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1st June 2019, 22:55 #1
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Confused  transmission line component in Virtuoso and ADS
Hi,
I am learning to design matching network with distributed elements. Usually when we design stub matching, we get the line lengths from smith chart. Now when I look at TLIN in ADS it has parameter E(electrical length) and TLINE in virtuoso has delay time. In ADS's smith chart utility also angle (I guess it is electrical length ) is given when stub or line are chosen as matching element. I know there are mathematical relations among these parameters but I am confused why they are not consistent. Someone please clarify. Thanks

2nd June 2019, 07:17 #2
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Re: Confused  transmission line component in Virtuoso and ADS
Cadence Virtuoso is a Design Framework.
This does not make sense at all, even if you mean "analogLib/tline".
Use correct terminology.
"analogLib/tline" is a just symbol.
It is used by various simulators, e.g. Keysight ADSsim, Synopsys HSPICE, Cadence Spectre, etc.
What simulator do you use from Cadence Virtuoso ?
You can use Keysight ADSsim from Cadence Virtuoso.
If you mean Spectre Primitive, "tline", it is derived from SPICE which is oriented for signal delay originally.
That's all.
HSPICE Syntax
Code:Ideal Telement Transmission Lines Syntax General form: Txxx in refin out refout Z0=val TD=val [L=val] + [IC=v1,i1,v2,i2] Txxx in refin out refout Z0=val F=val [NL=val] + [IC=v1,i1,v2,i2]
On the other hand,
TLIN (Ideal 2Terminal Transmission Line)
TLIN4 (Ideal 4Terminal Transmission Line)
in ADSsim are oriented for RF application.

2nd June 2019, 08:14 #3
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Re: Confused  transmission line component in Virtuoso and ADS
I am using spectre simulator but mostly I never used HSPICE syntax or something, I only use GUI.
I see so analoglib/tline is used, if I want signal delay. Actually I am solving the from boook Microwave Transistor Amplifiers analysis and design, 2nd edition by Guillermo Gonzalez. So I am stuck on how to solve it using smitch chart utility in ADS to find those line length and implement the schematic in Virtuoso.

2nd June 2019, 08:20 #4
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Re: Confused  transmission line component in Virtuoso and ADS
Last edited by pancho_hideboo; 2nd June 2019 at 08:32.

2nd June 2019, 08:47 #5
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2nd June 2019, 09:47 #6
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Re: Confused  transmission line component in Virtuoso and ADS
You didn't yet clarify where you see inconsistency of different parameters (electrical length, delay, phase angle) used to describe transmission line circuits. As you state, they are clearly related.

2nd June 2019, 10:18 #7

2nd June 2019, 11:05 #8
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2nd June 2019, 11:46 #9
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Re: Confused  transmission line component in Virtuoso and ADS
This makes sense, So I always need to convert from electrical length (EL, found in smith chart utility) to physical length(EL*lambda/360) and use it in analogLib/tline.
   Updated   
Thanks, your comments are valuable. is this normalized electrical length equal to electrical length ( in terms lambda)/ lambda ?
Finally, I understood there are three parameters ..
1.Electrical length (in terms of lambda)
2.Electrical length (in terms of angle)
3.Physical length

2nd June 2019, 13:55 #10
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Re: Confused  transmission line component in Virtuoso and ADS
Physical length is not required at all in Spectre Primitive, "tline".
Yes.
nl is len/lamda.
lamda=vel*c/f
td=len/(vel*c)=nl*lamda/(vel*c)=nl/f
Spectre Primitive, "tline" does not have this.
angle=360*f*td
Attached figure is "analogLib/tline" for ADSsim not Spectre.Last edited by pancho_hideboo; 2nd June 2019 at 14:14.

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2nd June 2019, 14:54 #11
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2nd June 2019, 15:08 #12
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Re: Confused  transmission line component in Virtuoso and ADS

3rd June 2019, 08:27 #13
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3rd June 2019, 10:11 #14
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Re: Confused  transmission line component in Virtuoso and ADS
MDS which was one of ancestor of ADS was frequency domain simulator originally.
This is true for Libra.
Transient Analysis was introduced at MDS5.0 first.
So TLIN and TLIN4 are oriented for frequency domain.
Of course, they are effective in time domain.
ADSsim can read HSPICE and Spectre netlist directly.
Here SPICE primitive “tline” is converted to ADS primitive “TLIN4” internally.
See http://literature.cdn.keysight.com/l.../Txxxxxxx.htmlLast edited by pancho_hideboo; 3rd June 2019 at 10:21.

8th June 2019, 15:28 #15
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Re: Confused  transmission line component in Virtuoso and ADS
Hi, I have to visit this again. I have done a few examples and they gave me correct results but this particular one is displaying wrong input impedance. I hope I am not sharing any sensible information, this example is also taken from the same book I've mentioned above. I should get 15+j30 ohm but I got 15.6j15.6 at 40 GHz.
I want to know whether the way I have connected the Tline is correct for the stub and why I didn't get 15+j30 ohm.

8th June 2019, 15:32 #16
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Re: Confused  transmission line component in Virtuoso and ADS
Your connection is completely wrong as open stub.

8th June 2019, 17:22 #17
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8th June 2019, 17:36 #18
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Re: Confused  transmission line component in Virtuoso and ADS
Last edited by pancho_hideboo; 8th June 2019 at 17:45.

12th June 2019, 10:55 #19
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Re: Confused  transmission line component in Virtuoso and ADS
I know I didn't get exact 15+j30 ohm but I am still wondering what changes I need to make in connections to have correct open stub
To be frank, I don't even know why there are TLIN and TLIN4 and their purposes. I could only find this information http://edadocs.software.keysight.com...ine+Components

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12th June 2019, 11:16 #20
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