Develop The Circuit Of NMR Logging Tool In High Temperature Based On System-in Packaging

Compared with the ordinary logging tool,high temperature logging equipment needs to take into account the electrical performance and heat resistance at the same time,in which the thermal reliability of the circuit is the basis and key to its stable work.This thesis introduces a system-in package?SiP?to solve the problem of reliable operation of electronic circuits in high-temperature nuclear magnetic resonance?NMR?logging tool,which is of great significance to the development of high temperature logging tools in China.The thermal design and simulation of SiP verify its low thermal resistance characteristics,and exploit the technology of SiP to design and implement two functional modules,lock-in amplifier?LIA?and pulse sequence generator module,which are the important parts of high-temperature NMR logging tool.High-temperature LIA is mainly composed of low-noise amplifier circuit and acquisition and processing circuit.In this thesis,the design of the low noise amplifier circuit and based on the look-up table to implement digital phase sensitive detection algorithm are analyzed in detail.The high temperature pulse sequence generator take the CPMG pulse sequence as an example.The internal logic module and the working mode are described in detail.Experiments results show that the non-linearity error of the LIA is not more than1.736%,the gain is stable at 96.2dB,the Q value is up to 1043,and the square error of the band characteristic is 0.0039 in the 200?environment.Also results show that the delay time of the rising and falling edge of the pulse is not more than 3.2ns and 3.35ns respectively,beside,the Q factor of critical path is not Less than 15,eye error rate BER no more than 10^-50.In the laboratory conditions,the CuSO4 solution was used as the sample,and the whole instrument was tested before logging.After comparison,the test performance was good at 200?and room temperature.From the circuit board and the whole instrument in this thesis,it is proved that the SiP technology can effectively solve the reliability problem of the electronic circuit in the high temperature NMR logging tool.