Design Of 50MHz Phase Frequency Detector And Charge Pump For Continuous Wave Radar Frequency Source

With the rapid development of wireless communication technology,milimeter wave(MMW)integrated circuit has found an increasingly wide utillization in all fields.Nowadays,Frequency Modulation Continuous Wave(FMCW)radar is widely used in the field of vehicle collision avoidance.77GHz automotive anti-collision radar is the current research hotspot of millimeter wave integrated circuits.The frequency synthesizer is an indispensable and important port to provide a stable local oscillator signal in the FMCW radar system.As the key modules of the phase-locked loop(PLL)frequency synthesizer,phase frequency detector(PFD)and charge pump(CP)determine the final performance of the system.Based on the 0.13?m SiGe BiCMOS process,this subject designs and implements a 50MHz phase frequency detector and charge pump for a FMCW radar frequency source.With the previous analysis of the working principle and the phase noise transfer mechanism of the charge pump type PLL,the design indexes of PFD and CP are given,and the structure of PFD and CP are proposed according to the design indexes.This design presents a non-linear PFD structure.When the absolute value of phase difference between the two input signals is less than?(|??|<?),The PFD outputs a pulse signal which is proportional to the phase difference.When the absolute value of phase difference is greater than?and less than 2?(?<|??|<2?),the PFD maintains a constant output and exhibits a non-linear phase detection character,which can accelerate the locking process of the PLL.The charge pump uses a constant-g_m rail-to-rail operational amplifier to interconnect the output node and the reference node in order to improve the accuracy of current matching.In addition,a bandgap reference circuit and a reference current source are designed separately,thus no external reference current is needed.The schematic level design,pre-simulation,layout design and post-simulation of the non-linear PFD and CP have done with Cadence software,and the PFD/CP chip is finally manufactured and verified by testing.The test results show that the non-linear PFD has no dead zone,and the phase detection range is(-1.93?,1.93?).The charging or discharging current of CP is approximately 196.5?A and the static current mismatch between charge and discharge current is less than 1%when the node voltage of CP's output is between 0.6V and 2.8V.The PFD/CP chip's working current is 1.9m A under 3.3V power supply in total.The PFD/CP structure presented in this project has been applied in 77GHz continuous wave radar frequency source,and can also be used in other charge pump type PLL frequency source after appropriate improvement.