Sgs-thomson Microelectronics S.a.

Thomson Semiconducteurs

Gerard S De Ferron

Roberto Gastaldi

Jean-Marie Bernard Gaultier

Serge Fruhauf

An electrically-programmable integrated circuit memory in which the selected memory cell is read by comparing its current output with that of a reference cell, plus a bias current. The bias current is different in test mode than it would be during a normal read operation. The result of this is that, in test mode, cells whose current output is marginal in the unprogrammed state will be detected as faulty, even though those same cells would correctly be read as unprogrammed.

Integrated memory having improved testing means

A voltage switch-over circuit, depending on a switch-over signal, delivers either a first voltage Vpp or a second voltage Vcc at its output, the voltage Vpp being greater than the voltage Vcc. The said circuit consists of a first MOS transistor with one of its electrodes connected to the voltage Vcc and a set of two series-connected MOS transistors with one of their electrodes connected to the voltage Vpp and with their two gates connected together so as to create a floating node at the common point between the two MOS transistors, the other electrode of the first MOS transistor and the other electrode of the set of two MOS transistors being connected together, and the gates of the first MOS transistor and those of the set of two MOS transistors respectively receiving the switch-over signal and the reverse switch-over signal.

Growing community of inventors

Fuveau, France

Gerard S De Ferron