一种71 dB动态范围的低噪声可编程增益放大器

A 71-dB Dynamic Range Low-Noise Programmable Gain Amplifier

介绍了一种采用0.18μm CMOS工艺制作的动态范围达71 dB、步长为1 dB的低噪声可编程增益放大器。为了克服传统的三运放仪表放大器共模输入范围受限的缺点,本设计采用了电流模架构,实现轨到轨的共模输入范围。内部运放采用斩波来减小其失调电压和低频1/f噪声。增益控制由粗调级和精调级两部分来实现,粗调级将电压信号转换为电流信号,精调级将电流信号恢复为电压信号,最终实现宽范围和高精度。仿真结果表明,该设计总共实现了-3 dB~68 dB的增益范围和1 dB的步长;在48 dB增益下1 Hz到100 kHz的等效输入噪声为3.573μV,1 kHz处CMRR和PSRR分别为118.9 dB和120.6 dB。

A 71-dB-dynamic range,1-dB-step,low-noise programmable gain amplifier based on 0.18μm CMOS process was presented.The current model architecture was adopted to achieve R2R common mode input range(CMIR),considering the constrained CMIR of traditional instrument amplifier with three opamps.The internal opamps’offset voltage and low-frequency 1/f noise were reduced by chopper.The control of gain was achieved by coarse adjustment and fine adjustment,the voltage signal was converted into current signal by coarse adjustment,and the fine adjustment restored the current signal to voltage signal basing on the coarse adjustment,finally wide range and high precision were realized.The simulation results showed that the gain range of-3 dB-68 dB and step of 1 dB were totally obtained;the equivalent input noise from 1 Hz to 100 kHz at 48 dB was 3.573μV,CMRR and PSRR at 1 kHz were 118.9 dB and 120.6 dB respectively.