**Negative Feedback Amplifiers:**

Negative feedback is a technique used in amplifiers to reduce distortion, increase stability, and improve overall performance. It involves feeding a portion of the output signal back to the input in an opposite phase. This feedback signal helps to regulate and control the amplifier's behavior. In the case of negative feedback amplifiers, the following statements are true:

**a) Bandwidth of the amplifier decreases:**
Negative feedback amplifiers have a reduced bandwidth compared to their open-loop counterparts. This is because the feedback signal introduces phase shifts and reduces the gain at higher frequencies, thereby limiting the amplifier's frequency response. The feedback network often includes resistors and capacitors that act as low-pass filters, attenuating high-frequency components.

**c) Noise of the amplifier decreases:**
Negative feedback helps in reducing the noise in amplifiers. The feedback signal, being an opposite phase, cancels out a portion of the noise present in the output signal. This leads to a reduction in the overall noise level of the amplifier. The noise reduction is particularly significant at lower frequencies.

**d) Distortion of the amplifier decreases:**
Negative feedback amplifiers exhibit reduced distortion compared to their open-loop counterparts. The feedback signal helps to compensate for nonlinearities in the amplifier's transfer function. By feeding a portion of the output signal back to the input with an opposite phase, the feedback signal counteracts the nonlinear effects, resulting in lower distortion. The overall linearity and fidelity of the amplifier are improved.

**b) Stability of the amplifier decreases:**
This statement is incorrect. Negative feedback actually enhances the stability of amplifiers. By introducing feedback, the amplifier's gain is reduced, making it less prone to oscillations and instability. The feedback signal helps to regulate the amplifier's gain and dynamics, increasing stability and preventing unwanted oscillations.

In summary, negative feedback amplifiers have a reduced bandwidth, decreased noise level, and lower distortion compared to their open-loop counterparts. However, they offer increased stability due to the regulating effects of feedback.