Differential Amplifier & CMRR Calculator

Differential Amplifier & CMRR Calculator

Calculate the differential gain and the common mode rejection ratio (CMRR) of an op-amp differential amplifier.

* Enter resistor values in ohms.

Step 1: Enter Resistor Values

e.g., 1000 Ω (between \(V_1\) and inverting input)

e.g., 4700 Ω (feedback from output to inverting input)

e.g., 1000 Ω (between \(V_2\) and non-inverting input)

e.g., 4700 Ω (between non-inverting input and ground)

Ideal Differential Gain: \( A_d = \frac{R_2}{R_1} \)
Common-Mode Gain (due to resistor mismatch): \( A_{cm} = \frac{R_2}{R_1} – \frac{R_4}{R_3} \)
CMRR: \( \text{CMRR (linear)} = \frac{A_d}{|A_{cm}|} \) and \( \text{CMRR (dB)} = 20 \log_{10}\left(\frac{A_d}{|A_{cm}|}\right) \)