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university:courses:electronics:text:chapter-9 [06 Jun 2017 17:19] – [9.2.5 common emitter and source Lab Activities] Doug Merceruniversity:courses:electronics:text:chapter-9 [06 Jun 2017 17:26] – [9.3.4 Output impedance, current follower or common base/gate amplifier] Doug Mercer
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 Again looking at the small signal models in figure 9.3.1 we see that for both the BJT case and the MOS case the output impedance is the parallel combination of R<sub>L</sub> and r<sub>o</sub>. We can generally assume this is true if we consider that V<sub>in</sub> is driven from a low impedance (nearly ideal) voltage source. If this is not the case then the finite output impedance must be added in series with r<sub>o</sub>. If the input of the current follower is driven by the relatively high output impedance of a transconductance amplifier such as the common emitter or source amplifier from earlier then the output impedance for the combined amplifier can be very high. For most practical applications we can ignore r<sub>o</sub> because it is very often much larger than R<sub>L</sub>.  Again looking at the small signal models in figure 9.3.1 we see that for both the BJT case and the MOS case the output impedance is the parallel combination of R<sub>L</sub> and r<sub>o</sub>. We can generally assume this is true if we consider that V<sub>in</sub> is driven from a low impedance (nearly ideal) voltage source. If this is not the case then the finite output impedance must be added in series with r<sub>o</sub>. If the input of the current follower is driven by the relatively high output impedance of a transconductance amplifier such as the common emitter or source amplifier from earlier then the output impedance for the combined amplifier can be very high. For most practical applications we can ignore r<sub>o</sub> because it is very often much larger than R<sub>L</sub>. 
  
 +**ADALM1000 Lab Activity, [[university:courses:alm1k:alm-lab-cb|BJT Common Base Amplifier]]**\\
 +**ADALM1000 Lab Activity, [[university:courses:alm1k:alm-lab-cg|BJT Common Gate Amplifier]]**\\
 +**ADALM1000 Lab Activity, [[university:courses:alm1k:alm-lab-fca|Folded Cascode Amplifier]]**
 ==== 9.4 Voltage followers (also called Emitter or Source follower or Common collector or drain amplifiers) ==== ==== 9.4 Voltage followers (also called Emitter or Source follower or Common collector or drain amplifiers) ====
  
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 ====9.4.5 Voltage Follower (common collector or drain) Lab Activities ==== ====9.4.5 Voltage Follower (common collector or drain) Lab Activities ====
  
-[[university:courses:electronics:electronics-lab-11|BJT Emitter follower]]\\ +**ADALM1000 Lab Activity 11, [[university:courses:alm1k:alm-lab-11|BJT Emitter follower]]**\\ 
-[[university:courses:electronics:electronics-lab-11m|MOS source follower]]\\+**ADALM1000 Lab Activity 11M, [[university:courses:alm1k:alm-lab-11m|MOS Source follower]]**
  
 +**ADALM2000 Lab Activity 11, [[university:courses:electronics:electronics-lab-11|BJT Emitter follower]]**\\
 +**ADALM2000 Lab Activity 11m, [[university:courses:electronics:electronics-lab-11m|MOS Source follower]]**
  
 =====9.5 Series Feedback: emitter/source degeneration===== =====9.5 Series Feedback: emitter/source degeneration=====
university/courses/electronics/text/chapter-9.txt · Last modified: 07 Oct 2020 16:37 by Doug Mercer

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