| 摘要 |
PURPOSE:To make a titled circuit small in size and economical, by only one amplifier circuit without using a resistance network. CONSTITUTION:An input electric signal from each input terminal Ai produces optical signals 2 with an electrooptic conversion element connected to each terminal and the optical signals are received with photodetectors 3 opposing thereto. Only an electric signal from an input terminal A1 is turned on to be picked up from an output terminal B and electric signals from other input terminals are turned off. In such a state, a control signal P1 is turned on, and a bias voltage applied to the detectors 3 is reversed with a bias voltage switching circuit 4, control signals at other terminals are turned off and the bias voltage is Voff. Thus, photodetectors in off-state cause high resitance and act as load resistances for the photodetectors in on-state normally without shortening a load resistance 6 normally, allowing to make unnecessary a synthesizer with one amplifier 8 for signal amplification. |
