I'm working my way through Malvino/Bates "Electronic Principles 7ed", and looking at the example of emitter fixed bias. I don't think the text is pointing me wrong or anything, but I'm a bit confused.
Attached is a snip of an example, using Falstad's applet. The NPN has a beta of 100.
My question is - what controls the base current in this context? As I understand it, the emitter (and thus collector) current will be fixed to that of Vbb - Vbe (4.3v in the example), divided by the emitter resistance, so it comes out to 1.95mA. The base current ends up being simulated at about 19.8uA.
How does the base current get limited?
I understand that if the emitter is grounded and the base is biased to 19.8uA, a Beta of 100 would mean 1.98mA through the collector/emitter circuit. But I haven't seen any mention that a fixed CE current will control the base, too - is this true?
Attached is a snip of an example, using Falstad's applet. The NPN has a beta of 100.
My question is - what controls the base current in this context? As I understand it, the emitter (and thus collector) current will be fixed to that of Vbb - Vbe (4.3v in the example), divided by the emitter resistance, so it comes out to 1.95mA. The base current ends up being simulated at about 19.8uA.
How does the base current get limited?
I understand that if the emitter is grounded and the base is biased to 19.8uA, a Beta of 100 would mean 1.98mA through the collector/emitter circuit. But I haven't seen any mention that a fixed CE current will control the base, too - is this true?
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