| 摘要 |
<p>PROBLEM TO BE SOLVED: To suppress an image frequency signal on the condition that the increase in a noise index and the decrease in an electric power eliminated are eliminated in a signal of input target frequency. SOLUTION: A 1st gate (G1) of a dual-gate FET 3 is connected to an input terminal 1 via an input matching circuit 2, an output terminal 5 is connected to the drain (D) of the FET 3 via an output matching circuit 4, and the source (S) is grounded. Then a parallel resonance circuit 16 having a coil 14 and a capacitor 15 arranged in parallel is connected between a 2nd gate (G2) of the FET 3 and the ground. Consequently, the loss of the parallel resonance circuit does not affect the signal power, an output decrease of the input signal and an increase in its noise index are suppressed, and the image frequency signal is suppressed.</p> |
