Digital receiver design for an offset IF LFM-CW SAR

This paper describes the digital receiver for the microASAR, a small, powerful, LFM-CW SAR. The digital receiver uses a high-speed ADC providing three key benefits; namely: 1) the de-chirped signal can be at an arbitrary intermediate frequency (IF), enabling better RF filtering; 2) quantization noise can be reduced via digital filtering; and 3) the flexibility to enable the SAR to operate in both de-chirped and pulsed modes. This paper also outlines the FPGA design used for most applications.