A 1-V CMOS audio amplifier for low cost hearing aids

The paper describes a very low-cost analog audio amplifier IC for hearing aid devices. The amplifier employs an effective offset cancellation analog circuit aimed to ensure a low quiescent consumption even in case of strong mismatch due to silicon manufacturing. The consumption is 500-muA from a 1.3-V battery supply (excluded mic/loudspeaker biasing) but the hearing aid can operate down to 1-V. Measurements confirm that the nominal THD of the circuit is lower than 1-% at 10-mW output power. The die area (including pads) is lower than 1.5-mm
²
in a standard 0.35-mum CMOS process (high-res poly option).