A millimeter-wave highly linear VCO MMIC with compact tuning voltage converter

This paper presents a fully integrated highly linear and low phase noise voltage controlled oscillator (VCO) with a novel compact tuning voltage converter for millimeter-wave applications. The tuning voltage converter consists of only a few diodes and resistors and has nonlinear characteristics to correct varactor tuning curves. We fabricated the millimeter-wave VCO MMIC employing InGaP/GaAs HBT process. The MMIC chip size is 2.55 mm x 1.4 mm, in contrast the voltage converter has the size of 0.35 mm x 0.70 mm. The measured tuning sensitivity of 97 +/- 12 MHz/V is achieved for voltages between 0 V and 5 V, and the temperature dependency is very small. Also the phase noise performance is -110.7 dBc/Hz at 1MHz offset from the carrier when the oscillation frequency is 38.2 GHz. This linearization technique can greatly reduce the configuration of the conventional software linearization system.