Volume control circuit

摘要

A volume control circuit includes an input circuit, which may be a differential amplifier, for converting an input signal to 1st and 2nd currents. The 1st current contains a 1st signal component and the 2nd current contains a 2nd signal component whose phase is opposite to the phase of 1st signal component. The input circuit is coupled to 1st and 2nd divider circuits which may be a doubly balanced differential amplifier. A volume control signal is applied to the 1st and 2nd divider circuits. The 1st divider circuit divides or attenuates the 1st current according to the volume control signal and generates a 1st divided current. The 2nd divider circuit divides or attenuates the 2nd current according to the volume control signal and generates a 2nd divided current. The current division ratio of each of the 1st and 2nd divider circuits is changed with the magnitude of the volume control signal. The 1st and 2nd divided currents are converted to an output current by a current mirror including inverted Darlington connected transistors. The output current is converted to an output signal by an output circuit.