A single-supply inductorless CMOS class G speaker amplifier

This paper presents a single-supply inductorless Class G speaker amplifier for portable applications. It is capable of driving a loudspeaker of up to 8Ohm in parallel with a 220pF capacitive load while consuming a quiescent current of 5mA. Unlike other Class G amplifiers that rely on triple-well process technology, the proposed Class G power amplifier is realized using standard twin-well 0.35um CMOS process technology. This design contains only four power transistors while eliminating any usage of inductor or power diodes. With a 3.6V single supply, the peak load power is 1.45W. An A-weighted signal-to-noise ratio (SNR) of 97.3dB is achieved. At the maximum final output signal of 2.037Vrms without clipping, the THD is 0.0404% at 20kHz and 0.0212% at 1kHz, respectively. Due to reduced electro-magnetic interference (EMI), the proposed Class G amplifier is suitable for EMI concerned audio applications.