Post on 13-Jul-2018
“New Features for Solving HSD Challenges with ADS 2013”
1
New Features for
Solving HSD Challenges with ADS 2013
Implementation ofTouchstone Version 2.0
in ADS 2013.06
Agilent EEsof EDA
Radek Biernacki
June 17/18/20, 2013
Copyright © 2013 Agilent Technologies
“New Features for Solving HSD Challenges with ADS 2013”
Outline
Copyright © 2013 Agilent Technologies 2
Why Touchstone 2.0
ADS Implementation
Touchstone 2.0 Format
Notes on differential ports
Notes on mixed-mode n-port parameters
Some hints for using Touchstone data
“New Features for Solving HSD Challenges with ADS 2013”
Historical Note
Copyright © 2013 Agilent Technologies 3
S-parameters have been used for many decades to characterize linear
sub-circuits, passive and active devices, interconnects, EM co-simulation,
etc.
Growing interest in S-parameter representation of linear sub-circuits
among the SI/PI engineers.
PI engineers observed improved accuracy when different reference
impedances were used for power than those for signal ports.
The legacy Touchstone format accommodated only the same reference
impedance for all ports.
“New Features for Solving HSD Challenges with ADS 2013”
The Role of the IBIS Open Forum
Copyright © 2013 Agilent Technologies 4
IBIS Open Forum is a standardization organization that supports I/O
buffer modeling (I/O Buffer Information Specification) with the focus on
signal and power integrity.
http://www.eda-stds.org/ibis/
The IBIS organization took the initiative to standardize on the Agilent’s
Touchstone format.
With Agilent’s permission the official Touchstone File Format Specification
Version 2.0 has been developed, and ratified in 2009.
http://www.eda-stds.org/ibis/touchstone_ver2.0/touchstone_ver2_0.pdf
“New Features for Solving HSD Challenges with ADS 2013”
Notes on Per-Port Reference Impedances
Copyright © 2013 Agilent Technologies 5
ADS has always allowed different per-port reference impedances
– CITI files
– datasets
This included complex reference impedances, useful for power match
In view of several ways to deal with complex impedances, IBIS decided to
it was sufficient to allow real impedances only.
“New Features for Solving HSD Challenges with ADS 2013”
Version 1.0 Format
Copyright © 2013 Agilent Technologies 6
The original Touchstone File Format had never been officially
standardized, though it was a de-facto standard.
A few of the original rules have been slightly relaxed with time, including
– three character file name extension as needed for more than 9-port data (e.g., *.s12p)
– reliance on the file name extension
– limited number of data items per line
The IBIS standardization initiative included also the legacy Touchstone
files. They are now referred to as Version 1.0 files. This has effectively put
an end to somewhat uncontrolled attempts to extend the original format
by various vendors.
“New Features for Solving HSD Challenges with ADS 2013”
A Typical Version 1.0 File
Copyright © 2013 Agilent Technologies 7
! Created Fri Nov 21 11:25:57 2003
# Hz S MA R 50
! freq magS11 angS11 magS21 angS21 magS12 angS12 magS22 angS22
1e+009 0.995383394 167.294765 0.075127918 …
2e+009 0.98389341 153.496417 0.163021787 …
3e+009 0.955822028 137.049238 0.281341042 …
4e+009 0.884013749 115.091936 0.457067209 …
5e+009 0.694146948 81.6998692 0.711192239 …
! 2 Port Noise Data
1e+009 …
3e+009 …
5e+009 …
“New Features for Solving HSD Challenges with ADS 2013”
Example of an Illegal Extension in aLegacy Touchstone File
Copyright © 2013 Agilent Technologies 8
! Four port data with different per-port reference impedances
# Hz S MA R 50 50 1 1
! freq magS11 angS11 magS12 angS12 magS13 angS13 magS14 angS14
! freq magS21 angS21 magS22 angS22 magS23 angS23 magS24 angS24
! freq magS31 angS31 magS32 angS32 magS33 angS33 magS34 angS34
! freq magS41 angS41 magS42 angS42 magS43 angS43 magS44 angS44
1e+009 0.995383394 167.294765 0.075127918 …
We have no plans to support such non-standard extensions.
A file like this can be easily converted to a Version 2.0 file.
“New Features for Solving HSD Challenges with ADS 2013”
Touchstone 2.0 Implementationin ADS 2013.06 Release
Copyright © 2013 Agilent Technologies 9
Import (read)
yes – complete features
all SnP, SnP_Diff and De_Embed components
no – for the DAC component (use SnP directly)
Export (write)
yes – Touchstone 1.0 (as before)
no – Touchstone 2.0 (for now)
SPOutput, Data File Tool, TouchstoneCombiner
“New Features for Solving HSD Challenges with ADS 2013”
Touchstone 2.0 Implementationin ADS 2013.06 Release – cont’d
Copyright © 2013 Agilent Technologies 10
Familiar SnP components
User does not have to identify the file version or act upon it!
“New Features for Solving HSD Challenges with ADS 2013”
Touchstone 2.0 Implementationin ADS 2013.06 Release – cont’d
Copyright © 2013 Agilent Technologies 11
All existing features of the SnP components are preserved:
– interpolation techniques
• linear, cubic
• cubic splines
• a few others
– interpolation domain
• real/imaginary
• magnitude/angle
• dB/angle
– extrapolation options
– passivity checking/enforcement
– causality enforcement
“New Features for Solving HSD Challenges with ADS 2013”
Touchstone 2.0 Distinct Features
Copyright © 2013 Agilent Technologies 12
• different reference impedances allowed for different ports
• mixed-mode n-port parameters
• includes the S, Y or Z matrix types
• format (IBIS style keywords)
• precise rules and specification
“New Features for Solving HSD Challenges with ADS 2013”
Touchstone Version 2.0 vs. Version 1.0Minor Differences
Copyright © 2013 Agilent Technologies 13
Z, Y, G, H matrices and Noise Resistance are no longer normalized.
Two-port data special order (S11, S21, S12, S22) is not required.
It is allowed to specify either the full matrix or the lower/upper half matrix.
“New Features for Solving HSD Challenges with ADS 2013”
Touchstone 2.0 Version Keyword andOption Line
Copyright © 2013 Agilent Technologies 14
[Version] 2.0
• the first keyword in the file
• required in Version 2.0 files
• prohibited in Version 1.0 files
The Option line is the same as in legacy files and it determines the units,
data type, data format and the reference impedance, for example
# GHz S MA R 50
• required in all Touchstone files
“New Features for Solving HSD Challenges with ADS 2013”
Touchstone 2.0 Number of Ports and Number of Frequencies Keywords
Copyright © 2013 Agilent Technologies 15
[Number of Ports] 6
• required in Version 2.0 files
• prohibited in Version 1.0 files
[Number of Frequencies] 501
• required in Version 2.0 files
• prohibited in Version 1.0 files
“New Features for Solving HSD Challenges with ADS 2013”
Handling Different Reference Impedancesin Touchstone 2.0 Files
Copyright © 2013 Agilent Technologies 16
[Reference] 50 50 0.1 0.1 50 50
• optional in Version 2.0 files
• prohibited in Version 1.0 files
• overrides the reference impedance setting in the Option line
The order of the entries must follow the port ordering (the same as the
row/column ordering in the data matrices).
The number of entries must equal the number of ports.
Complex reference impedances are not allowed.
“New Features for Solving HSD Challenges with ADS 2013”
Network Data in Touchstone Files
Copyright © 2013 Agilent Technologies 17
The actual n-port data is similar for both versions, but the
[Network Data]
• keyword is required in Version 2.0 files
• prohibited in Version 1.0 files
There are no limitations regarding the number of data items in a single
line.
“New Features for Solving HSD Challenges with ADS 2013”
Some Other Keywords inTouchstone 2.0 Files
Copyright © 2013 Agilent Technologies 18
[Two-Port Data Order] 12_21
• required in Version 2.0 files for 2-port data, otherwise prohibited
• the order is pre-defined as 21_12 in Version 1.0 files
[Matrix Format] Lower
• optional in Version 2.0 files for specifying Full, Lower, or Upper
• the order is pre-defined as 21_12 in Version 1.0 files
[Number of Noise Frequencies] 151
[Noise Data]
[End]
“New Features for Solving HSD Challenges with ADS 2013”
Example of Version 2.0 File
Copyright © 2013 Agilent Technologies 19
[Version] 2.0
# Hz S MA R 50
[Number of Ports] 2
[Two-Port Data Order] 12_21 ! Required for 2-port data; otherwise
prohibited
[Number of Frequencies] 5
[Reference] 50 50 ! Optional if the same reference
impedance is used
[Matrix Format] Full ! Optional – Full is the default
[Network Data]
! freq magS11 angS11 magS12 angS12 magS21 angS21 magS22 angS22
1e+009 0.995383394 167.294765 0.075127918
[Number of Noise Frequencies] 3
[Noise Data]
1e+009 …
[End]
“New Features for Solving HSD Challenges with ADS 2013”
Extensions in Version 2.0 Files
Copyright © 2013 Agilent Technologies 20
[Version] 2.0
# Hz S MA R 50
...
[Reference] 50 1
[Matrix Format] Lower !or Upper
[Mixed-Mode Order] D2,3 S5 C2,3 C4,1 D4,1
[Begin Information]
Any useful information for the user, but no action by EDA platforms
[End Information]
[End]
“New Features for Solving HSD Challenges with ADS 2013”
Notes on Differential Circuit Ports
Copyright © 2013 Agilent Technologies 21
Vdiff
P2+
I2V2
-
I2
V1
I1
P1+
Icommon
P1-
+
I1
P2-
one differential port consists of two “normal” single-ended ports.
The “-” node is common for the two single-ended ports.
Therefore, differential ports are 3-terminal objects; however, as we prefer to have just one (common) reference terminal for all the ports they may be perceived as 2-terminal objects – beware!
The mixed mode currents and voltages are linear combinations of the respective single-ended currents and voltages.
In Touchstone 2.0 it is required that the reference impedances for the two ports that form one differential port are identical.
“New Features for Solving HSD Challenges with ADS 2013”
Mixed-Mode Quantities
Copyright © 2013 Agilent Technologies 22
common mode voltage
differential mode voltage
common mode current
differential mode current
common mode incident wave
differential mode incident wave
common mode reflected wave
differential mode reflected wave
���,� � ��� � ��/2
���,� � �� ��
���,� � �� � ��
���,� � ��� ��/2
���,� � ����,� � ���,����,�/�2 ���,�)
���,� � ����,� � ���,����,�/�2 ���,�)
���,� � ����,� ���,����,�/�2 ���,�)
���,� � ����,� ���,����,�/�2 ���,�)
“New Features for Solving HSD Challenges with ADS 2013”
Mixed-Mode n-port Parameters inTouchstone Version 2.0 Files
Copyright © 2013 Agilent Technologies 23
Whether the file contains single-ended or mixed-mode n-port data (under
the [Network Data] keyword) is determined by the presence of the
following keyword.
[Mixed-Mode Order] D2,3 S5 C2,3 C4,1 D4,1
• optional in Version 2.0 files; indicates that the mixed-mode data rather than the single-ended data is given
• prohibited in Version 1.0 files
• the order of the entries follows the row/column ordering in the data matrices
• indices correspond to single-ended port ordering, consistent with the port ordering in the SnP symbol in the UI
• D indicates a “differential” quantity, C indicates a “common mode” quantity and S indicates the single-ended quantity for ports that are not a part of any differential port
“New Features for Solving HSD Challenges with ADS 2013”
Interpretation of [Mixed-Mode Order]
Copyright © 2013 Agilent Technologies 24
[Mixed-Mode Order] D2,3 S5 C2,3 C4,1 D4,1
“New Features for Solving HSD Challenges with ADS 2013”
Hints – Using Datasets
Copyright © 2013 Agilent Technologies 25
Parsing may be time consuming – for large number of ports create and
use datasets.
– binary files using ADS internal data structure
– faster to read
– no need for interpretation
– easily viewable in Data Display
Simply run S-Parameter simulation.
“New Features for Solving HSD Challenges with ADS 2013”
Hints – Verify Data Quality
Copyright © 2013 Agilent Technologies 26
View S-Parameter simulation results in Data Display.
Bad data may significantly affect the simulation results!
“New Features for Solving HSD Challenges with ADS 2013”
Hints – Impact of Bad Data
Copyright © 2013 Agilent Technologies 27
Example of what incorrect DC extrapolation may lead to.
“New Features for Solving HSD Challenges with ADS 2013”
Hints – Eliminate Unused Ports
Copyright © 2013 Agilent Technologies 28
Two techniques.
1.
– load unused ports
– run S-Parameter simulation on a subset of original ports
– subsequently use an n-port with fewer ports
– pay attention to the frequency plan and coverage
2.
– use the following unique ADS feature
“New Features for Solving HSD Challenges with ADS 2013”
Hints – Large SnP Reduction
Copyright © 2013 Agilent Technologies 29
OPTIONS
Options
Options1
MaxWarnings=10
GiveAllWarnings=yes
I_AbsTol=
I_RelTol=
V_AbsTol=
V_RelTol=
Tnom=25
Temp=25
“New Features for Solving HSD Challenges with ADS 2013”
Summary
Copyright © 2013 Agilent Technologies 30
• ADS has always allowed the use of different per-port reference
impedances for S-parameter data, yet the Touchstone files required
the same value for all ports.
• Touchstone Version 2.0 relaxes those limitations and unambiguously
defines the allowable format.
• Touchstone 2.0 provides the means to handle mixed-mode n-port data.
• In ADS 2013.06 the new format is adapted in a completely transparent
fashion. The user can use the new files exactly the same way the old
files were used.