Chip Design of 5.1~6 GHz Colpitts QVCO for WIMAX

A 5.1~6-GHz low-phase noise CMOS quadrature voltage control oscillator(QVCO) is described. Two differential pairs of each resonator have spate biasing transistors which are switched on and off by coupling input of each resonator. The proposed QVCO implemented in a 0.18-um CMOS technology. The QVCO consume 7.56mw. The phase noise of the proposed QVCO is measured to be -121 dBc/Hz at 1-MHZ offset, respectively.