| ??? 04/23/07 15:34 Read: times |
#137820 - whether offset can be calculated using a formula. Responding to: ???'s previous message |
Richard Erlacher said:
The common-mode input voltage affects the bias point of the input differential pair. Because of the inherent mismatches in the input circuitry, changing the bias point changes the offset voltage, which, in turn, changes the output voltage. RE Thank you Richard. I understood the effect of common mode voltage that when it increases, the offset voltage at the output increases and thus the desired output is not obtained. To overcome this we use opamps with high CMRR which suppresses the effects of these common mode voltages. Fine till this. But i also need to find whether there are any way (by calculation) to know the offset value that would be obtained at the output for a particular CMRR value say 85dB if common mode voltage is 1V. I dont know whether it can it be calculated using a formula or should it be found only by checking the OpAmp output for the above condition. I am yet to go through the materials i got from steve and you and hence would try to find if there are any methods to do such calculations. regard's Suresh. |
