一种用于斜坡补偿的振荡器设计

Design of an Oscillator Circuit for Slope Compensation

电流控制模式的开关电源变换器在占空比D>0.5时,存在次谐波振荡问题,因此必须进行斜坡补偿。在分析了峰值电流模式的DC/DC转换器中斜坡补偿原理的基础上,介绍了一种用于斜坡补偿的振荡电路,该振荡电路主要是通过对电容充放电的控制产生所需要的斜波,从而应用于DC/DC补偿。电路基于0.35μmCMOS工艺设计,并在Cadence下对电路进行整体仿真。结果表明该电路能在较大电源电压及温度范围内正常工作,能够提供1MHz的振荡信号。

The subharmonic oscillation is a problem for current-mode switching converters with the duty ratio D larger than 0.5, so the slope compensation is needed. The principle of the slope compensation of the peak-current mode DC/DC converter was analyzed. An oscillator circuit was presented, which was used for slope compensation. The ramp wave was generated by charging or discharging the capacitor and used for compensation of DC/DC. The circuit based on 0.35 btm CMOS technology was designed and simulated by using the tool of Cadence. The result shows the oscillating frequency is stable with the change of the supply voltage and temperature. The typical frequency of the oscillator is 1 MHz.