Linearity requirements for digital wireless communications

Linearity requirements, characterization, and simulation for digital wireless communications are discussed with emphasis on CDMA environments. A receiver's dynamic range and sensitivity in the presence of jammers are determined mainly by the linearity of the front-end low noise amplifier and mixer. In the transmitter, the power amplifier is operated in the large signal mode such that the RF current and voltage excursions sweep over active as well as cut-off and saturation regions of the transistors and cause baseband waveform distortion and RF spectral spreading.