The correct answer is: A. Reduces voltage gain.
Negative feedback is a technique used in electronic circuits to reduce the gain of an amplifier. It does this by comparing the output signal of the amplifier to a reference signal and then adjusting the input signal accordingly. This adjustment reduces the overall gain of the amplifier.
There are several reasons why negative feedback is used. One reason is to improve the stability of the amplifier. Another reason is to reduce distortion. Negative feedback can also be used to improve the frequency response of an amplifier.
There are several different types of negative feedback. The most common type is voltage feedback. In voltage feedback, the output signal is compared to a reference voltage and then the input signal is adjusted accordingly. This type of feedback is very effective in reducing the gain of an amplifier.
Another type of negative feedback is current feedback. In current feedback, the output current is compared to a reference current and then the input current is adjusted accordingly. This type of feedback is less common than voltage feedback, but it can be more effective in reducing distortion.
Negative feedback is a very important technique in electronic circuits. It is used in a wide variety of applications, including amplifiers, oscillators, and filters.
Here is a brief explanation of each option:
- Option A: Reduces voltage gain. This is the correct answer. Negative feedback reduces the gain of an amplifier by comparing the output signal to a reference signal and then adjusting the input signal accordingly.
- Option B: Increases the voltage gain. This is not the correct answer. Negative feedback reduces the gain of an amplifier, not increases it.
- Option C: Increases the gain band width product. This is not the correct answer. The gain band width product is a measure of the stability of an amplifier. Negative feedback can be used to improve the stability of an amplifier, but it does not necessarily increase the gain band width product.
- Option D: Reduces the input impedances. This is not the correct answer. Negative feedback can be used to reduce the input impedance of an amplifier, but it does not necessarily do so.