Abstract: A speaker driver applied to class G/class I with a single phase power supply is presented. Gain expanding and compressing technology are employed in the signal processing circuit to optimize power dissipation. The circuit is implemented in 0.18 μm N-well CMOS. Experimental results show that the speaker driver has a good audio sound quality and power efficiency. Less than 0.006% THD at a low power range and less than 0.4% at a medium power range can be obtained with a 1 kHz sine wave signal. Maximum output power of 360 mW can be gained at a load of 8 Ω . The power efficiency is about twice that of a traditional class AB driver at the power range of 80 mW and shows more than 18% improvement at the higher output power range.

Key words: class G/class I, speaker driver, single phase power supply, THD