What is meant by Early voltage?
The Early voltage is a parameter describing the variation of the transistor collector or drain current in the active or the saturation region of operation with the VCE or VDS , respectively. Real transistors show a small increase of the their collector/drain current with the VCE OR VDS.
What causes Early voltage?
The Early effect, named after its discoverer James M. Early, is the variation in the effective width of the base in a bipolar junction transistor (BJT) due to a variation in the applied base-to-collector voltage.
Can Early voltage be negative?
The Early voltage is negative; so, the combination of the voltage source and the resistor (the “electrical transistor”) acts as a current sink. Now the Early voltage is positive; so, the combination of this positive voltage source and the resistor acts as a current source.
How is the early voltage defined in math?
The EARLY voltage is a definition rather than a real existing and measurable quantity. It can be found using the slope of the output chracteristics Ic=f (Vce). Here, we have two alternatives: Ib=const or Vbe=const.
How is the early voltage defined, IB or VBE?
Assuming this is the case, either ib or vbe can be equivalently used to specify point in the bias in the definition of the early voltage.
How is the base voltage defined after a VCE increase?
* Following a Vce increase, the current Ic also increases (due to the shrinking of the base B-E junction). If Vbe is held constant, the base current Ib decreases (Ie=const because Vbe=const). This gives us the output characteristics with a certain positive slope for Vbe=const.
How is the early voltage defined in BJTs?
Moreover, in BJTs, the Early voltage is normally almost independent of the bias (the ic-vce curves in forward active region converge to the same point in the negative vce axis, which corresponds to the Early voltage).