge operating voltage and corresp. frequency selective evaluation of diagonal voltage

摘要

The photodetector arrangement has a current-carrying detector element (PD) with an illumination-dependent resistance value (RD) whose voltage drop is evaluated as the detector signal. The detector element forms part of a resistive bridge whose diagonal voltage difference (UD) is evaluated. The operating voltage applied to the bridge is modulated with a modulation frequency of between 100 Hz and 100 kHz. The evaluation of the diagonal voltage is performed frequency selectively using the modulation frequency. ADVANTAGE - Improved evaluation of even small useful signals.