Design Of PWM DC-DC Buck Switching Converter Based On CMOS Technology

PWM DC-DC switching converter is characterized as high efficiency, and is very suitable in battery-operated portable electronic devices, such as cellular phones, personal digital assistants (PDAs), and other palm-size devices. As such a result, it's in great demand in the market. But of all these kinds of PWM chips, almost all are designed by the foreign companies while none by domestic ones. To design a Buck, voltage-mode control PWM switching converter, the main tasks in this thesis are as follows:It has been done to develop the main topologic principle of a Buck, voltage-mode control PWM switching converter. Then the methods of how to compensate the error amplifier is introduced, a double-zero, double-pole construction is analyzed individually. At the output stage, the reason for introducing over-current-protection (OCP) and discontinuous inductor current mode (DICM) is shown.Every sub-circuit is designed reasonably according to the principle and character of PWM switching converter, such as: bandgap, error amplifier (EA), oscillator, narrow pulse generator, saw tooth generator, PWM comparator, PWM modulator, output stage, OCP circuit and low voltage comparator. It is analyzed in detail that how to realize every sub-circuits'functions according to different needs. Then a method that will reduce the noise in layout design is proposed. At last, simulation results, which can show that the circuit is correct, are given.Mistakes in the circuit and layout are found and corrected through debugging process. Finally silicon results are presented, these results show that although the performance of the chip designed in this paper does not entirely meet the original design targets and there is still some performance gap with the similar ones offered by name-brand companies such as Maxim and LTC, the PWM functions and DC to DC conversions are achieved.