A Buffer-Less Wideband Frequency Doubler in 45-nm CMOS-SOI With Transistor Multiport Waveform Shaping Achieving 25% Drain Efficiency and 46–89 GHz Instantaneous Bandwidth

A wideband high-efficiency frequency doubler leveraging transistor multiport waveform shaping is presented in this letter. Unlike the conventional push-push pair with grounded source terminals, both the gates and sources of the proposed doubler are simultaneously driven by 180° out-of-phase signals. As a result, the drain current bifurcation is greatly reduced, leading to suppression of the undesired 4th harmonic and significant enhancement of 2nd harmonic current. The EKV FET model is also adopted to mathematically analyze the current waveform shaping in both conventional and proposed topologies, which agrees well with the circuit simulations. Broadband fundamental matching and a dual-resonance 2nd harmonic trap filter together guarantee the wideband frequency doubling performance. Prototyped in 45-nm CMOS-silicon-on-insulator, the proposed doubler achieves 25% peak drain efficiency, instantaneously covering 46-89 GHz (64% fractional bandwidth).