Digital filter design and array synthesis using quadratic programming.
Chao Ying. Li · DR-NTU (Nanyang Technological University) · 2009
In the field of digital filter designs, all kinds of infinite impulse response (IIR) and finite impulse response (FIR) filters have their own closed-form design method except equiripple FIR filter. In this research based project, elliptic rational function with the characteristics of equiripple behavior and steep transition is applied to design closed-form equiripple FIR filter and to synthesize array beam pattern using quadratic programming. However, when elliptic rational function is used as template, the result can not follow the design template closely with decreasing stop band ripple performance due to the rational function nature. As a result, a few orthogonal polynomials such as Legendre polynomials and Laguerre polynomials are studied to exploit new template for equiripple FIR filter design. Besides, a new equiripple FIR filter design method transformed Chebyshev polynomial is discovered, which is a suboptimal method to design filters. Optimizations of transformed Chebyshev polynomial are carried out and a few optimization results are presented.