A Cross-Correlator Chip for a Spaceborne Synthetic Aperture Radiometer

Future synthetic aperture interferometric radiometers, such as JPL's New Millenium Program, Geostationary Synthetic Aperture Microwave Sounder (GEO/SAMS) instrument, will employ a thinned array of hundreds of miniaturized receivers and a massively parallel cross-correlator system for digital signal processing. The objectives of Phase I are to develop, fabricate, and test a proof-of-design of a 64-baseline, 1-bit encoding, cross-correlator chip operating at clock frequency of 120 MHz to provide the critical design information for the development in Phase II of a radiation-hard, 1024-baseline correlator chip and of an engineering model of a 16,384-baseline cross-correlator system dissipating less than 8 W. To achieve the stated objectives, the following synergistic combination of approaches will be used: a) innovative expandable architecture to enable the construction of cross-correlator systems with any number of antennas , b) new bit-systolic arrays for operation at high frequency with low power consumption, c) novel radiation-hard digital circuit techniques, and d) advanced sub-micron CMOS fabrication technologies. The cross-correlator chip proposed in this project, if successfully realized, will enable the implementation of low-power cross-correlator systems for spaceborne synthetic aperture interferometric radiometers that will be capable of performing breakthrough measurements of the Earth's environment.