Direct Digital Predistorter for Linearization of RF Transmitter Power Amplifiers

HYPRES, in collaboration with University of Rochester, proposes to develop a novel RF transmitter architecture that extends digital signal processing into the RF domain. This "digital-RF" approach permits high-fidelity synthesis of broadband multi-carrier transmit waveforms, without the distortions associated with analog components. Most major signal processing operations, including up-conversion and initial stages of amplification, will be carried out in the digital domain, moving the digital-to-analog boundary as close as possible to the antenna. Furthermore, this will incorporate broadband digital predistortion correction for any remaining non-idealities in the transmission chain. At the low-power end, only superconducting electronics technology has the necessary speed, linearity, and precision for this digital-RF architecture. This will be supplemented by fast semiconductor switching amplifiers, which will dramatically improve the power-efficiency of the transmitter, while preserving a very high signal-to-noise ratio. Building on the successes of the Phase I project, HYPRES proposes to design, fabricate, and demonstrate the necessary digital-RF hardware using superconducting rapid-single-flux-quantum (RSFQ) integrated circuits. Further, we will develop digital-RF transmitter architectures for specific communications and phased-array radar systems relevant to defense applications. This will lead to the development and commercialization of a line of digital-RF transceiver products for the military and the commercial markets.