lecture10-140706.pdf

Lecture 10 – MOS Capacitor Model and Large Signal Model Dependence (3/10/14) Page 10-1

CMOS Analog Circuit Design © P.E. Allen - 2016

LECTURE 10 – MOS CAPACITOR MODEL AND LARGE

SIGNAL MODEL DEPENDENCE

LECTURE ORGANIZATION

Outline

• MOSFET capacitor model

• Dependence of the large signal model on process

Pages 77-86 and new material

Lecture 10 – MOS Capacitor Model and Large Signal Model Dependence (3/10/14) Page 10-2

CMOS Analog Circuit Design © P.E. Allen - 2016

MOSFET CAPACITOR MODEL

Submicron Technology

Physical perspective:

MOSFET capacitors consist of:

• Depletion capacitances

Lecture 10 – MOS Capacitor Model and Large Signal Model Dependence (3/10/14) Page 10-3

CMOS Analog Circuit Design © P.E. Allen - 2016

Deep Submicron Technology

Physical perspective:

MOSFET capacitors consist of:

• Depletion capacitances

• Charge storage or parallel plate capacitances

Lecture 10 – MOS Capacitor Model and Large Signal Model Dependence (3/10/14) Page 10-4

CMOS Analog Circuit Design © P.E. Allen - 2016

MOSFET Depletion Capacitors

Model:

1.) v

1 -

and

2.) v

> FC·PB

1+MJ

+

1 - (1+MJSW)FC + MJSW

Lecture 10 – MOS Capacitor Model and Large Signal Model Dependence (3/10/14) Page 10-5

CMOS Analog Circuit Design © P.E. Allen - 2016

SM Charge Storage (Parallel Plate) MOSFET Capacitances - C

3

and C

4

Overlap capacitances:

C

= C

3

= LD·W

·C

C

= gate-to-channel = C

eff

·(L-2LD)

= C

eff

·L

eff

C

= voltage dependent channel-

bulk/substrate capacitance