systems and methods for generating reference voltages are provided . a representative system comprises a resistor circuit ; a first switch coupled between a first end of the resistor circuit and a first power source ; a second switch coupled between the first end of the resistor circuit and a second power source ; a third switch coupled to a second end of the resistor circuit ; a fourth switch coupled to the second end of the resistor circuit ; a first resistor coupled between the first end of the resistor circuit and the first switch ; a second resistor coupled between the first end of the resistor circuit and the second switch ; a third resistor coupled between the second end of the resistor circuit and the third switch ; a fourth resistor coupled between the second end of the resistor circuit and the fourth switch ; and a control circuit for controlling the switches .