Or have they perhaps always been a bit of a niche product?
I've been working with op amp circuits on nights and weekends for about a year now. It was a fair amount of time before I encountered a current feedback op amp (CFA) even by mention, and only now that I come across one in an actual circuit I'm studying (LT1210 on page 3).
I was looking around for a nice jellybean CFA I could use to experiment around with a bit and notice:
- There are way fewer CFA's out there, at least at the places I looked
- All the CFAs offered by TI are OPAx models, I believe indicating they came along with their Burr Brown acquisition, implying TI didn't make any itself before or since. Roughly half of those are now obsolete.
- CFAs are generally "pricey" compared to the voltage feedback op amp (VFA) options that are out there. Say $5 to $10 compared to plenty of VFAs for around $1.
So I was wondering, did CFAs arise to meet a market need that perhaps has largely passed? Or were they kind of always a niche device; perhaps a compromise for when output speed and current were design priorities?
In short, how might one characterize the market life-cycle trajectory of CFAs? Are they something to be avoided (or substituted with something newer and better) for new designs? Or are they maybe a continuing good option for special cases and just don't have the volume to drive their price point lower?