Abstract: An electrically programmable memory array having rows and columns of floating gate type memory cells employs alternate output lines and ground lines between the columns of cells, providing a virtual ground arrangement. A row is selected by one part of an address input, and a column selected by another part. An output line on one side of the selected column is activated, and a ground line on the other side. A differential sense amplifier is responsive to the voltage on the selected output line and a reference voltage. The number of transistors needed in the decoder for the row select function is greatly reduced by employing predecoders which perform a 1-of-4 select for each pair of address bits, then using one of these select outputs to activate N multiplexers, and all the others as inputs to a decoder with N outputs to the multiplexers.

Abstract: An electrically programmable memory array having rows and columns of floating gate type memory cells employs alternate output lines and ground lines between the columns of cells, providing a virtual ground arrangement. A row is selected by one part of an address input, and a column selected by another part. An output line on one side of the selected column is activated, and a ground line on the other side. A differential sense amplifier is responsive to the voltage on the selected output line and a reference voltage. To speed up the access time of the memory, the ground select is implemented and applied first, then the output of the ground select is used to generate the column select. In this manner, the biasing sequence for the array can begin before the decode of the column select has been completed.

Abstract: An electrically programmable memory array having rows and columns of floating gate type memory cells employs alternate output lines and ground lines between the columns of cells, providing a virtual ground arrangement. A row is selected by one part of an address input, and a column selected by another part. An output line on one side of the selected column is activated, and a ground line on the other side. A differential sense amplifier is responsive to the voltage on the selected output line and a reference voltage. In a programming mode of operation, the application of high voltages to the row and column lines is controlled to prevent programming voltage from reaching a selected column until after all transistors in a row are turned on by programming voltage on a row line. This prevents unwanted programming conditions.

Abstract: An electrically programmable memory array having rows and columns of floating gate type memory cells employs alternate output lines and ground lines between the columns of cells, providing a virtual ground arrangement. A row is selected by one part of an address input, and a column selected by another part. An output line on one side of the selected column is activated, and a ground line on the other side. A differential sense amplifier is responsive to the voltage on the selected output line and a reference voltage. A power down mode of operation is provided in which current flow in various circuits of the device is greatly reduced. To speed up access time in exiting from power down, the reference voltage input to the sense amplifier is shifted during power down then when exiting returns to its operating value according to a time constant.