过钻具阵列声波测井采集电路设计与实现

Design and implementation of acquisition circuit for through bit array acoustic logging

针对过钻具阵列声波测井对信号采集电路高精度、大动态、低噪声、低功耗、高集成度以及各通道同步性好的要求,设计一种多通道数据采集电路。该电路采用各通道独立数字化方案以保证各通道信号采集的同步性,采用低噪音仪表放大器作为前置放大器以降低系统噪声,选用18位ADC扩大数字化动态,ADC输出采用菊花链连接以减少电路连线。实测结果表明:12通道采集电路功耗为550 mW,噪声均方根值小于13μV,信号测量动态范围达93 dB,单通道采集电路面积为19 mm×70 mm。因此,设计电路既能很好满足过钻具阵列声波测井信号采集要求,也可作为其他阵列声波测井信号采集的参考方案。

In order to meet the requirements for high precision, large dynamic, low noise, low power consumption, high integration and good synchronization in through bit array acoustic logging, a multi-channel data acquisition circuit is designed. A channel independent digitization scheme is proposed to ensure the synchronization of each channel. Low-noise instrumentation amplifier is chose as a preamplifier to reduce system noise. 18-bit ADC is used to expand digitization dynamics and the ADC output is daisy-chained to reduce the circuit connection line. The measured results show that the power consumption of the 12-channel acquisition circuit is 550 mW, the noise RMS value is less than 13 μV, the signal measurement dynamic range is 93 dB and the single-channel acquisition circuit area is 19 mm×70 mm. Therefore, the designed circuit not only satisfies the requirements for the acquisition of through bit array acoustic logging, but also can be used as a reference of other array acoustic logging.