A 2–16 GHz 65 nm CMOS Stepped-Frequency Radar Transmitter With Harmonic Rejection for High-Resolution Medical Imaging Applications

A 65 nm CMOS transmitter capable of providing signals over the wide 2 to 16 GHz frequency range for stepped-frequency continuous wave short-range medical radar applications is presented. It generates both the local oscillator signals required for quadrature downconversion in the receiver path, and the transmitter output signal, thus guaranteeing phase coherence between transmitter and receiver, essential requirement for correct radar operation. Made of a 6.5 to 18.4GHz PLL, an inductorless injection-locked programmable divider by 1, 2, or 4, and a harmonic rejection buffer, it features an average output power of -14 dBm, a phase noise at 10 MHz offset 129 dBc/Hz, a RMS jitter 0.68 ps, a reference spur level 48 dBc, a harmonic rejection 40 dBc, and a settling time of 2 μs.