一种应用于开关电容电路的0.9V自适应偏置OTA

A 0.9V Adaptive Biasing OTA for Switched-Capacitor Application

设计了一种应用于开关电容电路的自适应偏置的低电压、低功耗开关运算跨导放大器。采用负阻负载技术和自适应偏置技术,分别提高了放大器的增益和转换速率;采用电流镜型OTA技术降低功耗,并通过控制开关关断非工作状态下的运放电源,进一步降低了功耗。新型开关电容共模反馈电路的共模电压可在一个时钟周期内快速稳定,不增加额外功耗,不限制输出摆幅。在SMIC 0.18μm工艺下的仿真结果表明,OTA在0.9V供电下,直流增益达60dB,增益带宽积为1.81 MHz,转换速率为0.94V/μs,功耗为4.16μW。

A low voltage low power switched operational transconductance amplifier（OTA） with adaptive biasing circuit for switched capacitor circuits was designed. Negative resistance load technology and adaptive biasing technology were adopted to improve the system gain and slew rate respectively. Current mirror OTA technology was applied to reduce power consumption. A clock control switch was adopted to turn off the bias transistor for further power saving when the amplifier was under non-working state. A novel switched-capacitor common mode feedback circuit（SC CMFB） was designed to stabilize the quiescent operation point of the switched OTA. This SC CMFB could fully establish the stable common mode voltage within one clock cycle without extra power and output swing limit. Designed with SMIC 0.18 μm CMOS process, the OTA achieved a DC gain of 60 dB, a GBW of 1.81 MHz and a slew rate of 0.94 V/μs under 0.9 V voltage supply. The power consumption was about 4.16μW.