| 摘要 |
PURPOSE:To prevent electric characteristics and temperature characteristics from being affected by extracting an intermediate frequency signal in coarse coupling, applying the signal to a base-grounding type synthesizing amplifier to synthesize the signal and detecting the result to use one detection diode. CONSTITUTION:The an inputted intermediate frequency is amplified sequentially in-phase state by in-phase amplifiers 19-1-19-4. Then a part of the output signals of the amplifiers 19-1-19-4 is synthesized by a common base-grounding type synthesizing amplifier 20 having low input impedance via coupling resistors 20-1-20-5 having large resistance. The synthesized intermediate frequency is detected by a detection circuit 21 and converted into a DC voltage corresponding to the reception signal strength. Thus, one detection diode is enough to decrease the fluctuation of the temperature characteristics of the diode. |
