| 摘要 |
An optical receiver, for use with optical fibre or for receiving a beam in free space, has its detector device, usually a PIN diode (D) connected in series with a resistor (R1) and to the base of a gallium arsenide field effect transistor (FET). Although the latter is satisfactory at most frequencies of operation, in certain load conditions, instability can occur at Gigahertz frequencies. To overcome this, the source-drain path of the FET is shunted by 50 ohm resistor (R2) in series with a capacitor (C) of about 5 nanofarads. In addition the FET is coupled to a bipolar transistor amplifier by a relatively long wire bond (L) which acts as an inductive impedance at the frequencies at which this instability occurs. These measures between them suppress this instability. |
