With On-chip Current Sensing Current-mode Step-up Dc-dc Converter And Design

In today's consumer market, battery-operated portable electronic devices are in great demand. With more and more functions integrated in these devices, power management integrated circuits such as DC-DC converters with higher performance are mandatory.In order to meet the requirements, a current-mode boost DC-DC converter with current sensing technology on chip is designed in this thesis. It is based on UMC 0.6μm BCD process. A built-in power MOSFET with low on-resistance and a lossless current sensing circuit on chip provide fast and precise current mode control. Furthermore, the whole losses decrease and high efficiency up to 90% can be obtained. With wide input voltage range from 2.6V to 5.5V, an output voltage up to 12V can be generated. High frequency (640kHz or 1.2MHz selectable) allows easy filtering and faster loop performance. Slope compensation maintains stability at high duty cycle. Programmable soft-start can eliminate the inrush current when this converter starts up. At light loads, this converter works in skip-cycle mode to improve the efficiency. When it is shut down, the supply current is less than 0.1μA. This converter can operate in the temperature rage of -25℃to 85℃. It is suitable for LCD displays, PCMCIA cards, mobile phone, MP3 and other portable applications.In this thesis, basic principles and some key points of a current mode DC-DC converter were given firstly. Then, the whole chip diagram was proposed according to the design specification and the whole chip operational principle was introduced. Based on the whole chip function requirements, sub-block design and simulation were completed, including bandgap voltage reference, oscillator, slope compensation, current sensing, control and drive logic. At last, the whole chip function simulation and typical performance characteristics simulation were presented. In the conclusion of this thesis, the research value of this circuit was pointed out, but it was suggested that corner simulation and post-layout simulation should be indispensable.This thesis is a production of circuit principles and simulation practice. Based on the circuit principle analysis, the author simulated the sub-block circuits and the whole...