Design of a 4.2-5.4 GHz LC VCO for IEEE 802.11a Applications

In this paper, a 4.2-5.4 GHz, - G
m
LC voltage controlled oscillator (VCO) for IEEE 802.11 a standard is presented. The circuit is designed with AMS 0.35μm SiGe BiCMOS process that includes high-speed SiGe Heterojunction Bipolar Transistors (HBTs). Phase noise is -110.7 dBc/Hz at 1MHz offset from 5.4 GHz carrier frequency and -113.5 dBc/Hz from 4.2 GHz carrier frequency. A linear, 1200 MHz tuning range is obtained utilizing accumulation-mode MOS varactors. Phase noise is relatively low due to taking the advantage of differential tuning concept. Output power of the fundamental frequency changes between 3mW and 3.5mW depending on the tuning voltage. The circuit draws 2 mA without buffers and 14.5 mA from 2.5 V supply including buffer circuits leading to a total power dissipation of 36.25 mW. The circuit occupyies an area of 0.6 mm
²
on Si substrate.