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APECE-302: Radio & Television Engineering
Course Teacher: Dr. S.M. Riazul Islam
Date: 2012 Year, 05 Month, 08 Day
University of Dhaka, APECELecture Materials on APECE-302
1Web: www.riazulislam.com E-mail: [email protected]
Applied Physics, Electronics & Communication Engineering
University of Dhaka |APECE
DU
Lecture # 04
Contents
Noise and its Classification
Thermal Noise
Shot Noise
Addition of Noise from Different Sources
Addition of Noise in Cascaded System
Signal to Noise Ratio
Noise Figure
2Web: www.riazulislam.com E-mail: [email protected]
University of Dhaka, APECELecture Materials on APECE-302
Dr. SMR Islam
Noise and its classification
Noise: Unwanted Signal
External Atmospheric/static
Extraterrestrial
Man-made
Internal Thermal
Shot
Transit time
Misc (Flicker, Transistor thermal, partition)
3Web: www.riazulislam.com E-mail: [email protected]
University of Dhaka, APECELecture Materials on APECE-302
Dr. SMR Islam
Thermal noise
4Web: www.riazulislam.com E-mail: [email protected]
University of Dhaka, APECELecture Materials on APECE-302
Dr. SMR Islam
Resistor as a noise generator
Noise Power:
Thermal noise
5Web: www.riazulislam.com E-mail: [email protected]
University of Dhaka, APECELecture Materials on APECE-302
Dr. SMR Islam
Thermal noise
6Web: www.riazulislam.com E-mail: [email protected]
University of Dhaka, APECELecture Materials on APECE-302
Dr. SMR Islam
Shot noise
7Web: www.riazulislam.com E-mail: [email protected]
University of Dhaka, APECELecture Materials on APECE-302
Dr. SMR Islam
For a diode, rms shot noise current:
Adding thermal noise and shot noise component??
Overcome by taking R_eq
Addition of noise due to several sources
8Web: www.riazulislam.com E-mail: [email protected]
University of Dhaka, APECELecture Materials on APECE-302
Dr. SMR Islam
Several thermal noise sources in series:
Addition of noise in cascaded amplifiers
9Web: www.riazulislam.com E-mail: [email protected]
University of Dhaka, APECELecture Materials on APECE-302
Dr. SMR Islam
Equivalent I/P noise voltage:
Addition of noise in cascaded amplifiers
10Web: www.riazulislam.com E-mail: [email protected]
University of Dhaka, APECELecture Materials on APECE-302
Dr. SMR Islam
Signal to Noise Ratio (SNR)
11Web: www.riazulislam.com E-mail: [email protected]
University of Dhaka, APECELecture Materials on APECE-302
Dr. SMR Islam
Purpose?
Comparing two system’s performances
To know the relative signal strength at the same point
Noise Figure:
Greater than unity
>>> Noise Figure & Noise Temperature>>> Next Lecture>>>
Q & A
12Web: www.riazulislam.com E-mail: [email protected]
University of Dhaka, APECELecture Materials on APECE-302
Dr. SMR Islam
