Monolithic Current-mode Boost Dc Converter Design

With the development of the consumer electronics, automobile electronics and communication electronics, power management ICs have been more and more important, especially in the battery-operated portable systems.The topic about the thesis is the corporation with an abroad company. A high efficiency current mode boost DC/DC converter circuit using 0.6um BCD technology is presented in this paper. High switching frequency (1.2MHz) allows small output capacitor, output inductor and small PCB area. The device can produce an output voltage as high as 12V from an input as low as 2.6V. Soft-start is programmed with an external capacitor, which sets the input current ramp rate. In shutdown mode, current consumption is reduced to 0.1μA. At light loads, the architecture allows the chip to"skip"cycles to reduce power dissipation.In the circuit design, the basic principle and small signal model of the boost power stage are given at first, and then the stability and small signal model of the control loop are also analyzed, finally, the whole chip architecture and sub-block parameters are presented according to the application requirements.The chip is accomplished in the full cooperation with other team members, the author pays particular attention to the analysis of the whole chip architecture and three sub-block design: transconductance amplifier (OTA), voltage reference and current reference. Based on existed technologies, a new high order temperature compensated voltage reference and a creative current reference with high order temperature compensation are shown respectively.The author simulated all the sub-block and whole chip by HSPICE. The typical performance characteristics include: load transient response, efficiency, output voltage ripple, output voltage vs. load current, switching waveform, and soft-start time. The simulation results indicate that the IC has achieved the expectation, both function target and electrical characteristics. Although there are unavoidable disadvantages of the project, it is a worthwhile and valuable experience.