OPA810: TIA closed loop bandwidth mismatch

Michael Steffes

Part Number: OPA810

When I set up this sim with the 2020 model, I get 2.1Mhz F-3dB not the reported 3Mhz. That number is pretty close to equation 10 using an extracted GBP of 66MHz. 2.1MHz is also closer to Table 9.2 -was this a mistake or am I missing something? Also, 100kohm is a 100dB DC gain, not 90dB,

over 1 year ago

0 Anant Sinha over 1 year ago

TI__Intellectual 1550 points

Hi Michael,

We will check this and get back to you by tomorrow.

Regards

Anant

0 Michael Steffes over 1 year ago in reply to Anant Sinha

Guru 48395 points

I also noticed the label on that curve is incorrect, that top curve is the TIA response.

0 Anant Sinha over 1 year ago in reply to Michael Steffes

TI__Intellectual 1550 points

Michael,

Fig 9-14 is for the phase of TIA circuit. So 90 there is the phase shift and not the gain. Regarding the 3MHz number, I am looking into it why it's reported as 3Mhz and not 2.11MHz. I will get back to you on this soon.

And sorry I couldn't get which label are you saying is incorrect?

Regards

Anant

0 Michael Steffes over 1 year ago in reply to Anant Sinha

Guru 48395 points

Ok, the Figure 9-14 is just phase, I get it now, makes sense, no actual closed loop response plot it seems.

0 Anant Sinha over 1 year ago in reply to Michael Steffes

TI__Intellectual 1550 points

No problem Michael

0 Anant Sinha over 1 year ago in reply to Anant Sinha

TI__Intellectual 1550 points

Michael,

The 3Mhz quoted number is a typo error, it should actually be around 2.15MHz.

Regards

Anant

+1 Michael Steffes over 1 year ago in reply to Anant Sinha

Guru 48395 points

yea, the 2.1MHz is what I got in simulation and calculation. Thanks Anant,

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OPA810: TIA closed loop bandwidth mismatch