This paper presents an extended frequency range CMOS monolithic voltage-controlled oscillator (VCO) design. A negative feedback control algorithm is used to automatically adjust the VCO range according to the control voltage. Based on this analog feedback control algorithm, the VCO achieves a wide range without any pre-register settings. Low phase noise is achieved by using both coarse control and fine control in VCO. A 600 MHz to 3.3 GHz monolithic CMOS PLL based on this wide range and low phase noise VCO has been fabricated in TSMC 0.18 μm, 1.8V CMOS technology and is used in many different applications such as FC, GE, and SONET etc
