Design of broadband mm-wave and THz frequency doublers

Wideband high power generation is an essential and challenging part of many Terahehrtz systems. In this paper we review some of our recent demonstrations of Si/SiGe THz frequency multipliers that generate a wideband high power signal. The proposed design techniques blend the nonlinear modeling of the active device with new circuit topologies and high efficiency microwave structures. In the first prototype, using a 130-nm SiGe HBT process (fmax=280GHz), a wideband frequency doubler operating from 430 to 510 GHz is designed. The active doubler generates an unsaturated output power of -8.2 dBm, corresponding to 16.2 dB of conversion loss. The second circuit is a 220-275 GHz travelling wave frequency multiplier, which achieves a 3-dB bandwidth of 7.8% with a saturated output power of -6.6 dBm in a 65 nm bulk CMOS technology. The last circuit is a passive frequency doubler, based on a 65 nm bulk CMOS process. This doubler also achieves a high output power of -6.3 dBm at 478 GHz and a simulated bandwidth of 70 GHz.