A wide tuning range integrated 4GHz differential VCO for PLL

The design of a wide tuning range voltage controlled oscillator (VCO) for integrated phase locked loop (PLL) is presented. The circuit was implemented on a 0.35um bicmos technology. The VCO had 36% tuning range together with good figure of merit. The paper shows the design methodology used to obtain small tuning gain variation in the whole frequency, temperature and process variation range. Some design details are shown together with measurement results.