Voltage reference with programmable temperature coefficient and offset voltage compensation

This paper demonstrates an integrated circuit for compensation of errors in voltage references, that not only is able to compensate first order changes of the temperature coefficient, but can also correct for the offset error that is unavoidable in production due to variations in process conditions and mismatches. The temperature compensation circuit is programmable via three control bits, the remaining offset error is compensated by setting eight control bits and an external provided reference voltage. The compensation procedure can be controlled by an internal digital block or via external signals. The actual calibration data can then be saved in several possible ways (EPROM, laser fuses, external Memory, ...). Extensive simulations and measurements show that the described circuit reduces the average temperature error by more than 40% and the overall absolute error by more than 90% wth regards to the uncalibrated reference voltage.