Approximation circuit and method

摘要

An approximation circuit approximates a function f(x) of an input value "x" by adding at least the first two terms in a Taylor series (i.e., f(a) and f'(a)(x-a)) where "a" is a number reasonably close to value "x". The first term is generated by a first look-up table which receives the approximation value "a". The first look-up table generates a function f(a) of the approximation value "a". The second look-up table generates a first derivative f'(a) of the function f(a). A first multiplier then multiplies the first derivative f'(a) by a difference (x-a) between input value "x" and approximation value "a" to generate a product f'(a)(x-a). The approximation circuit can approximate the function f(x) by adding the third term of the Taylor series, (½)f''(a)(x-a)2.