A function generator based on quadratic B‐spline functions
Masaru Kamada, Kazuo Toraichi, Norio Nakamura · Electronics and Communications in Japan (Part III Fundamental Electronic Science) · 1993
Abstract An improved smooth analog signal generator is proposed which purges digital‐to‐analog (DA) conversion phase distortions. The author's previous system for such a generator had the following problems: 1) circuit parameter errors that accumulated at the circuit output due to the complicated circuit structure and 2) the output could turn out to be discontinuous because it was a subtle patchwork of discontinuous functions, even though theoretically they were smoothly connected. These problems have been avoided through careful tuning of the circuit parameters. The present paper proposes an improved system, free of the above problems. This was accomplished through the following: 1) the analog circuit was simplified by retaining as many functions as possible in the digital circuit and 2) the analog output signal was made inherently smooth through a linear combination of time‐limited smooth (i.e., B‐spline) functions. Consequently, the present system produces more accurate linear phase characteristics with easier circuit parameter tuning. Its effectiveness was evaluated on a trial product whose performance was compared to that of the previous generator.