OPA4191: OPA4191 in Filter Dezign Tool

I put your targets into Filterpro - those R's and Q's are too high, you may need to look at a DABP design, just put that term into an e2e search, 

Dear Michael, thank you

Excuse me, I have non clearly understand. You reported, that "those R's and Q's are too high". And what can this lead to? Will such a filter be unstable?

Q's is the filter quality factor?  And what is the "R's"?

I am basically satisfied with the 500 Hz pass-band, if 200 Hz it is difficult to implement.

I will look DAPB dezign in e2e.

 Why is the program Filter Dezign Tool not working correctly? Although, from the fourth try the Filter Dezign Tool worked correctly!

TIA

Sincerely,

Vladimir Naumenkov

Most of these filter programs will cheerfully deliver math based solutions calling for elements that will introduce other issues (high R's can cause noise and phase margin issues) will Q's > than say about 6 will require RC precision you can't buy. 

Anyway, I had a couple of DABP files I adjusted to your requirements, for some reason I could not get the OPA191 model to give good results, but the OPA1678 I had used previously looks pretty good nominally, I can run this monte' carlo with the indicated accuracy, it will have quite a spread I suspect, 

4th order DABP with OPA1678 working.TSC

This actually looks pretty good zoomed in monte carlo (400 cases), going to 500Hz would improve it, 

I am having trouble getting my replies to show up correctly, let me repeat the most recent design, 

Here is a zoomed in nominal where I had to reset the 2nd stage so the standard values hit the targets better. You can buy more accurate RC's in standard values steps much more easily, I will attach the most recent TINA file as well, 

8372.4th order DABP with OPA1678 working.TSC

Oh and incidentally, 

The more recent TI online filter tool has a much improved user interface but the internals rests on the circa 1990 Filterpro design code from BurrBrown (I think). That tool was mainly math based and was also very good in a lot of ways. It works with SallenKey or MFB implementation assumptions which gets the implementations into trouble for Q>6 say. The DABP came along much later and is not encoded into the vendor tools I don't believe - It might be in some of the 3rd party tools, but those fall way short in matching requirements to parts (as does the TI tool). Once you have your targets, then you get into op amp limitations that quide you to reasonable parts looking at 

1. GBP

2. noise

3. slew rate

4. output swing, 

5 etc. 

Dear Michael, thank you!

Excuse me, please send the 4th order DABP with OPA1678 working.TSC again. I can't open it in the TINA-TI. The file may be damaged.

TIA

Sinserely,

Vladimir Naumenkov

strange, your second file doesn't want to open either ...

well, in the end I see the circuit - I will draw it in TINA myself!

well this is a V7 save, I can try V9 also, I wonder if the RC tolerance feature I used in V11 does not port out the file - 

0511.4th order DABP with OPA1678 working.TSC

ok, here is a V9 save, 

3527.4th order DABP with OPA1678 working.TSC

Great, good to know - I will start using the V9 for this, 

The whole online filter design effort is huge and many layered. I tried to do a benchmark effort here -

https://www.edn.com/testing-op-amp-tools-for-their-active-filter-design-accuracy-and-dynamic-range/

https://www.edn.com/active-filter-design-tools-shootout/

Thanks, Michael! 

Looks like the issue is resolved. I will close this thread now, please reply to reopen if you have any additional questions. 

Dear Michael, dear Tamara!

I have begun that tried to find out why the program Filter Design Tool does not work. But then it began to work  suddenly. But my main problem not in it!  

The filter, that you sent me, is very interesting and I will definitely check it on the model. But hard to find capacitors 16 nF and 27 nF with 1% tolerance. 

I need a band-pass filter at 1873 Hz. I calculated a filter at a -3dB band 200Hz. This is a “filter 1” circuit. I need to receive a signal with phase manipulation (phase-shift keying signal), please see this signal at a figure 1. The moment of change of a phase is shown by an arrow. I set the size of a filter quality Q= 10 (“filter 1”).

The signal after the filter 1 had the form represented on a fig 2. That is, after phase change some time undesirable oscillatory process took place, which is shown by a red line. It stirs to normal work of the receiver - we cannot correctly define the moment of change of a phase. My drawing not so exact, but an essence, I think, is clear.

Then, I have changed parameters of the filter, I have increased considerably a pass-band (approximately to 1500 Hz and even more) and have set filter quality Q = 1, please see “filter 2” circuit. Then, process of change of a phase began to occur as is shown in drawing 3 (green line). Such form of a signal suits us, but here the filter 2 already ceases to be the normal filter!

QUESTIONS: 1) Whether it is possible to avoid long oscillatory process at the moment of change of a phase and thus not to increase strongly pass-band of the filter? The pass-band of 400-500 Hz  would suit us.  Process of change of the phase, shown in fig 3, suits us, and that is shown in fig 2, does not arrange us. There can be a problem that the GBP value is insufficient? Here, generally, 2 MHz is necessary. I used TLV170. 

2) Can I feed phase-shift keying signal at a circuit in TINA-TI?

TIA

Sincerely,

Vladimir Naumenkov

1258.Figures 1-3.docx

1616.Filter 1.TSC3617.Filter 2.TSC

Well Vladimir, you should take that last text and start a new thread - i will answer the cap question, but TI will have to take the rest - 

Here you are using the Mouser web site, non-stocked but you can find others that are -