PSP+: A Simple Method to Extend PSP Model for SOI MOSFETs

Application

(Mail: ljun77@163.com)2015.06.27

Jun Liu, Kai LuCompact Device Modeling Group

Key Laboratory for RF Circuits and Systems of Ministry of Education, Hangzhou Dianzi University

Model Introduction PSP+ Modeling MethodModel TopologyModel Extraction & Simulation

Model Verification DC Modeling Results RF Small Signal Fitting Results RF Power Switch Simulation

Substrate Network Extraction Method Four-port S-parameter based extraction method Testkey and results

Summary

OutlineF

Model Introduction PSP and PSP + PSP+ is directly extended on PSP103.2, VA version PSP model core is perfectly inherited to PSP+, the math structure of the model is as the same as that used in PSP 103.2

Modeling Method Five electrical in/out nodes, with a novel dVbi model for Irb modeling SOI mode selector, 1 = PD&FD, 0 = PD, 2 = Bulk Parasitic BJT model is simplified from MEXTRAM 504 Surface potential based back gate (BOX) charge calculation Complete substrate network and scaling rules

Advantages Standard PSP model core + Customized characterizing given PSP+ more possibilities, including a quickly model Extraction based on PSP

Model Topology

Qfed: BG (BOX) fringe capacitance from E to D

PSP+ = PSP Core + BG MOS CAP + BSIM SOI dVbi + BJT

Qfes: BG (BOX) fringe capacitance from E to S Qbg: BG MOS structure caused charege

BJT ModelMEXTRAM 504 can also use BSIM SOI BJT model

Floating Body effect Vsb = Vsb - dVbi dVbi is borrowed from BSIM SOI

FD Device No dVBI and BJT needed

PD Device FB and BJT model needed

Fig. Model topology

Source Code & Model Simulation Verilog-A version is now ready for circuit application Simulator: Cadence Spectre, Agilent ADS, HSPICE..

Model Parameter Extraction Follow PSP extraction follow (MBP/Proplus/IC-CAP + Defined sub-model extraction follow (IC-CAP)

Model Introduction PSP+ Modeling MethodModel TopologyModel Extraction & Simulation

Model Verification DC Modeling Results RF Small Signal Fitting Results RF Power Switch Simulation

Substrate Network Extraction Method Four-port S-parameter based extraction method Testkey and results

Summary

Outline

F

Benchmark Testing (in-house manufactured) Cgc = Cgs + Cgd + CgbMOS CAP1:MOS CAP2:MOS CAP3:

Fig.CAP1~3 measurements and model fitting results

DC Base-band test structure Totally 25 PD devices manufactured in 0.18um SOI technology Vdd = 2.5VW = 0.5um to 10um, L = 0.2um to 10um

Model Base-band global fitting DC Ids vs Vgs

Model Base-band global fitting gm = dIds/dVgs

Model Base-band global fitting Ids vs Vds

PMOSFET

Vds=0v~-2.5v(step:-0.05v)

Vgs=-0.5v~-2.5v(step:-0.5v)

NMOSFET

Vds=0v~2.5v(step:0.05v)

Vgs=0.5v~2.5v(step:0.5v)

Model Base-band global fitting gds =dIds/dVds

PMOSFET

Vds=0v~-2.5v(step:-0.05v)

Vgs=-0.5v~-2.5v(step:-0.5v)

NMOSFET

Vds=0v~2.5v(step:0.05v)

Vgs=0.5v~2.5v(step:0.5v)

Model Base-band global fitting Igate

Model RF performance global fitting PMOSFET W=1um L=0.5um NF=16

Model RF performance global fitting PMOSFET W=2.5um L=0.5um NF=16

Model RF performance global fitting PMOSFET W=10um L=0.3um NF=32

Model Introduction PSP+ Modeling MethodModel TopologyModel Extraction & Simulation

Model Verification DC Modeling Results RF Small Signal Fitting Results RF Power Switch Simulation

Substrate Network Extraction Method Four-port S-parameter based extraction method Testkey and results

Summary

Outline

F

17

Advantages of 4-portS parmeters under all modesAll parasitics including substrate parasitics could be extracted directlyBenifits in layout area consumption

S

G

G

G

G

S

G-D Mode

S

G

G

G

G

S S

G

G

G

G

S

S-D Mode G-S Mode

Why Four-port network?

4-port Network B-S Mode

S

G

G

G

G

S

B-G Mode B-D Mode

S

G

G

G

G

SS

G

G

G

G

S

Extraction Method

Rg

Cgs Cgd

Dsb Ddb

Rs Rd

RbCsbox Cdbox

Rsub Csub

G

S D

E

B

Cgb

Parasitics for PD SOI

Body related parasitics

BSsb

imag(Y )C2 frequency

= 2

BDdb

imag(Y )Cfrequency

=

2GB

gbimag(Y )C

frequency= 1

bBB

RReal(Y )

=

18

( )2

gggg

imag YC

frequency=

Gate related parasitics

GSgs

Imag(Y )C =2 freq

GDgd

imag(Y )C =2 frequecy

2 2

gA - A - 4ABR =

2AB2 2

ggA frequency C=

GGB = Real(Y )

1 1( ( ) ( ) )s GS g gdR = Real - Y - R j C +

1 1D( ( ) ( ) )d G g gsR = Real - Y - R j C

+

Source and drain resistance

2 2

1 2 2 2 2

1 / / =1 1

gd g gd ggd

g gd g gd g

C R C RY j C j

R C R C R

= ++ +

2 2

2 2 2 2 2b

1 / / =1 1

db b db bdb

db b db b

C R C RY j C jR C R C R

= ++ +

3 1 2DDY Y Y Y=

sub3

1R = Real( )Y

Y1 Y2 Y3

Rg

Cgd Cdb

Rb

Cdbox

Rsub Csub

D

G B Sub

19

Substrate Resistance YDD equivalent circuit

BB 1sbox sb

1 1 1( + ) Z2 j C j Cb

Z R

= + +

13 sbox

1 1Y

Zj C

= +

1 BB3 sb

1 1Z 2 2Y b

Z Rj C

= 1

1(Z )Csubimag

=

sbox 31

1 1Y

Zj C

= sboxs

( )C boximag j C

=

Rb

Csbox+Csb

Cdbox+Cdb

RsubCsub

sb db sbox dboxC C C C

Z1

20

ZBB equivalent circuit

Box and Substrate Capcitance

RG

Rsub Csbox

CGS

21

Extraction ResultsNMOSFET

Wfinger= 2m

Lg=0.13 m

No. of finger (NF)= 4~64

NF NF

NF NF

22

Simulation Results

PSP+ aimed at SOI modeling, including DC&RF

PSP + is provided with advantages of PSP,BSIMSOI and

MEXTRAM

PSP+ provided excellent accuracy for SOI RF modeling

Four-port network modeling could solve the problem of

substrate related parasitics with direct extract method

Summary

23

PSP+: A Simple Method to Extend PSP Model for SOI MOSFETs ApplicationOutlineModel IntroductionModel TopologySource Code & Model SimulationOutlineBenchmark Testing (in-house manufactured)Model Base-band global fittingModel Base-band global fittingModel Base-band global fittingModel Base-band global fittingModel Base-band global fittingModel RF performance global fittingModel RF performance global fittingModel RF performance global fittingOutlineWhy Four-port network? 18Substrate Resistance Box and Substrate Capcitance 21 22 23