Voltage Controlled Ring Oscillators: Design Prospective & Applications

Voltage Controlled Oscillator (VCO) is the most important part of wired and wireless communication systems; including clock and data recovery, frequency synthesis, microprocessor clock generation, phase-locked loops,delay-locked loops, bio-medical transceivers, pacemakers etc. Low phase noise and wideband frequency coverage are two crucial issues in VCO design. Various ring VCOs are implemented using different techniques; each one having specific characteristics. The first proposed ring VCO is based on current steering technique that increases the current of the VCO and it generates high oscillation frequency. Other proposed ring VCO is based on differential pair configuration resulting in high oscillation frequency with less area. Ultra-low power proposed ring VCO is having power dissipation in the range of W. The two other proposed designs are based on reverse bias technique for low power and variable resistor based VCO with high frequency of oscillation. A charge pump PLL using proposed ring VCO and its different functional blocks have also been designed. The wide locking range DLL is also designed which can be used in clock synchronization.