Non-volatile CMOS reference circuit

A voltage reference circuit provides a reference voltage that can be precisely programmed. The threshold voltage of a first non-volatile memory (NVM) transistor is programmed while coupled in parallel with a reference NVM transistor, wherein a first voltage is applied to the control gate of the first NVM transistor, and a reference voltage is applied to the control gate of the reference NVM transistor. The threshold voltage of a second NVM transistor is programmed while coupled in parallel with the reference NVM transistor, wherein a second voltage is applied to the control gate of the second NVM transistor, and the reference voltage is applied to the control gate of the reference NVM transistor. The first and second NVM transistors are then coupled in parallel, and a differential amplifier is used to generate a single-ended reference voltage in response to the programmed threshold voltages of the first and second NVM transistors.