带电压前馈的固定充放电时间锯齿波振荡器

Fixed Charge and Discharge Time Saw-Tooth Wave Oscillator with Voltage Feed-Forward

摘要:

设计了一种用于降压型DC-DC开关电源转换器的锯齿波振荡器。利用电压前馈方法和固定充放电时间方法,实现了锯齿波幅度随电源电压线性变化且频率固定的锯齿波振荡器,抑制了电源电压突变时的输出电压过冲。基于0.18 μm BCD工艺进行设计和仿真。仿真结果表明,该锯齿波振荡器产生的锯齿波频率为2.73 MHz。在2.7~5.5 V电源电压、-55 ℃~125 ℃温度范围内,频率偏移在±6%以内。振荡幅度在0.576~1.470 V范围内随电源电压线性变化。

Abstract:

A saw-tooth wave oscillator was designed for buck DC-DC converters. Voltage feed-forward and fixed charge and discharge time techniques were used to keep the amplitude of saw-tooth wave changing linearly and the frequency of saw-tooth wave constant while the supply voltage was changed. Therefore, the overshoot voltage was suppressed when the supply voltage was changed suddenly. Based on a 0.18 μm BCD process, the saw-tooth wave oscillator was designed and simulated. Simulation results showed that the frequency of the designed saw-tooth wave oscillator was 2.73 MHz. In the range of supply voltage from 2.7 V to 5.5 V and temperature from -55 ℃ to 125 ℃, the variation of frequency was within ±6%. The oscillating amplitude was changed linearly from 0.576 V to 1.470 V following the supply voltage.