IMS2011 in Baltimore: A Perfect Match
IMS 2011
Stability Analysis of Microwave Circuits S. Dellier, PhD
IMS2011 in Baltimore: A Perfect Match
AGENDA
• • • •
Introduction Existing methods STAN tool and application examples Q&A
www.amcad-engineering.com
IMS2011 in Baltimore: A Perfect Match
INTRODUCTION
• Stability analysis is a critical step of RF design flow • Classical methods are either not complete or too complex…
• Stability analysis need to be efficient (especially in large signal)
- Rigorous - Fast - User-friendly - Compatible with commercial CAD softwares www.amcad-engineering.com
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IMS2011 in Baltimore: A Perfect Match
EXISTING METHODS Linear analysis “small signal”
-
K factor Normalized Determinant Function (NDF) Stability envelope Pole-zero identification
• Non-linear analysis “large signal” -
Nyquist criterion NDF Bolcato, Di Paolo & Leuzzi, Mochizuki, … Pole-zero identification
www.amcad-engineering.com
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IMS2011 in Baltimore: A Perfect Match
EXISTING METHODS Linear analysis • Widely used: K factor (also µ and µ‟ now) - K>1 & |∆| Help to find the suitable • •
stabilization strategy Parametric Analysis implemented Monte-Carlo Analysis
www.amcad-engineering.com
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IMS2011 in Baltimore: A Perfect Match
STAN TOOL Integration in CAD Environment GENERATOR
Perturbation introduction node in
Var Eqn
VAR VAR1 fin=9.65 GHz Pin=12
Input power
ampli X1
Meas Eqn
Term Term1 Num=1 Z=50 Ohm
I_Probe I_sond
HARMONIC BALANCE HarmonicBalance HB1 Freq[1]=fin Order[1]=10 SS_MixerMode=yes SS_Start=f1 SS_Stop=f2 UseAllSS_Freqs=yes MergeSS_Freqs=yes
LOAD
out
P_1Tone cmp1198 Num=1 Z=50 Ohm P=polar(dbmtow(Pin),0) Freq=fin
Input frequency
CIRCUIT
v_sond Var Eqn
I_1Tone SRC1 I_LSB=polar(0.0001,0)
VAR VAR3 f1=fstart+fin+0.0001e9 f2=fend+fin
MeasEqn meas1 Zsond=mix(v_sond,{-1,1})/mix(I_sond.i,{-1,1}) frequency=ssfreq-fin
Var Eqn
VAR VAR2 fstart=4.325 GHz fend=5.325 GHz n_point=101
Start sweep frequency Stop sweep frequency Number of frequency points
Nonlinear stability analysis template
EDA Tool Templates for ADS, MWO… AC simulation for linear HB simulation for non-linear www.amcad-engineering.com
STAN tool integrated in IVCAD software User-friendly GUIs Slide 10
IMS2011 in Baltimore: A Perfect Match
STAN TOOL Automatic mode • The order of Hˆ ( s) is a priori unknown • Automatic algorithm for pole-zero identification in the context of stability analysis is integrated in STAN tool
n
H ( s)
(s z ) i 1 p
i
(s ) j 1
j
Mag(H0) (dB)
H ( j )
Phase(H0) (º)
H ( s)
Freq (GHz)
• This routine eases the use of pole-zero identification for multivariable stability analysis www.amcad-engineering.com Slide 11
IMS2011 in Baltimore: A Perfect Match
STAN TOOL Multi-nodes Node „n‟
v out
( i in ,fs )
A
B FET2
A- No oscillation detected in the common node
FET1 FET3 FET5
FET4 FET6
BOscillation detected in the transistor node
Odd mode (parametric frequency division) will determine the stabilization strategy www.amcad-engineering.com
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IMS2011 in Baltimore: A Perfect Match
STAN TOOL Multi-parameters • Analysis with swept parameter(s) • Verification for various conditions (Pin, Zload, …) • Optimization of stabilization networks
RG
PIN
f0, v out
( i in ,fs )
www.amcad-engineering.com
Zload Rstab
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IMS2011 in Baltimore: A Perfect Match
STAN TOOL Multi-parameters
• Application requires absence of spurious for a wide range of operating conditions
polar(inestables_HB1..mod,inestables_HB1..phase) S(1,1)
Example: 3-stage LDMOS DPA for SDR applications
• Multivariable large-signal stability analysis versus input frequency, input power and real Unstable and imaginary parts of load loads termination ZL. Frequency division (fin/2) detected
A. Anakabe et al. “Automatic Pole-Zero Identification for Multivariable Large-Signal Stability Analysis of RF and Microwave Circuits”, 2010 European Microwaev Conference, Paris, September 2010.
Stable loads freq (1.000GHz to 1.000GHz)
to 0.990)regions in Stablemod and(0.693 unstable the L plane for fin=500 MHz and Pin=17.1 dBm
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IMS2011 in Baltimore: A Perfect Match
STAN TOOL Monte-Carlo Example: L-Band medium power FET amplifier • Low frequency instability related to the input bias network
• Stabilization by the inclusion of a gate-bias resistor RSTAB • Monte Carlo sensitivity analysis for different RSTAB (5 % dispersion in all circuit parameters) 40
20
RSTAB = 44
0 -20 -40
-0.2 -0.1 0 Real Axis (MHz)
0.1
Imaginary Axis (MHz)
Imaginary Axis (MHz)
40
20
RSTAB = 70
0 -20 -40
-0.2 -0.1 0 Real Axis (MHz)
0.1
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IMS2011 in Baltimore: A Perfect Match
Q&A
Contact Stéphane Dellier E-mail:
[email protected] Phone: +33 555 040 531 www.amcad-engineering.com