Review of MOSFET Device Modeling Lecture 2 # 1University of Toronto ECE530 Analog Electronics

Review of MOSFETDevice Modeling

Review of MOSFET Device Modeling Lecture 2 # 2University of Toronto ECE530 Analog Electronics

MOS Device Structure

Review of MOSFET Device Modeling Lecture 2 # 3University of Toronto ECE530 Analog Electronics

NMOS and PMOS with Well

Review of MOSFET Device Modeling Lecture 2 # 4University of Toronto ECE530 Analog Electronics

MOS Symbols

Review of MOSFET Device Modeling Lecture 2 # 5University of Toronto ECE530 Analog Electronics

MOS Channel Formation

Review of MOSFET Device Modeling Lecture 2 # 6University of Toronto ECE530 Analog Electronics

I/V Characteristics

Review of MOSFET Device Modeling Lecture 2 # 7University of Toronto ECE530 Analog Electronics

I/V Characteristics

THGSeff

THGSoxd

VVV

VVWCQ

)(

Qd(x) WCox(VGS V (x) VTH)

I Qd v

Review of MOSFET Device Modeling Lecture 2 # 8University of Toronto ECE530 Analog Electronics

I/V Characteristics (cont.)

ID WCox[VGS V(x) VTH]v

DSV

V

THGSnox

L

x

D dVVxVVWCdxI00

])([

Given v E and E(x) dV (x)

dx

ID WCox[VGS V (x) VTH]ndV(x)

dx

ID nCoxW

L[(VGS VTH)VDS

1

2VDS

2 ]

Review of MOSFET Device Modeling Lecture 2 # 9University of Toronto ECE530 Analog Electronics

I/V Characteristics (cont.)

ID nCoxW

L[(VGS VTH)VDS

1

2VDS

2 ]

Review of MOSFET Device Modeling Lecture 2 # 10University of Toronto ECE530 Analog Electronics

Operation in Triode Region

ID nCoxW

L[(VGS VTH)VDS

1

2VDS

2 ]

ID nCoxW

L(VGS VTH)VDS, VDS 2(VGS VTH)

RON 1

nCoxW

L(VGS VTH)

Review of MOSFET Device Modeling Lecture 2 # 11University of Toronto ECE530 Analog Electronics

Operation in Active (Saturation) Region

ID nCoxW

L[(VGS VTH)VDS

1

2VDS

2 ]

ID nCox

2

W

L(VGS VTH)2

V 'DS VGS VTH (Pinch off )

Review of MOSFET Device Modeling Lecture 2 # 12University of Toronto ECE530 Analog Electronics

Active Region (cont.)

Active Region

Review of MOSFET Device Modeling Lecture 2 # 13University of Toronto ECE530 Analog Electronics

Transconductance, gm

gm ID

VGS VDS constan t

nCoxW

L(VGS VTH)

gm 2nCoxW

LID

2ID

VGS VTH

Review of MOSFET Device Modeling Lecture 2 # 14University of Toronto ECE530 Analog Electronics

Triode and Active Region Transition

Active Active

Review of MOSFET Device Modeling Lecture 2 # 15University of Toronto ECE530 Analog Electronics

Threshold Voltage and Body Effect

VTH MS 2F Qdep

Cox , where

MS gate silicon

i

subF nN

qkT ln

Qdep 4qsi F Nsub

Review of MOSFET Device Modeling Lecture 2 # 16University of Toronto ECE530 Analog Electronics

Threshold Voltage and Body Effect (cont.)

VTH VTH0 2F VSB 2F , 2qsiNsub

Cox

No Body Effect With Body Effect

Review of MOSFET Device Modeling Lecture 2 # 17University of Toronto ECE530 Analog Electronics

Channel Length Modulation

L' L L

1/ L' 1

L(1 L / L)

1/ L' 1

L(1 VDS), VDS L / L

ID nCox

2

W

L(VGS VTH)2 (1 VDS)

L L’

Review of MOSFET Device Modeling Lecture 2 # 18University of Toronto ECE530 Analog Electronics

Channel Length Modulation (cont.)

gm nCoxW

L(VGS VTH)(1 VDS)

gm 2nCox W

LID

(1 VDS)

gm 2ID

VGS VTH, (unchanged)

Review of MOSFET Device Modeling Lecture 2 # 19University of Toronto ECE530 Analog Electronics

Subthreshold Conduction

ID I0 expVGS

kTq

Review of MOSFET Device Modeling Lecture 2 # 20University of Toronto ECE530 Analog Electronics

MOS Layout

Review of MOSFET Device Modeling Lecture 2 # 21University of Toronto ECE530 Analog Electronics

Device Capacitances

Review of MOSFET Device Modeling Lecture 2 # 22University of Toronto ECE530 Analog Electronics

Layout for Low Capacitance

Review of MOSFET Device Modeling Lecture 2 # 23University of Toronto ECE530 Analog Electronics

G-S and G-D Capacitance

Review of MOSFET Device Modeling Lecture 2 # 24University of Toronto ECE530 Analog Electronics

MOS Small Signal Models

ro VDS

ID

1

ID /VDS

1nCox

2

W

L(VGS VTH)2

1

ID

Review of MOSFET Device Modeling Lecture 2 # 25University of Toronto ECE530 Analog Electronics

Bulk Transconductance, gmb

gmb ID

VBS

nCox

2

W

L(VGS VTH)

VTH

VBS

gmb gm

2 2F VSBgm

Also,

VTH

VBS

VTH

VSB

2

(2F VSB) 1/ 2

Review of MOSFET Device Modeling Lecture 2 # 26University of Toronto ECE530 Analog Electronics

Gate Resistance

Review of MOSFET Device Modeling Lecture 2 # 27University of Toronto ECE530 Analog Electronics

MOS Small Signal Model with Capacitance

Review of MOSFET Device Modeling Lecture 2 # 28University of Toronto ECE530 Analog Electronics

C-V of NMOS