Photodetector-based scanning device e.g. for optical recording carriers, such as CD and DVD, has voltage control circuit based on operational amplifier and MOSFET elements

摘要

A optical recording carrier e.g. for compact disc, scanning device is designed to avoid a voltage coupling between a detection unit (1) and an evaluation/analysis unit (3) where both units (1;3) operate in the same voltage range, and has a control circuit (7,8), based on an operational amplifier (7) and a transistor e.g. MOSFET (8), associated with the evaluation device (3), and used for holding the value of the input of the connection (2) at the value of a reference voltage (Vref), or at a value proportional to it