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All-FET Op-Amp?

6/13/2000 12:57 PM
Ray Ivers
All-FET Op-Amp?
Does anyone know of an op-amp that uses FET's from input to output? Types such as the LF353 just have one FET pair at the input, and the remaining stages are bipolar, I believe.  
Ray Ivers  
I've posted this at the Music Electronics and Guitar Amps Discussion areas as well. Thanks to all.
6/13/2000 1:04 PM
paul perry

National Semiconductor LMC660 comes to mind.  
Observe the maximum power rail limits, I fried some..
6/13/2000 1:10 PM
Ray Ivers

Thanks! I'll try it out, and stay within rail limits for sure.  
6/13/2000 3:27 PM

The Analog Devices OPA604 is all FET, I believe. It's supposed to be so good you don't even have to use coupling caps with it.
6/14/2000 2:01 PM
paul perry

"It's supposed to be so good you don't even have to use coupling caps with it."  
Hmmmm... I expect it has very low leakage, but there is more than one reason why you would want a coupling capacitor sometimes, especially in pedals.
6/13/2000 3:48 PM
Mike I.

I have used the Texas Instruments TLC272 (dual) and TLC274 (quad) for battery powered audio applications. These are single supply CMOS op amps, the AC specs are comparable to the 4558, they will work from a 3 volt supply, up to a maximum of around 16 V. Texas Instruments also has other higher performance CMOS op amps available (at higher price of course).
6/18/2000 10:02 AM
carl margolis

These days a large portion of the new audio speed op amp series from TI, AD, NS, and B-B are pure CMOS. LT, for some reason has not moved in this direction as completely as the others have. TI, in particular has a large range of low noise CMOS op amps avaiable. BTW, The OPA 604 part is from BB, and is not all fet, but the direct signal path is "all" fet. Barrie Gilbert (of AD) wrote an interesting article in EDN recently about the future of Bipolar where he discusses some of the reasons for the current trend to CMOS for op-amps

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