Built-in self trim for non-volatile memory reference current

摘要

A non-volatile memory built-in self-trim mechanism is provided by which product reliability can be improved by minimizing drift of reference current used for accessing the non-volatile memory and for performing initial trimming of the reference current. Embodiments perform these tasks by using an analog-to-digital converter to provide a digital representation of the reference current (Iref) and then comparing that digital representation to a stored target range value for Iref and then adjusting a source of Iref accordingly. For a reference current generated by a NVM reference bitcell, program or erase pulses are applied to the reference cell as part of the trimming procedure. For a reference current generated by a bandgap-based circuit, the comparison results can be used to adjust the reference current circuit. In addition, environmental factors, such as temperature, can be used to adjust the measured value for the reference current or the target range value.

主权项

1. A method comprising:
converting a non-volatile memory (NVM) reference current to a digital NVM reference current value, wherein said converting is performed by an analog-to-digital converter (ADC) coupled to a generator of the NVM reference current; comparing the digital NVM reference current value to a target value range; if the digital NVM reference current value is outside the target value range, adjusting the generator of the NVM reference current to produce an adjusted NVM reference current, wherein
an adjusted digital NVM reference current value associated with the adjusted NVM reference current is within the target value range, andthe target value range comprises a lower limit and an upper limit of the target value range; adjusting one or more of the digital NVM reference current value, the lower limit of the target value, and the upper limit of the target value in response to temperature data provided by a temperature sensor, if needed; and wherein said converting, comparing, and adjusting are performed by components of a system-on-a-chip comprising a NVM.