A voltage generator includes a first trim unit and a second trim unit. The first trim unit generates a first voltage variable depending on temperature variation and a second voltage invariable irrespective of the temperature variation based on a power supply voltage, and performs a first trim operation by changing a level of the second voltage. The level of the second voltage at a first temperature becomes substantially the same as a level of the first voltage at the first temperature based on the first trim operation. The second trim unit generates an output voltage based on the power supply voltage, the first and second voltages, a reference voltage and a feedback voltage, and performs a second trim operation by adjusting variation of the output voltage depending on the temperature variation based on a result of the first trim operation.