frequency the signal generated by the oscillator of fig3 will also be referred to as the oscillation signal the frequency of the signal generated by the oscillator of fig3 will also be referred to as the oscillation signal frequency the oscillation signal can be transmitted via the output terminal 134 to an external device not shown the oscillator of fig3 has an oscillating section and a frequency control section the oscillating section is of the colpitts type the variable capacitance diode 113 the inductors 115 and 120 and other parts compose a resonator whose resonance frequency determines the oscillation signal frequency the frequency of the signal generated by the oscillator of fig3 the resonance frequency of the resonator that is the oscillation signal frequency depends on the capacitance of the diode 113 the capacitance of the diode 113 depends on a voltage applied thereacross the diode 118 serves to selectively short circuit the inductor 120 with respect to an rf radio frequency signal the resonance frequency of the resonator that is the oscillation signal frequency depends on whether or not the inductor 120 is short circuited a first control voltage is applied between the first input terminal 110 and the ground the first control voltage is transmitted to the variable capacitance diode 113 via the resistor 112 thus a voltage depending on the first control voltage is applied across the variable capacitance diode 113 accordingly the capacitance of the diode 113 varies in accordance with the first control voltage this means that the oscillation signal frequency can be controlled or adjusted in response to the first control voltage a second control voltage is applied between the second input terminal 111 and the ground the.