A compensation circuit is disclosed for compensating bias levels of an operational circuit in response to variations in a supply voltage. The compensation mechanism identifies variations in the supply voltage by comparing the voltage of a selected node of the operation circuit with a relatively constant or fixed reference voltage. Based on the results of the comparison, the compensation mechanism adjusts selected bias levels in the operational circuit, preferably using current stealing circuitry, so that the functionality and performance of the operational circuit can be substantially maintained. A biasing circuit for biasing one or more differential pairs is also disclosed.