| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a bias circuit that can protect a receiving transistor against damage from excessive input in a simple configuration without deteriorating receiving noise performance. <P>SOLUTION: A bias circuit used for a receiving amplifier that does not have any excessive input protection circuits includes a gate bias circuit 8 connected to a gate terminal of a receiving transistor 2 constituting the receiving amplifier, and a drain bias circuit 9 connected to a drain terminal of the receiving transistor 2. The gate bias circuit 8 has change detection means for detecting a change in gate current Ig or gate voltage Vg of the receiving transistor 2 at excessive input to generate a change signal. The drain bias circuit 9 reduces drain voltage Vd to the receiving transistor 2 in response to the change signal at excessive input. <P>COPYRIGHT: (C)2012,JPO&INPIT |
