Highly Efficient Harmonically Tuned InP D-HBT Push-Push Oscillators Operating up to 287 GHz

Integrated push-push oscillators, achieving high output power at 210, 235 and 287 GHz, were realized in a 0.5 μm emitter double-heterojunction InGaAs/InP HBT (D-HBT) technology with a maximum oscillation frequency f
_max
of 335 GHz and a breakdown voltage (V
_bceo
) of 4V. The oscillators are based on a balanced Colpitts topology in which a strong second harmonic signal is generated by combining the differential signals at the collector and by reactively tuning the output impedance of the oscillator using a shorted stub. Three oscillators were realized using this topology. A high-power output signal of more then 0 dBm is obtained for oscillators operating at 210 and 232 GHz, an improvement of 5 dB compared to the output power measured on an identical push-push oscillator without 2
^nd
harmonic tuning. Close to -3 dBm output power is obtained at an output frequency of 280 GHz by further reducing the resonator length. By reducing the current, a maximum output frequency of 287 GHz is obtained.