A Two-Point Modulation Voltage Controlled Oscillator Design and Implementation : Design and Implementation

Gaussian Filtered Minimum Shift Keying (GMSK) based on phase locked loop (PLL) two-point modulation technology has good performance in high and low frequency responses. In this paper, we mainly analyze a sort of characteristics of the voltage-controlled oscillator (VCO) in the two-point modulation system of PLL and complete the design of the LC type two modulated VCO IC based on CSMC 0.35 $\mu \mathrm{m}$ CMOS process, simulation and verification, chip tape-out by Empyrean EDA tools. The center frequency of designed VCO is 324 MHz, and the oscillation range is from 306 MHz to 342 MHz when the range of the coarse control pin Vctrl voltage is 0-3.3V, and the fine control pin Vfm are 1V and 3V with the corresponding outputs at 323.95 MHz and 324.05 MHz as the voltage of the coarse control pin Vctrl is set at 2.2V.