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Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical Engineering und Computer Science University of Hannover Germany

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Page 1: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Thermal Noise in Nonlinear Devices and Circuits

Wolfgang Mathis and Jan Bremer

Institute of Theoretical Electrical Engineering (TET)

Faculty of Electrical Engineering und Computer ScienceUniversity of Hannover

Germany

Page 2: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Content

1. Deterministic Circuit Descriptions

2. Stochastic Circuit Descriptions

3. Mesoscopic Approaches

4. Steps in Noise Analysis in Design Automation

5. Bifurcation in Deterministic Circuits

6. Bifurcation in Noisy Circuits and Systems

7. Examples

8. Conclusions

Page 3: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

1. Deterministic Circuit Descriptions

2. Stochastic Circuit Descriptions

3. Mesoscopic Approaches

4. Steps in Noise Analysis in Design Automation

5. Bifurcation in Deterministic Circuits

6. Bifurcation in Noisy Circuits and Systems

7. Examples

8. Noise Analysis of Phase Locked Loops (PLL)

9. Conclusions

Page 4: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

1. Deterministic Circuit Descriptions

A. Meissner, 1913

Bob Pease, National Semiconductors

Page 5: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Real Circuit

Modelling

Circuit-Model

Models for Electronic Circuits

Partitioning b

b

Electrical and Electronic Circuits: The Ohm-Kirchhoff-Approach

Page 6: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

b

b

Electrical Circuits are defined in

1 1,..., ; ,.( , ..) : ,( )bb

bbi ii uu u Z := R R

Space of all currents and Voltages

O

( , ) ( , ) 0, : ;b b b b kR Ri u F i u F k b O := R R R R R

Description of resistive NW elements:

Ohm Space

K

Description of connections:

( , ) 0 0, ( , ) exaktb bi u Ai B u A B K := R R

Kirchhoff Space

S :=K OState-Space

of Electrical Circuits

Page 7: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

S

0 ( , )g x y

( , )dx

f x ydt

DAE System:

Differential-

algebraic System

DAE Systems consist of manye.g. (100-) thousand Equations

numerical solutions necessary!

Dynamics electronic Circuits (Networks)

Special Cases: State-Space Equations (ODEs) ( )dx

F xdt

Capacitors Inductors

Page 8: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

D e t e r m i n i s t i c D e s c r i p t i o n : O D E s

d x

d tF xi

i ( )

w h e r e

: ( 1 , , )n niF i n a n d x R R R

00 )(, xtx

00 )( xtx

Are initial value problems suitable for studying the qualitative behavior?

Deterministic Description: ODEs

Initial value problems suitablefor studying

the quantitative behavior!

Page 9: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Reformulation of the deterministic Dynamics

Qualitative behavior: Considering a whole family of systems

IRStxxxFdt

dxi

i )(),( 00

( )p x

where

generalized Liouville equation

( , ) ( ( ))tp x t p xP

1

ni

i i

p Fp

t x

Dynamics of a Density Function p (Frobenius-Perron-Operator ):tP

Set of Initial Values

Density Function p

Page 10: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Thermal Noise in linear and nonlinear electrical Circuitswith noise sources

Noise Model

2. Stochastic Circuit Descriptions

Page 11: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Microscopic

Approach

DeviceModelling

Circuits

Network Thermodynamics

Deterministic Approach

Circuit Equations

GeneralizedLiouville Equation

Generalization: (Non)linear Circuits including noise

DeterministicCircuits

MacroscopicApproach

NoisyCircuits

MesoscopicApproaches

Page 12: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Microscopic Approach: Statistical Physics

drift movemente.g.Recombination-

Generation-Noise

Multi-Body System (approx. 1023 particles)

C. Jungemann (see his talk this morning)

Page 13: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Noisesources

as inputs

D y n a m ic s o f t h e D e n s i t y F u n c t io n p : ( m a th e m a t ic a l e q u iv a le n t to S O D E )

2 2

1 , 1

( ) 1 ( )

2

n ni

i i ji i j

p Fp p

t x x x

F o k k e r - P la n c k e q u a t io n

3. Mesoscopic Approaches

Remarks: Fokker-Planck equation as modified generalized Liouville equation

Stochastic ODE (SODE):

( ) ( )ii i

dxF x x

dt

: ( 1, , ) andn niF i n x R R R

white noise and ( ) coupling coefficienti x

The Langevin Approach:

Page 14: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Deterministic Circuit

(without inputs)

Langevin’s Approach:

Noisy input output

Applications: e.g in Communication Systems

Transmission of noisy signals through a deterministic channel

(Mathematics: Transformation of stochastic processes)

Page 15: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

iij j

ji

dxA x

dt

Physical Interpretation of SODE (Langevin, 1908)

a) Linear Case

iij j

j

dxA x

dt

( white noise, konst.)i

Average:ii

ij j ij jj

ij

i

d xdxA x A x

dt dt

=0

stoch.

Conclusion: First Moment satisfies a determinstic differential equation

Page 16: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

( )ii i

dxF x

dt

b) Nonlinear Case ( white noise, konst.)i

( )ii

dxF x

dt stoch.

Average: ( ) ( )iij i j i

d xdxF x F x

dt dt

=0

( )jF x Coupling ofMoments

(van Kampen, 1961)

Compare: In nonlinear systems

Deterministic nonlinear System:

Energetic Coupling of Frequencies

Sinusoidal input

Coupling of

Moments

of the probility density

Stochastic nonlinear System:

Page 17: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Alternative: Analyzing nonlinear circuits including noise

Numerous papers

Methods:

• Calculation of desired spectra

• Numerical Methods in Stochastic Differential Equations

• Geometric Analysis of Stochastic Differential Equations

Extraction of Noise Sources (then using the Langevin approach)

Page 18: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

1. Motivation 5

Stochastic Equation

dw)II2(qdt1kT

quexpIduC ss

Average: (first moment)

2

2

s ukT

q

2

1u

kT

qIu

dt

dC

Thermodynamic Equilibrium:

Fluctuations-Voltage-Converter

However: Brillouin‘s Paradoxon of nonlinear electrical Circuits

Contradiction against the second law of thermodynamics

(white noise sources in device models are forbidden: …., Weiss, Mathis, Coram, Wyatt (MIT))

PN-Diode

White noise

:

„A diode can rectifyits own noise“

White noise

Page 19: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Electrical current is related to noisy electron transport

internal noise (cannot switched off)

in nonlinear systems (electrical circuits) Drift Movement

phys.

No systematic extraction of deterministic equations

The entire behavior has to be described as a stochastic process

Assumption: description as a Markov process

Nonlinear Electronic Circuits

Mesoscopic Approach based on statistical thermodynamics

Page 20: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

“First Principle” Mesoscopic Approach for Circuits with Internal Noise

Starting Point: Markovian Stochastic Processes are defined by the Chapman-Kolmogorov Equation (Integral equation for the transition probability density)

),( tx

Types of Markov Processes

time domain probability density domain

Stochastic differential Equation (SODE)

Fokker-Planck equation

mathematical equivalent!

more general partial differentialequations for the

probability density domain

General solutions of the Chapman-Kolmogorov equation by the Kramers-Moyal series

Page 21: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Derivation of the Kramers-Moyal Coefficients for nonlinear systems by Nonlinear Nonequilibrium Statistical Thermodynamics (Stratonovich):

„Thermal noise“:

In thermodynamical equilibrium

( )

the equilibrium density function is known:

However: Restricted to reciprocal circuits (no transistors!)

„Irreversible Statistical Thermodynamics of Circuits“

Weiss; Mathis (1995-2001), Dissertation (Weiss) 1999

kT

W

eq

X

ep

(stable)

Perturbation analysis for calculating coefficients

Page 22: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Kramers-Moyal Equation

)t,X(p)X(KXX!m

)1(

t

)t,X(pm1

m1 m11m

mm

?

Circuit Equations )kT(o)X(KXdt

d

Thermodynamic Equilibrium )kT/Wexp()X(p Xeq

Detailed Balance (Reciprocity)

Nonlinear „distributed“ Generalization

of the Nyquist’s Formula

Statistical Thermodynamics of Thermal Noise in Nonlinear Circuit Theory

Using Stratonovich‘s Approach: Basic is the Markov Assumption

determination

Page 23: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

3.1 Anwendung: Vollständige nichtlineare Netzwerke

Network Equations

U

)U,I(M

dt

dU)U(C

I

)U,I(M

dt

dI)I(L

- Reciprocal

- DAE Description (Index 1)

Mixed Potential M: Dissipation

M(I,U) = F(I) - G(U) + (I,U)

Complete Reciprocal Circuits: Brayton-Moser Description

Nonlinear Circuits (Weiss und Mathis (1995-1999))

Starting Point:

Page 24: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Y)0(X ,

F o k k e r -P la n c k E q u a t io n : „ D is t r ib u te d N o is e “

)U,I(P)U,I(

t

)U,I(p1

21 1

21

L

)0(F ,

21

2

1

II 21

2111

1

IL

U

12

2111

1

UC

I

1

21

C

)0(G ,

2

1

UU

S ig n a l

21

kT21

21

LL

)0(F ,

21211

kTII

2

21

21

CC

)0(G ,

21UU

2

)U,I(p N o is e

S D E „D if fe re n t ia l“ N y q u is t F o rm u la

,dU

)0(dIkT2S I dI

)0(dUkT2S U

N o is e S o u r c e

Linear Approximation: , (0)X Y

Page 25: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

, ,(0) 1/ 2 (0)X Y Y Y Quadratic Approximation:Quadratische Approximation:

YY)0(2/1Y)0(X ,,

3. Anwendung auf Schaltungen und Bauelemente 13

Kramers-Moyal Equation: „Distributed Noise“

)U,I(t

)U,I(p1

321 1

321

L

)0(F

2

1 ,

1I

321 1

321

32 C

)0(GII ,

1U

32UU

+ kT

21 21

221

LL

)0(F,

1I

+ kT

21 21

221

CC

)0(G,

1U

321 21

321

LL

)0(FkT3

,

21II

2

321 21

321

3 CC

)0(GkTI ,

21UU

2

3U

321 3121

321

LLL

)0(F)kT(2

,2

1 2 3

3

I I I

)t,U(p

there is no equivalent Noise Source Model

3

22not of

Fokker-Planck type

Page 26: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Cubic Approximation: , , ,

1 1(0) (0) (0)

2 6X Y Y Y Y Y Y

)U,I(P)U,I()U,I(

t

)U,I(p21

2

1321 31

3321

432

14321 4321 1

4321

432

11

4321 IILL

)0(FkT3UUU

UC

)0(GIII

IL

)0(F

6

1 ,,,

4321 21

2

1321 31

3321

LL

kT

12

1U

UCC

)0(GkT3 ,

4321 ,c

4

43

214321 L

kTII

II)0(F2

2

,

4321 21CC

kT

12

143,21

c

4

43

21

3321 C

kTUU

UU)0(G2

2

,

)0(F4LLL

)kT(4321

4321 321

,

2

413242314321 ,,, ccc

44

4

321IL2

kTI

III

3

)0(G4CCC

)kT(3321

4321 321

,

2

413242314321 ,,, ccc )U,I(p

UC2

kTU

UUU44

4

321

3

R a u s c h e n t h e r m o d y n a m i s c h n i c h t v o l l s t ä n d i g b e s t i m m b a rNoise cannot be determined thermodynamical!

Page 27: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Our Approach of Noise Spectra Calculations

StratonovichMachine

Current-VoltageRelation

Circuit Topology

PhysicalAssumptions

Correct NoiseSpectra

(if the physicalassumptions valid)

Note: Assumptions are not satisfied if non-thermal effects are included (hot electron effects)

Page 28: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

The “Thermodynamic Window”of a Circuit

Currents and Voltages

Microscopic Behavior

Page 29: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Stochastic Diff.Equ. ( Noise Source )

duC )u(K dt IS dw

Signal Noise

Fokker-Planck Equation ( distributed Noise )

t

)t,U(pC

)U(KU

21

)t,U(p 2I

2

2

C

S

U

)t,U(p

Network Equation K(U) = - U / R

Thermodynamic Equilibrium )kT/Wexp()U(p Ceq

Linear RC Networks: Classical Result

Nyquist‘s Formular (linear approximation)

)/1(2 RGkTGSI

our approach

equivalent SODE

Dissipation Fluctuation

Page 30: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

3 . 2 N i c h t l i n e a r e s R C N e t z w e r k : L i n e a r - q u a d r a t i s c h e N ä h e r u n g

N e t w o r k O D E 22

2

UdU

)0(gd

2

1U

dU

)0(dg

dt

dUC

S O D E dwudu

)0(gd

2

1

du

)0(dgkT2dt

C

kTu

du

)0(gd

2

1u

du

)0(dgduC 2

22

2

2

C/kTu 2 t h a t i s S h o r t C i r c u i t

G e n e r a l i z e d N y q u i s t F o r m u l a

U

dU

)0(gd

2

1

dU

)0(dgkT2S

2

2

I

Some Results: Nonlinear RC Network (Linear-quadratic Approximation)

our approach(equivalent SODE)

Page 31: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

22

T

s

T

s

Ts U

U

I

2

1U

U

I1

U

UexpI)U(g

U

U

I

2

1

U

IkT2S 2

T

s

T

sI )U(IqIq2 s )U(O 2

Results about Thermal +Noise in Semiconductor Devices (Weiss, Mathis: IEEE Electron Devices Letters 1999)

1. Schottky Diode

Shot Noise!

Note: Shot noise has a thermal background (see Schottky (1918))

our approach

Page 32: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

MOSFET:

IS

DStGS U

2

1UUkT2

tGS

DS

2tGS

2DS

tGS

DS

tGStherm,I

UU

U

2

11

UU

U

3

1

UU

U1

UUkT2S

DStGS U

2

1UUkT2 2

DSUO

2. MOSFET

2( )DSO UthermIS

known from microscopic analysis (see textbooks):our approach

2DSDStGSD U

2

1UUUI

known from

(simple model)

Page 33: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

JFET:

IS

0GSdiff

DS

0

GSdiff0

UUU4

U

U

UU1gkT2

,yx

3

2yx

yx2

1yx

3

4yx

gkT2S2/32/3

222/32/3

0therm,I

0

GSdiff

0

DSGSdiff

U

UUy,

U

UUUx

therm,IS

0GSdiff

DS

0

GSdiff0

UUU4

U

U

UU1gkT2 )U(O 2

DS

3. JFET

2( )DSO UthermIS

known from microscopic analysis (e.g. van der Ziel (1962):

2/1

0

2/3GSdiff

2/3DSGSdiff

DS0DU

UUUUU

3

2UgI

our approach

Page 34: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

4. Steps of Noise Analysis in Design Automation

• First Generation: LTI-Noise Models Linear Noise Analysis based on Schottky-Johnson-Nyquist (Rohrer, Meyer, Nagel: 1971 - …)

Small-signal noise models do not work if e.g. bias changes occur,oscillators, more general nonlinear circuits

Idea: „Linearization with respect to an operational point (constant solution)“

State Space

Page 35: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

• Second Generation: LPTV Models Variational Linear Noise Analysis of Periodical Systems (Hull, Meyer (1993), Hajimiri, Lee (1998))

Useful for periodic driven systems, however heuristic assumptionsand concept will be needed for oscillators (Leeson‘s formula)

Idea: „Linearization with respect to a periodic solution“

State Space

Page 36: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

• Third Generation: SDAE Models Noise Analysis by Stochastic Differential Algebraic Equations (Kärtner (1990), Demir, Roychowdhury (2000))

0 ( , )g x y

( , )dx

f x ydt

DAE System:

Differential-

algebraic System

+ Noise (stochastic processes)

Systematic Results in Phase Jitter of Oscillators as well asother nonlinear systems (e.g. PLL),however the onset of oscillations cannot described

)()()()( txfxgdt

dxxB

Page 37: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Given: , Cgs, Cds, RL, y22; Choice: CG, CL (influence of Cgs and Cds „small“)

fosz

L

Cgs//CG Cds//CL

RLgm

Linearization?

What is happened if the circuit is non-hyperbolic?

x

x

x

CI0 2 4 6 8 10 12 14 16 18 20

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

The dynamical behavior of state space equations is related to the dynamics of the „linearized“ equationsin hyperbolic cases.

Theorem of Hartman-Grobman:

FET Colpitts Oscillator

5. Bifurcation in Deterministic Circuits

Non-reciprocal

Barkhausen or Nyquist Criteria

Page 38: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

In certain cases Limit Cycles can be observed

damping term

Example: Sinusoidal Oscillators

( ) x x x x x 2 2 1 0

Obvious solution: x t t or x t t( ) cos ( ( ) sin )

positive

State space interpretation:

x

x

Type of damping

2 2( 1) 0x x

Periodic Solution

negative

Page 39: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Idea: (Poincaré; Mandelstam, Papalexi - 1931)

Embedding of an oscillator (equation) into a parametrized family of oscillator (equations)

( ) x x x x x 2 2 0embedding

with

( ) x x x x x 2 2 1 0

Example: Van der Pol equation

Analysis of Systems with Limit Cycles

Page 40: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Cut

planeCut

plane

BifurcationPoint

Andronov-Hopf Bifurcation

Stable equilibriumpoint

Limit Cycle

State Space

x

x

Page 41: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Poincaré-Andronov-Hopf Theorem (1934,1944)

( , ), : n nx f x f R R RLet

with f ( , )0 0 for all in a neighborhood of 0. If

• the Jacobi matrix includes a pair of

imaginary eigenvalues • the other eigenvalues have a negative real part •

D fx ( , )0 0 1 2, j

d

d 1 0 0( )

• the equilibrium point for asymptotic stable 0

Then there exist

• an asymptotic stable equilibrium point for • a stable limit cycle for

( , ) 1 0( , )0 2

Page 42: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Transient Behavior of a Sinusoidal Oscillator(Center Manifold Mc)

Page 43: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Concept for Analysis of Practical Oscillators

• Transformation of the linear part: Jordan Normal Form

• Transformation of the Equations: Center Manifold

• Transformation of the reduced Equations: Poincaré-Normal Form

• Averaging

( , ), : n nx f x f IR IR IR

Symbolic Analysis(MATHEMATICA, MAPLE)

Page 44: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

6. Bifurcation in Noisy Circuits and Systems

Different Concepts:

I) The physical (phenomenological) approach (e.g. van Kampen)

Behavior of P.D.F. p neara stable equilibrium point

initialP.D.F.

initialP.D.F.

Behavior of P.D.F. p neara unstable equilibrium point?

Special Case: Dynamics in a Potential U(x)

U(x) U(x)

?

Page 45: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Dynamical Equation:'( )

dxU x

dt

Fokker-Planck

2

2'( )

p pU x p

t x x

42

2 0 uni

0 bi

moda

moda( )

l

lx

x

statp x C e

stationary

( )2

2

!)0 '( ) (

U x

stat

pU x p p x C e

x x

42 0 single we

e.g. l

( )2 >0 double we

l

ll

xU x x

3t t t tdx x x dt dW

SODE

Page 46: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

For the equilibrium P.D.F. p(x) changes its type0

It is called P-bifurcation (e.g. L. Arnold)

Obvious disadvantage: (Zeeman, 1988)“It seems a pity to have to represent a dynamical system by y static picture”*

* Arnold, p. 473 ** Arnold, p. 473

II) The mathematical approach (e.g. L. Arnold)

Observation:**

One-one correspondence: stationary P.D.F. and invariant measures (I.M.)

Consider more general invariant measures (if exist)

D(ynamical)-Bifurcation Point of a family of stochastic dynamics with a ergodic I.M. ( . . . )w r t R

D

“Near” we have another I.M. with D

D

Page 47: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Question: Is there any relationship between these types of bifurcation

In general, there is not!

Our example: (above)

The corresponding invariant measure to

is unique*

42

2 0 uni

0 bi

moda

moda( )

l

lx

x

statp x C e

There is noD-Bifurcation

Remark: There are cases with D-bifurcation but no P-bifurcation*

* Arnold, p. 476

Page 48: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Case 1: Pitchfork Bifurcation

3t t t t tdx x x dt x dW

D P

0D 2

2P

Invariant Measures

0

q

q

q

q

Page 49: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Case 2: Andronov Bifurcation

3 21 1

0 0 1 0 0

1 0t t t tdx dt x dt x dWx x x

D1 P

1D 0P

D2

2D

0 stable

invariantmeasures

0

1

saddle

stable

0

1

2

unstable

stable

saddle

Page 50: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Main Questions: There are stochastic generalizations of geometric theorems

• Hartman-Grobman

• Poincaré-Andronov-Hopf

• Center Manifold

• Poincarè Normal Form

Global H-G: Wanner, 1995 (local H-G: still open question) Arnold, Schenk-Hoppe Namachchivaya 1996

Boxler 1989, Arnold, Kadei 1993

Elphick et al. 1985, C.+G. Nicolis 1986 (physics)Namachchivaya et al. 1991 Arnold, Kedai 1993, 1995Arnold, Imkeller 1997

Remark: Until now a research program (Arnold, ...)

Page 51: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Meissner oscillator and van der Pol’s equation

Meissner‘s Tube Oscillator

BEu

2

2 2 20 1 2 3 02

0

2 3 0BE BEBE BE BE

d u duRM k k u k u u

dt L dt

1 2 3, ,k k k

R

C

0 ,L M

20

0

1

L C

7. Examples

Page 52: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Normalization and Scaling:

1 12 2 2 2 20 0 1 0 2 1 2 0 3 1 22 2

0

0 10

2 3

x xdR

Mk k Mx x k Mx xx xdtL

1 2( , )BE BEx u x u

1 1

22 2 1 2

000 1 0

1 0 t

x xd dt

x x xx

xdW

2 20 1 0 3

0

where

:= , : Wiener p3 1, rocesst

RMk k M

LW

Noisy frequency:20 2:white noise( ) and 0k

(using results from Arnold, Imkeller 1997)

Page 53: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Linearization:

1 1

2 2

0 1 0 0

1 0 t

x xd dt x dW

x x

Center Manifold: 2 20If 0 ! , < 4 : / 4d R

2-dim. Center space and no stable space

Normal Form in Resonant Case: (polar coordinates)

Solution of stochastic cohomology equation results(see approach: Arnold, Imkeller, 1997)

Page 54: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

BEu1 2 3, ,k k k

RC

0 ,L M

20

0 0

1

L C

2

2 3 20 1

32 3 02

0

2 3 0BBE BE

BE BE BE E

d u R duM k k u k u u

dt L dtu

Meissner oscillator with nonlinear capacitor

Duffing-van der Pol equation

q

Page 55: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Normal Form in Resonant Case: (polar coordinates)

Solution of stochastic cohomology equation results(results: Arnold, Imkeller, 1997)

2 23 2 2

2

5 212 4 sin 2 sin 4 cos 2

2 2 8t t t

t t t t d t t t t td d d

r r rd r r r dt r r dW

2 2 2 22

2 2

3 5 36 3 11 1 cos 2 cos 4 sin 2

4 2 2 2 2t t t t

t d t t t t td d d d d d

r r r rd r dt dW

1 1

3 22 2 1 1 2

00 1 0 0

1 0 t

x xd dt x dW

x x x x x

noisycase

Page 56: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Pardoux-Wihstutzformula

1988

2

41,2 2

,2 8 d

O

determinsticAndronov-Hopf

bifurcation0

0

0

2 1

0

0, 0 0,

first stochasticD-Andronov-Hopf

bifurcation

Stability is lost

Ljapunov-Exponents:

0 stochastic

P- Andronov-Hopfbifurcation

0

Page 57: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

8. Noise Analysis of Phase Locked Loops (PLL)

Equivalent Base-band Modell:

F(s)+ KA sin(.)

0

t

d

0

( )sintd d

K A f t ddt dt

sin ,d d

K A tdt dt

State Space Equation

( )t

ˆ t

t( )x t

( )e tF(s)=1

F(s)P

VCO

Phase Detector Lowpass Filter

Voltage Controlled Oscillator

( )s t

( )r t

Page 58: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

2nd order PLL with ideal Integrator

1

1

2 sin

sin

n

dx

d

d x

d

Equivalent Base-band Modell

System State Space Equation:

Page 59: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Noisy state equation

Formally, one obtains:

But:

How do we interpret this equation, if n’(t) is not exactly known?

- need generic results

noise

Page 60: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Noisy state equation

Necessary Assumption:

PLL-bandwidth is small compared with BW of the noise-process

- sufficient to model n’(t) as white noise again

- rewrite state equation as SDE

Page 61: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Normalized SDE

After time-normalization and introducing parameters from linear PLL noise theory, one obtains:

Interpretation:

• SDE in the Stratonovich sense

• dw() = (t)d: increment of a normalized Wiener process

• BL: loop noise bandwidth, : frequency offset between input and VCO output, : SNR in the loop

Page 62: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

The Euler-Maruyama scheme (1)

• based on Ito-Taylor expansion ) consistent with Ito-calculus

• Ito stochastic integrals ) evaluate Riemann sum approximation at lower endpoint

Consider the scalar Ito-SDE

And the corresponding Euler-Maruyama scheme

Page 63: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

The Euler-Maruyama scheme

Consistency with Ito-calculus

Noise term in the EM scheme approximates the Ito stochastic integral over interval [tn, tn+1] by evaluating its integrand at the lower end point of this interval, that is

Page 64: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Phase-acquisition time

• Time to reach locked state from an initial state

Page 65: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Transient PDF – Lock-in

Page 66: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Meantime between cycle slips

Page 67: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

Simulation approach

• numerically solve the SDE using the Euler-Maruyama scheme

• estimate probabilities using relative frequencies

• verify the accuracy with the results from the Fokker-Planck method

• a relative tolerance level of 5% was allowed

Still no simulation required more than 5 minutes on a standard PC

Page 68: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

9. Conclusions

• Determinstic and stochastic behavior are related in time domain and density function domain

• Physical description of noise with a nonlinear Langevin equation fails with respect to its physical interpretation

• For thermal noise in nonlinear reciprocal circuits a well-defined theory is available (L.E. as approx.)

• For nonhyperbolic circuits (e.g. oscillators) first concepts for a geometric theory is available

• There is a difference between P- and D-Bifurcation

• Stochastic D-Andronov-Hopf theorem is illustrated by means of versions of a Meissner oscillator circuit

Page 69: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

10. References

• B. Beute, W. Mathis, V. Markovic: Noise Simulation of Linear Active Circuits by Numerical Solution of Stochastic Differential Equations. Proceedings of the 12th International Symposium on Theoretical Electrical Engineering (ISTET), 6 - 9 July 2003, Warsaw, Poland

• Mathis, W.; M. Prochaska: Deterministic and Stochastic Andronov-Hopf Bifurcation in Nonlinear Electronic Oscillations, Proceedings of the 11th workshop on Nonlinear Dynamics of Electronic Systems (EDES), 161- 164, 18-22 May 2003, Scuols, Schweiz

• W. Mathis: Nonlinear Stochastic Circuits and Systems – A Geometric Approach. Proc. 4th MATHMOD, 5-7 Februar 2003, Wien (Österreich)

• L. Weiss: Rauschen in nichtlinearen elektronischen Schaltungen und Bauelementen - ein thermodynamischer Zugang. Berlin; Offenbach: VDE Verlag, 1999. Also: Ph.D. thesis, Fakultät Elektrotechnik, Otto-von-Guericke-Universität Magdeburg, 1999.

• L. Weiss, W. Mathis: A thermodynamic noise model for nonlinear resistors, IEEE Electron Device Letters, vol. 20, no. 8, pp. 402-404, Aug. 1999.

• L. Weiss, W. Mathis: A unified description of thermal noise and shot noise in nonlinear resistors (invited paper), UPoN'99, Adelaide, Australia, July 11-15, 1999.

• L. Weiss, D. Abbott, B. R. Davis: 2-stage RC ladder: solution of a noise paradox, UPoN'99, Adelaide, Australia, July 11-15, 1999.

• W. Mathis, L. Weiss: Physical aspects of the theory of noise of nonlinear networks, IMACS/CSCC'99, Athens, Greece, July 4-8, 1999.

• W. Mathis, L. Weiss: Noise equivalent circuit for nonlinear resistors, Proc. ISCAS'99, vol. V of VI, pp. 314-317, Orlando, Florida, USA, May 30 - June 2, 1999.

• L. Weiss, W. Mathis: Thermal noise in nonlinear electrical networks with applications to nonlinear device models, Proc. IC-SPETO'99, pp. 221-224, Gliwice, Poland, May 19-22, 1999.

• L. Weiss, W. Mathis: Irreversible Thermodynamics and Thermal Noise of Nonlinear Networks, Int. J. for Computation and Mathematics in Electrical and Electronic Engineering COMPEL, vol. 17, no. 5/6, pp. 635- 648, 1998.

• W. Mathis, L. Weiss: Noise Analysis of Nonlinear Electrical Circuits and Devices. K. Antreich, R. Bulirsch, A. Gilg, P. Rentrop (Eds.): Modling, Simulation and Optimization of Integrated Circuits. International Series of Numerical Mathematics, Vol. 146, pp. 269-282, Birkhäuser Verlag, Basel, 2003

TET References:

Page 70: Thermal Noise in Nonlinear Devices and Circuits Wolfgang Mathis and Jan Bremer Institute of Theoretical Electrical Engineering (TET) Faculty of Electrical

• L. Weiss, M.H.L. Kouwenhoven, A.H.M van Roermund, W. Mathis: On the Noise Behavior of a Diode, Proc. Nolta'98, vol. 1 of 3, pp. 347-350, Crans-Montana, Switzerland, Sept. 14-17, 1998.

• L. Weiss, W. Mathis: N-Port Reciprocity and Irreversible Thermodynamics, Proc. ISCAS'98, vol. 3 of 6, pp. 407-410, Monterey, California, USA, May 31 - June 03, 1998. *

• L. Weiss, W. Mathis, L. Trajkovic: A Generalization of Brayton-Moser's Mixed Potential Function, IEEE CAS I, vol. 45, no. 4, pp. 423-427, April 1998.

• L. Weiss, W. Mathis: A Thermodynamical Approach to Noise in Nonlinear Networks, International Journal of Circuit Theory and Applications, vol. 26, no. 2, pp. 147-165, March/April 1998.

Further references:

• Langevin, P., Comptes Rendus Acad. Sci. (Paris) 146, 1908, 530• W. Schottky, W.: Über spontane Stromschwankungen in verschiedenen Elektrizitätsleitern, Ann. d. Phys. 57, 1918,

541-567• J. Guckenheimer; P. Holmes: Nonlinear oscillations, dynamical systems, and bifurcation of vector fields. Springer-Verlag, Berlin-Heidelberg 1983• N.G. van Kampen: Stochastic Processes in Physics and Chemistry. North Holland, Amsterdam 1992• R.L. Stratonovich.: Nonlinear Thermodynamics I. Springer-Verlag, Berlin-Heidelberg, 1992• L. Arnold: The unfoldings of dynamics in stochastic analysis. Comput. Appl. Math. 16, 1997, 3-25• W. Mathis: Historical remarks to the history of electrical oscillators (invited). In: Proc. MTNS-98 Symposium, July

1998, IL POLIGRAFO, Padova 1998, 309-312.• L. Arnold; P. Imkeller: Normal forms for stochastic differential equations. Probab. Theory Relat. Fields 110, 1998,

559-588• L. Arnold: Random dynamical systems. Berlin-Heidelberg-New York 1998• W. Mathis: Transformation and Equivalence. In: W.-K. Chen (Ed.): The Circuits and Filters Handbook. CRC Press &

IEEE Press, Boca Raton 2003