Design Of A 2/3-Phase PWM Controller Based On BiCMOS Process

As the fast development of the microprocessor, the power supply technique has to improve accordingly. It has become a large challenge for power designer to solve the complex issues such as much higher power consumption, tighter operating-voltage tolerance and faster transient response. The new generations of CPU need multiphase voltage regulators. Multiphase power management system has many merits. It can dissipate power consumption and alleviate the thermal stress in the outer component. It makes it possible to use smaller and less-expensive inductors and capacitors due to the reduced ripple current and faster transient response. It can deliver much more current up to 100A with the output voltage lower than 1V.The author design a PWM controller chip which provide a flexible, wide-range and extreme cost-effective high-density voltage regulation solutions for various high-density power supply application. The chip implement both voltage and current loops to achieve good regulation, and current loop is used for channel current balance. By using DAC out of the chip can make the output voltage change from 1.08V to 1.93V.The chip can work in 2 or 3 phases by the circuit of changing phases. The chip adopoted advanced BiCMOS process can make the gain of error-amplifier achieve 80dB. Every sub-circuit is designed reasonably, such as: bandgap, error amplifier, oscillator, ramp pulse generator, PWM comparator, mux, output stage, OCP circuit and UVLO.The error-amplifier, GM and the reference circuit need the good performance of bipolar transistor , so the author adopted advanced 0.6μm BiCMOS process which can make the performance of anolog circuit good. BiCMOS process combines bipolar device with CMOS device effectively, so it not only holds CMOS circuit's virtues of low power, high integration density, but also obtain bipolar circuit's merits of high speed strong driving power. The technological design point of BiCMOS are concisely proposed in this dissertation.This IC adopted 0.6μm BiCMOS process model on the Cadence workstation. By using several advanced EDA software, such as spectures and Hspice etc. The author has finished simulation and verification every subcircuit, and a few important electrical parameter and characteristic. The paper gives simulation results, which can show that the circuit is correct. Dracula software tool is used to do the design rules check and electrical rules check. This chip can send to produce.