Design Of Voltage Controlled Ring Oscillator For Clock And Data Recovery

Clock and Data Recovery(CDR)is an important circuit in the interface of serial data transmission,which generates the needed clock for circuit system according to the serial data.Voltage Controlled Oscillator(VCO)is an important circuit which generates clock signal in CDR circuit and affects the jitter performance of CDR circuit,so it has important research significance.This paper designs a wide tuning range multiloop ring VCO which has a temperature compensation circuit in order to make the output clock signal more stable in different temperature.The ring VCO consists of multiloop ring VCO,frequency doubler and temperature compensation circuit.The frequency doubling technique is beneficial to the design of wide operating range and low jitter CDR.The improved frequency doubler which consists of XOR gate,makes full use of the multi-phase clock signal to achieve frequency doubling,whose structure is simpler and operating frequency range is wider.The temperature compensation circuit uses a positive temperature coefficient voltage to tune the variable capacitor in order to reduce the frequency temperature drift problem of oscillator,which avoids the deterioration of the phase noise caused by the up conversion of low frequency noise from the tail current source in the traditional temperature compensation circuit.The chip is designed by the TSMC40 nm process.The post simulation result shows that the VCO can work stably in the frequency range of 3.85GHz?6.04 GHz in the full process angle and-20??120? and the phase noise at the frequency offset of 1MHz is not less than-90 d Bc/Hz,the core power consumption of VCO is about 26 mW,and the temperature deviation of the oscillator output frequency is less than ± 1.7%.In summary,this design meets the design requirements.