Outline

Common Source(CS) Configuration

Transfer Characterstics in Common Source(CS) Configuration

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Outline

Common Source(CS) Configuration

Transfer Characterstics in Common Source(CS)

1

• Body Effect

CMOS

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Recap

2

Recap

Chapter 4 MOS field-Effect Transistors (MOSFETs)

Figure 4.9CMOS TransistorEffect Transistors (MOSFETs)

Figure 4.9Transistor

Common Source Amplifier

Biasing to be doneTo work at appropriate VGS

and corresponding ID

Common Source Amplifier

Two port Network

Common Source AmplifierCommon Source Amplifier

V0 = VDD- iDRD

Transconductance Amplifier

Converted to Voltage Amplifier

I-V Characterstics of common Source amplifer

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CB

Q

iD

of common Source amplifer

Q vGS= vIQ

vDS = vo

A

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I-V Characterstics of common Source amplifer

7

of common Source amplifer

I-V Characterstics of common Source amplifer

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CB

Q

iD

of common Source amplifer

Q vGS= vIQ

vDS = vo

A

Load Line

Slope of Load Line ?

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Y = m x + C Equation of straight line

I-V Characterstics of common Source amplifer

x + C Equation of straight line

Slope of Load line

of common Source amplifer

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CB

Q

iD

I-V Characterstics of common Source amplifer

vGS= vIQ

vDS = vo

A

of common Source amplifer

Case I

Case II

Transfer CharactersticsSource

vGS = 0.6

vGS = 1.2V

11

Characterstics of common Source amplifer

vt = 0.7

vDD = 5V

RD = 1K

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I-V Characterstics of common Source

12

of common Source amplifer

XA :Cut off AB: Saturation

VDD

VDD =VDSQ

VOB

VOC

Transfer Characterstics of common Source

iD

BC:Triode Region

of common Source amplifer

Digital Applications

Transfer Characterstics of common Source

14Digital Applications

of common Source amplifer

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I-V and Transfer

15

V and Transfer Characterstics

Operation as Switch

Digital Applications16

Operation as Switch

Digital Applications

Saturation

VDD =VDSQ

VOB

Operation as Linear AmplifierOperation as Linear Amplifier

Saturation

VDD =VDSQ

VOB

The positive peaks of the output signals might

VDSQ close to VDD ?

VDSQ close to Triode region ?

The positive peaks of the output signals might bump into VDD

close to VDD ?

close to Triode region ?

Chapter 4 MOS field-Effect Transistors (MOSFETs)

Figure E4.27Selection of Q pointEffect Transistors (MOSFETs)

Figure E4.27Selection of Q point

Slope of Load line based on RD

Cutoff Region

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Cutoff Region

20

Saturation Region

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Saturation Region

21

Saturation Region

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VDD =VDSQ

VOB

Saturation Region

22

Saturation

Saturation Region

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Saturation Region

23

Triode Region

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Triode Region

24

Triode Region

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Triode Region

25

Triode Region

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We know

Triode Region

26

Biasing by Fixing V

2/12/2015 EEE C424/ECE C313

Biasing by Fixing VGS

EEE C424/ECE C313 27

Selection of RD ?

Chapter 4 MOS field-Effect Transistors (MOSFETs)

Figure 4.30

FIGURE 4.30 Biasing using a fixed voltage at the gate, basic arrangement; (b) reduced variability in ID

Biasing by Fixing VGS and Connecting Resistance in the source

Effect Transistors (MOSFETs)

Figure 4.30

FIGURE 4.30 Biasing using a fixed voltage at the gate, VG, and a resistance in the source lead, RS: (a)

Biasing by Fixing VGS and Connecting Resistance in the source

FIGURE 4.30 (c) practical implementation using a single supply (e) practical implementation using two

Practical implementation using single and two supplies

FIGURE 4.30 (c) practical implementation using a single supply (e) practical implementation using two supplies.

Practical implementation using single and two supplies

FIGURE 4.30 (d) coupling of a signal source to the gate using a capacitor

Coupling of a Signal Source to the gate using a capacitor

FIGURE 4.30 (d) coupling of a signal source to the gate using a capacitor CC1

Coupling of a Signal Source to the gate using a capacitor CC1

Biasing MOSFET using large drain to gate feedback resistor R

Biasing MOSFET using large drain to gate feedback resistor RG

Biasing MOSFET using constant current source

Biasing MOSFET using constant current source

Implementation of constant current source using Current Mirror

Implementation of constant current source using Current Mirror