| 摘要 |
PURPOSE:To improve the distortion factor at noisy environment by connecting a collector-emitter of a bipolar transistor (TR) in series with a drain of a junction FET of the first stage receiving a reception signal, increasing an impedance between a collector and emitter of the bipolar TR as a noise input signal increases and increasing the source potential of the junction FET of the 1st stage. CONSTITUTION:An AGC circuit 12 (comprising a detection/control circuit 12 and a TR11) operated at a strong input is added as shown in Fig. and a source voltage is boosted by flowing a current in response to an input signal level to a source resistor 6 of the junction FET10 of the 1st stage receiving a reception signal from an antenna 7 at its gate. No distortion even at the reception of a strong input signal is generated because the drain and gate source potential is at a high potential to the gate even when a drain-source voltage of the FET10 approaches ''0'' and the P-N junction is reverse-biased always by using the TR11 connected in cascade with the drain of the FET10. |
