Wideband Envelope Modulator Design for Wideband Power Amplifiers

A wideband and high-efficiency envelope modulator is proposed for envelope tracking and envelope elimination and restoration transmitters. The modulator can achieve a power added efficiency of 80% for the envelope of WLAN 802.11a/g signal. The modulator is tested with a high efficiency power amplifier. In the transmitter, the phase signal fed into the power amplifier is modulated by the clipped envelope signal. This relaxes the critical time alignment requirement between the envelope and the phase signal paths in a traditional envelope elimination and restoration transmitter. As a result, the transmitter can achieve an overall PAE of 34.3% while complying with the WLAN 802.11a/g spectrum mask.