The Study And Design Of Current Mode Pulse-Width Modulator Based On BiCMOS Process

The thesis is based on the project"Research and Design of low voltage power supply management IC based on BiCMOS process"by Xi'an Microelectronics technology research institute. It mainly implements current mode pulse width modulator which incorporates systematic design as well as each concrete module subcircuit study and design.The current mode control PWM contained several innovative features, such as: 500μA very low start-up current and 100μA operating current; Internal soft start and full cycle restart after fault; 0 minimum duty cycle and 100% maximum duty cycle; 100ns Leading Edge Blanking circuit has been built into IC; under voltage lockout function; Totem-Pole output has high current amplitude.At first, the thesis introduces the kinds of switched power and the principle of each kind. It has detailedly discussed the principles, advantages and disadvantages of current mode control PWM, and then, the theory of slope compensation is derivated in current mode control PWM. Moreover, the detailed analysis of mainly subcircuit is made, including principle,concrete circuit , simulation and verification, especially on folded Cascode error amplifier.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. According to design requirement, it eventually implemented low current, low power, high density current mode pulse width modulator. At last, the thesis introduces practical application circuit in the switched power supply.