Integrated Wide-Band CMOS Spectrometer Systems for Spaceborne Telescopic Sensing

For spaceborne instrumentation, the prohibitive cost of a flight traditionally favors programmable solutions such as field programmable gate arrays (FPGAs). As scientific goals become more ambitious, the FPGA-based solutions are showing limitations, especially with restricted launch vehicle capacity and available solar power. In this paper, modern integrated circuit technology is adopted to realize two fully integrated spectrometer SoCs to support spaceborne telescopic sensing. The system specifications are derived from the scientific principles of radio-frequency spectroscopy while each component strives for a simple and reliable implementation. Realized in 65-nm CMOS technology, Design A operates at 2.6 GHz with a three-bit ADC, a 2048-point FFT with 8192-point polyphase filter bank, and a billion-count accumulator. Design B more than doubles the bandwidth, reaches 6 GS/s by interleaving the ADC. The FFT size is also quadrupled to 8192. Both designs include integrated phase locked loops and tunable clock distribution networks. Design A consumes a peak power of 650 mW and Design B consumes 1.5 W. They represent the highest level of integration among similar endeavors and achieve orders of magnitude of improvement over traditional solutions in terms of size, weight, and power consumption. Both designs are actively involved in NASA's spectroscopy missions.