Patent ID: 8649532

Claim:
An electronic volume circuit, comprising: a first signal processing circuit and a second signal processing circuit that are cascaded together, wherein the first signal processing circuit is a multi-channel mixing circuit including a first operational amplifier including an inverting input terminal, a non-inverting input terminal and an output terminal, plural input resistors inputting one or more signals to the inverting input terminal of the first operational amplifier, and a feedback resistor connected between the inverting input terminal and the output terminal of the first operational amplifier, and wherein the first operational amplifier of the multi-channel mixing circuit is configured to receive, and add, multiple signals input, via the input resistors of the multi-channel mixing circuit, through the inverting input terminal of the first operational amplifier, and wherein the second signal processing circuit includes a second operational amplifier including an inverting input terminal, a non-inverting input terminal and an output terminal, an input capacitor inputting a signal output from the first operational amplifier to the inverting input terminal of the second operational amplifier, with the non-inverting input terminal connected to a ground source, and a resistor and a capacitor connected in parallel between the inverting input terminal and the output terminal of the second operational amplifier.