Application of the time-variable feedback to the input amplifiers of pulse magnetic resonance spectrometers: Theoretical considerations

A. V. Koptioug

Research output: Contribution to journalArticlepeer-review

Abstract

An analytical model for the optimization of the signal-to-noise (S/N) performance for the receiver with input resonance circuit and variable feedback is developed. It is shown that by varying the feedback type and depth optimization of the receiver the best S/N performance could be achieved. This approach is based upon a resonator-receiver model with lumped elements. These assumptions are relatively general for the model to be applicable for the design of both continuous and pulse receivers in radio-frequency and microwave bands. The overall S/N performance of the receiver upon the noise properties of its elements and the feedback settings in the input amplifier is studied for different parameter settings. It is shown that the separate optimization of individual elements does not necessarily lead to the best S/N performance of the receiver, especially when bandwidth properties and noise contribution of the elements are substantially different. It is shown that critical coupling of the amplifier to the resonance structure could be far from optimum. In some cases the optimum S/N performance could be achieved with coupling settings below the critical value. But under the assumptions made the coupling above the critical value does not correspond to the best receiver S/N performance. Suggestions on the optimum architecture of magnetic resonance spectrometer receivers with variable feedback are made.

Original languageEnglish
Pages (from-to)513-537
Number of pages25
JournalApplied Magnetic Resonance
Volume22
Issue number4
DOIs
Publication statusPublished - 2002
Externally publishedYes

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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