1. Algorithms for Synthesis and Average
Distribution of Variable Sized MOS Components
for Efficient Analog VLSI Devices
Mahmudul Faisal Al Ameen
Md. Didar Islam
Syed Akhter Hossain
Mahmudul Faisal Al Ameen
Md. Didar Islam
Syed Akhter Hossain
Dept. of Computer Science & Engineering
East West University
Power IC Ltd.

2. Background
Causes of Mismatch: Random Fluctuation
Peripheral Fluctuation Areal FluctuationNo Fluctuation
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3. Background
Causes of Mismatch : Process Biases
Intended Ratio:
2/4 = 0.5
Actual Ratio:
(2+0.1)/(4+0.1) = 0.512
The Systemic Mismatch:
(0.512-0.5)*100/0.5 = 2.4%
.05 4.0 2.0.05
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4. Background
Variation in Stress causes Change of Resistivity of Silicon (piezoresistive)
Ideal: Equal Stress Actual: Stress Variation
Causes of Mismatch: Stress Gradients
Stress Gradients:
Isobaric contour plot
Isobar
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5. Background
• Diffusion Interaction
• Pattern Shif
• Temperature Gradients and Thermoelectrics
• Electrostatic Interactions
Causes of Mismatch: Others
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6. Background
4.0 4.0 4.0 4.0 4.0 4.0
A A A AB B
4.0 4.0 4.0 4.0 4.0 4.0
A B B AA A
Minimizing Mismatch: Interdigitation
Interdigitation is better
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7. Problem Overview
Matching Pattern: Cross Coupling
A B A B A B A B
B A B A B A B A
A B C A B C A B C
C A B C A B C A B
B C A B C A B C A
A B C A B C A B C
Matching Pattern: Common Centroid
C B C
B A B
C B C
B A A
A A B
A B A
Matching Pattern: Average Distribution
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8. Problem Overview
Matching Pattern: Interdizitatized Common Centroid
A B B A A B B A
B A A B B A A B
A B B A A B B A
B A A B B A A B
A B B A A B B A
A B B A A B B A
B A A B B A A B
B A A B B A A B
A B B A A B B A
A B A A B A A B A
B A B B A B B A B
B A B B A B B A B
A B A A B A A B A
A B C C B A A B C
C B A A B C C B A
C B A A B C C B A
A B C C B A A B C
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9. Solution
• Conventional Method
– Manual Matching Component
• Automated Technique is still Absent
• Main Objective of the Work is to Automate the Manual
Process
– Faster Matching
– Better Perfection
– Improved Optimization
– Better Diversity in Design
15
Techniques
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10. Solution
Device Template Scripting: Syntax & Semantics
Key Description
TEMPLATE <HEADER> ‘n’ <DATA>
HEADER ‘//’ [File Version] ‘,’ [Creation Date]
DATA {<LINE> ‘n’}+
Symantec: A set of text line
LINE {<FILE>|<VARIABLE>|<RECT DATA>|<INPUT>}
RECT DATA [Rectangle name] ‘:’ <PROPERTY> ‘=’ <VALUE>
Symantec: set value to a property of a Rectangle
PROPERTY [‘L’ | ‘R’ | ‘T’ | ‘B’ | ‘N’ | ‘W’ | ‘S’]
Symantec: indicates left, right, top, bottom, GDSII layer, etc.
VALUE [Constant | <EXPRESSION>]
Symantec: a double value or an iteration for a set of objects
INPUT <VARIABLE> ‘= INPUT’
Symantec: get value from user for length and width
VARIABLE {‘A’ – ‘Z’ | ‘a’ – ‘z’ | ‘0’ – ‘9’ | ‘ ’}+
Symantec: A series of alphanumeric characters including space
FILE [Rectangle name] ‘=’ ‘”’ [File path] ‘”’ {‘,’ Constant}*
Symantec: Parsing of the file before going to next line and include all
objects of the file in the current file. Specially necessary for include
DRC rule set for an specific technology
EXPRESSION [<VARIABLE > <OP> < EXPRESSION > | <VARIABLE > ]
Symantec: a variable or set of variables with operators
OP [ ‘+’ | ‘-’ ]
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11. Solution
NMOS: Cross section
NMOS: Top view
Poly silicon (7)
Contact (11)
N-Implant (9)
Oxide (1)
Top
Left
Vertical
Series
Lengt
hWidt
h
Single
Defaul
t
Device Template Scripting: Description of Device
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12. Solution
Device Template Scripting: Example
FILE = "NMOS_Rules.drs"
L = INPUT
W = INPUT
POLYa.N = 7
ODa.N = 1
NIMPa.N = 9
CONTa.N = 11
CONTb.N = 11
POLYa.L = 0
POLYa.R = POLYa.L + L
ODa.T = 0
ODa.B = ODa.T + W
POLYa.T = ODa.T - POLY_OUT_OD
POLYa.B = ODa.B + POLY_OUT_OD
CONTa.R = POLYa.L - CONT_OUT_POLY
CONTa.L = CONTa.R - CONT_WIDTH
CONTa.T = ODa.T + CONT_IN_OD
CONTa.B = ODa.B - CONT_IN_OD
CONTb.L = POLYa.R + CONT_OUT_POLY
CONTb.R = CONTb.L + CONT_WIDTH
CONTb.T = CONTa.T
CONTb.B = CONTa.B
ODa.L = CONTa.L - CONT_IN_OD
CONT_OUT_POLY = 0.4
CONT_WIDTH = 0.5
CONT_IN_OD = 0.3
OD_IN_NIMP = 0.4
CONT_SPACE = 0.5
NMOS_Rules.drs
NMOS.dts
• DRS: Device Rules Scripting
• DTS is a device description language
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13. Solution
Matching Algorithms: Interdigitation Common Centroid
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14. Solution
Matching Algorithms: Cross Coupling
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15. Solution
Matching Algorithms: Common Centroid Symmetry
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16. Solution
Matching Algorithms: Single Symmetry Row
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17. Solution
F~CompSynth: The Fast & Dynamic Component Synthesizer
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18. Solution
Start
Add From
DTS File
Matching
Wizard
Manual
Draw
Editing / Resizing
Export to GDSII File
End
F~CompSynth: The Work Flow
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19. Solution
F~CompSynth: Matching Wizard
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20. Experimental Result
• Cost of Algorithms
– Time Complexity: O(N)
• N is total number of fingers to be placed
– Memory Complexity O(2N)
• Variable Sized Component Synthesis
• Component Matching
• Mathematical Prediction Testing
• Placement of the Fingers of the Components
Experiment Category
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21. Experimental Result
Variable Sized Component Synthesis
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22. Experimental Result
Component Matching
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23. Experimental Result
Placement of the Fingers
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24. Limitations & Future Works
• Mathematical Prediction Tuning
– Defining three ‘W’s, the Weights
• Learning DTS
– Visual DTS Editor
• Special Purpose Tool
– Auto Routing
– General Editing
– Simulation
• Finding the Best Solution
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25. THANK YOU
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