Equivalent Circuit Model with Nonlinear Characteristics of Zener Diode

Extracted from SPICE Model for ESD Simulation

M. Aoki,

T. Matsushima, T. Hisakado, O. Wada

Kyoto University, Japan

Outline Equivalent Circuit Model with Nonlinear Characteristics of

Zener Diode Extracted from SPICE Model for ESD Simulation

1. Background

– Predicting immunity of ESD

– ICIM-CPI model

2. Proposal of modeling and approach

– Equivalent circuit model

– Represent nonlinearity of Zener Diodes

3. Simulation

– ESD test simulation

– Results / discussions

4. Conclusion

Background

Predicting immunity of ESD

Background：Electrostatic discharge(ESD) causes errors of ICs due to its high voltage

3

ESD current

Demands:

Predicting the immunity behavior to ESD or pulse disturbance

in the design stage of the devices.

BREAK

Next : Immunity macro model

Equivalent CircuitExpression

SPICE Model Immunity Macro Model

Temperature dependence

Highly confidential

Constructed by external measurement

effective also in the absent of SPICE

ESD protections

Background

Predicting immunity characteristic of ESD

4

Voltage-dependent elements

FB

PPN

VDD1 VDD2

GND1 GND2

T1

T2

T3

[S]Disturbance

Goal: Construction of Equivalent Circuit Model

A

a

Designing ESD protection circuit easily

Simulation in time domain

Using a function approximation

to express nonlinear characteristics

Background

ICIM-CPI model

ICIM-CPI model(Integrated Circuit for IMmunity behavioral

simulation – Conducted Pulse Immunity)

5

Future IEC 62433-6

・Nonlinear behavior of IC: PDN+NLB

・Time-domain simulation

PDN

[S]

ICIM-CI

IB

Freq

...

1.0E+7

2.0E+7

PT

15.2

17.8

VOUT

5.1

5.11

T1

T2

GND1

T3

T4

GND2

DI DO

OOT5

(Passive Distribution

Network)

(Immunity Behavior)

T5

ICIM-CI model(Integrated Circuit Immunity Model

for Conducted Immunity)

IEC 62433-4

・Linear: PDN(Passive Distribution Network)

・Frequency-domain simulation

Conventional NewFor CW disturbance For Pulse disturbance

(Non Linear Block)

FB

PPN

VDD1 VDD2

GND1 GND2

T1

T2

T3

[S]Disturbance

Background - Immunity macro model (ICIM-CPI model)

Description of ICIM-CPI model

ICIM-CPI model(Integrated Circuit for Immunity behavioral simulation – Conducted Pulse Immunity)

PDN (Passive Distribution Network)…Linear transmission

NLB(Non Linear Block)…Nonlinear behavior (Voltage dependency)

6

Future IEC 62433-6

PDN Block

― passive elementsEx)package inductance

stray capacitance

NLB Block

― ESD protections

Ex)diodes, MOSFET

FB

PPN

VDD1 VDD2

GND1 GND2

T1

T2

T3

[S]Disturbance

Background - Immunity macro model (ICIM-CPI model)

Description of ICIM-CPI model

ICIM-CPI model(Integrated Circuit for Immunity behavioral simulation – Conducted Pulse Immunity)

7

Future IEC 62433-6

10 50 100 500 10000.1

0.51

510

50100

500

Frequency [MHz]

|Z |

[

Z11

Z22

PDN block

NLB: I-V Curve

ie) Measurement, TLP

PDN: S-parameters

FB

PPN

VDD1 VDD2

GND1 GND2

T1

T2

T3

[S]Disturbance

11 12 130

0.01

0.02 SPICE model Approximation method

VD [V]

I D [

A]

NLB block

Our proposal and approach

Equivalent circuit model

ICIM-CPI model(Integrated Circuit for Immunity behavioral simulation – Conducted Pulse Immunity)

8

Future IEC 62433-6

How to extract and represent the

NLB behavior?

Equivalent Circuit Model

1. Extract nonlinear characteristics by measurement

2. Use an appropriate function and approximate the characteristic

Equivalent Circuit

ExpressionI (V)C(V)

Voltage-dependence

9

Our proposal and approach

Equivalent Circuit Model

Target: Zener diode (simple case)

𝑅𝐷𝐶𝐷

: Nonlinear resistor

: Nonlinear junction capacitance

Extract characteristics

(by measurement or SPICE)

…PDN

…NLB

Equivalent CircuitExpression

L

RD CDDV

ID

L

DV

ID

* DPTZ12B D model* PKG: PMDS,Vz=12V at

Iz=20mA,Pd=1W* Model Generated by ROHM

* All Rights Reserved* Commercial Use or* Resale Restricted* Date: 2015/09/16.MODEL DPTZ12B D

+ IS=6.1497E-15

𝐼𝐷 =

𝑛

exp(𝑎𝑛𝑉𝐷𝑛)

Extract data by DC characteristic

𝑅𝐷 :Voltage-controlled current source

Function

Approximate

using least squares method

Our proposal and approach

Represent Nonlinearity (I-V characteristic)

D

D

RD

CD

11 12 130

0.01

0.02 SPICE model

VD [V]

I D [

A]

11 12 130

0.01

0.02 SPICE model Approximation method

VD [V]

I D [

A]

I-V characteristic

10

D

Vector

Network

Analyzer

DC Feed

DC Block

Measured by Vector Network Analyzer

Get Z-parameters (Voltage dependency)

Find C from the inclination of line

:Voltage-controlled capacitor𝐶𝐷

RD

CD

Approximate

using least squares method

Compare

Our proposal and approach

Represent Nonlinearity(C-V characteristic)

Continue…

11

0V

5V

10V

Find C from the inclination of line

Approximate

using least squares method

Our proposal and approach

Represent Nonlinearity(C-V characteristic)

𝐶𝐷 = 𝛼0 0.5 + 𝑉𝐷−1𝑁

Function

RD

CD

0 5 10

200

300

400

CD

[pF

]

VD [V]

SPICE model Approximation curve

0 5 10

200

300

400

CD

[pF

]

VD [V]

SPICE model

:Voltage-controlled capacitor𝐶𝐷

12

105 106 107 108 10910-2

10-1

100

101

102

103

0V 5V 10V

|Im

{Z

}|

f[Hz]

0V

5V

10V

Simulation

ESD test simulation

RD

CD

ESD gun

Validate the model by comparing responses to ESD

Does ESD

responses

match?

For ESD test simulation … Using characteristics extracted from SPICE model

For actual measurement ... Using ESD gun and

characteristics extracted from measurement

Used Device is

PTZ12B (ROHM)

13

RD

CD

ESD gun

Simulation

ESD test simulation

Level

1

2

3

4

V[kV]

2

4

6

8

Peak[A]

7.5

15

22.5

30

t [ns]r

0.7 – 1.0

0.7 – 1.0

0.7 – 1.0

0.7 – 1.0

I (30ns)[A]

4

8

12

16

I (60ns)[A]

2

4

6

8

IEC61000-4-2 test standard

Circuit for ESD current generation

Does ESD

responses

match?

14

214 348

75 nH 2.4 uH

7 pF 143 pF

Simulation

Characteristics of the proposed model

𝑅𝐷 :Voltage-controlled current source

𝐼𝐷 =

𝑛

exp(𝑎𝑛𝑉𝐷𝑛) 𝐶𝐷 = 𝛼0 0.5 + 𝑉𝐷

−1𝑁

Value Value

a

a

a

a

a

a

a

a

0

1

2

3

4

5

6

7 5.71E-04

-2.43E-02

4.07E-01

-3.39-3.20E01

2.77E01

-3.15E01

1.48E01

𝐶𝐷 = 281.6 × 0.5 + 𝑉𝐷−13

Approximate

Next : Results

RD

CD

:Voltage-controlled capacitor𝐶𝐷

15

Simulation

Results / Discussion

0 20 40 60 80 1000

10

20

Time [ns]

I [A

]

0 20 40 60 80 1000

10

20 SPICE model Proposed model

Time [ns]

I [A

]

0 2 4 6 8 10

0

100

200

300

400

500

Time [ns]

V [

V]

SPICE model Proposed model

Input current

The results from the proposed models were in good agreement

with the results from SPICE model

IEC61000-4-2 test standard

Level V[kV] Peak[A] t [ns]r I (30ns)[A] I (60ns)[A]

3 6 22.5 0.7 – 1.0 12 6

𝐼𝐷 𝑉𝐷

MATCH MATCH

16

D

D

ESD gun

RD

CD

When C was linear…

Different

When the capacitor is set to a linear value,

the model CANNOT express ESD response correctly.

0 5 10

200

300

400

CD

[pF

]

VD [V]

0 5 10

200

300

400

CD

[pF

]

VD [V]

CD = 200pF

CD = 150pF

The evidence supporting the importance of voltage dependency

17

Simulation

Results / Discussion

0 5 10 150

5

10

15

Time[ns]

V [

V]

SPICE model Proposed model Linear C: 150pF Linear C: 200pF

Conclusion

Demand: Predicting the immunity behavior to ESD

Proposal: Equivalent circuit model using function approximation

𝐶𝐷 = 𝛼0 0.5 + 𝑉𝐷−1𝑁

𝐼𝐷 =

𝑛

exp(𝑎𝑛𝑉𝐷𝑛)

0 2 4 6 8 10

0

100

200

300

400

500

Time [ns]

V [

V]

SPICE model Proposed model

0 5 10 150

5

10

15

Time[ns]

V [

V]

SPICE model Linear C: 150pF Linear C: 200pF

Results: The ESD test results simulated using the proposed model

correlate well with the results using SPICE model

18