A balanced InGaP-GaAs Colpitt-VCO MMIC with ultra-low phase noise

A balanced VCO-MMIC based on a coupled Colpitt topology with a fully integrated tank is presented. The design was focused on achieving minimum phase noise by optimization of the tank-circuit including the varactor, maximizing the tank-amplitude, and designing the VCO for Class C operation. A minimum phase noise of less than -112 dBc at an output power of 5.5 dBm is achieved at 100 kHz carrier offset and 6.4 GHz oscillation frequency. To our best knowledge, this is the lowest reported phase noise to date for a varactor based VCO with a fully integrated tank. The MMIC was designed and fabricated in a commercial InGaP-GaAs HBT foundry MMIC-process