一种用于低压降稳压器频率补偿的压控电流源

A Voltage Controlled Current Source for LDO Frequency Compensation

利用小信号压控电流源(VCCS)电路产生所需零点,是一种先进的低压降稳压器(LDO)频率补偿方法。文章分析了VCCS频率补偿方法的原理和VCCS电路对LDO的瞬态响应及电源抑制(PSR)特性的改善作用,并提出了一种新的VCCS电路结构。该电路结构功耗低、占用面积小,在直到5 MHz的频率范围内,都有近乎理想的性能。采用这种结构的VCCS电路,基于0.5μm CMOS工艺,设计的一款300 mV压降,2.5 V输出电压,最大100 mA输出电流的LDO电路,具有很好的频率响应、瞬态响应和电源抑制特性。该LDO电路所用全部片上电容的总值不到1pF。

Using voltage controlled current source （VCCS） to create a zero is a novel scheme for frequency compensation of LDO regulators. This paper analyzes the scheme, and reveals that the VCCS circuit conduces to improvements of transient response and power suppression ratio （PSR） performance of the LDO. A new area-compact VCCS circuit, which has a nearly ideal performance in wide frequency spectrum up to 5 MHz, is also presented. Using the VCCS, an LDO with 300 mV dropout voltage, 2.5 V output voltage and 100 mA output current is designed in 0.5 μm CMOS technology with excellent frequency performance, transient response and PSR performance. The total value of on-chip capacitors employed in this LDO is less than 1 pF.