Programmable arrays for data conversions between analog and digital

Abstract

Converters such as digital-to-analog converters (DACs) and analog-to-digital converters (ADCs) use conversion arrays containing non-volatile memory cells to provide references that depend on the threshold voltages of the memory cells. The array contains sets (for example, rows) of the memory cells where each memory cell in a set corresponds to a digital value and has a threshold voltage that is equal to the analog voltage mapped to the digital value. An ADC applies an analog input signal to the gates of reference cells in a set and generates a digital signal according to which of the memory cells conduct. The ADC does not require comparators and has a low circuit area, low power consumption, and high speed. A DAC selects a memory cell corresponding to a digital input value and reads the memory cell to generate an analog output signal equal to the threshold voltage of the memory cell. An ADC and a DAC can use the same conversion array to ensure that the ADC inverts the conversion that the DAC performs. Programming the threshold voltages of memory cells in the conversion array selects or changes the conversion performed and can implement linear and non-linear conversions.