Research And Design Of Current-Mode Boost PWM SMPS

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.Current control realizes the dual-loop control on the basis of voltage mode control by using current feedback, which can improve the stability and transient response performance of the system. Nowadays, the low-power switch mode power supply (SMPS) in portable electronic product generally adopts this control technique. At present, pulse width modulation(PWM) is one of the most popular modulation mode applied in the SMPS, because in the condition of high load, it has advantages of high efficiency, high precision, and excellent ability of avoiding noise interference.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 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, PWM comparator, slope compensation and error amplifier.By using 0.18um complementary metal oxide semicondutor(CMOS) model, a bandgap reference circuit was designed. The circuit is simulated by Hspice. When operating at a 5V power supply with the temperature range from-25℃to 80℃, the device has a temperature coefficient of 9.14 ppm/℃; It outputs a voltage of 1.25V±43mV at a room temperature, when the power supply varies for 3V to 5V. Through the analogous report which is got by Hspice with a 0.18um CMOS technologies and 1.8V Power supply, we know the comparator has reached our aim. We have got the result that the gain is 143dB, the bandwidth is 377kHz.Finally, in conclusion we point out the meaning and shortages of the design and some work such as LAYOUT needing to do in the future.