# How to Calculate the Emitter Current, Ie , of a Transistor

The emitter current, Ie, of a transistor is the amplified output current of a bipolar junction transistor.

There are several ways to find the emitter current, Ie, of a transistor. And it all depends on what information is already known about the transistor:

### 1st Way To Calculate Emitter Current Ie

**DC Analysis**

Doing DC analysis of the transistor circuit is the most common way of finding out the value of Ie in the circuit.

The equation to solve for Ie is:

So we must solve for Vbb and RB in order to solve for Ie.

The value of Vbb is computed by:

Next we compute the value of RB:

Now we can calculate the value of the emitter current, Ie, in the circuit:

**Example**

Using the example of the values for the resistors and the voltage, Vcc, above, we're going to solve for Ieq.

### 2nd Way to Calculate Emitter Current Ie

**Using Known Values**

If Ib (the base current) and β are known, Ie can be solved for by using the formula:

**Example**

If Ib=30µA and β=99, then the answer to the equation is:

### 3rd Way to Calculate Emitter Current Ie

**Using Known Values**

If Ic and β are known, then Ie can be calculated by the formula:

**Example**

If Ic= 2.97ma and β=99, then Ie is calculated out to be:

### 4th Way to Calculate Emitter Current Ie

**Using Known Values**

If Ib and Ic are known, Ie can be calculated using the formula:

**Example**

If Ic=3.95mA and Ib=50µA, then Ie calculates out to be:

Related Resources

How to Calculate the Base Current IB of a BJT Transistor

How to Calculate the Collector Current IC of a BJT Transistor

How to Calculate β of a BJT Transistor

How to Calculate α of a BJT Transistor

How to Calculate VBB of a BJT Transistor

How to Calculate VCE of a BJT Transistor

How to Calculate Vπ of a BJT Transistor

How to Calculate Rπ of a BJT Transistor

How to Calculate GmVπ of a BJT Transistor Circuit

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