基准电流源的小信号分析与设计

Small Signal Analysis and Design of Reference Current Source

研究了一种常用Widlar型基准电流源结构，分析电源电压对于基准电流的影响。通过引入小信号分析方法，建立基准电流源的小信号等效模型，运用反馈电路分析理论，得出基准电流与电源电压之间的关系。进而通过改进基准电流源的结构以增大反馈回路增益，减小电源电压对于工作点的影响，设计出一个具有高电源抑制比的基准电流源。该电路经由UMC 0.6μmBICMOS工艺仿真，当电源电压在2.7～5．5V时，其电源抑制比高达193dB，电压调整率仅为250×10^-6／V。

A conventional Widlar reference current source was presented and the influence of the power supply voltage on the reference current was analyzed. Based on the equivalent small signal model of the circuit, using the feedback theory, the relationship between reference current and power supply was described. By improving the configuration of the reference current source, the loop gain was increased and the effect of supply voltage on the working point was reduced, a high PSRR reference current source was designed. The circuit was simulated with UMC 0.6μm BICMOS technology process. When the power supply voltage is 2.7V to 5.5 V, the reference current has a PSRR of 193 dB and a power supply regulation of 250 × 10-6/V.