The curve between the collector current versus the potential difference between the base and emitter is
The natural logarithm of the collector current depends directly on the the potential difference between the base and the emitter.
The curve between the collector current and the saturation is
The collector current depends directly on the saturation current.
The magnitude of the thermal voltage is given by
kT/q is the correct mathematical expression for the thermal voltage.
The correct relation between the transistor parameters α and ß are related by
Only expression α = ß/ß + 1 is the correct expression that relates α and ß.
The correct expression relating the emitter current Ie to the collector current Ic is
Ie = Ic/α or Ic = α Ie
The value of the thermal voltage at room temperature can be approximated as
Thermal voltage is given by kT/q which at T = 25 degrees Celsius is approximately 25 mV.
The correct relation between the emitter current Ie and the base current Ib is given by
The correct mathematical expression are Ie = (1 – ß) Ib and Ib = (1 – α) Ie respectively.
The Early Effect is also called as
At a given value of vBE, increasing vCE increases the reverse-bias voltage on the collector–base junction, and thus increases the width of the depletion region of this junction. This in turn results in a decrease in the effective base width W. Also the saturation current is inversely proportional to the width, the saturation current will increase and also makes collector current increases proportionally. This is the Early Effect. For the reasons mentioned above, it is also known as the base-width modulation effect.
For the BJT to operate in active mode Collector-Base junction must be
The BJT operates in active mode when the collector-Base junction is reversed bias. Also doping cannot prevent saturation of the transistor.
Collector current (Ic) reaches zero when
Ic = Is exp (Vbe/Vt) – Isc exp(Vbc/Vt). In this expression put ic = 0 and simplify.