Worst Case CMRR for 0.1% Resistors The output shifts 40mV (worst case) for 0.1% resistor tolerance The output shifted 4μV for ideal resistor (limited by CMRR of Op-Amp) 10,000x difference between ideal and practical resistors.
Monte Carlo Analysis CMRR 0.1% Resistors Monte Carlo Analysis shows expected distribution of CMRR The majority of the population has poor CMRR (i.e. CMRR < 70dB) Better CMRR could be achieved with tighter tolerance (i.e. 0.01%) Worse CMRR could be achieved with looser tolerance (i.e. 1%)
Monolithic IC vs. Discrete Resistors Laser trim gets better accuracy then 0.1% resistors. Resistor Drift Cancels Tested system (i.e. CMRR, Gain, and other specifications assured) Smaller area and lower overall cost.