# What is the input impedance of emitter follower?

## What is the input impedance of emitter follower?

Emitter follower low-frequency gain, input impedance, and output impedance. The emitter follower (Figure 5.11(a)) is a buffer stage with high input impedance, low output impedance, and a gain of approximately unity.

**What is the input impedance of an op amp?**

The input impedance of an op amp is the impedance that is seen by the driving device. The lower the input impedance of the op amp, the greater is the amount of current that must be supplied by the signal source.

**What is the input impedance of a common emitter amplifier?**

Common emitter amplifier impedance levels The input impedance is typically around 1kΩ, although this can vary considerably according to the circuit values and conditions.

### What is emitter follower in op amp?

Emitter follower is a case of negative current feedback circuit. This is mostly used as a last stage amplifier in signal generator circuits. The important features of Emitter Follower are − It has high input impedance. It has low output impedance.

**When a negative voltage feedback is applied to an amplifier its input impedance is?**

Feedback increases input impedance while decreasing output impedance.

**What is input and output impedance of op amp?**

The ideal op-amp has infinite input impedance and zero output impedance because it’s easy to make the input impedance lower (put a resistor in parallel) or the source impedance higher (put a resistor in series).

#### Why is the input impedance of op amp high?

Op amps have high input impedance and low output impedance because of the concept of a voltage divider, which is how voltage is divided in a circuit depending on the amount of impedance present in given parts of a circuit. Op amps are voltage gain devices.

**What is the output for an op amp with negative feedback?**

equal to the input. increased. fed back to the inverting input.

**What is the output impedance of an emitter follower?**

Assuming you are talking about an emitter follower constructed with a single transistor, the output impedance (measured looking into the emitter) is whatever impedance you see looking out of the base toward the source, divided by (1+β), where β is the forward current gain of the transistor under consideration.

## Why the op amp has high input impedance and low output impedance?

**What is positive and negative feedback in op-amp?**

In negative feedback a small portion of the output is subtracted from the input. In positive feedback, a small portion of the output is added to the input. Positive feedback makes the output go more in the direction of the input, it makes small changes of the input into bigger changes.