用于加速度计接口电路的可编程增益放大器

A PGA Applied in Accelerometer Interface Circuit

在传统开关电容可编程放大器基础上,利用分时复用、分时输出的技术,设计了一种新型可编程增益放大器。相比传统开关电容可编程放大器,该放大器能实现连续信号输出,实现的全差分结构能有效抑制共模噪声。采用相关双取样技术,消除了失调和低频噪声。采用程序控制开关电容阵列,实现了不同的放大倍数。该放大器采用0.18μm CMOS工艺,电源电压为3.3 V。仿真结果表明,实现了近似0.05 dB步进、0~17.5 dB的增益变化范围,可调增益达1 024种。在1 kHz频率时,输出噪声为42.68 nV·Hz^-1/2。

Based on the traditional switched capacitor programmable amplifiers, a novel programmable gain amplifier was designed through adopting time division multiplexing and time division output. Compared with the traditional switched capacitor programmable amplifiers, the new amplifier could realize not only continuous signal output but also fully differential structure, which could effectively suppress the common mode noise. The correlated double sampling technique was used to eliminate the circuit’s offset and low frequency noise. Different scales were achieved by adopting program-controlled switching capacitor arrays. The proposed amplifier was designed in a 0.18 μm CMOS process, and the power supply was biased at 3.3 V. The simulation results showed that the new amplifier could achieve approximately 0.05 dB step, 0~17.5 dB gain variation range, and 1 024 kinds of adjustable gains. In addition, the output noise was 42.68 nV/Hz^-1/2 at 1 kHz.