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

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 (%-fVCO/%-VDD) changes from 3.5%-fVCO/1%-VDD to 0.0073%-fVCO/1%-VDD within the Vctrl 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 (KVCO) characteristics, and is suitable for the phaselocked loop used in flat-panel display interfaces that operate from 0.3 to 2 Gbits/s.