If the differential voltage gain and the common mode voltage gain of a...
Common Mode Rejection Ratio (CMRR) is a measure of how effectively a differential amplifier rejects common mode signals. It is defined as the ratio of the differential voltage gain to the common mode voltage gain.
Given:
Differential voltage gain = 50 dB
Common mode voltage gain = 2 dB
To find the CMRR, we can convert the gains from decibels to linear scale using the formula:
Gain (linear scale) = 10^(Gain (dB)/20)
Therefore, the differential voltage gain in linear scale is:
Differential voltage gain = 10^(50/20) = 316.23
The common mode voltage gain in linear scale is:
Common mode voltage gain = 10^(2/20) = 1.58
Now, we can calculate the CMRR using the formula:
CMRR = Differential voltage gain / Common mode voltage gain
CMRR = 316.23 / 1.58 = 200
Since the CMRR is a ratio, it is usually expressed in decibels. To convert the CMRR from linear scale to decibels, we use the formula:
CMRR (dB) = 20 log10(CMRR)
CMRR (dB) = 20 log10(200) = 46.02 dB
Therefore, the correct answer is option C) 48 dB.
Explanation:
The common mode rejection ratio (CMRR) is a measure of how well a differential amplifier can reject common mode signals. A high CMRR indicates good rejection of common mode signals, while a low CMRR indicates poor rejection.
In this case, the differential voltage gain is 50 dB, which means that the amplifier amplifies the difference between the two input voltages by a factor of 316.23. The common mode voltage gain is 2 dB, which means that the amplifier amplifies the average of the two input voltages by a factor of 1.58.
The CMRR is calculated by dividing the differential voltage gain by the common mode voltage gain. In this case, the CMRR is 316.23 / 1.58 = 200.
To express the CMRR in decibels, we use the formula CMRR (dB) = 20 log10(CMRR), which gives us 46.02 dB. Therefore, the correct answer is option C) 48 dB.
To make sure you are not studying endlessly, EduRev has designed Electrical Engineering (EE) study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in Electrical Engineering (EE).