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Purpose -The purpose of this paper is to design a low phase noise and high figure of merit, fully integrated, voltage-controlled oscillator (VCO) which was fabricated in TSMC CMOS 0.18-mm 1P6M process. Design/methodology/approach -A differential PMOS cross-coupled architecture VCO with the capacitive feedback technology was designed to increase the linearity of frequency tuning range and decrease the phase noise. Varactor determining the performance of tuning range is also a key component in the design of VCO. The authors adopt the accumulation-mode MOS varactor. The output spectrum and the phase noise are measured by E5052A spectrum analyzer. Findings -The VCO is successfully fabricated in TSMC RF CMOS 0.18um 1P6M process. The measured tuning range is from 10.875 GHz , 11.1 GHz with control voltage from 0 to 1.5 V. The measured phase noise is as low as 2 120.42 dBc/Hz at 1 MHz offset and the high FOM is 2189.5 dBc/Hz. The output spectrum is 210.51dBm with center oscillator frequency of 10.942 GHz. The core circuit without buffer consumes power of 15 mW from a 1.8 V supply voltage. Originality/value -This paper shows a fully integrated CMOS LCVCO architecture using capacitive feedback technology with low phase noise and high figure of merit for OC-192 SONET applications.

A new high figure-of-merit (FOM) and low-phase-noise 20.73-GHz voltage-controlled oscillator is designed for K-band applications in this paper. The capacitive feedback technique is used for the low-phase-noise VCO design. The VCO can be tuned from 20.817 GHz to 20.266 GHz. The measured phase noise is -115.57 dBc/Hz at 1 MHz offset from the carrier frequency. The corresponding FOM is calculated to be -190 dBc/Hz. The VCO is implemented with the TSMC 0.18 μm one-poly-six-metal 1.7 V mixed-signal/RF CMOS technology, and the chip size is 0.51 × 0.74 mm2.