Dynamic Interference Canceller for High Dynamic Range Analog to Digital Converter (ADC)

A longstanding problem with wideband radio receivers for sensitive naval applications (such as Signals Intelligence or SIGINT) is the high level of radio frequency (RF) interference including those from co-located RF transmitters. This proposal addresses the critical interference problem with an improved architecture that permits wideband cancellation of undesired high power signals, thereby providing better utilization of the dynamic range. In order to accomplish frequency-independent interference cancellation, a copy of interference signal (called the cancellation signal) with precise amplitude and true-time delay matching is subtracted from the receive signal. The cancellation signal is digitally controlled with adaptively programmable gain and delay components thereby facilitating high precision interference cancellation. The enabling component of the new architecture is a flux subtractor that performs accurate subtraction of one or more unwanted signals before the front-end of the receiver, and thus enhances its operation in a high EMI environment. The new scheme is particularly well-suited for a digital-RF transceiver architecture, featuring direct conversion of RF signals to digital. The adaptive interference canceller takes full advantage of high-speed digital cross-correlators, look-up tables, true-time delay elements, digital amplifiers, and ADCs.