Title :
A simple technique to evaluate the noise spectral density in operational amplifier based circuits using the adjoint network theory
Author_Institution :
Dept. of Electr. Eng., Indian Inst. of Technol.-Madras, Chennai, India
Abstract :
We use the adjoint network theory to get quick estimates of the noise contributed by various elements in linear time-invariant opamp based circuits. The noisy operational amplifier is represented using a or with an input referred noise voltage and current source. The adjoint model for this representation is derived. This makes the noise analysis of operational amplifier based circuits very simple and the contribution of the operational amplifiers to the output noise can be obtained very often by inspection. The method is applicable to amplifiers, active RC and MOSFET-C filters. Examples of circuits analyzed include the universal active filter and gyrator topologies.
Keywords :
RC circuits; active filters; active networks; circuit noise; operational amplifiers; spectral analysis; MOSFET-C filters; active RC filters; adjoint network theory; gyrator topologies; noise analysis; noise spectral density; operational amplifier; or; universal active filter; Active filters; Active noise reduction; Circuit noise; Circuit topology; Inspection; Intelligent networks; Operational amplifiers; Resistors; Transfer functions; Voltage; 65; Adjoint theory; noise; operational amplifier;
Journal_Title :
Circuits and Systems I: Regular Papers, IEEE Transactions on
DOI :
10.1109/TCSI.2004.836858
