Synthesis with negative resistors

In the realisation of networks for higher frequencies, the usual tendency of avoiding inductors is not always justifiable. In the paper, several realisation techniques for driving-point functions, using all three standard components (RLC) and a single negative resistor, are proposed. A realisation based on Darlington´s procedure is applied to the synthesis of a broad class of functions, called negative real functions, It is shown how any real rational function may be converted into a negative real one by the techniques of predistortion and resistance padding. Some constraints are given for a function to be realisable by applying a tunnel diode instead of the negative resistor. A modification of an RC-n.i.c. synthesis procedure is presented, resulting in a transformerless realisation of any rational function by means of an RLC network with a single negative resistor. Synthesis of a function having either its zeros or its poles in the left half of the complex-frequency plane is shown to be possible through partial-fraction expansion, combined with the use of a negative resistor. The resulting network is transformerless, and presents a very simple topology. Constraints on functions realisable by RLC components and tunnel diodes are discussed.