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This paper reports the design of two X band voltage controlled oscillators (VCO) implemented in the same ST Microelectronics SiGe BiCMOS technology and using the same active device. One VCO design is based on a parallel topology while the other one is based on a serial topology. The chips work with a single supply voltage of 3.3 V, and the measured phase noise performance for the feedback VCO is -85 dBc/Hz @ 100 kHz offset with a tuning range of 0.5 GHz and the simulated phase noise for the negative resistance VCO is -92 dBc/Hz @ 100 kHz offset with a tuning range of 1.1 GHz. Finally, an off chip solution is proposed to improve the phase noise performance.