Analysis And Development, Of The Low-field Pulsed Magnetic Resonance Preamplifier

This thesis begins with the principle and the whole circuit of low-field pulsedNMR (Nuclear Magnetic Resonance). According to the characteristic of the signalreceiving system circuit, we analyze the problems, which should be concerned in thepre-amplifier designing process, such as the characteristics of RF circuits, circuit'sinner-noise and EMC (Electromagnetic Compatibility), etc. And we put the problemhow to reduce system noise to the first place.In the thesis we give the prospects of the future expanding directions andtendency of amplifiers, based on the analysis of amplifier's growing history and latestachievements in China and other countries. We make a compare theoretically on theamplifiers' performance of some designs, including some amplifiers' design plansused in NMR instruments, amplifiers made in this lib before and the amplifier boughtfor use. Then we make some improvements based on the amplifier made in our labbefore and point out some problems in it's thesis on the theoretical analysis, designs,result predictions and measurements. Combining with the establishment of the designcircuit's noise model, we put forward some circuit design optimizing methods andadvices for noise matching. Then we make some tests and analysis works of thispre-amplifier to compare with the other two amplifiers.Also, in this thesis we analyze the layout, choices of the device, EMC and someother problems on the perspective of high-speed circuit, and give out some methodson the circuit total performance improvement. Then we make the point-to-pointimpedance measurements of this PCB to give a reference for the later research work.Finally, we summarizing the whole passage and point out some problems, whichshould be resolved in later works.For the convenience of using the analyze instrument, we make a summary of thetypical and often used functions of 4395A in the appendix.