OPA2211 datasheet discrepancy
Looking at Texas Instruments opamp OPA2211it mentions GBW of 80MHz at a gain of 100, and 45MHz at gain of 1:
Looking at the bandwidth graph from Figure 10 in datasheet:
It looks like 80MHz is unity gain bandwidth, and at a gain of 100 the bandwidth is around 800kHz as would be expected. I could not find any errata or other posts on forums about this. Is this just a datasheet mistake?
update:
It was clarified with Texas Instruments, and what they claim is that 80MHz is applicable bandwidth for A>=2, and 45MHz is applicable for unity gain (question on the TI forum):
I have not yet seen a definition like this, is this considered common practice?
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| User | Comment | Date |
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| Elleanor Lopez | (no comment) | Oct 29, 2024 at 07:49 |
You are right in that the gain at 80 MHz is clearly not 100. Both the initial marketing points and the graph seem to agree on a gain⋅bandwidth of 45 MHz.
There does appear to be a slight kink in the gain curve at 800 kHz, but it looks like the gain is a bit below 100 there. A gain of 100 at 800 kHz seems excessive given unity gain at 45 MHz. Maybe they are trying to say the gain falls off faster than 1/f above 800 kHz.
I would certainly ask for clarification from TI before relying on any of these parameters. Or, use a different amp with specs that don't contradict themselves.
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The 1st page of a datasheet is written by marketing. It can still give you an idea of what the chip is about, but it often contains the performance data under the best conditions. The conditions are rarely specified on the 1st page.
Always check the electrical characteristics section and the charts. That’s the engineering information, and the source of truth. If tables & charts don’t agree with the 1st page, then go by tables & charts.
When the 1st page doesn’t fully agree with tables & charts, that’s rarely an engineering error, that’s usually marketing and specsmanship.
It was clarified with Texas Instruments, and what they claim is that 80MHz is applicable bandwidth for A>=2, and 45MHz is applicable for unity gain (question on the TI forum): [...]
I have not yet seen a definition like this, is this considered common practice?
I remember seeing other op-amp datasheets with different GBWP (gain-bandwidth product) specifications for different bands. I wouldn't say that it's all that common. [Can't seem to find what op-amp model it was. It was a high speed op-amp with GBWP around 2 GHz. I'll add a link here when I come across it again, eventually.]
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