RRopAmp max output current limited

sergio.pesenti · October 2, 2024, 12:05pm

I observed an unexpected limitation of the output current provided by the Rail-to-Rail opamp model. I manage to further limit the current by setting Iout and Isnk, but never larger than ~25mA in the following bench:

V5 a 0 5
V1 b 0 2.5
Ã´A1 a 0 b a 0 ¥ ¥ ¥ ¥ ¥ ¥ ¥ ¥ ¥ ¥ ¥ RRopAmp Avol=1000Meg GBW=1000Meg Slew=1000Meg Rload=2K Phi=80 iout=100m isnk=100m
.tran 10µ
.plot I(V1)
.end

What is limiting this current?

OHara · October 2, 2024, 12:14pm

Apparently, the parameter Zx.
Ã-Device
ZX Output impedance×(GBW÷frequency) in voltage follower configuration 100Ω

RROpAmp is very complicated and not documented, so I don’t think we are meant to be using it yet.

sergio.pesenti · October 2, 2024, 12:59pm

Thanks OHara,
It seems to do the job: