A variable degeneration impedance supply circuit, including: two alternatively connected transistors; a capacitor circuit having a predetermined capacitance and serially connecting output terminals of the two transistors; and a switch for controlling on/off state between the capacitor circuit and the output terminal, according to a predetermined first control signal. The circuit further includes: at least one sub capacitor circuit arrayed in parallel to the capacitor circuit for serially connecting the output terminals of the two transistors; and at least one sub switch for controlling on/off state between the sub capacitor circuit and the output terminal, according to a predetermined control signal. Therefore, the magnitude of a degeneration impedance can be varied by controlling degeneration capacitance. Moreover, the variable degeneration impedance supply circuit can be advantageously applied to a voltage controlled oscillation circuit and a frequency divider circuit.