Patent ID: 6339548
Filing Date: 2002-01-15
Classification: G11C

Abstract:
In a memory device including at least one transistor having a gate, a drain, and a source and constituting a memory cell of a non-volatile type having a threshold voltage level, a sensing circuit for determining a state of the memory cell, the sensing circuit comprising:a first reference corresponding to a first threshold voltage level; a first comparing means coupled to said memory cell and to said first reference, said first comparing means for comparing said threshold voltage level of said memory cell to said first reference, and for outputting a first result; a second reference corresponding to a second threshold voltage level; a third reference corresponding to a third threshold voltage level; a second comparing means coupled to said memory cell and a selected one of said second reference and said third reference, said second comparing means for comparing said threshold voltage level of said memory cell to said selected one of said second reference and said third reference, and for outputting a second result; and a selector circuit coupled for receiving said first result, said selector circuit for selectively coupling said one of said second reference and said third reference to said second comparator in response to said first result.