TINA/Spice/TINA-TI: The question between FilterPro and TINA-TI

Yu-Hung

Expert 1130 points

Part Number: TINA-TI

Tool/software: TINA-TI or Spice Models

Hi,

I try to rebuild FilterPro filter in TINA-TI.

Case 1. Lowpass, Multiple Feedback, Butterworth, order 2, Gain: 1V/V, Frequency:10Hz

The input signal and output signal inversed.(-1V/V)

The frequency response is different too.

DPG3.TSC

Case 2. Lowpass, Shallen Key, Butterworth, order 2, Gain: 1V/V, Frequency:10Hz

The frequency response looks like different.

DPG2.TSC

I don't know where the problem is.

I would appreciate any help.

YHH

over 5 years ago

0 Herman Theodorus over 5 years ago

TI__Genius 9775 points

YHH,

When I look at your picture above, I notice that they are actually the same. All of them shows f-3dB of 10Hz whether it's FilterPro or TINA simulation.

Are you referring to the higher frequency discrepancies perhaps such as around 1MHz for your first case and 10kHz for the second case? If this is what you meant, it has something to with with the opamp. In FilterPro, it uses ideal opamp while in TINA, you're using real opamp model.

If you want to duplicate FilterPro plot, you can replace the opamp in TINA with ideal opamp by using VCVS (Voltage Controlled Voltage Source) component and set the gain to let's say 10000x

Herman

0 Yu-Hung over 5 years ago in reply to Herman Theodorus

Expert 1130 points

Hi Herman,

Thank you for your reply.

When I use VCVS, it looks like almost the same with FilterPro. (besides the phase)

But I don't know why input/output signal are Inverting. (Gain is 1V/V in FilterPro)

0 Herman Theodorus over 5 years ago in reply to Yu-Hung

TI__Genius 9775 points

It is inverting because you choose an inverting configuration. Multiple Feedback LPF architecture is an inverting configuration. If you want it to be non-inverting, then you choose the other one which is Sallen-Key architecture.

0 Yu-Hung over 5 years ago in reply to Herman Theodorus

Expert 1130 points

Hi Herman,

Yes, I know.
But I guess the Gain is -1 V/V, not 1 V/V.

right?

0 Herman Theodorus over 5 years ago in reply to Yu-Hung

TI__Genius 9775 points

Yup, that's correct.

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TINA/Spice/TINA-TI: The question between FilterPro and TINA-TI