An 1-GHz CMOS voltage-controlled oscillator

In this paper we present the design of a CMOS voltage-controlled oscillator. The circuit is designed based on a 0.6 /spl mu/m spdm CMOS technology. We use NMOS devices as variable capacitors for the implementation of negative impedance to achieve circuit oscillation. The control voltage of the circuit is ranged from 0 to 3 volts. The circuit oscillates at 1 GHz frequency.