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7th order Low pass Butterworth Filter

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asho_234

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butterworth schematic

Hi all
I try to make a simulation for 7th order Low pass Butterworth Filter by orcad
that is the orignal circuit



and that is my drawing on orcad



and that is AC sweep parameter



then when runing i meet that error



What is my mistake?

I`m sorry for my bad language "I don`t speak English well"
 

second order butterworth filter

I cannot see any DC sources for providing power to your circuit.
(Vdd resp. Vss).
 

7th order butterworth bandpass

VDD & VSS exist but not appear in pic.

and That is orcad file to try to run it.

**broken link removed**
 

is butterworth a bad filter

I can find no error in your schematic. I have simulated just one of your opamp stages - and the result is as expected: lowpass response of second order.

Now you should do the following:

1.) Simulate only the first part of the circuit - that is the RC-element together with the first two-opamp stage. For this purpose, disconnect R7 from the opamp output and ground R7 (in order to avoid an error mesage).
This should give you a lowpass of third order.

2.) At the same time check the value of the power supplies. The DC bias values of app. 360kvolts look very strange. Even if something is wrong, I cannot understand why the power supply is at such a high value. Perhaps you should do this test at first.

Good luck and report about the results.
 

    asho_234

    Points: 2
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seventh order butterworth

LvW said:
I can find no error in your schematic. I have simulated just one of your opamp stages - and the result is as expected: lowpass response of second order.

Now you should do the following:

1.) Simulate only the first part of the circuit - that is the RC-element together with the first two-opamp stage. For this purpose, disconnect R7 from the opamp output and ground R7 (in order to avoid an error mesage).
This should give you a lowpass of third order.

2.) At the same time check the value of the power supplies. The DC bias values of app. 360kvolts look very strange. Even if something is wrong, I cannot understand why the power supply is at such a high value. Perhaps you should do this test at first.

Good luck and report about the results.

thanks for interesting

i try (1)



and the output is



(2) i put the input power 5v i can`t understand that high output valus 8O
 

butterworth filter circuit

Your schematic shows a ground potential of 6.445MV . This should be 0 volts.
Something must be wrong with your power supply.
Please, show it within your schematic.

But independent on this point
1.) Use an input ac voltage of only 1V (in this case the output is identical to the gain)
2.) The output voltage should be in dB. This gives the BODE-diagram which normally is used to show the frequnecy response.

Sometimes it helps to make a complete new schematic on a new page (in your case, for the first part only).
 

i hate orcad

I think, you are using a ground symbol not implicitely connected to the SPICE ground (0) node. The standard ground symbol is AGND, a triangle with a "0".
 

what is a 7th order low pass filter?

LvW said:
Your schematic shows a ground potential of 6.445MV . This should be 0 volts.
Something must be wrong with your power supply.
Please, show it within your schematic.

But independent on this point
1.) Use an input ac voltage of only 1V (in this case the output is identical to the gain)

the same error

Added after 3 minutes:

FvM said:
I think, you are using a ground symbol not implicitely connected to the SPICE ground (0) node. The standard ground symbol is AGND, a triangle with a "0".

the result is

ERROR -- Less than 2 connections at node GND
ERROR -- Voltage source and/or inductor loop involving V_V2
You may break the loop by adding a series resistance

Added after 3 minutes:

any one can tell me agood program alternative to orcad but more flexible than orcad
now i hate orcad
 

alternative zum butterworth -filter

do u want to use the same circuit configuration?if not nesessry then use three 2nd order butterword filters in casecade & a 1st order of same cutoff also insert voltage follower between each two states to overcome impedence mismatch problem,check this circuit out and see weather ur problem is solved or not,do u've 2nd order butterwords configuration pic available or not ?if not i'll send u
 

butterworth filter power and order

Quote: any one can tell me agood program alternative to orcad but more flexible than orcad
now i hate orcad


I´m afraid, another program cannot repair errors made by the user.
 

second order bandpass butterworth

I think Orcad (actually SPICE respectively PSPICE) is very flexible and I wouldn't expect that using other tools generally helps. There are some frequent problems in circuit simulation setup. I can't see from the distance, which are present in your circuit. Regarding the GND node issue, I think the new created error suggests, that there is a problem. Also the recently posted files included *.opj only, *.dsn and others have been mising.

It may be helpful to build the simulation circuit incrementally as LvW suggested and check for meaniningful behaviour after adding the first OP. This implies, that you have a basic understanding of what the circuit elements are actually doing. Otherwise, the benefit of circuit simulation would be in doubt anyway.
 

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