水声传感器调理电路设计

Design of conditioning circuit for underwater acoustic sensor

由于水下环境极其恶劣且水声传感器输出信号微弱,在传输微弱信号时又常常受到其他信号的干扰而不能直接用于后级采集电路,因此需要对水声传感器的输出信号进行一系列处理。设计一种水声传感器调理电路,主要包括前置放大电路、滤波电路、单端转差分电路。该电路采用了低功耗、极低噪声、超低偏置电流的高速仪表放大器AD8421和低功耗、低噪声、低偏置电流的运算放大器AD8022,其中滤波电路由四阶有源SK高通滤波器与二阶有源MFB低通滤波器级联构成。仿真和测试结果表明,该电路可实现固定增益为20 dB,较宽的通频带100 Hz~500 kHz,截止频率处的衰减小于1 dB,短路等效输入噪声不大于2μVrms。该电路的噪声性能较一般信号调理电路更优异且电路结构更简单,可以灵活运用于微弱信号的采集和处理。

As the underwater environment is very bad and the output signal of the underwater acoustic sensor is weak,and the transmission of the weak signal is often interfered by other signals and cannot be directly used in the post-stage acquisition circuit,a series of processing is required for the output signal of the underwater acoustic sensor.A conditioning circuit for underwater acoustic sensor is designed,which mainly includes a preamplifier circuit,filter circuit,and single-ended to differential circuit.In the circuit,the high-speed instrumentation amplifier AD8421 with low power consumption,extremely low noise and ultra-low bias current and an operational amplifier AD8022 with low power consumption,low noise and low bias current are adopted.The simulation and testing results show that the circuit can achieve a fixed gain of 20 dB,a wide passband of 100 Hz~500 kHz,a attenuation of less than 1 dB at the cutoff frequency,and a short-circuit equival input noise of no more than 2μVrms.The noise performance of the circuit is better and the circuit structure is better simple than that of the general signal conditioning circuit,which can be flexibly applied to the acquisition and processing of weak signals.