Amplifier fundamentalsII:amplifier saturation,frequency response

This post will let you know about amplifier saturation here you will discover the answers of question like WHY DISTORTION TAKES PLACE IF THE INPUT SIGNAL MAGNITUDE IS MUCH HIGHER THAN THE REQUIRED??
WHAT IS FREQUENCY RESPONSE AND HOW IT'S MEASURED??

AMPLIFIER SATURATION:-

Practically speaking, the amplifier transfer characteristic remains linear over only a limited
range of input and output voltages. For an amplifier operated from two power supplies the
output voltage cannot exceed a specified positive limit and cannot decrease below a specified
negative limit. The resulting transfer characteristic is shown in Fig., with the positive and negative saturation levels denoted L + and L_, respectively.

      

FREQUENCY RESPONSE OF AMPLIFIER:-

the input signal to an amplifier can always be expressed as the sum of sinusoidal signals. It follows that an important characterization of an amplifier is in terms of its response to input sinusoids of different frequencies. Such a characterization of amplifier performance is known as the amplifier frequency response.

Fig shows a linear voltage amplifier fed at its input with a sine-wave
signal of amplitude Vt and frequency w

Measuring the frequency response of a linear amplifier. At the test frequency co, the amplifier
gain is characterized by its magnitude (V0/Vi) and phase angle ϕ

Whenever a sine-wave signal is applied to a linear circuit, the resulting output
is sinusoidal with the same frequency as the input. In fact, the sine wave is the only signal
that does not change shape as it passes through a linear circuit. Observe, however, that the
output sinusoid will in general have a different amplitude and will be shifted in phase relative
to the input. The ratio of the amplitude of the output sinusoid (Vo ) to the amplitude of the
input sinusoid (Vi) is the magnitude of the amplifier gain (or transmission) at the test frequency w. Also, the angle ϕ is the phase of the amplifier transmission at the test frequency w. If we denote the amplifier transmission, or transfer function as it is more commonly known, by T(w), then
                                                


The response of the amplifier to a sinusoid of frequency w is completely described by |T(w)|
and <T(w). Now, to obtain the complete frequency response of the amplifier we simply
change the frequency of the input sinusoid and measure the new value for |T | and <T. The
end result will be a table and/or graph of gain magnitude |T(w)| versus frequency and a
table and/or graph of phase angle |<T(w)| versus frequency. These two plots together constitute
the frequency response of the amplifier; the first is known as the magnitude or
amplitude response, and the second is the phase response.

AMPLIFIER BANDWIDTH:-

The band of frequencies over which the gain of the amplifier is almost constant, to within a certain number of decibels (usually 3 dB), is called the amplifier bandwidth.

typical magnitude response of amplifier