Non-linear mapping of threshold voltages for analog/multi-level memory

Abstract

An analog-to-analog converter uses programmable conversion arrays containing non-volatile memory cells to provide references that depend on the threshold voltages of the memory cells, with the type of conversion dependent on the threshold voltages of the cells. An analog input signal is applied to an analog-to-digital conversion array for conversion to a digital signal. The digital signal is applied to a digital-to-analog conversion array for conversion to an analog output signal. A memory cell in the digital-to-analog conversion array is selected corresponding to the digital signal and reads the memory cell to generate the analog output signal, which is equal to or has a one-to-one correspondence with the threshold voltage of the memory cell. The conversion arrays can be programmed with suitable threshold voltages to implement desired conversions, such as logarithmic conversion for voice applications or random conversions for signal encryption.