Timeline for How does the collector feedback bias circuit work?
Current License: CC BY-SA 4.0
14 events
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| Oct 14, 2022 at 16:38 | comment | added | jonk | @LvW Thanks for that! I'll spend a little more time on it, shortly. But that looks about like what I would have hoped. Great! | |
| Oct 14, 2022 at 11:34 | comment | added | LvW | It can be shown that for small signals (linearization of block diagrams) BOTH diagrams give the same result for the function delta (Ic)=f((delta Vcc) rsp. ic=f(vcc). I think this prooves the identity of both diagrams, | |
| Oct 14, 2022 at 7:45 | comment | added | LvW | In my contribution (Edit) I have added "my blockdiagram". What do you think about it? (I will try to show a better diagram - not handwritten - soon) | |
| Oct 13, 2022 at 18:41 | comment | added | jonk | @LvW I knew it could be done (symmetry tells me such) and I was tempted. But it really makes me feel nice to hear that you attempted the alternative approach. I'd very much like to see it! | |
| Oct 13, 2022 at 16:12 | comment | added | LvW | Inspired by your block diagram I tried an alternative representation with Ic=f(Vbe). At the moment I can't upload it ("server error"). I will try later. | |
| Oct 13, 2022 at 10:17 | comment | added | jonk | @LvW The OP had elsewhere asked me for an accurate NFB diagram (different question I'd answered elsewhere.) Didn't want KCL/KVL. Didn't want broad explanations that avoided an NFB diagram. It gradually became clearer to me what he was looking for. I haven't seen anything like this, either. However, it generates all the same equations that you'd get with KCL/KVL (avoiding the non-linear block.) The result for Vc shows the point you made about a divider between base and Vcc. The block diagram works. I made it up from the schematic with the idea to use the usual NFB blocks and summing junctions. | |
| Oct 13, 2022 at 7:51 | comment | added | LvW | Let me say that the block diagram you have created is rather novel, I think. Up to now - I have never seen something similar. There is a simple block diagram for Re-feedback - however without the small "counter effect" you have mentioned. I think this effect does exist also for Re-feedback. | |
| Oct 13, 2022 at 7:46 | comment | added | jonk | @LvW The OP was more interested in seeing a block diagram with NFB. So that was my focus. Not quantifying specific details. Apparently, I was right about my guess? Agreed that the logarithm of Ic translates to a small effect on Vbe, though. A 1% change in Ic is about 260 uV change in Vbe, memory serving. | |
| Oct 13, 2022 at 7:14 | comment | added | LvW | I think, however, this "counter effect" - caused by the small slope of the Ic=f(Vce) curve - is rather small and will not reduce the stabilization effect considerably. | |
| Oct 13, 2022 at 6:51 | history | edited | jonk | CC BY-SA 4.0 |
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| Oct 13, 2022 at 3:09 | history | edited | jonk | CC BY-SA 4.0 |
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| Oct 13, 2022 at 0:47 | vote | accept | Heroz | ||
| Oct 12, 2022 at 23:52 | history | edited | jonk | CC BY-SA 4.0 |
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| Oct 12, 2022 at 23:04 | history | answered | jonk | CC BY-SA 4.0 |