A 100-180-GHz InP Distributed Frequency Doubler with 11.5 dBm Peak Output Power using a Power-Bandwidth Enhancement Technique

This paper presents a wideband distributed frequency doubler operating from 100 to 180 GHz, generating an output power from 11.5 to 8.5 dBm. To achieve a flat response over the entire 3-dB output power bandwidth, we developed a push-push doubler core using triple-stacked HBTs and equalizing capacitors. The new equalizing capacitors improve the doubler’s input line loss, allowing the use of more cores and larger transistor sizes for higher second harmonic generations at high frequencies. In the meantime, stacked HBTs enlarge the voltage swings at the cores’ outputs, and the output line combines the high swings across a wide bandwidth. The fabricated distributed doubler demonstrates a peak output power of 11.5 dBm at 167 GHz, a 3-dB power bandwidth of 80 GHz, and a fractional power bandwidth of 57.1%. Up to 190 GHz, conversion gain is higher than -4 dB, with a peak of -1 dB at 140 GHz.