| 摘要 |
PURPOSE:To obtain a stable tuning control voltage by forming a tuning part with opposite electrodes via a thin dielectric layer and also controlling the tuning part with an output voltage of a D/A converter and a PLL circuit. CONSTITUTION:A signal inputted to an input terminal 61 is amplified by an amplifier 62 and the result is fed to a mixer 63. On the other hand, a local oscillation signal is oscillated at an oscillation section comprising a tuner 58, a PLL circuit 59 and a feedback amplifier 60 and fed similarly to a mixer 63, mixed with an output of the tuner 53 and an intermediate frequency signal is outputted to an output terminal 64. Further, each tuning frequency of respective tuners 52, 53 and 58 is controlled variably by the setting of a tuning control digital signal code inputted to a common input terminal 65 for tuning control of respective D/A converters 56, 57 and the PLL circuit 59. |
