Patent ID: 9025793
Filing Date: 2015-05-05
Classification: H03G

Abstract:
1. An audio signal processing circuit comprising: a selector having a plurality of input ports that receive respective analog audio signals, and configured to select an analog audio signal at one of the plurality of input ports; an oscillator configured to generate a master clock signal; an analog gain control circuit configured to amplify the analog audio signal received from the selector with a gain set for each input port, wherein the analog gain control circuit frequency-divides the master clock signal with a first frequency-dividing ratio so as to generate a first transition clock signal and gradually changes the gain when the gain is switched in synchronization with the first transition clock signal; and an A/D converter configured to frequency-divide the master clock signal with a second frequency-dividing ratio so as to generate a first conversion clock signal and to convert an output signal of the analog gain control circuit into a first digital audio signal using the first conversion clock signal, wherein the audio signal processing circuit is monolithically integrated on a single semiconductor substrate; and wherein the first frequency-dividing ratio is different from the second frequency-dividing ratio, thereby reducing beat noise.