A Ka-band direct oscillation HBT VCO MMIC with a parallel negative resistor circuit

This paper describes a low phase noise Ka-band VCO MMIC employing InGaP/GaAs HBT processes. The VCO has the following two features: a novel circuit comprising negative resistors arranged in parallel that achieves a steep phase slope, and a tuning circuit with two resonators that offers a wide tuning range and steep phase slope. Measurement results of the developed VCO show a phase noise ranging from –111 to –114 dBc/Hz at an offset frequency of 1 MHz, and a tuning bandwidth above 1.1 GHz in a 38-39 GHz band.