Extending dynamic range of RF PWM transmitters

A multilevel RF PWM transmitter architecture using power combining is proposed. Multilevel RF PWM is realised by driving one or two power amplifiers with a PWM signal, while the others are turned off or working at full power. By changing the number of amplifiers driven by RF PWM, the duty cycles can be kept out of the pulse swallowing regions, and the dynamic range can be greatly extended. In this way, the advantages of RF PWM can be made available also to standards which require large dynamic ranges, such as the WLAN standard.