Which of the following statements is/are true for a BJT with respect to its DC current gain  ?

The base of an npn BJT T1 has a linear doping profile  as shown below. The base of another npn BJT T2 has a uniform doping  of . All other parameters are identical for both the devices. Assuming that the hole density profile is the same as that of doping, the common-emitter current gain of T2 is

For a narrow base PNP BJT, the excess minority carrier concentrations (for emitter, for base, for collector) normalized to equilibrium minority carrier concentrations (for emitter,for base, for collector) in the quasi-neutral emitter, base and collector regions are shown below. Which one of the following biasing modes is the transistor operating in?

The Ebers-Moll model of a BJT is valid

The injected excess electron concentration profile in the base region of an NPN BJT, biased in the active region, is linear, as shown in the figure. If the area of the emitter-base junction is 0.001 , = 800  in the base region and depletion layer widths are negligible, then the collector current  (in mA) at room temperature is ____________

(Given: thermal voltage = 26 mV at room temperature, electronic charge q=1.6 × C)

If the base width in a bipolar junction transistor is doubled, which one of the following statements will be TRUE?

An NPN BJT having reverse saturation current is biased in the forward active region with  = 700 mV. The thermal voltage () is 25 mV and the current gain (β) may vary from 50 to 150 due to manufacturing variations. The maximum emitter current (in µA) is ________.

An increase in the base recombination of a BJT will increase         

Consider two BJTs biased at the same collector current with area  = 0.2 µm × 0.2 µm and  = 300 µm × 300 µm. Assuming that all other device parameters are identical, kT/q = 26 mV, the intrinsic carrier concentration is 1 × , and q = 1.6 × C, the difference between the base-emitter voltages (in mV) of the two BJTs  is _____.

In a uniformly doped BJT, assume that ,  and  are the emitter, base and collector dopings in , respectively. If the emitter injection efficiency of the BJT is close unity, which one of the following conditions is TRUE?

The DC current gain (β) of a BJT is 50. Assuming that the emitter injection efficiency is 0.995, the base transport factor is        

The phenomenon known as “Early Effect” in a bipolar transistor refers to a reduction of the effective base-width caused by

If for a silicon n-p-n transistor, the base-to-emitter voltage  is 0.7V and the collector-to-base voltage  is 0.2V, then the transistor is operating in the

Consider the following statements  and .

: The β of a bipolar transistor reduces if the base width is increased.

: The β of a bipolar transistor increases if the doping concentration in the base in increased.

Which one of the following is correct?

The neutral base width of a bipolar transistor, biased in the active region, is 0.5 μm. The maximum electron concentration and the diffusion constant in the base are  and  respectively. Assuming negligible recombination in the base, the collector current density (the electron charge is  coulomb)

The early effect in a bipolar junction transistor is caused by

In a common emitter BJT amplifier, the maximum usable supply voltage is limited by

For a typical n-p-n transistor, as shown in the figure we have the following data available
 and Collector doping
 and Emitter doping

Minority carrier life time in the Base region is

Under Punch-through condition the  volts.

Here  is the built in potential of Base-collector junction. Emitter Injection efficiency can be assumed as 1 for this transistor.

Evaluate Base Width  and the current gain . [Standard data for this question is:  coulombs;  .

For silicon at, ; ; ]

If a transistor is operating with both of its junctions forward biased, but with the collector base forward bias greater than the emitter – base forward bias, then it is operating in the

The common-emitter short circuit current gain  of a transistor

In a bipolar transistor at room temperature, if the emitter current is doubled the voltage across its base-emitter junction

The break down voltage of a transistor with its base open is  and that with emitter open is  then,

A BJT is said to be operating in the saturation region of

 - cut off frequency of a bipolar junction transistor

In a transistor having finite β, the forward bias across the base emitter junction is kept constant and the reverse bias across the collector base junction is increased. Neglecting the leakage across the collector base junction and the depletion region generating current, the base current will __________.

A P-N-P transistor shown in the figure has uniform doping in the emitter, base and collector regions, where in the doping concentrations are  per ,  per ,  per , respectively. The minority carrier diffusion lengths in the emitter and the base regions are 5 microns and 100 microns, respectively. Assuming low level injection conditions and using the law of the junction, calculate the collector current density and the base current density and the base current density due to base recombination. [Suitable approximations may be made if required]. In all the regions of the transistors per sec  per sec,  per , KT/q=26 mV,