Research And Design Of Fully Integrated Six-phase Interleaved Buck Circuit

With the development of modern System on a Chip(SOC),the demand for high integration,miniaturization and on-chip power supply is more and more urgent,especially in the application field of microprocessor.However,the large value of inductance and capacitance used by traditional DCDC power supply brings difficulties for on-chip integration.Only off-chip inductance and capacitance components can be used,which reduces the integration degree of the system and increases the volume of the power supply.The switching power supply with multiphase interleave structure can reduce the current ripple,and meanwhile,by increasing the working frequency of the circuit,the required area of passive devices can be greatly reduced,so as to achieve the goal of full integration.This thesis starts with the working principle of six-phase interleaved Buck circuit and analyzes its advantages over single-phase Buck circuit.Then,a new type of circuit structure based on current hysteresis control and master-slave control current-sharing method has been put forward,which can improve the system stability,transient response speed and current balance ability.Next core circuit module such as the power level and feedback module,delay phase-locked loop module,digital analog converter module,start module and reference voltage generate module were analyzed and designed.By using high-speed comparator structure,the problem of time delay of the loop can be solved.And the problem of the phaselocked loop lock cycle has been solved with the logic circuit which can detect and adjust the length of the delay line.The topological structure proposed above with low delay circuit,can raise working frequency up to 30 MHz,decrease the inductance to 192 n H,and reduce the output capacitance to 1.5u F,so the lc can be fully integrated into the chip package,witch lay the foundation for the fully integration of monolithic chip buck converter.The circuit design in this thesis is based on TSMC 0.18 um BCD process.The six-phase interleaved Buck circuit was built,and the stability,transient characteristics and current balance ability of the whole circuit are simulated and verified by Cadence software.The simulation results indicate that the circuit structure can achieve the adjustable output of 1.5V～ 2.2V at the input voltage of 4V～ 5.5V,and the output current ripple is as low as 70 m A with5 A maximum output current,the stable operating frequency is 30 MHz,and the maximum efficiency is 80.7%,with high stability,fast load response performance and current balance ability.