I am confused between Voltage Shunt and Current Shunt Also mention why R2 shouldn't be considered as feedback as it is emitter degeneration resistance

Consider the above circuit why can't I consider the current being one sampled the only problem I see in doing that is that there is no load but if I consider the amplifier to of type series series that should not be a problem as current is going to considered as output quantity and why will I need to worry about load for its measurement.

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    \$\begingroup\$ This looks like a homework problem, and is the third question you have asked in 24 hours regarding feedback and similar transistor circuits. Please tell us what you do understand about this circuit, about "voltage shunt", and about "current shunt". Ask a specific question. \$\endgroup\$ – Elliot Alderson Jun 21 at 12:20
  • \$\begingroup\$ Yes I am revising Feedback circuits chapter so it explains all questions from that side and i am confused as all of circuit where i have seen feedback element taken from collector or drain the feedback type happens to be voltage type feedback I am confused as My professor told me that output and feedback topologies are two different things and just because the output is shown to be voltage it doesn't conforms that feed backed quantity be voltage. \$\endgroup\$ – SUNITA GUPTA Jun 21 at 13:33
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    \$\begingroup\$ .. as My professor told me that .. for nearly all of your questions: why not ask the professor? (S)he's paid to teach you, if something is unclear then you asking questions elsewhere doesn't help making this person a better professor (due to lack of feedback, yes, pun intended: -) ). Also: discuss with your fellow students, having a discussion about things can often really help. \$\endgroup\$ – Bimpelrekkie Jun 21 at 13:50
  • \$\begingroup\$ @Bimpelrekkie You see it was online but logically he held class so he happened to be my professor but their was no option of feedback.So I asked doubt here.And let me get it straight neither are problems home work nor am I trying to judge professor (In fact the concepts he had taught are a way clearer) but the drawback was no feedback so doubts cannot be discussed . Plz clear this or I will have no option but cram "feed back from collector => voltage feedback" \$\endgroup\$ – SUNITA GUPTA Jun 21 at 16:13
  • \$\begingroup\$ For sure we have a global negative feedback loop. And we are sample the voltage. Because If we short the load and the feedback goes to zero (output voltage goes zero), that's voltage feedback. And the feedback signal is in parallel (shunt) with the input. Therefore we have voltage-parallel feedback. \$\endgroup\$ – G36 Jun 21 at 16:33

This looks like a Series-Shunt circuit topology. The way I learned it was that after you identify the feedback circuit, trace the path from the input to that circuit. If you passed through an active device, it is series, otherwise it is shunt. Repeat that process for the output. Then if it is input series, and output shunt it is called "series-shunt."

Feedback is literally the "feeding" of the output "back" into the input. R2 is not in the path of the output signal to the input, thus it is not part of the feedback circuit (beta circuit).

  • \$\begingroup\$ I am not getting from where to trace I mean are you asking me to trace from R4 to collector of Q3.... \$\endgroup\$ – SUNITA GUPTA Jun 21 at 13:37
  • \$\begingroup\$ And regarding R2 consider current at input increases the current through R2 will also increase thus causing decrease in Vbe that is how negative feedback looks like. And doesn't it looks like emitter degeneration resistance used in series series feedback. \$\endgroup\$ – SUNITA GUPTA Jun 21 at 13:40
  • \$\begingroup\$ @SUNITAGUPTA No, I am asking you to trace from the V2+ node to the top node of R4 (which is part of the "B" circuit or feedback circuit) and from the V1+ node to the collector of Q3 (which I'm pretty sure is part of the feedback circuit as well). Because you have to travel through an active device (a BJT in this case) to get to the feedback circuit from the input, but do not have to travel through an active device to get the feedback circuit from the output, the whole circuit is considered a series-shunt circuit. \$\endgroup\$ – Coolt22 Aug 5 at 13:53
  • \$\begingroup\$ @SUNITAGUPTA That is because the input is in series with an active element in respect to the feedback circuit, while the output _shunts_the feedback circuit to a rail. \$\endgroup\$ – Coolt22 Aug 5 at 13:54
  • \$\begingroup\$ @SUNITAGUPTA And regarding R2 being part of the feedback circuit: all active elements naturally have built in feedbacks. That is what makes them active. But that natural component level feedback (which you are describing) is different than a feedback circuit. One enables the device to operate correctly, the other is a tool in circuit design. For example, if you disconnect the V2+ node from the top node of R4, you will remove the circuit feedback, but not remove the natural component feedbacks. \$\endgroup\$ – Coolt22 Aug 5 at 14:02

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