135N. Driver stages, output stages, Class A and Class B

Comments · 17

• MR

  @MrGaarde · 4 years ago

  I enjoyed the lecture, taking me back to the mid eighties to start nineties, when I designed bipolar integrated circuits. We used to adjust the bias current in the bias diodes in the diver stage so that we had a class A current flowing in the output transistors. This way we got a lower cross over distortion. We also put a small resistor in series with the npn emitter. This was a part of a protection circuit for limiting the short circuit current. One of the drawbacks of this classic class AB output stage is the need for a high voltage supply. If you make a bipolar output stage where the output is at the collectors it is possible to get as close to rails as a saturation voltage. I am still in IC design and as a famous designer said in the nineties: ‘ Someday the mos devices will get so small that they will go directly from sub threshold into velocity saturation and we will be back at bipolars’, not to mention the leak in the gate :-) Thanks for your lecture.

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• CO

  @corydiehl764 · 6 years ago

  Awesome, this is where my uni stopped with the lectures on this topic. Really looking forward to 50 more videos of new content :)

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• KA

  @karlivares8401 · 4 years ago

  Great !

• OH

  @ohigefly · 5 years ago (edited)

  うちの親父は「100Vだと肘まで、200Vだと肩まで感電する」と言ってました。

• AN

  @anders5611 · 5 years ago

  Incredible lectures prof. Hajimiri ! Thank you very much.

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• ZI

  @zinhaboussi · 2 years ago

  <a href="https://www.youtube.com/watch?v=1px4JAzHxCo&amp;t=2">00:02</a> Driving a resistive load is necessary for circuits to deliver energy.<br><a href="https://www.youtube.com/watch?v=1px4JAzHxCo&amp;t=130">02:10</a> Driver stages and output stages in amplifiers<br><a href="https://www.youtube.com/watch?v=1px4JAzHxCo&amp;t=413">06:53</a> Lowering voltage reduces current through the output stage.<br><a href="https://www.youtube.com/watch?v=1px4JAzHxCo&amp;t=552">09:12</a> The problem with driving an amplifier to push a speaker to full power<br><a href="https://www.youtube.com/watch?v=1px4JAzHxCo&amp;t=872">14:32</a> Class A amplifier operation and limitations<br><a href="https://www.youtube.com/watch?v=1px4JAzHxCo&amp;t=1026">17:06</a> Combining current sink and source for effective operation<br><a href="https://www.youtube.com/watch?v=1px4JAzHxCo&amp;t=1303">21:43</a> Understanding the need for a dead zone due to transistors&apos; VBE on requirement.<br><a href="https://www.youtube.com/watch?v=1px4JAzHxCo&amp;t=1440">24:00</a> Tug-of-war between currents in driver stages<br><a href="https://www.youtube.com/watch?v=1px4JAzHxCo&amp;t=1722">28:42</a> Efficiency defined as power delivered to the load vs. DC power.<br><a href="https://www.youtube.com/watch?v=1px4JAzHxCo&amp;t=1860">31:00</a> Power delivered to the transistor causes heat<br><a href="https://www.youtube.com/watch?v=1px4JAzHxCo&amp;t=2141">35:41</a> Bipolar transistors have specific junctions and characteristics<br>Crafted by Merlin AI.

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• PL

  @pl5094 · 6 years ago (edited)

  <a href="https://www.youtube.com/watch?v=1px4JAzHxCo&amp;t=1740">29:00</a> When finding the efficiency of a class AB amplifier, is the biasing current not taken into account? Is it because the bias current is much smaller than the DC current in the amplifier such that the bias current can be ignored? <br> <br><a href="https://www.youtube.com/watch?v=1px4JAzHxCo&amp;t=2025">33:45</a> is this circuit topology (PMOS on top, NMOS in the bottom) intended to be a switching converter? <br> <br>Can the negative terminal of a class B/AB amplifier connected to the ground instead of the negative supply voltage? If so, then the output of the amplifier must have a non-zero DC value? <br> <br>Is it correct to say that the max time-averaged efficiency happens when the amplitude of the output voltage is closest to the supply voltage? On the other hand, the max instantaneous efficiency happens when Iq = Imax (i.e. when the transistor operates at the edge of the saturation region)?

• BA

  @bayareapianist · 7 years ago (edited)

  You did not finish your very last subject. &nbsp; Do bjts latach up like SCRs? SCRs are used in power circuits. &nbsp; Please upload your follow up lecture. &nbsp; Thanks

• مل

  @ملكةزماني-ذ4ر · 6 years ago

  What is the minimum value of the DC biasing current in class A output stage? Explain you answer.

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• MA

  @Maryam-dt4bf · 6 years ago

  What is the minimum value of the DC biasing current in class A output stage

• مل

  @ملكةزماني-ذ4ر · 6 years ago

  Hi, I have a question

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