NMOS-only Class-D output stages based on charge pump architectures

An NMOS only Class-D output driver which uses charge pump techniques in a low voltage CMOS technology is presented. Compared to conventional Class-D output stages, the given implementation shows a gate area reduction of 45%, resulting in efficiency improvements. The circuit has been simulated in a 0.13µm process and is implemented using 3.3V I/O devices. The structure does not violate any gate-oxide reliability rules.