Rail-to-rail regulating voltage-controlled oscillator with low supply and ground noise sensitivity

Abstract

A rail-to-rail (R-to-R) regulating voltage-controlled oscillator (VCO) is employed to generate multiple-phase clocks for clock and data recovery in a display driver IC (DDI). To achieve a low supply and ground noise sensitivity, the proposed R-to-R regulating method generates VSP and VSN as the supply and the ground of the VCO instead of VDD and VSS. By applying the proposed method, the frequency-VDD variation rate of the VCO (%-f(VCO)/%-VDD) changes from 3.5%-f(VCO)/1%-VDD to 0.0073%-f(VCO)/1%-VDD within the V-ctrl range of 0.5-1.2 V. The DDI is fabricated in a 1P6M 0.18 m 1.8 V CMOS technology for the interface block and in a 1.6 m 18 V CMOS technology for the DAC. The R-to-R regulating VCO has a tuning range of 140-240 MHz with linear and small gain (K-VCO) characteristics, and is suitable for the phase-locked loop used in flat-panel display interfaces that operate from 0.3 to 2 Gbits/s.