A 32–42-GHz RTWO-Based Frequency Quadrupler Achieving >37 dBc Harmonic Rejection in 22-nm FD-SOI

In this letter, we propose a 32-42-GHz frequency quadrupler that performs digital logic operations between four phase-shifted differential signals at one-fourth of the output frequency. The four phase-shifted signals are generated via a 10-GHz rotary traveling-wave oscillator (RTWO) and are symmetrically routed to the quadrupler using a CMOS buffered clock tree. The harmonic rejection ratio (HRR) is enhanced by employing a differential LC filter tuned at its output center frequency. The proposed frequency quadrupler is implemented in 22-nm FD-SOI CMOS. At 37 GHz, it produces an output power of -4 dBm with a 10% drain efficiency. It consumes 4 mW from 0.8-V supply and occupies a core area of 0.021 mm2. The worst-case HRR for fundamental, second, third, and fifth harmonics are 41.3, 48.6, 41.3, and 37.3 dBc, respectively.