A circuit having a centralized PT compensation circuit to provide compensation signals to localized I/O blocks on the chip. Process variations and temperature variations tend to be approximately uniform across an integrated circuit chip. Thus, a single, centralized PT compensation circuit may be used instead of one PT compensation circuit per I/O section as with solutions of the past. Further, the PT compensation circuit may generate a digital code indicative of the effects of process and temperature. Further yet, each section of I/O block may have a local voltage compensation circuit to compensate the voltage variation of the I/O block. The voltage compensation circuit utilizes an independent reference voltage. The reference voltage is generated by the PT compensation circuit, which is placed centrally in the IC chip and hence any need to repeat the reference generation for each I/O block is eliminated.