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 μm 1.8 V CMOS technology for the interface block and in a 1.6 μm 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.