95.2. Impact of Feedback on Frequency Response

In general, we can say that it is valid for even other linear circuit, but our specific focus it will be on amplifier. And also the when you say frequency response, it is primarily our focus it will be on gain of the amplifier, but that is also applicable for impedance.

This chunk introduces the concept of feedback in amplifiers and how it impacts frequency response. Frequency response refers to how the output of a system responds at different frequencies. In the context of amplifiers, feedback affects the gain, which is essentially how much an amplifier increases the strength of a signal. This relationship is crucial for understanding the performance of audio devices, radio transmitters, and other electronics.

Think of an amplifier as a loudspeaker that has to adjust the volume of sound based on how loud or soft a source is. If there's feedback that detects how loud the sound is coming out, it can reduce its output if the sound is too loud, just like an automatic volume control that prevents distortion.

The concepts we will be covering today it is primarily how the locations of the poles are getting changed, in the feedback system and that is due to the location of the amplifier poles and also the poles of the feedback network.

This chunk discusses poles in feedback systems. Poles are specific frequencies in a system where the behavior of the system changes significantly, typically where the gain drops. The presence of feedback can shift these poles, which can lead to changes in stability and response characteristics of the amplifier circuit. When we analyze such systems, we need to understand how the insertion of a feedback loop modifies these critical points.

Imagine a car engine that runs smoothly until it reaches a certain speed ('pole'). If you add a turbocharger (feedback), it might change how the engine performs at higher speeds; it could make it more powerful or cause it to stall if not calibrated properly. In electronics, if poles shift to undesired frequencies, it could lead to issues like distortion or instability.

Suppose this A is having one pole then what is its influence on the location of the pole of the feedback system? So, to start with let you consider case I, we assume that β it is independent of frequency. So, we can say that β is remaining constant.

In the case of a system with a single pole, the feedback introduces changes without complicating the structure. Since feedback (represented by β) is assumed to be a constant, we can analyze how it affects the overall gain and how the effective pole shifts. This shift gives us new insights into the stability and performance of the feedback system. It implies that as feedback increases, the overall gain reduces, leading to a shift in the frequency response.

Consider adjusting the bass on a stereo system. If you increase the bass (feedback), the overall sound level might drop or become less clear, indicating that adjustments have consequences on sound clarity and quality. Similarly, in an amplifier, increasing feedback reduces gain but stabilizes the output.

We shall focus on the situation where the amplifier may be having one pole or maybe it is having two poles or maybe three poles.

This section emphasizes the need to understand the feedback transfer function and loop gain while dealing with multiple poles in amplifiers. The loop gain influences how feedback alters the response across multiple frequency ranges, which can significantly affect system behavior, such as damping and bandwidth. The complexity of the system increases with more poles, but analyzing their interaction gives us a deeper knowledge of electronic systems.

Think about a group of singers (poles) harmonizing. If one singer sings louder (feedback), it can shift the balance of the group, changing how good the harmony sounds. In electronics, adjusting feedback can similarly modify how well a circuit operates under varying conditions.

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