A 300-GHz Wideband Injection Locked Frequency Quadrupler in 250-nm InP DHBT Technology

A sub-THz band frequency quadrupler with a frequency range of 250 to 350 GHz is presented in this paper using 250-nm InP DHBT technology. The circuit employs a D-band frequency doubler with an H-band injection-locked push-push oscillator to produce x4 frequency. A collector-to-base feedback technique is introduced to boost the harmonic output power of the injection-locked push-push Colpitts oscillator. The proposed quadrupler showed 4th harmonic peak output power of −3.3 dBm and 1.75 % DC-RF efficiency at 328-GHz.