Timeline for What is the actual input resistance of a BJT transistor (amplifier circuit especially)?
Current License: CC BY-SA 4.0
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| Oct 21, 2021 at 13:13 | history | edited | Andy Brandi | CC BY-SA 4.0 |
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| Oct 21, 2021 at 12:12 | comment | added | Andy Brandi | In the case of your schematic, it is hard to tell without context. Maybe they are disregarding the BE junction and placing an actual resistor \$R_{in}\$ in there, which would then be the input resistance of the circuit. This would be valid for large input voltages. Or maybe it is really supposed to be the small-signal input impedance. In any case, for the general common-emitter circuit (as can be seen here), the large-signal \$R_{in}\$ is definitely not constant. | |
| Oct 20, 2021 at 13:18 | comment | added | MSKB | I thought $R_{in}$ to be a resistor. Is R_{in} a hypothetical concept which does not exist but we consider that it does? | |
| Oct 20, 2021 at 12:50 | history | edited | Andy Brandi | CC BY-SA 4.0 |
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| Oct 20, 2021 at 12:35 | history | answered | Andy Brandi | CC BY-SA 4.0 |