Analog electronic computation of the finite-time Fourier transform for power spectral density measurements

Author

Peter Chien-Nan Yih

Date of Award

5-1991

Degree Type

Thesis

Degree Name

Master of Science

Major

Electrical Engineering

Major Professor

J. M. Rochelle

Committee Members

T. V. Blalock, D. W. Bouldin

Abstract

A new approach to obtain the finite-tinie cosine transform of a time-domain noise signal to measure the noise power spectral density was implemented. This technique employs an analog electronic circuit to perform the cosine transform. This technique can be extended to obtain the finite-time Fourier transform as well. A reference sine wave generator was set to the frequency of analysis to obtain the cosine transform from the Cosine Transform Circuit ( CTC ). The CTC works on the principle that the input noise signal is multiplied with the reference cosine wave and then this product is integrated for a finite time T. A mathematical study was performed, of the use of a rectangular window model integration to obtain the finite-time cosine transform with zero phase of a cosine model function θ_s and zero phase of the reference cosine wave θ_r- with respect to zero integration time. This simple model gave a different result for a 0 to T integration versus a -T/2 to T/2 integration, which led to further mathematical study. Computer modeling of the effects of various flicker noise comer frequencies as well as high-pass filtering of the noise signal upon this ideal integration model, as well as that of the case of averaging of θ_r and θ_s or white noise was performed. An analysis showing the θ_r- independence for the complete Fourier transform was performed. A general analysis for the cosine transform and sine transform of a model cosine noise source was performed. This general study showed that in order for the Fourier transform result to be independent of θ_r and θ_s, and f_rT , the reference sinusoid frequency times the integration period, θ_r and θ_s averaging must occur. Various sources which affected the accuracy of the resulting cosine transform of the CTC was examined. Noise power spectral density of P-type transistors of a MOSIS MOSFET transistor array of varying gate area was measured.

Recommended Citation

Yih, Peter Chien-Nan, "Analog electronic computation of the finite-time Fourier transform for power spectral density measurements. " Master's Thesis, University of Tennessee, 1991.
https://trace.tennessee.edu/utk_gradthes/12571