This paper considers the design of digital all-pass finite impulse response
filters in the minimax sense. Our proposed algorithm is a numerical techni
que to obtain the optimal filter coefficients by using a primal affine scal
ing variant of Karmarkar's algorithm. Under this approach, we formulate the
design problem in terms of minimizing the magnitude and phase errors simul
taneously or minimizing the magnitude and group delay errors simultaneously
. Computer simulation shows the effectiveness of the proposed design techni
ques.