| 摘要 |
PURPOSE:To eliminate the need for an externally mounted LC circuit by providing a local oscillator circuit outputting a pulsating current frequency appearing at the terminal voltage of an impedance element in series with the power supply of an inverter ring oscillator as a local oscillation frequency. CONSTITUTION:An RF frequency signal from an antenna 1 is mixed with a local oscillation signal from a local oscillator 5 by a mixer circuit 3 via an RF amplifier 2 and used as an IF signal, and outputted via an IF filter 20 and an IF amplifier 4. On the other hand, a converter 6 outputs a voltage Vc according to the frequency data from a memory 7 operated externally. The output current of an inverter ring oscillator 51 of the local oscillator 5 is controlled by the voltage Vc, a pulsating current is extracted by a current control FET as a voltage and fed to the mixer 3 via a BPF 53 and an amplifier 54.
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