V–I converter-based voltage-controlled oscillator with improved linear gain characteristic

A voltage-current (V-I) converter-based voltage-controlled oscillator (VCO) is adapted to generate multiple-phase clocks for clock and data recovery for a display driver IC. The proposed V-I converter changed the second-order current equation of the VCO to a first-order current equation of the VCO, to achieve a wide operating frequency range, a linear gain (K_VCO) within a wide control voltage, low power, and a small area without any extra circuits, such as a low-to-full amplifier. Owing to the V-I converter, K_VCO is changed from 8.43 to 2.05 MHz/mV with a wider V_ctrl range, and its tuning range is changed from 114 to 452 MHz with a linear gain characteristic. The proposed VCO is implemented in a 1P6M 1.8 V technology and is suitable for the phase-locked loop used in flat-panel display interfaces that operate from 0.3 to 2 Gbit/s.