A Novel Ku-Band RTD-Based Quadrature VCO for Low Power Applications

This letter presents the design and fabrication of a Ku-band resonant tunneling diode (RTD)-based quadrature voltage-controlled oscillator (QVCO) with low dc power consumption and good phase noise characteristics using an InP-based RTD/HBT MMIC technology. In order to achieve a low power operation, an InP-based RTD is used for microwave quadrature signal generation based on an excellent inherent negative differential resistance (NDR) characteristic of the RTD achieved at a low applied voltage. The fabricated QVCO core shows a low dc power consumption of 1.46 mW with excellent phase noise of -121.14 dBc/Hz at a 1 MHz frequency offset. The obtained figure-of-merit (FOM) is -202.8 dBc/Hz at an oscillation frequency of 14.6 GHz, which is one of the best values among Ku-band quadrature VCOs reported up to date.