Collaborative Research: Iterative Downconversion for Broadband Signal Digitization

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The objective of this research is to investigate innovative frequency channelized architectures for broadband analog-to-digital conversion. The approach employs a broadband analog iterative filter bank based on a spatially unfolded cascade of image-reject down-conversion stages. For an N-stage cascade, the input is concurrently decomposed into 2 to the power of N-1 contiguous channels; each digitized using converters clocked at 1/(2 to the power of N-1) of the input Nyquist rate. All down converter local oscillators are derived from a single reference with a cascade of compact, low power, divide-by-2 stages. The architecture potentially allows for frequency scalable resolution.Intellectual Merit: The approach in this research does not suffer from limitations of traditional high-speed time-domain samplers, such as requirements for extremely fine time resolution. It also avoids a major implementation bottleneck in current frequency-domain approaches arising from the requirement for multiple non-harmonically related local oscillators. Performance limitations due to finite image-rejection, local oscillator spurs, and phase noise are addressed with circuit-level innovations. Broader Impacts: The innovations in signal digitization capability address a critical need for technology advances in multiple areas with broad societal and scientific impact including computing, communications, sensors, medicine, and fundamental science. The unique architecture is expected to enable new signal-processing intensive implementations utilizing multi-resolution and frequency scalable designs with diverse applications in these areas. Graduate and undergraduate students involved in this research will gain expertise in theoretical and experimental aspects of the design of high-performance digitizers and signal processors. The results of this research will be disseminated through publications and seminars and will be incorporated into graduate courses taught by the PIs.