Abstract: A method of digital filter network design using observers is presented. This method consists in providing the required close loop system pole positions, and obtaining a digital filter network satisfying the characteristics of the system; whereas the conventional logarithmic frequency method is based on the open loop logarithmic frequency properties, in which the choice of the network depends on the experience of the designer in making system's properties approach the desired ideal properties by way of engineering graphical curves. The former method depends on digital simulation computation and lays stress on realization of the network design on a digital computer, but the latter method relies on designer's experience and lays stress on physical realization of the network design.State vector and matrix vector representations are used in the numerical program calculation for digital network design through the computer. It makes modification and re-design work easier.