Dear Dennis... EN-Genius Network's Dennis Feucht answers your design queries in his new Circuit Design Clinic! September, 2007

EN-Genius Network presents a new, interactive analog design service to readers! Send us your design questions (with relevant data; schematics in JPEG or GIF, please) for some free engineering advice from EN-Genius Network's circuit consultant, Dennis Feucht, on how you might solve a design problem or improve circuit performance. Submissions may be edited for clarity or brevity, and submitters and their email addresses will remain anonymous (unless otherwise indicated). Please send your questions to Dennis here.

Commodity IC Data: CA3080, LM13600 and LM13700

by

Dennis L Feucht

Q: I have noticed that not all the op amps offered commercially by companies such as National Semiconductor Corp. (NSC) or Harris are normal. What exactly is a Norton amplifier really good for? And also, why would I ever want to use a transconductance amplifier such as the CA3080, or the LM13600, LM13700?

A: In the previous article we looked at the LM3900 transresistance amplifier. Here, the other unusual parts are marveled over. These amplifiers either apply, or are the precursors of, Barrie Gilbert’s translinear concept that he pioneered several decades ago. Translinear circuits are versatile and IC product designers at RCA (CA3080) and NSC (LM13600, LM13700) must have appreciated what Motorola did in implementing a four-quadrant translinear multiplier as the MC1495 (and MC1496).

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