High Sensitivity Analog to Digital Converter (ADC)

For SIGINT and surveillance applications the higher sensitivity is of prime importance enabling interception of weak signals. For cellular communications, higher sensitivity results in an increased coverage range of a base station, thereby effecting enormous cost savings, by utilizing fewer base stations per given area. However, the amplitude sensitivity of the receiver is limited by its noise figure and any increase in sensitivity necessitates corresponding reduction in the receiver noise figure. In the framework of this project we propose to design a high sensitivity ADC with an intrinsically lower noise floor. To achieve this objective we plan to investigate multiple approaches involving use of different sensitive comparators. One of the approaches is to use a comparator biased in Metastable regime where the comparator has 10 times higher sensitivity. Another approach to build the high sensitivity ADC is to incorporate a DC SQUID as a quantizer and use delta-sigma architecture. SQUIDS are most sensitive detectors of change in magnetic field and can help improve the sensitivity of the ADC. Moreover, the delta-sigma noise shaping pushes the noise to higher frequencies thereby reducing in-band noise and enabling higher sensitivity in the desired band of interest. A third approach is to use a very high sensitivity comparator based parametric quantron that are classical analog of flux qubits. The high sensitivity ADC also serves as a critical element of another proposed goal of developing the subranging ADC where multiple ADC are concatenated to enable higher dynamic range. By increasing both sensitivity and dynamic range, the subranging ADCs will produce a performance leap well beyond the state-of-the-art.