Dear Dennis...
EN-Genius Network's Dennis Feucht answers your design queries in his new Circuit Design Clinic!
August 2007 |
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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: LM3900 Transresistance Amplifier
Q: I have noticed that not all the op amps offered commercially by companies such as National Semiconductor or Harris (now Intersil) are normal. What exactly is a Norton amplifier good for? And, also, why would I ever want to use a transconductance amplifier such as the LM13600/LM13700, or the older CA3080?
A: These components are indeed commodity ICs in that they are low in cost and are readily available. These particular parts are not voltage-in, voltage-out op amps, and they are usually not best applied where voltage amplifiers are able to be used. Most familiar op-amp circuits are best implemented with voltage-amplifying op amps or, for fast applications, with current-feedback op amps which, conceptually, have both voltage and current inputs.
Read the entire response here (116 KB PDF) " target="_blank">here (116KB PDF)
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