[Trevor]

On 15/10/2017 7:48 PM, John Williamson wrote:
On 15/10/2017 08:40, Don Pearce wrote:
On 14 Oct 2017 23:47:58 -0400, (Scott Dorsey) wrote:
The minimal op-amp is at least four transistors, maybe five if you want
decent output current drive.* Two for the differential input, one for
the
intermediate gain stage, then one (or two if you want to make it
push-pull)
for the output stage.* Add a couple constant current sources, a
compensated
reference on the output pair, and the number of components climbs
pretty fast.
--scott

Unless you use an integrated op amp. 5532 is probably my favourite
do-everything op amp. The count becomes one op amp and two resistors.

I think that Scott is making the point that inside the black box of the
op amp IC, there are many, many active components, all of which have a
potential effect on noise and linearity.

Hardly relevant what is inside IF the performance and cost meet your
requirements surely?

Trevor.