Nonlinear distortion and noise are ever-present impairments in electronic circuits. Knowing individual contributions of these disturbances from different elements to the overall output is useful for optimizing circuits. Determining noise contributions from individual elements is routinely done in standard circuit simulators. For distortion though, such facility is not usually available. In this talk we will see how distortion contributions from individual elements can be calculated in a standard circuit simulator without oversimplifying the circuit or getting into details of the nonlinear device models. This is done by replacing the relevant element by another whose first order term is the same, but higher order terms are different, and observing changes in distortion. The new element is realized by combining multiple instances of the original element. The principle is demonstrated by applying it to a common source amplifier with a nonlinear load, a second order RC filter with nonlinear resistors, and a two stage fully differential opamp.
Nagendra Krishnapura is an associate professor in the VLSI group of the department of Electrical Engineering of the Indian Institute of Technology, Madras. He works in the area of analog and mixed-signal integrated circuits and signal processing. He graduated with a Ph.D. from Columbia University, New York in Oct. 2000. He obtained his B. Tech. degree in electronics and communications engineering from the Indian Institute of Technology, Madras, in 1996. Between 2000 and 2005, he worked as a senior design engineer at Celight, Inc. and Multilink(later Vitesse Semiconductor) where he designed integrated circuits for high speed communications. From 2003 to 2005, he was an Adjunct Assistant Professor and taught courses on Analog Circuit Design at Columbia University.