A Single-Chip X-Band Chirp Radar MMIC with Stretch Processing

A single-chip X-band chirp radar transceiver with direct digital synthesis (DDS) for chirp generation is presented. The radar chip, including receiver, transmitter, quadrature DDS, phase-locked loop (PLL) and analog to digital converter (ADC), has been implemented in a 0.13 mu m BiCMOS technology. The stretch processing technique is employed to translate the time interval between the received and the transmitted chirp signals to a single tone at the baseband output with greatly reduced bandwidth, which allows for the use of a low-cost ADC with a reduced input bandwidth of 10MHz for digitizing the received RF chirp with a bandwidth of 150MHz. A Weaver receiver with a dc-offset is employed in order to use a single ADC for detecting the received quadrature signals with image rejection. A quadrature 1GHz DDS with an inverse sinc function for zero-order hold correction is implemented to provide the chirp signals for both receiver and transmitter. A wide-tuning PLL frequency synthesizer is integrated to generate the local oscillator (LO) signals as well as the clock signal for the DDS and ADC. The implemented radar-on-chip (RoC) MMIC occupies a die area of 3.5 x 2.5mm(2). With a 2.2V supply voltage for analog/RF and a 1.5V supply for digital, the chip consumes 326mW in the receive mode and 333mW in the transmit mode.