一种高Q值单频水声信号放大提取电路的设计

Design for Amplifying Extracting Circuit of a High-Q Single Frequency Underwater Acoustic Signal

摘要:

针对水声信号所处环境复杂、背景噪声源多的特点,提出了一种基于JFET的超低噪音放大电路,该电路选用两片低噪音的场效应管2SK170作为第一级放大器件,经过CR高通滤波连接到同相放大电路,整体电路增益可达70dB;为进一步提升接收信号信噪比,结合双T滤波器特点优化设计出一种高Q值选频电路;通过Multisim14仿真表明,设计的电路在1 Hz处的电压噪声密度仅为2.4 nV/Hz^0.5,滤波器Q值可达25.6,结合实际电路测试结果表明,设计的电路能够满足水声测量要求。

关键词:水声信号;放大电路;噪声;Multisim;滤波

Abstract:

Aiming at the characteristics of complicated environment and multiple noise sources for underwater acoustic sig-nal, an ultra-low noise amplifying circuit based on JFET is proposed. This circuit adopts 2 low noise JFETs 2SK170 as the first stageamplifiers , which is connectd to in-phase amplifying circuit through CR high-pass filtering, and the gain of overall circuit is up to 70dB. In order to further enhance SNR of received signal, a high-Q frequency selective circuit is optimized and designed in combina-tion with the characteristic of dual-T filter. The Multisim 14 simulation results show that the voltage noise density of the designed cir-cuit under 1 Hz is only 2.4 nV/Hz^0.5 , and the filter's Q value can reach 25.6. Combined with actual test results , the designed circuitis proved to meet underwater acoustic measurement requirements.

Key words:underwater acoustic signal ; amplifying circuit; noise ; Multisim; filtering