Patent attributes
A battery portion (BAT) or another type of voltage shift portion is provided for shifting a control voltage (V2) in a direction which causes the anode potential of a variable-capacitance diode (VD) to be a negative potential and superimposes its battery voltage (Vb) on the control voltage (V2). Specifically, the battery portion (BAT) is inserted in a direction which causes the control voltage (V2) to be decreased and operates such that [control voltage (V2)−battery voltage (Vb)] is applied to the anode terminal of the variable-capacitance diode (VD). Then, the voltage applied to the variable-capacitance diode (VD) is [control voltage (V2)−control voltage (V1)−battery voltage (Vb)]. Thus, the variable capacitance range of the variable-capacitance diode (VD) is increased.
