i need help for filter designing

Dear
suppose i have a bessel filter that is a maximally flat filter and have a flat group delay and have a bad magnitude response (relative to butterworth filter) and i want to improve the magnitude response and have that flat groupdelay.
or suppose i have a butterworth filter that have a good magnitude response but a bad groupdelay response (relative to flat groupdelay), so, iwant to improve the GD.
consequently, i want a filter with a "GD response similar to bessel and magnitude response similar to butterworth".
best regards,
m229

You can improve phase characteristic by the addition of phase correctors, i.e. bilding an nonminimum phase filter. Phase correctors have unity gain and frequency dependent phase characteristic.

maranaza

With FilterSolutions program you can calculate GD equalization cells for lowpass filters. I think program is downloadable somewhere at Elektroda.

Hi,
Each filter type is associated with particular properties ( phase and amp responses). For your case you will have to compromise either your requirements or add extra elements or go for tuning at the implementation level). Refer Williams and taylors book on filter design for phase correction.

cheers

Dear brmadhukar;
where can i find this book?
thanks,
m229