System for recording voice as analog values programmed into single bit cells EEPROMs or flash EEPROM

摘要

An incoming audio analog signal is sampled at a Nyquist criterion rate. The particular analog value sampled at each period causes one of a suite of programming algorithms to be selected and applied to a particular EEPROM memory cell. For example, there can be 256 different programming algorithms in the suite that open-loop result in a zero to full range analog multi-state data being recorded in each memory cell. The programming algorithms can vary the programming pulse heights, pulse widths and number of pulses applied to the selected memory cell. For a corrected readback, each or a representative spread of programming algorithms are "test-fired" at corresponding reference memory cells to establish a calibrator scale customized for each whole EEPROM device. The readback mechanism compares the multi-state data returned from analog sensing each memory cell to the reference memory cell calibration values to find a match. The matching reference cell directly identifies the original programming algorithm used and indirectly pinpoints the original analog value that appeared at the input at the instant of sampling. The readback signal is synthesized from such extracted or interpolated information using signal generators.