A difference amplifier has output v0 10043 V when the input

A difference amplifier has output v_0 = 1.0043 V when the inputs are v_i1 = -100 mV, and v_i2 = +100 mV. With inputs v_i1 = v_i2 = 10 V, the output is v_0 = 0.4153 V. Determine the CMRR, expressed in dB.

Solution

The common mode gain(When Vi1=Vi2)AC=0.4143V/10=0.04153

The differentila volage=100mV-(-100mV)=200mV

The differential mode gain AD=1.0045/200mV=5.0225

CMRRin dB=20log₁₀(AD/AC)=20log₁₀(5.0225/0.04153)=41.65dB