| 摘要 |
An optical receiver with extended dynamic range includes an optical detector (3), a transimpedance amplifier (1, 2) and a variable impedance network (D, Tr1). The d.c. component of the detector output is employed to control the variable impedance such as to prevent overload of the detector and the transimpedance amplifier front end (1). The a.c. and d.c. components of the feedback signal are separated by a capacitor (C2) so that only the a.c. component is coupled to the front end. The voltage drop across resistor r due to the d.c. component of the detector output serves to switch on transistor Tr1 at high input light levels, a.c. components being removed by a filter network (R3, C3), and permit diode D to conduct excess current away from the detector and the front end. The FET first stage of the transimpedance amplifier is replaced by a bipolar device for bit rates in excess of 30 MBits/s. <IMAGE>
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