Approximation and construction of the network containing variable elements
Atsushi Kawakami, Shinichi Takahashi, Jun Tajima · Electronics and Communications in Japan (Part I Communications) · 1981
Abstract A variable network is a network in which a designated input‐output characteristic can be obtained continuously by varying continuously a specific parameter. This paper describes two methods of approximating the desired variable characteristics by a rational transfer function and constructing it as a concrete network. In the conventional method, an approximation with good accuracy is obtained by raising the orders of the complex frequency s and the variable parameter λ. The actual construction of the network becomes difficult because of the higher orders. Two methods are proposed in this paper to avoid this difficulty. In the first method, the approximated transfer function is divided into unit blocks, lower order for the complex frequency s and a bilinear form for the variable parameter λ. By this method, the actual construction of a network can be simplified considerably. In the second method, the desired characteristics are approximated in the form of a transfer function in which the denominator polynomial is resolved into the polynomials of s and λ, respectively. The approximated transfer function in this form has a merit in that it can be realized with a minimal number of dynamic elements and variable elements in the network construction. Moreover, its stability is independent of λ.