introduction to amplifier

1. As it can be seen in the figure (15) that the frequency response for the unity gain dropped
slightly by increasing the frequency that is because the internal components of the op-amp
fail at high frequency. The decreasing of the voltages gain is due to the design of the op-amp
which has a simple none-pole frequency response , the gain bandwidth product is nearly
independent of the gain at which it is measured .That means the gain-bandwidth will be equal
to the unity gain bandwidth of the amplifier. ). For an amplifier in which negative feedback
reduces the gain to below the open-loop gain, the gain–bandwidth product of the closed-loop
amplifier will be approximately equal to that of the open-loop amplifier. The finite bandwidth
of an op-amp limits the performance at high frequencies. However, The non-linearly distorts
the shape of a given output frequency, the bandwidth of the op-amp causes the output
amplitude to decrease with increasing frequency, as well as incur some phase shift relative to
the input, which is a linear effect. The culprit is typically compensation capacitance internal
to the op-amp, provided to guarantee a one-pole response, guarantee a stable response when
feedback is applied. Moreover, the finite bandwidth can cause linear distortion if the input
waveform consists of more than one sinusoid, each experiencing a different phase shift and
amplitude reduction due to the one-pole response. While the response is still linear, the output
waveform may look completely different from the input. The compensation is important to
lower the bandwidth of the gain by inserting a dominant pole using capacitor to control
stability in order the gain won’t exceed -180° of the loop phase. The figure “20” shows three
different bandwidth with three different capacitors and it shows that when using a big value
of capacitor the bandwidth will be smaller , means it is an inverse relation between the
capacitance and the value of bandwidth which prove the theory explain in theoretical review
was correct where the 3dB bandwidth increased by decreasing capacitor . According to the
result, when there is no compensation capacitor used in inverting op-amp, the output signal
from the oscilloscope shows a distorted signal at figure 16 and 19 .It is cause by the rate of
change of the inverting op-amp is exceeded the slew rate of the op-amp. The uncompensated
amplifier contains very large bandwidth which will maintain high output gain in high
frequency.