General analogue-to-digital transformation

The paper describes a new approach to the approximation problem of discrete-time IIR-type filters by introducing a general analogue to digital (s-z) transformation for preserving the frequency characteristics. All known s-z transformations based on numerical integration methods become simple special cases. The transformation proposed operates on the poles and zeros of continuous-time s-plane transfer and characteristic functions. Each continuous-time s-plane filter yields three equivalent discrete-time z-plane functions using the same s-z transformation. The resulting z-plane functuions are stable and realisable using available discrete-time building blocks.