A unified approach to the realization of canonic RC-active, single as well as variable, frequency oscillators using operational amplifiers

Abstract

A general, unified and systematic approach is employed to study realization of operational amplifier (OA) based sinusoidal RC-active oscillators. Both single frequency and variable frequency operations are investigated. A set of circuits is found for each case. The sets consist of 12 and 16 circuits respectively. The circuits are canonic, that is, they require the minimum number of active and passive components. For each circuit, the single frequency set requires one OA, two capacitors and four resistors, while the variable frequency set needs one OA, two capacitors and five resistors. Both sets are shown to be complete in that generation of any additional canonic circuit is not possible. Variable frequency oscillators are all single resistor controlled. They are classified into four groups according to the nature of their dependence on the variable resistor. All the circuits are laboratory tested. Experimental results agree closely with the theoretical analysis. Representative test results are included.