WEBENCH® Tools/OPA703: Filter Designer does not work as expected

Amit Ashara

Part Number: OPA703
Other Parts Discussed in Thread: TINA-TI, TLV9062, OPA2227, TLV6741, OPA322,

Tool/software: WEBENCH® Design Tools

Hello All

When designing a BandPass filter, the selection tools allow proper entry of data and show the filter response as expected. Especially when I am performing a gain of 5 dB. However on simulation it shows that the gain is -150 dB. Is there some functional entry issue or there is a tool issue.

I do not see the problem for Low Pass or High Pass filter

over 7 years ago

0 Gustaf Falk Olson58 over 7 years ago

TI__Prodigy 610 points

Hi Amit,

Could you provide some additional information about the simulations you ran so that we can reproduce the error. A couple of screenshot of the filter designer requirements window (all your inputs) and the results that are produced by WEBENCH for the selected filter response type (Bessel, Butterworth, ...) would be much appreciate.

All the best,

Gustaf Falk Olson

0 Tim Claycomb over 7 years ago

TI__Genius 15410 points

Hello Amit,

Are you seeing the issue when you are working in WEBENCH Filter Designer? Or are you seeing the issue when you put your design into TINA-TI?

If you are seeing the issue in TINA-TI can you please attach the TINA-TI file you are working with?

Thank you,

Tim Claycomb

0 Amit Ashara over 7 years ago in reply to Gustaf Falk Olson58

TI__Guru**** 244380 points

Hello Gustaf

Attached is the document with the Webench Screenshot. I have selected the 1db Chebyshev filter.Webench.docx

0 Amit Ashara over 7 years ago in reply to Tim Claycomb

TI__Guru**** 244380 points

Hello Tim,

No, I have not used the TINA-TI yet, only the Webench tool.

0 Gustaf Falk Olson58 over 7 years ago

TI__Prodigy 610 points

Hi Amit,

The problem seems to be that WEBENCH, for some reason, opted for an amplifier with a minimum supply voltage that is higher than the 3.3V single-supply you had selected for your design.

The OPA703 has a minimum total supply voltage of 4V and the OPA2227, which was the selection when I tried to reproduce your error, has a minimum supply voltage of 5V (see above). When I changed to a dual supply or increased the supply voltage to 10V, the error disappeared, as expected. Below is a Bode plot of the closed-loop response at 10V single supply. At 3.3V single supply, there are however plenty of amplifiers that meet the minimum GBWP requirement of 6.5MHz, such as the TLV9062, TLV6741 and OPA322.

Thanks for highlighting this issue for us. We will convey it to the WEBENCH team and have it fixed.

All the best,

Gustaf Falk Olson

0 Amit Ashara over 7 years ago in reply to Gustaf Falk Olson58

TI__Guru**** 244380 points

Hello Gustaf

Thanks for the solution. I ran the same and it shows the correct response now.

One small note though: I tried selecting the OPA322, but it does not have a simulation mode. TLV9062 and TLV6741 does not come in the full OP-AMP list.

0 Gustaf Falk Olson58 over 7 years ago in reply to Amit Ashara

TI__Prodigy 610 points

Hi Amit,

Good to hear it remedied your problem. I would have expected the OPA322 to have a WEBENCH model, so it is helpful to get your feedback so that we can fill in this gap. The TLV9062 and TLV6741 just released or is about to release to market and we're working on the simulation models. However, the former has a very good TINA-TI model if you'd like to try it out in simulations. Both devices will set a new standard in regards to price vs performance and that's why I suggested them.

All the best,

Gustaf Falk Olson

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WEBENCH® Tools/OPA703: Filter Designer does not work as expected