ecm2d.weebly.com · Web viewTo plot the transistor characteristics of a Common – Emitter configuration and to find the h – parameters to the same. Equipment required: Equipment

1. DIODE CHARACTERISTICS

Aim: To study the diode characteristics under forward and reverse biased conditions.

(1) Junction Diode(2) Zener Diode

Equipment required:

Name of the equipment Range QuantityPower Supply (0 – 30) V 1 No

Ammeter (0 – 30) mA(0 – 100) µA

1 No1 No

Voltmeter (0 – 1) V(0 – 30) V

1 No1 No

Circuit: Forward Bias

Fig A

Circuit: Reverse Bias

Fig B

Procedure:

Forward Bias:

(i) Connect the circuit as per the circuit diagram.(ii) Vary the power supply voltage in such a way that the readings are taken in steps of

0.1 V in the voltmeter till the power supply shows 20V.(iii) Note down the corresponding ammeter readings.(iv) Plot the graph between V and I.

(v) Find the dynamic resistance .

Reverse Bias:

(i) Connect the circuit as per the circuit diagram.(ii) Vary the power supply voltage in steps of 1 V till the voltmeter reads 20V.(iii) Note down the corresponding ammeter readings.(iv) Plot the graph between V and I.

(v) Find the dynamic resistance .

Result: Forward and Reverse bias characteristics of Junction and Zener diodes are plotted and their dynamic resistance is as follows:

Dynamic resistance r Junction Diode Zener DiodeForward BiasReverse BiasModel Graph:

I (mA)

-I (µA)

V (V)-V (V)V1 V2

I1

I2

VB

VB : Break down Voltage

ΔV

ΔI

Testing of Diode:

Connect negative probe of the multimeter to the cathode and positive probe to the anode. The meter will not show any reading. Now inter change the connections. i.e. negative probe of the multimeter to the anode and positive probe to the cathode. The meter will show reading. If in both of these positions, the diode does not show any reading, then the diode is open and if in both these positions diode shows reading (of low resistance), then the diode is leaking. If in both these positions diode shows zero ohms, then the diode is short. If we take the voltage drop across the diode under forward based condition, it will show 0.6 to 0.7 V for a silicon diode and 0.2 to 0.3 V for a Germanium diode.

Review Questions:

1) For which substance the width of the forbidden band lies between a conductor and an insulator?

2) What is biasing?3) How does the temperature affect the breakdown voltage?4) What is volt equivalent of temperature VT? 5) What is diode resistance?

2. CLIPPING AND CLAMPING CIRCUITS

Aim: To observe the clipping waveform in different clipping configurations and to study the clamping circuits as (a) Positive clamping circuits (b) Negative clamping circuits

Equipment Required:

Equipment Range QuantitySignal Generator (0 – 1) MHz 1 No

Cathode Ray Oscilloscope (0 – 20) MHz 1 NoPower Supply (0 – 30) V 1 No

Circuit Diagram:

Clipping Circuits:

Clipping Circuits:

Fig 1. (a)

1KΩ

5 V1 KHz

0.7 V+

-

+

-2 V

VO

+

-

Fig 1. (b)

Fig 1. (c)

2 V

Fig 1. (d)

Fig 1. (e)

Fig 2. (a)

Fig 2. (b)

Fig 2. (c)

Fig 2. (d)

Clamping Circuits:

Procedure:

(1) Connect the circuits as per the circuit diagram.(2) Set the input signal voltage (say 5V, 1KHz) using signal generator.

C

R

(3) Observe the output waveforms using CRO operated in dc mode.(4) Sketch the observed waveform on the graph sheet.

Clamping Circuits:

Design equations:

Given f = 1KHz, T = τ = 1/f = 1X10-3 sec = RC

Assuming C = 0.1 µF; then R = 10 KΩ.

Procedure:

(1) Connect the circuits as per the circuit diagram.(2) Set the input signal voltage (say 5V, 1KHz) using signal generator.(3) Observe the output waveforms using CRO operated in dc mode.(4) Sketch the observed waveform on the graph sheet.

Review Questions:

1)What is a clipper or a limiter circuit?2)Which circuit is used for amplitude selection?3)What is a clamper circuit?4)What is the role of τ = RC time constant in clamper circuits?5)What is the difference between positive and negative clampers?

3. TRANSISTOR CHARACTERISTICS

Aim: To plot the transistor characteristics of a Common – Emitter configuration and to find the h – parameters to the same.

Equipment required:

Equipment Range QuantityPower Supply (dual channel) (0 – 30) V 1 No

Ammeter (0 – 10) mA and (0 – 1) mA 2 Nos (1 No each)Voltmeter (0 – 30) V and (0 – 2) V 2 Nos (1 No each)

Circuit Diagram:

Procedure:

Input characteristics:

(1) Connect the circuit as per the circuit diagram.(2) Set VCE = constant (say 5 V) and vary VBE in steps of 0.1V and note down the

corresponding IB. (3) Repeat the above procedure for VCE = 10 V, 15 V, etc…(4) Plot the graph between VBE and IB for constant VCE.(5) Find the h – parameters: (a) hfe : Forward Current Gain

(b) hie : Input impedance

Output characteristics:

(1) Connect the circuit as per the circuit diagram.(2) Set IB = constant (say 20 µA) and vary VCE in steps of 1V and note down the

corresponding IC. (3) Repeat the above procedure for IB = 40 µA, 60 µA, etc…(4) Plot the graph between VBE and IB for constant VCE.(5) Find the h – parameters: (a) hre : Reverse Voltage Gain

(b) hoe : Output admittance

Model Graph:

Input characteristics:

Output characteristics:

Tabular column:

Input characteristics: VCE = Constant

VBE (Volts) IB (µA)

VBE1 VBE2

IB2

IB1

VBE Volts

IB µA

VCE Volts

ICO

IB4

IB3

IB2

IB1

VCE = constant

IC mA

IC2

IC1

Output characteristics: IB = Constant

VCE (Volts) IC (mA)

Result:

Parameter Practical readingshfe

hie

hre

hoe

Review Questions:

1) What is the biasing condition for a transistor in active region?2) What are dependent and independent variables in BJT model?3) What is meant by a Bipolar Junction Transistor?4) What are the main features of selecting h – parameters for BJT modelling?5) What is base spreading resistance in BJT?

4. FET CHARACTERISTICS

Aim: To plot drain and transfer characteristics for the given FET and to find the drain resistance and trans-conductance.

Equipment required:

Equipment Range QuantityPower Supply (dual channel) (0 – 30) V 1 No

Ammeter (0 – 30) mA 1 NoVoltmeter (0 – 30) V 2 Nos

Circuit Diagram:

Procedure:

Drain Characteristics:

(1)Connect the circuit as per the circuit diagram.(2)Set the gate voltage VGS = constant (say -1 V) and vary the drain voltage VDS in steps of

1V and note down the corresponding drain current ID. (3)Repeat the above procedure for VGS = 0 V, +1 V, etc…(4)Plot the graph between VDS and ID for constant VGS.

(5)Find the drain resistance .

Transfer characteristics:

(1) Connect the circuit as per the circuit diagram.(2) Set the drain voltage VDS = constant (say +5 V) and vary the gate voltage VGS in steps

of 1V (negative voltage) and note down the corresponding drain current ID.

(0-30) V

+-

68KΩ

+-

+ -

+-

1KΩ(0-30) mA

(0-30) V

(0-30) V (0-30) V

BFW 10

(3) Repeat the above procedure for VDS = +10 V, +15 V, etc…(4) Plot the graph between VGS and ID for constant VDS.

(5) Find the trans-conductance .

Model Graph:

Drain Characteristics:

Transfer Characteristics:

Tabular column:

Drain characteristics: VGS = Constant

VDS (Volts) ID (mA)

ID mA

VDS V

ID2

ID1

VGS4

VGS3

VGS2

VGS1

VDS1 VDS2

VGS = constant

ID mA

ID2

ID1

VGS (Volts) VGS2 VGS1

VDS = Constant

Transfer Characteristics: VDS = Constant

VGS (Volts) ID (mA)

Result:

Parameter Practical readingsrD

gm

µ = rD x gm

Review Questions:

1) What are the distinguished characteristics of a FET over a BJT?2) What are the advantages and disadvantages of FET?3) Why it is FET called so?4) What is pinch – off voltage?5) What is Voltage Variable Resistance (VVR) in a FET?6) What is the main application of a VVR in a FET?

5. PHOTO DETECTOR

Aim: Study of photo Detector’s characteristics

1. Light dependent resistor

2. Photo diode

3. Photo Transistor

Equipment Required:

S. No Equipment Range Quantity

1.Power Supply

(Dual Channel)(0-30) V 1

2. Ammeter (0-10) mA 1

3. Voltmeter(0-10) V(0-30) V

2

Circuit Diagram:

Light Dependent Resistor:

Photo Diode:

(0-10) V(0-10) V

(0-30) V

(0-10) mA680 Ω

DC bulbLDR

1 KΩ

(0-30) V

(0-10) V (0-10) V (0-30) V

(0-100) µA680 Ω

DC bulb

1 KΩ

(0-30) V

Photo Transistor:

Procedure:

Light Dependent Resistor:

1. Connect the circuit as per the circuit diagram.

2. Maintain a known distance (say 5 cm) between the DC bulb and the LDR.

3. Vary the voltage of the bulb in steps of 1V and note down the resistance value across the LDR using multimeter.

4. Plot the graph: V vs R.

Photo Diode:


2. Maintain a known distance (say 5 cm) between the DC bulb and the Photo Diode.

3. Set the voltage of the bulb (say 2V), vary the voltage of the diode in steps of 1V and note down the corresponding diode current IT.

4. Repeat the above procedure for VL = 4V, 6V etc.

5. Plot the graph: VT vs IT for a constant VL.

Model Graph:

(0-10) V (0-10) V (0-30) V

(0-10) mA680 Ω

DC bulb

1 KΩ

(0-30) V

Photo Diode

Photo Transistor

Note: Repeat the Photo Diode experiment procedure for Photo Transistor also.

Review Questions:

1. What is the difference between Diode and Photo Diode?

2. What is meant by dark current in Photo Diode?

3. What is a Photo Transistor?

R (Ω)

V (Volts)IT

(µA)

VT (Volts)

V3V2V1

IT (mA)

VT (Volts)

V3V2V1

V4

Light Dependent Resistor

4. What is the working principal of LDR?

5. What is the roll of DC bulb in this experiment?

6. SELF BIAS BJT AMPLIFIER

Aim: To design and implement the self bias circuit amplifier and obtain

1. Bias Resistance 2. Measures of gain 3. Frequency response.

Equipment Required:


1. Power Supply (0-30) V 1

2. CRO (0-20) MHz 1

3. Function Generator (0-1) MHz 1

Design:

Given data: VCC = 15V, IC = 1 mA, hfe (obtain from multimeter or manual)

For active condition

Circuit Diagram:

Procedure:


2. Set Vs = 50 mV, using the signal generator.

3. Keeping the input voltage constant, vary the frequency from 0 to 1MHz in regular steps and note down the corresponding output voltage.

4. Plot the graph: gain (dB) vs. frequency.

5. Find the input and output impedances.

6. Calculate the bandwidth from the frequency graph.

Tabular Column:

Vs = 50 mV

S. No Frequency Vo (Volts) Gain = Vo/ Vi Gain (dB) = 20 log(Vo/ Vi)

VS = 50 mV

Freq = (0-1 ) MHz

+VCC

Model Graph:

Result:

Parameter Theoretical Practical

Gain(Mid band)

Bandwidth

Review Questions:

1. Define amplification?

2. What is biasing? Why it is necessary?

3. Mention the applications of CE amplifier, justify?

4. Universal biasing technique is preferred over any other biasing technique. Why?

7. SINGLE STAGE RC COUPLED AMPLIFIER

Aim: To design and implement the RC coupled amplifier circuit and to find

1. Cut-off frequencies 2. Band Width 3. Mid Band gain

4. Input/output impedance.

Equipment Required:



2. CRO (0-20) MHz 1


Design:

Given data: VCC = 15V, IC = 1 mA, fL = 100Hz, Stability factor = (0-10), hfe (obtain from multimeter or manual), AVS = 50 dB, IE = 1.2mA.

Gain formula is given by

Assuming,

Effective load resistance is given by RL eff = RC// RL

Emitter resistance is given by

Where, re is internal resistance of the transistor

On applying KVL to output loop, we get

VCC = ICRC + VCE + IERE

Where VE = IERE

Find RC =?

From equation, find RL =?

Since IB is very small when compared with IC.

IC = IE

VB = VBE + VE

Stability factor

Find RB =?

RB = RB1 // RB2

Find RB1 and RB2

Input impedance Zi = (RB // hie)

Output impedance Zo = RC // RL

Input coupling capacitance is given by

XCi = Zi / 10

Find Ci =?

Output coupling capacitance is given by

XCo = (RC // RL)/10

Find Co =?

By pass capacitance is given by

Find CE =?

Circuit:

Procedure:

1. Connect the circuit as per the circuit diagram.2. Set Vs = 50 mV, using the signal generator.3. Keeping the input voltage constant, vary the frequency from 0 to 1MHz in regular

steps and note down the corresponding output voltage.4. Plot the graph: gain (dB) vs. frequency.5. Find the input and output impedances.6. Calculate the bandwidth from the frequency graph.

VS = 50 mV

Freq = (0-1 ) MHz

RS

CCi

RB1

RB2

RC

RE

CCo

CE

RLV

i

Vo

+VCC

Tabular Column:

Vs = 50 mV


Model Graph:

Result:


Input impedance Zi = RBB / hie

Output impedance Zo = RC // RL

Gain(Mid band)

Bandwidth

Review Questions:

1. Why is negative feedback used in RC Coupled amplifier?

2. Why 3dB line in gain calculations?

3. Mention applications of RC Coupled amplifier.

4. What is the phase angle in RC Coupled amplifier?

8. FET AMPLIFIER

Aim: To determine the parameters of the single stage JFET amplifier (Common Drain).

1. Band Width 2. Mid Band Gain 3. Input and Output impedances.

Equipment Required:



2. CRO (0-20) MHz 1


Design:

Given data: IDSS = 10mA; VP = -4V; fL = 50Hz; VDD = 12V; RS = 680Ω.

From the DC bias condition

For which

Find VGS =?

VDD = IDRD + VDS + VS

Since ID = IS (IG = 0)

Assume RS = 500Ω

Find RD =?

Find

The value of gm at the bias voltage is given by

Find gm =?

Find rm =?

With RS completely by passed the largest amplifier gain is given by

Find AV =?

For which RGS = open and RGS = 100MΩ


XCi = RGS / 10

Find Ci =?


XCO = (RD // RL) / 10

Find CO =?

By pass capacitor is given by

Find CS =?

Circuit:

Procedure:


2. Set Vs = 50mV, using the signal generator.





VS = 50mV

Freq = (0-1 ) MHz

R’S

Ci

RE

Co

RL

Vi

+VD

D

RG

S

CS

RD

RS

VO

Tabular Column:

Vs = 50mV


Model Graph:

Result:


Input impedance

Output impedance

Gain(Mid band)

Bandwidth

Review Questions:

1. What are the advantages of FET amplifier over conventional transistor amplifier?

2. List out the applications of FET amplifier, justify?

3. What are the factors, which influence the higher cut- off frequency?

4. What components, which influence the lower cut-off frequency?

9. CASCODE AMPLIFIER

Aim: Design and test the cascode amplifier for the given specifications and find the following

1. Mid Band Gain 2. Input/output impedance

Equipment Required:



2. CRO (0-20) MHz 1


Design:

Given data:

VCC = 15V, fL = 1 KHz, S = (2-10), IE1 = IE2 = 1mA, RL = 4.7KΩ.

AVT = 100, β1 = β2 = 100, RS = 600Ω.

Assume

RL eff = Rc // RL

hie1 = β1 re1

β1 = β2

IE1 = IE2

re1 = re2

Gain is given by

With RL = re2 = hib2 of transistor 2 and

Total gain is given by

AVT = AV1AV2 = 100

Find AV2 =?

Calculate RC from RL eff = Rc // RL

On applying KVL to output loop, we get

VCC = ICRC + VCE1 + VCE2 + VE

Find RE =?

Since β1 = β2 = 100, IB1 = IB2

Assume R3 = 4.7KΩ, I3 = VB1 / R3

Find I3 =?

I2 = I3 + IB1

Find I2 =?

R2 = [VB2 – VB1] / I2

I1 = I2 + IB2

Find I1 =?

R1 = [VCC – VB2] / I1

Find R1 =?


XC2 = (hie2 // RL // R3) / 10

Find C2 =?

XC1 = (hie1 // R1 // R2) / 10

Find C1 =?


XCO = (RC // RL) / 10

Find CO =?

By pass capacitor is given by

Find CE =?

Circuit:

Procedure: 1. Connect the circuit as per the circuit diagram.2. Set Vs = 50mV, using the signal generator.3. Keeping the input voltage constant, vary the frequency from 0 to 1MHz in regular

steps and note down the corresponding output voltage.4. Plot the graph: gain (dB) vs. frequency.5. Find the input and output impedances.

VS = 50mV

Freq = (0-1 ) MHz

RS

CCi

R1

R2

RE

CCo

RL

Vi

+VCC

Q1

Q2

R3

CE

RC

C

I1

I2

I3

IB2

IB1


Tabular Column:

Vs = 50mV


Model Graph:

Result:


Input impedance

Output impedance

Gain(Mid band)

Bandwidth

Review Questions:

1. What is the difference between darlington pair and cascode amplifier?

2. What is the phase angle in darlington pair amplifier?

3. What is the phase angle in cascode amplifier?

4. List out the particular applications of darlington pair amplifier and cascode amplifier. Justify?

10. DARLINGTON PAIR (COMMON COLLECTOR AMPLIFIER)

Aim: Design and test a darlington current amplifier and find the following

2. Current Gain 2. Voltage Gain 3. Band Width 4. Input/output impedance

Equipment Required:



2. CRO (0-20) MHz 1


Design:

Given data:

VCC = 12V, fL = 50Hz, S = (0-10), IE = 1mA, RL = 1KΩ.

AV ≤ 1, AI = AI1 * AI2

Since hfe1 = hfe2,

AI = (hfe) 2

From DC bias analysis, on applying KVL to the output loop, we get

VCC = VCE + IERE,

,

RE eff =?

VE = IERE eff,

RE eff = RE // RL,

Find RE =?

Find RB =?

RB = R1 // R2

VB = VBE + VE

Find R1 & R2 =?

Zi1 = 2 hie + (1+ hfe1) RE

Find Zi1 =?

Zieff = Zi1 // RBB

Zo = RE // [((RS // RB) + 2 hie)/ (hfe) 2]

Find Zo =?

Find Ci =?

Find CE =?

Circuit:

Procedure:


2. Set Vs = 1 V, using the signal generator.





Tabular Column:

Vs = 1 V


Model Graph:

VS = 1 V

Freq = (0-1 ) MHz

RS

CCi

R1

R2 R

E

CC

o

RL

Vi

Vo

+VC

C

Q1

Q2

Result:


Input impedance

Output impedance

Gain(Mid band)

Bandwidth

Documents

ecm2d.weebly.com · Web viewTo plot the transistor characteristics of a Common – Emitter configuration and to find the h – parameters to the same. Equipment required: Equipment