A 2.4-GHz high-efficiency multilevel outphasing WLAN transmitter and an integration RF subsampling receiver for adaptive PA linearization.
This talk presents a 2.4-GHz multilevel outphasing WLAN transmitter and an adaptive PA linearization technique using RF integration subsampling. The multilevel outphasing transmitter with switching RF PAs and discrete supply modulators achieves improved modulation bandwidth and efficiency over envelope tracking PAs. However, the linearity of multilevel outphasing transmitters is sensitive to PVT variations. In order to provide necessary PA linearization, whose adaptation to PVT variation is performed in the background without using a dedicated training signal, an observation receiver need to continuously sample the PA output. To capture high-order nonlinearities, observation receivers typically require high-speed high-resolution ADCs. For wideband signals, such high-performance ADC requires significantly large footprint and power consumption. The presentation will discuss techniques to realize a low-power observation receiver by exploiting RF integration subsampling. Transmitter-side information priori allows the extraction of PA nonlinearity from the PA output signals that are subsampled below the Nyquist rate. At the expense of increased adaptation time, RF integration subsampling technique allows observation receivers to reduce ADC sampling rate requirement by orders of magnitude.