Documents

Lec-11 frequency resonse of bjt - iit g.pdf

Description
Description:
Categories
Published
of 14
All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.
Share
Transcript
  Analog & Digital Electronics Course No: PH-218Lec-11: Frequency Response of BJT Amplifiers Course Instructors:  Dr. A. P. VAJPEYI Department of Physics, Indian Institute of Technology Guwahati, India 1  Frequency Response of CE BJT Amplifier C  f  X  C  ××= π  21 Assumingthatthecouplingandbypasscapacitorsareidealshortsatthemidrangesignalfrequency,themidrangevoltagegaincanbedeterminedby 2 ', ) \  \ ( e LC mid v r  R R A  =  In the low frequency range, BJT amplifier has three high-pass RC circuits, namely input, bypass and output RC circuit,that affect its gain.  The lower cutoff frequency of a given common emitter amplifier will be given by the highest of the individual RC circuits. f C-low = MAX(f c-input ,f c-output ,f c-bypass )  Low Frequency Response of Input RC circuit The input RC Circuit  basein  R R R − =  \  \  \  \ R 21in in V  RV   =   3  As the signal frequency decreases, X  C1 increase, This causes less voltage across the input resistance of the amplifier at the base and because of this, the overall voltage gain of the amplifier is reduced. ninc  R X   221  +  Decibel Bel is a form of gain measurement and is commonly used to express amplifier response. The Bel is a logarithm measurement of the ratio of one power to another or one voltage to another. ) / (log 1210  PPG  = It was found, that the Bel was too large a unit of measurement for ) / (log20)( ) / (log10)( 12101210 V V dBG PPdBG ==   4  practical purposes, so the decibel (dB) was defined such that 1B =10dB 0 dB reference It is often convenient in amplifiers to assign a certain value of gain as the 0 dB reference This does not mean that the actual voltage gain is 1 (which is 0 dB); it means that the reference gain, is used as a reference with which to compare other values of gain and is therefore assigned a 0 dB value. The maximum gain is called the midrange gain and is assigned a 0 dB value. Any value of gain below midrange can be referenced to 0 dB and expressed as a negative dB value.
Search
Tags
Related Search
We Need Your Support
Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

Thanks to everyone for your continued support.

No, Thanks
SAVE OUR EARTH

We need your sign to support Project to invent "SMART AND CONTROLLABLE REFLECTIVE BALLOONS" to cover the Sun and Save Our Earth.

More details...

Sign Now!

We are very appreciated for your Prompt Action!

x