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1468 IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS--I: REGULAR PAPERS, VOL. 51, NO. 8, AUGUST 2004 Arbitrary Waveform DDFS Utilizing Chebyshev
 

Summary: 1468 IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS--I: REGULAR PAPERS, VOL. 51, NO. 8, AUGUST 2004
Arbitrary Waveform DDFS Utilizing Chebyshev
Polynomials Interpolation
Ashkan Ashrafi, Student Member, IEEE, Reza Adhami, Senior Member, IEEE, Laurie Joiner, Member, IEEE, and
Parisa Kaveh, Student Member, IEEE
Abstract--A new technique of arbitrary waveform direct digital
frequency synthesis (DDFS) is introduced. In this method, one pe-
riod of the desired periodic waveform is divided into sections,
and each section is approximated by a series of Chebyshev polyno-
mials up to degree . By expanding the resultant Chebyshev poly-
nomials, a power series of degree is produced. The coefficients
of this power series are obtained by a closed-form direct formula.
To reconstruct the desired signal, the coefficients of the approxi-
mated power series are placed in a small ROM, which delivers the
coefficients to the inputs of a digital system. This digital system con-
tains digital multipliers and adders to simulate the desired polyno-
mial, as well as a phase accumulator for generating the digital time
base. The output of this system is a reconstructed signal that is a
good approximation of the desired waveform. The accuracy of the
output signal depends on the degree of the reconstructing polyno-

  

Source: Ashrafi, Ashkan - Department of Electrical and Computer Engineering, San Diego State University

 

Collections: Engineering; Computer Technologies and Information Sciences