Abstract: Complex polyphase nonlinear equalizer (cpNLEQs) mitigate nonlinear distortions generated by complex in-phase/quadrature (I/Q) time-interleaved analog-to-digital converters (TIADCs). Example cpNLEQs upsample the digital waveform emitted by the TIADC, e.g., by a factor of two, then separate the upsampled digital waveform into upsampled in-phase and quadrature components. Processors in the cpNLEQs create real and imaginary nonlinear compensation terms from the upsampled in-phase and quadrature components. The nonlinear compensation terms are downsampled, and the downsampled imaginary nonlinear compensation term is phase-shifted, then combined with the downsampled real component to produce an estimated residual distortion. Subtracting the estimated residual distortion from the digital waveform emitted by the TIADC yields an equalized digital waveform suitable for further processing.

Abstract: Described is a space-time digital power amplifier that can be used to generate an arbitrary waveform for a carrier signal. The space-time digital power amplifier employs temporal modulation of transmit signals generated by an array of transmitter modules. The RF signals transmitted from the array are spatially combined through free space propagation to generate the desired waveform. Advantageously, no digital-to-analog conversion is required and upconversion is unnecessary. The digital power amplifiers for the transmitter modules can be combined in a single chip package. The space-time digital power amplifier enables high power efficiency to be realized using pulse-shaped waveforms thus eliminating any need for the power amplifiers to operate over a wider bandwidth with a spectrally unconfined waveform.

Abstract: Complex polyphase nonlinear equalizer (cpNLEQs) mitigate nonlinear distortions generated by complex in-phase/quadrature (I/Q) time-interleaved analog-to-digital converters (TIADCs). Example cpNLEQs upsample the digital waveform emitted by the TIADC, e.g., by a factor of two, then separate the upsampled digital waveform into upsampled in-phase and quadrature components. Processors in the cpNLEQs create real and imaginary nonlinear compensation terms from the upsampled in-phase and quadrature components. The nonlinear compensation terms are downsampled, and the downsampled imaginary nonlinear compensation term is phase-shifted, then combined with the downsampled real component to produce an estimated residual distortion. Subtracting the estimated residual distortion from the digital waveform emitted by the TIADC yields an equalized digital waveform suitable for further processing.

Abstract: Described is a space-time digital power amplifier that can be used to generate an arbitrary waveform for a carrier signal. The space-time digital power amplifier employs temporal modulation of transmit signals generated by an array of transmitter modules. The RF signals transmitted from the array are spatially combined through free space propagation to generate the desired waveform. Advantageously, no digital-to-analog conversion is required and upconversion is unnecessary. The digital power amplifiers for the transmitter modules can be combined in a single chip package. The space-time digital power amplifier enables high power efficiency to be realized using pulse-shaped waveforms thus eliminating any need for the power amplifiers to operate over a wider bandwidth with a spectrally unconfined waveform.