A WR-3 Band Fundamental Voltage-Controlled Oscillator With a Wide Frequency Tuning Range and High Output Power

This paper presents a 300-GHz voltage-controlled oscillator (VCO) with a wide frequency tuning range and high output power. To generate fundamental oscillation at 300 GHz, a cascode cross-coupled pair is employed as a VCO core instead of a conventional common-emitter pair. Capacitive emitter degeneration is added to the VCO core to achieve a wide bandwidth of a negative conductance. In addition, the phase of the oscillation feedback loop is analyzed and optimized to further extend the tuning range. The VCO is fabricated in a 0.25- \mu \text{m} InP DHBT technology ( f_{\mathrm {T}}/f_{\mathrm {max}} = 392 /859 GHz). Measurements show that the VCO frequency is tuned from 272.4 to 310.8 GHz with a peak output power of 1.5 dBm. To the best of authors' knowledge, this is the widest tuning range of 38.4 GHz (a fractional bandwidth of 13.2%) among the reported fundamental VCOs at the WR-3 band.