A temperature sensor includes a plurality of temperature coefficient voltage generators, one or more converters and at least one variable voltage or current source. The temperature coefficient voltage generators are used for generating multiple temperature coefficient voltages. The converters, coupled to the temperature coefficient voltage generators, are used for converting the temperature coefficient voltages to digital values. The at least one variable voltage or current source, each coupled to at least one of the temperature coefficient voltage generators, includes a first variable voltage or current source for outputting a first voltage or current in a first time period, and outputting a second voltage or current in a second time period, wherein the second voltage or current is different from the first voltage or current such that there exists a shift between a first voltage-temperature curve in the first time period and a second voltage-temperature curve in the second time period.