Scribd
Upload
13 views10 pages

EC3021E: Analog MOS Integrated Circuits: Dhanaraj K. J. Associate Professor ECED, NIT Calicut

The document discusses the characteristics and operating regions of enhancement type MOSFETs, including the equations for drain current in different regions. It provides examples of calculations for drain current based on given parameters and conditions. Additionally, it references key textbooks for further reading on analog CMOS integrated circuits.

Uploaded by

keerthanab230375ec
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
13 views10 pages

EC3021E: Analog MOS Integrated Circuits: Dhanaraj K. J. Associate Professor ECED, NIT Calicut

The document discusses the characteristics and operating regions of enhancement type MOSFETs, including the equations for drain current in different regions. It provides examples of calculations for drain current based on given parameters and conditions. Additionally, it references key textbooks for further reading on analog CMOS integrated circuits.

Uploaded by

keerthanab230375ec
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
You are on page 1/ 10

EC3021E: Analog MOS Integrated Circuits

Dhanaraj K. J.
Associate Professor
ECED, NIT Calicut
When
𝑉𝐷𝑆 = 𝑉𝐺𝑆 −𝑉𝑇

The charge control relation at drain is

QN (L ) = −Cox VGS − VDS − VT  = 0

No inversion layer at the drain end of the


channel

Pinch off

ID does not increase much after pinch off


Operating Regions

MOSFET Bipolar Transistor


Quadratic Characteristic Exponential characteristic
Saturation; VDS>VGS-VT Active; VCB>0
Triode/Linear; VDS<VGS-VT Saturation; VCB<0
Zero gate current Finite base current
Drift current Diffusion current
n-channel MOSFET p-channel MOSFET

The MOSFETs that we discuss here are enhancement type


MOSFETs

4
n-channel MOSFET p-channel MOSFET

The MOSFETs that we discuss here are enhancement type


MOSFETs

5
Linear
region
 W VDS2

  nCox (VGS − VT )VDS − ; VGS  VT , VDS  VGS − VT
ID =  L 2 
  nCox W (V − V )2 ; V  V , V  V − V
 2 L GS T GS T DS GS T

Saturation
 nCox = k '
n → Process transconductance parameter region
W
k'
n = kn → Device transconductance parameter
L

  VDS2

 k n (VGS − VT )VDS − ; VGS  VT , VDS  VGS − VT
ID =   2 
 k n (V − V )2 ; V  V , V  V − V
 2 GS T GS T DS GS T

6
A Silicon n-channel MOSFET has μn= 600 cm2 /V-sec, Cox= 1.2x10-7 F/cm2
, W=50μm, L=10 μm and VT= 0.8V. Find the drain current when i) VGS=2V
and VDS=1V ii) VGS=3V and VDS=5V

1) VGS>Vth, VDS<VGS-VT. Hence MOSFET is in linear/triode region

ID=μnCox(W/L)[(VGS-VT)VDS-VDS2/2]

=252μA

2) VGS>Vth, VDS>VGS-VT. Hence MOSFET is in saturation region

ID=μnCox(W/L)[(VGS-VT) 2/2]

=871.2μA
Q. Find Vx for the following circuit if kn=200A/V2. VT=1V

kn
T1→ saturation; I D1 = (5 − Vx − 1)2
2
 Vx2 
T2→ linear; I D2 = k n  (5 − 1)Vx − 
 2 

1 Vx2
(5 − Vx − 1) = (5 − 1)Vx −
2

2 2
Vx2 − 8Vx + 8 = 0

 Vx = 1.17V

8
1. Razavi B. Design of Analog CMOS Integrated Circuits, 2001. New
York, NY: McGraw-Hill. 2017;587(589):83-90
2. P. Allen & D. Holberg, CMOS Analog Circuit Design, 3rd Edition,
Oxford University Press, 2013
3. Streetman, B.G. and Banerjee, S., 2001. Solid state electronic
devices. Prentice-Hall of India.
4. Jan M Rabaey, Digital Integrated Circuits - A Design Perspective,
Prentice Hall, 2nd Edition, 2005

9
EC3021E: Analog MOS Integrated Circuits, Monsoon Semester 2025-26 10

You might also like