Design and Optimization of Multi-Band 3.1-4.8GHz VCO for UWB Communication System

A multi-bands voltage controlled oscillator (VCO) based on LC resonator circuit is presented in this work. Two methods of optimization are applied to multi-band VCO circuit in order to confirm and to compare their results. These optimization techniques are the geometric program (GP) and graphical method. Theory results of each optimization method agree on the optimum component size of the multi-band VCO circuit. The operation range of the VCO is extended to cover eight frequency bands from 3.1GHz to 4.8GHz of which the tuning range is 42.5%. The phase noise is -118dBc/Hz, -123dBc/Hz and -123dBc/Hz at 1 MHz offset frequency from carrier frequency of 3.432GHz, 3.96GHz and 4.488GHz, respectively. The power consumption of multi-band VCO is 18mW from a 2.5V supply voltage. Simulated results show the performances of these methods, in fact, low phase noise and low power are obtained with the optimum components size of achieved result of optimization methods.