600-GHz High-Power Signal Sources Based on 250-nm InP HBT Technology

Two 600-GHz radiation signal sources, a single- and four-element oscillators, have been developed based on a 250-nm InP heterojunction bipolar transistor technology. The single-element unit oscillator adopts the common-emitter cross-coupled structure with reactive emitter degeneration, which enables second harmonic oscillation around 600 GHz with enhanced output power. Based on the unit oscillator, the four-element coupled oscillator with cascaded two-way shunt power combiners was developed to further increase the output power. Both oscillators are integrated with on-chip patch antennas with simulated antenna gain of 3.5 dBi and directivity of 8.0 dBi at 600 GHz. The measured oscillation frequencies of the two signal sources are 580-586 GHz and 583-591 GHz, respectively, varied with the base bias. They exhibited the measured peak effective isotropic radiation power (EIRP) of 1.1 and 2.7 dBm, respectively, which correspond to the radiated output power of -7.5 and -5.9 dBm. The total dc power consumptions are 34.5 and 129.6 mW, which lead to the estimated dc-to-RF efficiencies of 0.52 and 0.2% for the two sources. The measured phase noises are -88.6 and -90.1 dBc/Hz at 10-MHz offset frequency for the single- and four-element oscillators, respectively.