Patent ID: 6757650
Filing Date: 2004-06-29
Classification: G10L

Abstract:
An excitation vector generator, comprising:a seed storage device that stores a plurality of seeds; a non-linear digital filter that outputs different vector streams in accordance with values of said plurality of seeds; and a switcher that switches a seed to be supplied to said non-linear digital filter from said seed storage device, wherein said non-linear digital filter comprises: an adder having a non-linear adder characteristic; a plurality of filter state holding sections to which an output of said adder is sequentially transferred as a filter state; and a plurality of multipliers that multiply a filter state, output from each of said filter state holding sections, by a gain and send a multiplication value to said adder, seeds read from said seed storage device being supplied to said filter state holding sections as initial values of said filter states, said adder having an externally supplied vector stream and said multiplication values output from said plurality of multipliers as input values and produces an adder output according to said non-linear adder characteristic with respect to a sum of said input values, said gains of said multipliers being fixed in such a way that poles of said digital filter lie outside a unit circuit on a Z plane.