A Behavioral and Temperature MeasurementsBased Modeling of an Operational Amplifier
Using VHDL-AMS
17th IEEE International Conference on Electronics, Systems and Systems
Athens-13th December 2010
Sahbi Baccar12, Timothée Lévi1, Dominique Dallet1,
Vladimir Shitikov2, François Barbara2
1 IMS Laboratory- Université Bordeaux 1, France
2 Schlumberger Riboud Product Center (SRPC), Clamart, France
1
Outlines
Outline
Motivation and Context
Op-amp Description and Characterization
Development of HT Op-amp Models
Conclusion and Prospects
2
Outlines
Motivation and Context
HTE (high temperature electronics),
a recent growing market with specific circuit requirements
Market
Temperature (°C)
Down-hole Instruments
150-300
Turbine Engine
200-300
Internal Combustion
Engine
>150
Validity of SPICE industrial components models in HT?
Reviewing transistor
factors in HT
??
3
Outlines
Motivation and Context
SPICE: among first simulator for ICs
Working conditions effect modeling in
SPICE macro-model?
VHDL-AMS language: modern tool for
AMS and multi-domain modeling and
simulating
huge time of computation: 23.5 hours
for simulating a feedback of a
PLL loop!!
Emergence of:
- new simulators
- new modeling approaches
HTE Behavioral Modeling
4
Outlines
Outline
Motivation and Context
Op-amp Description and Characterization
Development of HT Op-amp Models
Conclusion and Prospects
5
Op-amp Description and Characterization
High Temperature Front End
Amplifier
Anaog Filter
6
Outlines
Op-amp Description and Characterization
Op-amp
Stage 1
Stage 2
Input Stage
Gain Stage
Vos , Ios, PSRR,
CMRR, Rin,Cin, Zcm…
Aol, GBPW, fol,
SR-, SR+..
Stage 3
Output Stage
Voutlimp, Voutlimn,
Rout…
performance parameters
7
Outlines
Outline
Motivation and Context
Op-amp Description and Characterization
Development of HT Op-amp Models
Conclusion and Prospects
8
Outlines
Development of HT op-amp Models
Parameter Measurement(T1,
T2,..)
Fitting by Mathematical
Functions
Error
Evaluation
HT Behavioral Model
Development
Simulation
9
Outlines
Development of HT op-amp Models
Input Stage Model
Ib(T)/2
2Zcm
inp+
Vcm+(T) Vs(T)
Vos(T) CMRR(T) PSRR+(T)
Ios(T)
inp-
Rin
Cin
Vcm-(T)
Vs(T)
CMRR(T) PSRR-(T)
2Zcm
inpo1
inpo2
Ib(T)/2
10
Outlines
Development of HT op-amp Models
Middle Stage Model
K=Aol(T)
fol(T).Aol(T)=GBW(T)
wol(T)=2 .fol(T)
SR+(T), SR-(T),
Iomax(T),gm
inp+
Vine
AOL (0)
jf
1
fOL
inp_po1
Ig
Ig=Vine.gm
AOL ( f ) 
Vg
LTF 
K
1 s
Vop
inp_po2
inpSlew rate,
Transconductance
First Order LPF
sub-stage 1
sub-stage 2
 1 dVop

Vg  1 AOL  
.
 Vop 
 OL dt

11
Outlines
Development of HT op-amp Models
Output Stage Model
inp_out
Voutlimp(T)
Rout
output
Iout
Vout
inn_out
Voutlimn(T)
Voltage limiter sub-stage
Impedance Stage
12
Outlines
Simulation Results and Discussions
Voltage Offset and Saturation Voltage
Voutlimp (T1=25°C)
Voutlimp (T2=150°C)
T=25°C
T=150°C
Vos (T1=25°C)
Vos (T2=150°C)
Voutlimn (T1=25°C)
Voutlimn (T2=150°C)
Op Amp Developed
Model
Rs=1K
Rl=1K
Vin
Test-bench circuit
13
Outlines
Simulation Results and Discussions
Voltage Offset and Saturation Voltage
 15V
T=25°C
T=150°C
Input Voltage
Rf=10K
Op Amp Developed
Model
Rs=1K
Rl=1K
Vin=1V
Test-bench circuit
14
Outlines
Simulation Results and Discussions
Frequency Response and Open-Loop Gain
Temperature Increases
T=150°C
T=25°C
100dB  Aol (dB, T1  25C )
100dB  Aol (dB, T2  150C )
Op Amp Developed
Model
Rs=1K
Rl=1K
Vin
Test-bench circuit
15
Outlines
Parameter Extraction and Model Validation
Title: Comparison of measured and simulated
voltage offset for different temperatures
16
Outlines
Outlines
Motivation and Context
Op-amp Description and Characterization
Development of HT Op-amp Models
Conclusion and Prospects
17
Outlines
Conclusion and Prospects
A novel behavioral op-amp model in HT
Simulation of major op-amp performance parameters
Modeling methodology based on measurement of
performance parameters
Confirmation of VHDL-AMS abilities as a useful and
modern modeling language
A first step to model the whole analog-front end of a data
acquisition system: Op-amp, Filter and ADC
18
Outlines
References
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VHDL,” IEE Proc. Circuits, Devices and Systems, vol. 143, 1996, pp. 380.
[2] F. Pecheux, C. Lallement and A. Vachoux, “VHDL-AMS and Verilog- AMS as alternative
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automotive environment: high-temperature electronics,” Electronics Packaging Manufacturing,
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[5] S. Baccar, S.M. Qaisar, D. Dallet, T. Levi, V. Shitikov and F. Barbara, “Analog to digital
converters for high temperature applications: The modeling approach issue,” Instrumentation
and Measurement Technology Conf. (I2MTC) IEEE, pp. 550-554, Austin, 3-6 May 2010
[6] G.B. Clayton et S. Winder, Operational Amplifiers, Fifth Edition, Newnes, 2003.
[7] P.J. Ashenden, G.D. Peterson and D.A. Teegarden, The System Designer's Guide to VHDLAMS: Analog, Mixed-Signal, and Mixed- Technology Modeling, Morgan Kaufmann, 2002.
[8] H. Qin, F. Wang, “ Modeling of Operational Amplifier based on VHDLAMS”, in Proc. IEEE
International Conference on Electronics Circuits and Systems 2006, pp. 894-897, Nice, 10-13
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December 2010
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