Question: How Total Emitter Current Is Dependent On Base And Collector Current?

Why the collector current is independent of collector to base voltage?

The collector current can only exist because transistor’s base region injects “backwards charges” into the “wrong side” of the CB diode.

In a normal reverse-biased diode, there is a strong e-field in the junction, appearing inside the insulating depletion-layer..

Why is VBE 0.7 V?

For an unbiased transistor, considering only the BE junction which is a pn junction diode, 0.7V is the potential barrier. In an npn transistor base is positive(p) and emitter is negative(n). … But in a pnp transistor the base is negative(n) and emitter is positive(p) so the vbe=-0.7V.

What is NPN vs PNP?

PNP sensors produce a positive output to your industrial controls input, while NPN sensors produce a negative signal during an “on” state. … NPN, or “sinking” output sensors, work in the opposite way, sinking ground voltage to an input when it’s on.

Why base current is weaker than collector current?

Answer: Base is much narrower and thinner than collectors,hence the majority of charge carriers are received by collector. Hence,collector current is greater than base current.

Is VBE always 0.7 V?

VBE is the voltage that falls between the base and emitter of a bipolar junction transistor. VBE is approximately 0.7V for a silicon transistor. For a germanium transistor (which is more rare), VBE is approximately 0.3V. Again, this formula, can be used for either silicon or germanium transistors.

Why VCE SAT is 0.2 V?

Because the charge carriers injected from the base effectively eliminate the depletion zone between the collector and emitter. The collector current doesn’t have to overcome the P-N junction potential because the base current has neutralized it.

How do you calculate emitter current?

Calculate the emitter current, which is the current flowing from the emitter to ground. Use the formula Ie = (Vbb – Vbe)/[Rb/(Beta + 1) + Re] where Ie is the variable for the emitter current and Vbe is the base to emitter voltage. Set Vbe to 0.7 volts, which is the standard for most transistor circuits.

Can a transistor amplify DC?

Yes,by using direct coupling(transistors) amplifier we will amplify low frequency (DC) signals. … A transistor is certainly capable of taking a small-current input signal and controlling a high-current output at the same voltage, thereby amplifying the power of the input signal whether it’s AC or DC.

Can transistors increase current?

A transistor can be used to increase current. You’ll have a low current path, from base to emitter in an NPN, and a higher current path from collector to emitter. The collector current will be a multiple of the base current if the circuit allows it.

Why is base current so small?

hey mate! Few electrons injected by the emitter into the base of an NPN transistor fall into holes. … Most of the emitter current of electrons diffuses through the thin base into the collector. Moreover, modulating the small base current produces a larger change in collector current.

How do transistors amplify current?

A transistor acts as an amplifier by raising the strength of a weak signal. The DC bias voltage applied to the emitter base junction, makes it remain in forward biased condition. This forward bias is maintained regardless of the polarity of the signal.

How does current flow in a transistor?

The NPN transistor is designed to pass electrons from the emitter to the collector (so conventional current flows from collector to emitter). … The base still controls current flow, but that current flows in the opposite direction — from emitter to collector.

What is quiescent point?

The operating point of a device, also known as bias point, quiescent point, or Q-point, is the DC voltage or current at a specified terminal of an active device (a transistor or vacuum tube) with no input signal applied. A bias circuit is a portion of the device’s circuit which supplies this steady current or voltage.

What is the relationship between collector current and base current?

What is the relationship between the base-emitter and collector-emitter voltages of a bipolar transistor? Generally, the current that flows from the emitter to the collector or vice versa is the base current times the DC current gain (hFE). Note, however, that hFE varies with the collector-emitter voltage (VCE).

Why does collector current increase with base current?

Hello, an increase in base current means more bias to the transistor which further means collector current will also increase but till the limiting value of the transistor parameters. However, if you try to push more current to the base, collector current would no more increase but the transistor may break down.

How do you calculate collector current?

How to Calculate the Collector Current, Ic, of a TransistorUsing Known Values.Example. If Ib=35μa and β=100, then Ic calculates out to be:Using Known Values.Example. If Ie=4ma and β=150, then the value of Ic is computed to be:Using Known Values. If base current, Ib, and emitter current, Ie, are known, then Ic can be calculated by the formula:Example.

What is base current?

The base current, IB, of a transistor is a crucial current of a bipolar junction transistor. Without this base current, the transistor can’t turn on. There are several ways to find the base current, IB, of a transistor.

How is VBE calculated?

Vbe ranges from 0.6 to 0.7 V for a silicon transistor. Assume Vbe = Vb = 0.7 V. Using Kirchhoff’s Law for the left-hand base loop, Vr = Vbb — Vbe = 3 V — 0.7 V = 2.3 V. Calculate “Ib,” the current through the base resistor.