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Turin

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Aug 30^th, 2010, 3:19am

I'm trying to simulate a simple passive circuit (lowpass eliptical filter) but i don't seem to get that right result in the simulation.I tried some thing but still it does not seem to work. I'm just asking if anyone here see sth that i'm missing and don't do right.

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Also irrelevant to the first question can someone explain in the ideal OpAmp in the ADS2004 library what does pins 4 and 5 are for nad how are they used?(last pic)

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Thanks

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pancho_hideboo

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Re: For anypne tha has any experience on ads...
Reply #1 - Aug 30^th, 2010, 4:39am

Turin wrote on Aug 30^th, 2010, 3:19am:

I'm trying to simulate a simple passive circuit (lowpass eliptical filter)
but i don't seem to get that right result in the simulation.

Before using simulator, can you understand filter theory correctly ?

Cutoff frequency of your LPF is 1Hz, isn't it.
However you set start frequency of AC analysis as 1kHz.

Set AC analysis like followings.
�Start=0.01Hz
�Stop=10KHz
�Log Sweep=21pts/dec

Set x-axis as logscale in graph plot

Turin wrote on Aug 30^th, 2010, 3:19am:

Also irrelevant to the first question can someone explain in the ideal OpAmp in the ADS2004 library what does pins 4 and 5 are for nad how are they used?(last pic)

What on earth do you mean by "nad" ?

See http://edocs.soco.agilent.com/display/ads2009/OpAmpIdeal+%28Ideal+Operational+Am...
It is very clear for meaning of pin-4 and pin-5.

BTW, why don't you use following ?
http://edocs.soco.agilent.com/display/ads2009/OpAmp+%28Operational+Amplifier%29

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« Last Edit: Aug 30^th, 2010, 8:52am by pancho_hideboo »

Kita━━━━━━(ﾟ∀ﾟ)━━━━━━ !!!!!
http://www7.plala.or.jp/ungeromeppa/flash/kita.html
http://www.youtube.com/watch?v=mjIxGh55bMM&feature=related

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Turin Junior Member Offline Posts: 28 Greece	Re: For anypne tha has any experience on ads... Reply #2 - Aug 31^st, 2010, 2:54am Actually the filter is 1Mhz...At least according to the book I took the parameters from. And the nad is a typo...I mean and.... I Want to use an ideal opamp to do some comparisons.... Thanks man...
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pancho_hideboo

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Re: For anypne tha has any experience on ads...
Reply #3 - Aug 31^st, 2010, 5:52am

Turin wrote on Aug 31^st, 2010, 2:54am:

Actually the filter is 1Mhz...
At least according to the book I took the parameters from.

It can never be fc=1MHz.

Surely consider values of L and C in your filter.

For example, L=0.8255H, C=0.399F for parallel LC tank in your filter.
So attenuation pole frequency is located around f0=1/(2*pi*sqrt(L*C))=0.277Hz.

I think cutoff frequency of your LPF is 1/(2*pi)=0.16Hz.

See attached figure.
Transfer function of your filter circuit shows LPF charactereristics with attenuation pole at 0.268Hz actually.

Before using simulator, learn very very very very very very very very basic theory of filter circuits surely.

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test_Turin_001.png

« Last Edit: Sep 1^st, 2010, 3:53am by pancho_hideboo »

Kita━━━━━━(ﾟ∀ﾟ)━━━━━━ !!!!!
http://www7.plala.or.jp/ungeromeppa/flash/kita.html
http://www.youtube.com/watch?v=mjIxGh55bMM&feature=related

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pancho_hideboo Senior Fellow Offline Posts: 1424 Real Homeless	Re: For anypne tha has any experience on ads... Reply #4 - Sep 2^nd, 2010, 8:15am Attached figure is a comparison between Hv(Conventional Voltage Transfer Function) and S21. You have to use S21 for characterization of LC filter.
Back to top	test_Turin2.png Kita━━━━━━(ﾟ∀ﾟ)━━━━━━ !!!!! http://www7.plala.or.jp/ungeromeppa/flash/kita.html http://www.youtube.com/watch?v=mjIxGh55bMM&feature=related IP Logged

Turin Junior Member Offline Posts: 28 Greece	Re: For anypne tha has any experience on ads... Reply #5 - Sep 8^th, 2010, 9:42am Thanks for the help!
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