Wideband Ring VCO for Cognitive Radio Five-Port Receiver

This paper presents an wideband ring VCO for cognitive radio five-port based receivers. Also presents testbenches to demonstrate the improvement of five-port architecture in homodyne receivers. A three-stage differential topology us-ing transmission gates was adopted to implement the VCO in order to maintain wide and linear tuning range and a low phase-noise. Monte-carlo analysis were performed for evaluating the phase-shift response, which should be 120o between stages. Those analysis will be used to develop a be-havioral model of the VCO with focus on five-port receiver simulations allowing time-saving. It was observed a fairly linear correlation between control voltage and oscillation fre-quency in the range between 200 MHz and 1800 MHz. The VCO was designed for IBM 130nm CMOS technology