Differential power bus comparator

摘要

A method and an apparatus for generating an output voltage for an integrated circuit having multiple power supplies. A comparator circuit is coupled to receive power supply lines from the power bus of an integrated circuit. The power supply lines received from the power bus have different voltages which may vary depending on the particular application. The comparator compares the voltage potentials present on the power supply lines and determines which power supply line carries a voltage having the highest potential. The comparator then generates a corresponding select signal wherein the value of the select signal indicates which particular power supply line has the highest voltage potential. A multiplexor is coupled to receive the select signal as well as the power supply lines from the power bus. Based on the value of the select signal, the multiplexor generates the output voltage in response to the select signal wherein the output voltage is substantially equal to the voltage potential of the power supply line having the highest voltage potential.