OPA2210: OPA2210 THD plots

Hi Angel,

I don't find it strange, because G = -1 means a noise gain of 2 and less linearizing feedback compared to G = 1 with a noise gain of 1.

Also, the outstanding common mode rejection helps that the OPAmp does not see the higher common mode voltage of voltage follower (G = 1).

OPA1622 and OPA1656 show the same behaviour.

Kai

Thanks for the response, Kai!

I would generally agree, however the next in line, the OPA2211 seems to favor the inverting configuration. See Fig.3 in Datasheet SBOS377L.

Why the huge difference? They seem to share the same general topology.

Anyway, I need a dual op-amp that can do better than -120dB THD+N with Rs=Rf=Rl=10k, G=-1, output level 4Vrms. The other specs of 2210 fit the bill.

Besides the OPA2211, which has higher current noise, could you recommend a suitable device?

Hi Angel,

The OPA2211 was a new, very low-noise op amp TI introduced back in 2006, almost 15 years ago. It used our newest, lowest noise semiconductor process available at the time. It uses a more conventional bipolar transistor front end, albeit one employing an optimized very low noise design.

The OPA2210 uses our latest super-beta bipolar process that achieves low voltage noise and also achieves low current noise. Since it the input bias current is a fraction of that of a standard bipolar input the lower current noise is a benefit.

Kai addressed the differences in the THD+Noise curves for Gains of -1 V/V and +1 V/V and I don't have anything to add regarding the results found in the graphs. Our characterization team developed the graphs for both products and do use industry accepted practices and techniques to make the measurements.

Have a look at the OPA1662 audio op amp. It is specified with a 2 k load, so your combination of 10 k resistors is a lighter load than 2 k. Its THD+Noise is typically for a G = +1, f = 1 kHz, VO = 3 VRMS,  –120 dB. There may be other in the SoundPlus family that come even closer to fulfilling your needs. See the them at:

https://www.ti.com/amplifier-circuit/op-amps/audio/products.html

Regards, Thomas

Precision Amplifiers Applications Engineering

Thanks, Thomas!

I'd be really happy to see a consistent set of plots for every one of your wonderful creations. A good example is Fig.7 in OPA1662's datasheet, SBOS450C.
Looking at the datasheets of all mentioned products, I'm left with the impression that the increase in THD toward the upper end of the frequency with decreasing loads seems to be more related to the output stage losing steam, rather than the input stage topology. I may be wrong..

To keep this thread short and readable, a final question: may I ask for a similar set of plots for the OPA2210 as the one mentioned above? Wish I had an APx555 handy, would have taken me under 30 minutes..

Thanks again!

Angel,

I am working remotely. I am asking some of my colleagues what we might be able to support. Please give me some time to receive an answer.

Regards, Thomas

Precision Amplifiers Applications Engineering