Patent ID: 6489846
Filing Date: 2002-12-03
Classification: H03F

Abstract:
A distortion compensating device for compensating an input-output characteristic of an amplitude and a phase of amplifying means, comprising:a distortion compensating device provided with amplitude compensating means for conversion of an in-phase signal I and an orthogonal signal Q into an in-phase signal Iâ€²=f(vi) and an orthogonal signal Qâ€²=f(vq) for compensating a voltage amplitude, where vi represents a voltage of the in-phase signal and vq represents a voltage of the orthogonal signal; and means for performing the conversion by applying vi and vq to a function constituted by using two coefficients a and b and given as f(v)=âˆ’{fraction (1/2)}Â·bÂ·log((aâˆ’gÂ·v)/(a+gÂ·v)), the coefficients a and b being obtained as two parameters that fit the input-output characteristic of the amplifying means to a hyperbolic tangent function vout=aÂ·tan h (bÂ·vin), where vin and vout represent an input voltage and output voltage respectively of the amplifying means, and g represents a linear gain.