US 7,254,071 B2 · Flash memory devices with trimmed analog voltages

Abstract

A flash memory device of the multi-level cell (MLC) type, in which control gate voltages in read and programming operations and a bandgap reference voltage source are trimmable from external terminals, is disclosed. In a special test mode, control gate voltages can be applied to a selected programmed memory cell so that the threshold voltage of the cell can be sensed. A digital-to-analog converter (DAC) use for programming and a second read/verify DAC apply varying analog voltages and are sequentially used to verify the programming of an associated set of memory cells in this special test mode, with the DAC input values that provide the closest result selected for use in normal operation. These DAC's are dependent on the value of a reference source that my also be trimmed.

Claims17

Dependent claims

A non-volatile memory device, comprising:

an array of non-volatile memory cells arranged in rows and columns;
circuitry for addressing at least one selected memory cell;
circuitry for sensing the state of the at least one selected memory cell;
circuitry for programming the at least one selected memory cell;
an analog voltage generator circuit for generating an analog voltage in the non-volatile memory device at a first selected voltage varying from a first nominal voltage level;
an external terminal, for receiving a voltage to be applied to the at least one selected memory cell in a special test mode, and for performing a control function in a normal operating mode;
and
control logic for placing the device into the special test mode and into the normal operating mode, responsive to received commands.

5 more elements

Dependencies are inferred from the claim text.

Flash memory devices with trimmed analog voltages

Life of this patent

Flash memory devices with trimmed analog voltages

Life of this patent

Abstract

Claims17