- #1
Mark9
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Hello all,
The Ebers-Moll equation as I understand it is: Ic = Is*exp((Vbe/Vt) -1). Question1: Assume fixed temperature; if Vbe is approximately 0.6 volts, as is typically used in transistor current source analysis, then how does Ic change at all? A core issue here is that I was under the impression that since Vbe is basically due to diode forward drop, that Vbe should be approximately constant. I'm looking to understand the NPN transistor as transconductance device(Vbe controls Ic), but the way I'm reading things, the equation just gives me a constant Ic(for fixed Temp). Question2: If the answer is that Vbe does indeed vary, then please clarify how this is possible. I thought that diodes maintained constant(approximately) forward voltage drop over a wide range of currents.
Thank you in advance to any takers!
Mark
The Ebers-Moll equation as I understand it is: Ic = Is*exp((Vbe/Vt) -1). Question1: Assume fixed temperature; if Vbe is approximately 0.6 volts, as is typically used in transistor current source analysis, then how does Ic change at all? A core issue here is that I was under the impression that since Vbe is basically due to diode forward drop, that Vbe should be approximately constant. I'm looking to understand the NPN transistor as transconductance device(Vbe controls Ic), but the way I'm reading things, the equation just gives me a constant Ic(for fixed Temp). Question2: If the answer is that Vbe does indeed vary, then please clarify how this is possible. I thought that diodes maintained constant(approximately) forward voltage drop over a wide range of currents.
Thank you in advance to any takers!
Mark