147451 Electronic Circuits II & Simulation Lab

II Yr / IV sem

Department of ECE

Page 1

147451 Electronic Circuits II & Simulation Lab CIRCUIT DIAGRAM: CURRENT- SERIES FEEDBACK AMPLIFIER: Without feedback: Without feedback:

II Yr / IV sem

12Vdc

R1 51K

RC 2.4K C2

C1 0.1uF Vin = 20mV f = 20 Hz 20KHz

Q1

0.1uF

BC107A

RL 4.7K R2 9K RE 600

+CRO

CE 5.3uF

Department of ECE

Page 2

147451 Electronic Circuits II & Simulation Lab

II Yr / IV sem

1. CURRENT SERIES FEEDBACK AMPLIFIERAIM:1. To design a Current Series feedback amplifier for the following specifications. Vcc=12 V, Ic=2mA,VBE=0.6V, hfe=200. 2. To plot the frequency response graph for the amplifier with and without feedback. 3. To calculate the following parameters with and without feedback a) Voltage gain b) Bandwidth

EQUIPMENTS REQUIRED:RANGE EQUIPMENT Power supply CRO Function generator (0-30)V (0-20)MHz (0-1)MHz QUANTITY 1 1 1

COMPONENTS REQUIRED:COMPONENT BJT Resistors Capacitors BC107 QUANTITY 1

DESIGN:Given Specifications are Vcc=12 V, Ic=2mA,VBE=0.6V, hfe=200. Rule of Thumb:

IC IE re=26mV/IE re=2610-3/210-3 = 13 hie=hfe re=2.6 K Department of ECE Page 3

147451 Electronic Circuits II & Simulation Lab CURRENT- SERIES FEEDBACK AMPLIFIER: With Feedback:

II Yr / IV sem

12Vdc

R1 51K

RC 2.4K C2

C1 0.1uF Vin = 20mV f = 20Hz 20KHz R2 9K

Q1

0.1uF

BC107

RL 4.7K RE 600 CRO

+

0

Department of ECE

Page 4

147451 Electronic Circuits II & Simulation Lab To find RE:

II Yr / IV sem

To find RC:

To find biasing resistors R1 and R2: Current through R2:

Applying Voltage divider rule,

Department of ECE

Page 5

147451 Electronic Circuits II & Simulation Lab MODEL GRAPH: Frequency Response of Current Series Feedback Amplifier

II Yr / IV sem

Bandwidth without feedback = f3 f2. Bandwidth with feedback = f4 f1.

Department of ECE

Page 6

147451 Electronic Circuits II & Simulation Lab

II Yr / IV sem

by solving (1) & (2) we get

To find CE:

Let the smallest frequency f = 500 Hz

To find CC:

rin=hie=2.6K XCC=3.2K CC=1/ (2fXcc)

Department of ECE

Page 7

147451 Electronic Circuits II & Simulation Lab TABULATION: Without Feedback: Frequency Vo Volts Gain = Vo/Vs

II Yr / IV sem

Vin = Gain (dB) = 20log(Vo/Vs)

With feedback: Frequency Vo Volts Gain = Vo/Vs Vin = Gain (dB) = 20log(Vo/Vs)

Department of ECE

Page 8

147451 Electronic Circuits II & Simulation Lab PROCEDURE:

II Yr / IV sem

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 20Hz to 20 KHz 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 graph. 7. Note the phase angle, bandwidth, input and output impedance. 8. Remove emitter resistance (RE), i.e., feedback loop, and follow the same procedure (1 to 7).

RESULT: Thus the Current-series feedback amplifier was designed for the given specifications and the frequency response graph was plotted for the circuit with and without feedback. The results are summarized as follows:Current Series With Without Feedback Feedback Bandwidth Voltage Gain

Department of ECE

Page 9

147451 Electronic Circuits II & Simulation Lab

II Yr / IV sem

CIRCUIT DIAGRAM: VOLTAGE-SHUNT FEEDBACK AMPLIFIER: Without feedback:

12Vdc

R1 51K

RC2.4K C2

C1 0.1uF Vin = 20mv f = 20Hz 20KHz

Q1

0.1uF

BC107A

RL 4.7K R2 9K RE 600 CRO

+

CE 5.3uF

Department of ECE

Page 10

147451 Electronic Circuits II & Simulation Lab

II Yr / IV sem

2. VOLTAGE SHUNT FEEDBACK AMPLIFIERAIM:1. To design a Voltage Shunt feedback amplifier for the following specifications. Vcc=12 V, Ic=2mA,VBE=0.6V, hfe=200. 2. To plot the frequency response graph for the amplifier with and without feedback. 3. To calculate the following parameters with and without feedback a. Voltage gain b. Bandwidth

EQUIPMENTS REQUIRED:EQUIPMENT Power supply CRO Function generator RANGE (0-30)V (0-20)MHz (0-1)MHz QUANTITY 1 1 1

COMPONENTS REQUIRED: COMPONENT BJT Resistors Capacitors RANGE BC107 QUANTITY 1

DESIGN:Given Specifications are Vcc=12 V, Ic=2mA,VBE=0.6V, hfe=200. Rule of Thumb:

IC IE re=26mV/IE re=2610-3/210-3 = 13 hie=hfe re=2.6 K Department of ECE Page 11

147451 Electronic Circuits II & Simulation Lab VOLTAGE-SHUNT FEEDBACK AMPLIFIER: With Feedback:

II Yr / IV sem

12Vdc

R1 51K 1 R5 2.2K C1 0.1uF VAMPL = 20mV f=20Hz-20KHz V2 C4 0.1uF Q1

R3 2.4K C2 0.1uF

BC107A

RL 4.7K R2 9K 9K R4 600 CRO

+

C3 5.3uF

To find RE: Department of ECE Page 12

147451 Electronic Circuits II & Simulation Lab

II Yr / IV sem

To find RC:

To find biasing resistors R1 and R2: Current through R2:

Applying Voltage divider rule,

MODEL GRAPH: Department of ECE Page 13

147451 Electronic Circuits II & Simulation Lab

II Yr / IV sem

Frequency Response of Voltage-shunt Feedback Amplifier

Bandwidth without feedback = f3 f2. Bandwidth with feedback = f4 f1.

Department of ECE

Page 14

147451 Electronic Circuits II & Simulation Lab

II Yr / IV sem

by solving (1) & (2) we get

To find CE:

Let the smallest frequency f = 500 Hz

To find CC:

rin=hie=2.6K XCC=3.2K CC=1/ (2fXcc)

Department of ECE

Page 15

147451 Electronic Circuits II & Simulation Lab TABULATION: With Feedback: Frequency Vo Volts Gain = Vo/Vs

II Yr / IV sem

Vin = ------ V Gain (dB) = 20log(Vo/Vs)

Without feedback: Frequency Vo Volts Gain = Vo/Vs Vin = V Gain (dB) = 20log(Vo/Vs)

Department of ECE

Page 16

147451 Electronic Circuits II & Simulation Lab PROCEDURE:

II Yr / IV sem

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 20Hz to 20 KHz 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 graph. 7. Note the phase angle, bandwidth, input and output impedance. 8. Connect the feedback resistor (Rf) between the base and the collector to form the feedback loop, and follow the same procedure (1 to 7). RESULT: Thus the Voltage-shunt feedback amplifier was designed for the given specifications and the frequency response graph was plotted for the circuit with and without feedback. The results are summarized as follows:Voltage-shunt With Without Feedback Feedback Bandwidth Voltage Gain

SERIES AND SHUNT FEEDBACK AMPLIFIER Sample viva questions:1. 2. What are the advantages of negative Feedback amplifier when compare with amplifier? 3. What will happen to the Bandwidth, gain, output and input resistance of voltage series feedback amplifier because of feedback? 4. Define negative feedback. 5. What is the type of feedback employed in feedback amplifier? 6. Compare Oscillator and Amplifier. 7. Define Desensitivity and Sensitivity factor. 8. When a feedback amplifier is said to be stable? 9. A common emitter circuit without By-pass capacitor is called a negative current feedback circuit why? 10. Current series amplifier is a Transconductance amplifier: Justify? 11. Voltage Shunt amplifier is a Transresistance amplifier: Justify? 12. A common collector amplifier circuit is an example of which negative feedback circuit? CIRCUIT DIAGRAM: Department of ECE Page 17

147451 Electronic Circuits II & Simulation Lab

II Yr / IV sem

RC PHASE SHIFT OSCILLATOR:

Department of ECE

Page 18

147451 Electronic Circuits II & Simulation Lab

II Yr / IV sem

3. DESIGN OF RC PHASE SHIFT OSCILLATOR AIM:1. To design and construct a RC Phase shift oscillator for the following specifications. Vcc = 12V, Ic = 2mA, VBE = 0.6V, hfe = 200, f = 2 KHz, C = 0.01F 2. To plot the output sine waveform graph for the Oscillator.

EQUIPMENTS REQUIRED:EQUIPMENT Power supply CRO RANGE (0-30)V (0-20)MHz QUANTITY 1 1

COMPONENTS REQUIRED: COMPONENT BJT Resistors Capacitors RANGE BC107 QUANTITY 1

DESIGN:Given Specifications are Vcc = 12V, Ic = 2mA, VBE = 0.6V, hfe = 200, f = 2 KHz, C = 0.01F Rule of Thumb:

IC IE re=26mV/IE re=2610-3/210-3 = 13 hie=hfe re=2.6 K

Department of ECE

Page 19

147451 Electronic Circuits II & Simulation Lab

II Yr / IV sem

MODEL GRAPH:

Department of ECE

Page 20

147451 Electronic Circuits II & Simulation Lab To find RE:

II Yr / IV sem

To find RC:

To find biasing resistors R1 and R2: Current through R2:

Applying Voltage divider rule,

Department of ECE

Page 21

147451 Electronic Circuits II & Simulation Lab

II Yr / IV sem

TABULATION:

Amplitude (Volts)

Time Period T (Seconds)

Frequency f (KHz)

Department of ECE

Page 22

147451 Electronic Circuits II & Simulation Lab

II Yr / IV sem

by