Method for trimming the temperature coefficient of a floating gate voltage reference

摘要

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 second NVM transistor. During programming, one or more capacitors are connected between the floating gate of the first NVM transistor and ground, and one or more capacitors are connected between the floating gate of the second NVM transistor and ground. The first and second NVM transistors are then coupled to a differential amplifier, which is used to generate a single-ended reference voltage in response to the programmed threshold voltage of the first NVM transistor. Bipolar transistors are selectively switched between the various capacitors and ground, thereby providing precise adjustment of the temperature coefficient of the voltage reference circuit.