Combining envelope elimination and restoration and predistortion techniques for use in IEEE802.11g systems

The envelope elimination and restoration (EE&R) transmitter inherently provides high-power efficiency for linear amplification, but it suffers out-of-band spectral re-growth from a number of distortion sources such as differential time delay between envelope and phase paths and nonlinear conversion and feed-through effect due to envelope variation of the radio frequency (RF) power amplifier. The combination of EE&R and predistortion techniques is discussed, which are used to compensate for the nonlinear distortions, and a modified RF phase signal is used to reduce the feed-through effect for an IEEE802.11g application. This results in an EE&R transmitter with a performance of - 37 dBc at the first adjacent channel power ratio (ACPR) and - 47 dBc at the second ACPR and an average power added efficiency of 47.3%.