A 210–320GHz Power-Combining Distributed Frequency Doubler with Tuned Pre-Amplification in 0.13µm SiGe BiCMOS

The paper presents the theory and design of a broadband distributed frequency doubler operating across 210–320GHz. We introduce power combining within the distributed structure, with two sets of distributed doublers driving a common transmission-line load. Passband characteristics over the desired frequency range are introduced with stagger-tuned narrowband pre-amplifier stages employed in each unit cell of the 15-stage doubler, which extends flat output power beyond fT. The 3V prototype in 0.13µm SiGe BiCMOS (fT/fMAX 300/450GHz) delivers 3.6dBm power at 300GHz to a 50Ω load, with a conversion gain of 13.6dB. It is the highest reported output power at 300GHz for Silicon and InP-HBT based frequency multipliers.