高速负载响应DC-DC开关电源IC设计

【作者】 胥锐；

【导师】 李平；

【作者基本信息】 电子科技大学 ， 微电子学与固体电子学， 2008， 硕士

【摘要】 近年来,电池供电便携式设备(如PDA、手机、MP3播放器等)的需求越来越大,对DC-DC开关电源IC的需求也日益增大,同时对其性能要求也越来越高。要求DC-DC转换器具有高转换效率,以延长电池供电时间;并具有良好的瞬态响应特性,以满足CPU、DSP和闪存等模块的要求。根据电池供电便携式设备的要求,本论文设计了一款高速负载响应DC-DC开关电源IC芯片。该芯片采用0.6μm CMOS工艺实现,集成有高精度基准电压源,振荡器,斜坡补偿功能电路,电流限制,电流采样电路,求和比较器,负载调整积分等电路模块。该芯片的输入电压范围为2.7V-5.5V,输出电压范围从输入到13V连续可调,工作频率为250KHZ,同时具有输出电压纹波小,转换效率高,负载调整能力强等特点。本文设计的开关电源芯片采用电流控制PWM调制方式,运用一种新颖的求和比较器电路来代替传统开关电源中误差放大器和PWM比较器的级联结构,减少了传统开关电源中误差放大器带来的误差和延时,加强了PWM调制的精度和速度,提高了系统的负载响应速度。根据系统需要,本文还利用了负载调整积分器来消除系统稳态误差,增强系统的负载调整能力。同时,本文还对系统的稳定性和芯片的效率进行了详细的分析。最后,本文利用仿真软件Hspice对整体电路进行了仿真验证。仿真结果表明,本文设计的DC-DC变换器在典型应用条件下,其输出电压纹波小于1%,最高转换效率超过85%,当负载电流从10mA跃变到100mA,其动态跌落量小于1%,恢复时间最快达25μs,利用负载调整积分器可以显著增强系统的负载调整能力,消除系统因负载调整引起的稳态误差。更多还原

【Abstract】 In recently year,there is a rapid increasing market demanding for battery-powered portable equipments(such as PDAs,Mobiles,etc),which requires the DC-DC converter with high efficiency to boost the battery supply capability and good large signal property to satisfy the special demand of the CPU,DSP and flash memory.We build a high speed load response DC-DC SMPS(Switch Mode Power Supply) IC which is fabricated with 0.6μm CMOS process and integrated with high precision voltage reference,OSC,Slope-compensation function circuit,current limit circuit, current sample circuit,sum-comparator,load regulation integrator and so on.The allowable input voltage ranges from 2.7V to 5.5V and its output voltage can be programmed between 2.7V and 13V,and its operation frequency is 250 kHz.It also has some excellent characteristics,such as lower output ripple,high convert efficiency,and strong ability of load regulation.The SMPS presented by this thesis is based on current control PWM modulation. We use a novel circuit structure in this thesis,which is used to predigest the cascade of error amplifier and PWM comparator used in traditional SMPS:sum-comparator.The sum-comparator can reduce the error and delay caused by the error amplifier in the traditional SMPS.For this,it could improve the speed and precision of PWM modulation and enhance the load response performance.The load regulation integrator is given to eliminate the steady state error in system and enhance the ability of load regulation according to the system demand.In addition,we analyze the stability of the system and the efficiency of the IC carefully.At the end of the thesis,we simulate the whole circuit by Hspice.Through the simulation result,under a typical application,the DC-DC conveter’ features show as follows:output voltage ripple is less than 1%,the highest convert efficiency is up to 85%.When the load current step from 10mA to 100mA,the dynamic sag is less than 1%and the fastest restore time is 25μs.In addition,load regulation integrator can enhance the load regulation ability of the system effectively and eliminates the steady state error caused by load regulation.更多还原