Some Wenzel "Cleanup" Sims

[jackinnj]

I thought it would be interesting to look at how some opamps would perform in the Wenzel "Finesse Voltage Regulator Noise" circuit:

AD797 vs LM833


AD797 vs NE5534:

[jackinnj]

I put a 10uS pulse of 100mV on the 15V rail -- I think this is best compared on the workbench:

[agdr]

Interesting! Good info. I didn't know the ne5534 was that good. One special request if you get the chance someday - LME49990 vs. AD797 in the shunt.

What transistor are you using for the pulldown, a 2N4401?

[jackinnj]

National doesn't have a model for the LME49990. Yes, this is the circuit with the 2N4401, just a little op-amp rolling.

NE5534 is "that good", it's just that it's been around for so long.

[agdr]

Yep, new(er) isn't always better. Good stuff!

One more request, if possible: the LME49860 vs the AD797 in the shunt. The spice file is here

http://www.national.com/pf/LM/LME49710.html#Tools

It is the LME49710 page but the file is actually the LME49860 - which is probably just a higher voltage LM4562 under the hood.

I'm going to order some NE5534's tonight. Looks like a good chip to have around.

[jackinnj]

Obviously, they are just simulations. The noise -- a 10k resistor is injected into the 15V rail. BW is limited to 1Hz:



the impulse test looks about the same:

[agdr]

Thanks for running that! True, just sims, but good enough to mess around with a few (NE5534) and see what they can do.

The (sim) overshoot on the AD797 and LME49860 in response to the pulse is interesting. The NE5534 on the other hand looks just slightly overdamped.