MULTISTATE PROM AND DECOMPRESSOR

摘要

A multistate PROM and decompressor comprises a PROM array (12) including a plurality of cells arranged to have a plurality of wordlines and a plurality of bitlines, where each cell is configured to have one of a plurality of threshold voltages (Vt0-Vtn). A Vt-detector (40) is coupled to the PROM array (12) and configured to receive a high voltage wordline (WLHV) signal that is ramped from a first voltage (e.g. 0V or ground) to a second voltage (e.g. Vtmax). The Vt-detector (40) is configured to compare the WLHV signal to a plurality of predetermined thresholds and to output a detector word in response to the WLHV signal. An addressed memory cell is selected by a wordline select signal and a bitline select signal. A wordline selector (22) is coupled to the PROM array (12) and configured to receive the WLHV signal. A bitline selector (30) is coupled to the PROM array (12) and configured to select a selected bitline carrying a bitline signal in response to the bitline select signal. A decompressor (50) is coupled to the Vt-detector (40) and the bitline selector (30) and is configured to receive the detector word and the bitline signal.