A 140–210-GHz InP Frequency Doubler Using a Low-Loss Low-Imbalance Marchand Balun
Phat T. Nguyen, Tyler Shepard, Natalie Wagner, Alexander N. Stameroff, Anh‐Vu Pham
Abstract
This letter presents a 140–210-GHz frequency doubler using a low-loss, low-imbalance Marchand balun. By employing co-planar waveguide (CPW) multiconductor coupled lines (MCCLs), the modified balun achieves an insertion loss, amplitude, and phase imbalances of less than 1.5 dB, 0.3 dB, and 1.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> across the 42–126-GHz bandwidth. When integrated with the doubler core, the balun’s low phase and amplitude imbalances enable the doubler to provide high fundamental rejection and good conversion gain without additional amplifiers. The doubler core is power-matched using second harmonic load pull and a wideband output matching network. The 140–210-GHz frequency doubler exhibits a peak output power, conversion gain, and fundamental rejection ratio (FRR) of 6.5 dBm, 0 dB, and 42 dBc, respectively.