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- 13th February 2017, 22:42 #1

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## [Moved]: How to simulate DC Nonlinear model?

Hi,

I have an equation that describes the linearity of my amplifier. and I want to make a plot based on the equation. How could I do that in ADS?

this the equation I have vo=a1+a2vi+a3vi^2, and I want to plot vo vs vi...

Please help,

thanks

- 13th February 2017, 22:42

- 14th February 2017, 01:29 #2

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## Re: How to simulate DC Nonlinear model?

Can you create a lissajous figure? It's the natural choice.

Excellent for observing whether your amplifier introduces distortion.

- 14th February 2017, 15:32 #3

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## Re: How to simulate DC Nonlinear model?

It is very easy.

Use SDD(Symbolically Define Device) or Verilog-A.

http://edadocs.software.keysight.com...efined+Devices

http://edadocs.software.keysight.com...he+SDD+and+UCM

- 13th March 2017, 21:38 #4

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## Re: How to simulate DC Nonlinear model?

Hopefully it's not too late to get back to you. Thank you for your help. The SDD example is really helpful.

I tried out the example, but it doesn't work as what I expect. Compression point, OIP2, and OIP3 do not match to my original amplifier.

I have the equations set up as follows.. K1, K2, and K3 are calculated base on gain, OIP2, and OIP3. Do I input anything wrong here?

- 15th March 2017, 14:28 #5

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## Nonlinear model of amplifier simulation using SDD

Hi all,

I would like to come up with a DC nonlinear model of an amplifier. I calculated k1, k2, and k3 based on gain, OIP2, and OIP3 of the amp. And now, I need to simulate the output voltage equation vo=k1vi+k2vi^2+k3vi^3. I use SDD2P block to simulate(as shown in the pictures below), but I could not get similar OIP2 and OIP3 values by doing HB simulations. Does anyone know what I've done wrong in the simulation setup?

Thank you so much!

- 15th March 2017, 14:28

- 18th March 2017, 11:28 #6

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## Re: Nonlinear model of amplifier simulation using SDD

Show me equations for k1, k2 and k3 you use.

http://edadocs.software.keysight.com...pageId=5923594

And you use "vi" in SDD without defining it.Last edited by pancho_hideboo; 18th March 2017 at 11:37.

- 20th March 2017, 07:08 #7

- 20th March 2017, 18:17 #8

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- 21st March 2017, 02:57 #9

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## Re: Nonlinear model of amplifier simulation using SDD

No.

I request equations for k1, k2 and k3.

- 21st March 2017, 02:57

- 21st March 2017, 15:24 #10

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## Re: Nonlinear model of amplifier simulation using SDD

- 21st March 2017, 16:22 #11

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## Re: Nonlinear model of amplifier simulation using SDD

First, set k2=0.

Can you get reasonable results when k2=0 ?

I think your equations for k2 and k3 are very suspicious.

See http://www.designers-guide.org/Model...rf-systems.pdf

There are many definition of IM2.

And IM2 is out of band.

Show me definition of your IM2.Last edited by pancho_hideboo; 21st March 2017 at 16:46.

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