| 摘要 |
PURPOSE:To decrease the change in the sensitivity of modulation due to band switching and the band switching width, by constituting selectively a capacitive element and an inductance element to a tuning circuit of an oscillator in response to the band switching. CONSTITUTION:A microstrip line resonator 1 is coupled between a transistor negative resistance generating circuit 3 and a varactor diode circuit 2, and a band switching circuit 4A to change over the frequency is constituted at the side of the varactor diode of this resonator 1. A PIN diode 22 is conductive by a DC bias voltage from a DC bias terminal 33 when a selecting switch 24 is turned on at first in performing the band changeover, a capacitor 21 is given to the tuning circuit of the oscillator to change over the frequency. Further, a PIN diode 28 is conductive by the DC bias voltage, a band changeover inductor 35 is given to the tuning circuit through a high frequency conducting capacitor 34, allowing to change over the other frequency. |
