| 摘要 |
PURPOSE:To form a variable gain amplifier with a wide band by employing a dual gate field effect transistor as a high frequency power amplifier element. CONSTITUTION:The 1st gate of the dual gate FETs 1a-1c is connected to connecting points 22a-22c between distributed constant lines 2a-2d of the 1st high frequency input line and the 2nd gate is connected to ground respectively in terms of high frequency through capacitors 6a-6c and biased by a DC bias voltage from a terminal 12 in terms of DC. Moreover, the drain of the dual gate FETs 1a-1c is connected to connecting points 23a-23c between distributed constant lines 3a-3d respectively and a termination resistor 5 is connected to a terminal opposite to an output terminal RFOUT of the high frequency output line. Thus, the bias voltage applied to the terminal 12 is varied to control the gain over a wide band. |
