A 1 watt audio amplifier in a standard digital 90-nm CMOS technology

An audio amplifier in a standard 90-nm CMOS technology is designed for direct battery hook-up in a mobile phone. Special techniques have been applied to run it from a supply voltage of up to 5.5 V. The circuit does not require a dedicated supply voltage generator, it can be integrated on the same chip with the digital signal processor, provides high output power, good power supply rejection and good efficiency.