Research And Design Of PWM Comparator For Switched-Mode Power Supply

As a core of the power management chip, PWM comparator must have high gain, suitable bandwidth and small offset voltage. At the same time,it must have a low power dissipation and a short response time. So, the key of designing this kind of comparator is keeping a tradeoff among all parameters of it. Based on the analysis and comparison of modulation and control modes of PWM SMPS (SWITCHED-MODE POWER SUPPLY) , a high performance PWM comparator applied in DC-DC SMPS power management is presented. This novel PWM comparator is simple in structure, high gain, small offset voltage and response time and low power.In the first chapter, the paper mainly introduced the PWM SMPS of development, background papers topics and its to be done. In the second chapter of this pape,we analysis the principle of PWM, draw the equivalent SPCIE model,and gives the netlist and the simulation results. And analysis the PWM SMPS control principle. In the 3rd chapter, we analysis PWM comparator of the paramenters and Performances, and enumerate some kinds of comparator and analysis their circuit principle. From the beginning of the fourth chapter, according to comparator the performance of the design indicators, and we are used of the basic CMOS analog circuits and analysis this paper applies to the SMPS PWM comparator in the various modules. And the all circuits of PWM comparator is be drawed. In the fifth chapter of this paper, we give the simulation results in detail in ShangHua 0.5um CMOS technologies through CADENCE SPECTRE Software. Simulation results shows that the required function of PWM comparator have be realized and reached our aim. We has got a result that the gain is 104.4dB, the bandwidth is 145KHz in -3dB gain, the offset voltage is 444uv, the arise response time is 99ns, the down response time is 60ns, and the power dissipation is 530uW. Then we get the advantages and shortcomings of our PWM comparator by compared with other comparators.Finally, in conclusion we point out the meaning and shortages of this design and some work such as LAYOUT needing to do in future.