一种低功耗大摆率Class-AB OTA电路设计

Design of a Class-AB OTA with low-power consumption and high slew rate

为提高低功耗条件下运放电路的工作速度,基于Class-AB复合型差分对、非线性电流镜传输、交叉耦合对管正反馈3种结构的有机组合,提出了一种高速运算跨导放大电路(OTA)的结构设计方案.该方案在低功耗条件下,电路具有优异的摆率倍增性能,同时电路小信号带宽与低频增益得到一定程度的改善.电路采用CSMC 0.5μm CMOS工艺进行设计并完成MPW流片.在5 V电源电压下测试得到的电路静态功耗仅为11.2μA,最大上升沿与下降沿摆率分别为10和2 V/μs,低频增益60 dB以上,单位增益带宽达到3 MHz.结果表明,新型Class-AB OTA电路比同类参考OTA电路具有更高的大信号瞬态响应品质因子.

To promote operation speed of operational transconductance amplifier（OTA） in low power condition,this paper presents a design of OTA with high speed based on the combination of Class-AB mode differential pair,nonlinear current mirror transfer and cross pair with positive feedback.In the low power condition,the circuit can get better slew rate boosting,meantime,some improvement in the gain band width（GBW） and DC voltage gain under the small signal condition can also be obtained.The circuit is designed and fabricated by CSMC 0.5μm process.Under the 5 V power supply,the test static power consumption is only 11.2μA,the maximum rising and falling slew rate are 10 and 2V/μs,respectively,and the voltage gain and gain bandwidth are larger than 60 dB and 3MHz respectively.The final results show that the new Class-AB OTA is superior to other similar OTA in transient figure of merit.