Negative Resistors and Their Series and Parallel Connection

Negative resistors are not physical devices but can be realized using positive resistors and operational amplifiers.Series and parallel connection of different kinds of resistors are discussed,including negative resistor and negative resistor,negative resistor and positive resistor.Conditions for operational amplifiers to work in linear zone are given in order to get negative resistor property.The equivalence transformation of circuits with resistors including negative resistors is the same as the circuits with only positive resistors.