A $K$ -Band CMOS UWB Radar Transmitter With a Bi-Phase Modulating Pulsed Oscillator

This paper presents a K-band CMOS UWB radar transmitter with highly accurate variable delay circuits and a bi-phase modulating pulsed oscillator. The UWB radar transmitter is composed of three blocks: variable delay circuits that consist of a digital synchronized counter and a Vernier delay line (VDL), a baseband control signal generator, and a pulsed oscillator. The VDL allows a high range accuracy level of several millimeters. Asymmetric signals generated by the baseband control signal generator can control the phase of each output pulse. Because the pulsed oscillator operates only for the duration of a pulse, it has an extremely low level of DC power consumption and no LO leakage. It is fabricated with 0.13-μm CMOS technology and a chip with dimensions of 0.98 mm × 0.69 mm. The output spectrum is centered at 26.0 GHz, and the pulse width is controllable from 280 to 680 ps. The peak output power is about 2 dBm.