In Reply to: Re: Request: very low power receiver/ AM detector posted by Terry Moreau on 04/03/00 at 9:14 PM:
Hello, em-em and Terry.
I'm sorry em-em, but I don't have a schematic to offer. I only suggested some possibilites to A.J. in hope that the suggestions would help him to develop a successful design.
Terry, the idea of using digital CMOS parts in their linear operating regions can work, but I wouldn't recommend it as a design practice because the manufacturers of those parts don't specify them for that kind of service.
Way back when, back when only digital parts were available in CMOS, there was an article in EDN Magazine suggesting that CMOS would be just dandy for making linear ICs. That article asked why no vendor offered any such thing at the time. It also documented some experimental linear circuits that the author had put together and tested, for which he reported very nice performances.
IC vendors got the point in a hurry! The first CMOS op-amps came out, I would guess, within six months of the publication of that article.
If today, you try to run digital CMOS ICs in their linear modes, you may very well obtain some fine performance too, but you could not be assured of getting that same performance in a product production line situation. Hence, my suggestion not to go that route.
Good luck, all.
John Dunn - President