A 4.5-5.8 GHz differential LC VCO using 0.35 μm SiGe BiCMOS technology

In this paper, design and realization of a 4.5-5.8 GHz, -G(m) LC voltage controlled oscillator (VCO) for IEEE 802.11a standard is presented. The circuit is implemented with AMS 0.35 mu m-SiGe BiCMOS process that includes high-speed SiGe Heterojunction Bipolar Transistors (HBTs). A linear, 1300 MHz tuning range is measured with on-chip, accumulation-mode varactors. Fundamental frequency output power changes between 1.6 dBm and 0.9 dBm, depending on the tuning voltage. The circuit draws 17 mA from 3.3 V supply, including buffer circuits. Post-layout simulations of the VCO led to 110.7 dBc/Hz at 1MHz offset from 5.4 GHz carrier frequency and -113.4 dBc/Hz from 4.2 GHz carrier frequency of phase noise. The circuit occupies an area of 0.6 mm(2), including RF and DC pads.