Presentation is loading. Please wait.

Presentation is loading. Please wait.

Qualitative Discussion of MOS Transistors. Big Picture ES220 (Electric Circuits) – R, L, C, transformer, op-amp ES230 (Electronics I) – Diodes – BJT –

Published byDarren McDonald Modified over 9 years ago

Similar presentations

Presentation on theme: "Qualitative Discussion of MOS Transistors. Big Picture ES220 (Electric Circuits) – R, L, C, transformer, op-amp ES230 (Electronics I) – Diodes – BJT –"— Presentation transcript:

1 Qualitative Discussion of MOS Transistors

2 Big Picture ES220 (Electric Circuits) – R, L, C, transformer, op-amp ES230 (Electronics I) – Diodes – BJT – Complementary Metal Oxide Semiconductor (CMOS) Field Effect Transistor (FET) Applications in Digital Integrated Circuits ES330 (Electronics II) – Explore Applications of CMOS in Analog Integrated Circuits

3 Topics Covered in ES330 Small Signal Model Body Effect

4 A Crude Metal Oxide Semiconductor (MOS) Device P-Type Silicon is slightly conductive. Positive charge attract negative charges to interface between insulator and silicon. A conductive path is created If the density of electrons is sufficiently high. Q=CV. V2 causes movement of negative charges, thus current. V1 can control the resistivity of the channel. The gate draws no current!

5 An Improved MOS Transistor n+ diffusion allows electrons move through silicon. (provide electrons)(drain electrons)

6 Typical Dimensions of MOSFETs These diode must be reversed biased. tox is made really thin to increase C, therefore, create a strong control of Q by V.

7 A Closer Look at the Channel Formulation Need to tie substrate to GND to avoid current through PN diode. Positive charges repel the holes creating a depletion region, a region free of holes. Free electrons appear at VG=VTH. VTH=300mV to 500 mV (OFF)(ON)

8 MOSFET as a Variable Resistor As VG increases, the density of electrons increases, the value of channel resistance changes with gate voltage. You can build an attenuator circuit. (i.e. a voltage divider)

9 Change Drain Voltage Resistance determined by VG.

10 Change Gate Voltage Higher VG leads to a lower channel resistance, therefore larger slope.

11 Length Dependence The resistance of a conductor is proportional to the length. fixed V D fixed V G

12 Dependence on Oxide Thickness Q=CV C is inversely proportional to 1/tox. Lower Q implies higher channel resitsance. fixed V D fixed V G

13 Width Dependence The resistance of a conductor is inversely proportional to the cross section area. A larger device also has a larger capacitance!

14 Channel Pinch Off Q=CV – V=VG-V OXIDE-Silicon V OXIDE-Silicon can change along the channel! Low V OXIDE-Silicon implies less Q.

15 VG-VD is sufficiently large to produce a channel VG-VD is NOT sufficiently large to produce a channel No channel Electrons are swept by E to drain. Drain can no longer affect the drain current!

16 Regions No channel (No Dependence on VDS)

17 Determination of Region How do you know whether a transistor is in the linear region or saturation region? – If VDS>(VGS-VTH) and VGS>VTH, then the device is in the saturation region. – If VDS VTH, then the device is in the linear region.

18 Graphical Illustration

19 Limited VDS Dependence During Saturation As VDS increase, effective L decreases, therefore, ID increases.

20 Pronounced Channel Length Modulation in small L

21 PMOS Transistor

22 IV Characteristics of a PMOS

Download ppt "Qualitative Discussion of MOS Transistors. Big Picture ES220 (Electric Circuits) – R, L, C, transformer, op-amp ES230 (Electronics I) – Diodes – BJT –"

Similar presentations

MICROWAVE FET Microwave FET : operates in the microwave frequencies

MICROWAVE FET Microwave FET : operates in the microwave frequencies
Basic MOS Device Physics

Basic MOS Device Physics
ECA1212 Introduction to Electrical & Electronics Engineering Chapter 6: Field Effect Transistor by Muhazam Mustapha, October 2011.

ECA1212 Introduction to Electrical & Electronics Engineering Chapter 6: Field Effect Transistor by Muhazam Mustapha, October 2011.
Physical structure of a n-channel device:

Physical structure of a n-channel device:
Metal Oxide Semiconductor Field Effect Transistors

Metal Oxide Semiconductor Field Effect Transistors
CMOS Transistors. Outline Qualitative Description of CMOS Transistor g m /I D Design Biasing a transistor Using g m /I D Approach Design Using Cadence.

CMOS Transistors. Outline Qualitative Description of CMOS Transistor g m /I D Design Biasing a transistor Using g m /I D Approach Design Using Cadence.
Chapter 6 The Field Effect Transistor

Chapter 6 The Field Effect Transistor
VLSI Design CMOS Transistor Theory. EE 447 VLSI Design 3: CMOS Transistor Theory2 Outline Introduction MOS Capacitor nMOS I-V Characteristics pMOS I-V.

VLSI Design CMOS Transistor Theory. EE 447 VLSI Design 3: CMOS Transistor Theory2 Outline Introduction MOS Capacitor nMOS I-V Characteristics pMOS I-V.
Lecture 11: MOS Transistor

Lecture 11: MOS Transistor
Introduction to VLSI Circuits and Systems, NCUT 2007 Chapter 6 Electrical Characteristic of MOSFETs Introduction to VLSI Circuits and Systems 積體電路概論 賴秉樑.

Introduction to VLSI Circuits and Systems, NCUT 2007 Chapter 6 Electrical Characteristic of MOSFETs Introduction to VLSI Circuits and Systems 積體電路概論 賴秉樑.
10/8/2004EE 42 fall 2004 lecture 171 Lecture #17 MOS transistors MIDTERM coming up a week from Monday (October 18 th ) Next Week: Review, examples, circuits.

10/8/2004EE 42 fall 2004 lecture 171 Lecture #17 MOS transistors MIDTERM coming up a week from Monday (October 18 th ) Next Week: Review, examples, circuits.
EE415 VLSI Design The Devices: MOS Transistor [Adapted from Rabaey’s Digital Integrated Circuits, ©2002, J. Rabaey et al.]

EE415 VLSI Design The Devices: MOS Transistor [Adapted from Rabaey’s Digital Integrated Circuits, ©2002, J. Rabaey et al.]
Lecture #16 OUTLINE Diode analysis and applications continued

Lecture #16 OUTLINE Diode analysis and applications continued
The metal-oxide field-effect transistor (MOSFET)

The metal-oxide field-effect transistor (MOSFET)
Chapter 5 – Field-Effect Transistors (FETs)

Chapter 5 – Field-Effect Transistors (FETs)
11/3/2004EE 42 fall 2004 lecture 271 Lecture #27 MOS LAST TIME: NMOS Electrical Model – Describing the I-V Characteristics – Evaluating the effective resistance.

11/3/2004EE 42 fall 2004 lecture 271 Lecture #27 MOS LAST TIME: NMOS Electrical Model – Describing the I-V Characteristics – Evaluating the effective resistance.
Week 8b OUTLINE Using pn-diodes to isolate transistors in an IC

Week 8b OUTLINE Using pn-diodes to isolate transistors in an IC
Chap. 5 Field-effect transistors (FET) Importance for LSI/VLSI –Low fabrication cost –Small size –Low power consumption Applications –Microprocessors –Memories.

Chap. 5 Field-effect transistors (FET) Importance for LSI/VLSI –Low fabrication cost –Small size –Low power consumption Applications –Microprocessors –Memories.
Dr. Nasim Zafar Electronics 1 - EEE 231 Fall Semester – 2012 COMSATS Institute of Information Technology Virtual campus Islamabad.

Dr. Nasim Zafar Electronics 1 - EEE 231 Fall Semester – 2012 COMSATS Institute of Information Technology Virtual campus Islamabad.
Lecture 0: Introduction. CMOS VLSI Design 4th Ed. 0: Introduction2 Introduction  Integrated circuits: many transistors on one chip.  Very Large Scale.

Lecture 0: Introduction. CMOS VLSI Design 4th Ed. 0: Introduction2 Introduction  Integrated circuits: many transistors on one chip.  Very Large Scale.

Similar presentations

Ads by Google