ElectronicsI_L27 - Lecture 27 Common Emitter Our circuit...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
Lecture 27
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Common Emitter Our circuit for the common emitter (CE) amplifier for the BJT looks exactly like the one for the MOSFET common source. We need the bypass capacitor to provide a continuous channel for the signal past the current source. Note here that we will have to concern ourselves with the voltage drop across R B unlike in the FET version. We expect to get better gains from the BJT because the transconductance tends to be much higher.
Background image of page 2
Small Signal CE • We can look at the terminal characteristics beginning with the input resistance. • Normally R B is much larger than R π so the input resistance is: • Note that this means it will be around a few kOhms, a bit low, but still workable. π R R R B in // = R R in
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
CE Amplifier • Next we can look at the voltage that actually makes it to the base of the BJT. • Taking into account the voltage divider effect: • Again is we consider R B to be large, the input voltage is: • At the output, the voltage is (Note this accounts for the Early effect): • This can be restated as the voltage
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/13/2012 for the course PHYSICS 16.365 taught by Professor Staff during the Summer '10 term at UMass Lowell.

Page1 / 10

ElectronicsI_L27 - Lecture 27 Common Emitter Our circuit...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online