High Performance HF-VHF All Digital RF Receiver Tested at 20 GHz Clock Frequencies

Abstract

Wireless applications would be less expensive, more flexible, and more robust if they had more digital and less analog circuitry. The problem is implementing digital signal processing at radio frequencies. Conventional data converters (ADCs and DACs) and digital circuits are simply not fast enough. However, superconductors can provide ultra fast mixed signal and digital circuits with the linearity and dynamic range required for true direct, digital-RF processing. These superconducting circuits are digital ICs based on Josephson junctions and "rapid-single-flux-quantum" logic (RSFQ), where switching speeds up to 750 GHz have been demonstrated enabling true digital-RF architecture at clock speeds eventually up to 160 GHz. This permits direct conversion between analog RF and digital baseband signals, replacing frequency and protocol-specific analog hardware with flexible digital processors. Data conversion in high frequency wireless applications at frequencies up to 50 GHz will soon become practical. Hypres recently delivered a HF-VHF all digital RF receiver (ADR) prototype to ONR. Testing of this ADR has demonstrated the superior performance of superconducting ICs in cryocooled systems. A US Navy laboratory is now evaluating the world's first complete prototype digital RF receiver capable of direct digitization from DC to 2 GHz