Q. (i) What are the different types of plots for frequency response in an RC coupled amplifier?
(ii) What is a Bode Plot? What are it's uses?
The different types of frequency response curves that can be plotted are:
1) Normalized gain versus frequency plot.
2) Decibel plot of normalized gain versus frequency plot
3) Phase plot of gain versus frequency plot.
Using this plot, we can find out:
(i)the upper cut-off frequency
(ii)the lower cut-off frequency
(iii)Bandwidth
This plot is very useful in applications of communication nature.
A Bode Plot is the piecewise linear plot of the asymptotes and associated breakpoints of the magnitude of gain versus frequency plot.
Using this, we observe that:
· A change in frequency by a factor of 2, equivalent to 1 octave, results in a 6-dB change in the ratio as noted by the change in gain from mid-value of lower cut-off frequency to it's full value.
· For a 10:1 change in frequency, equivalent to 1 decade, there is a 20-dB change in ratio as demonstrated between 1/10th of lower cut-off frequency to it's full value.