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Abstract

We present a pair of simple analog circuits designed to evaluate the cosine and sine of an input voltage that varies between −π and +π V. The circuit designs are based off of the Taylor series expansions of cos x and sin x about x = 0 (i.e. Maclaurin series expansions). For cos x and sin x, the series are truncated after the x6 and x5 terms, respectively. The coefficients of the various powers of x in the truncated series are fine tuned in order to give the best possible approximations to the trigonometric functions. The circuits are implemented using low-cost analog multiplier and operational amplifier integrated circuits.