Abstract: An integrated circuit ultraviolet-unerasable floating-gate memory, which includes EEPROM (or EPROM) memory cells totally enclosed by a metal mask. The metal mask includes metal projections which are anchored in substrate diffusions, to define a ring completely surrounding two (or four) floating-gate cells. The cells are single-polysilicon cells, in which the control gate is a diffusion. Signals are routed out through diffusions which go underneath the metal ring. A selection transistor, for each cell, is located outside the metal ring.

Abstract: To shorten the reading cycle of a memory, the memory cells of which comprise floating gate transistors, a circuit for pre-charging the bit lines of the memory is used, this circuit being independent of the reading sense amplifier proper. This pre-charging circuit includes a differential amplifier receiving, firstly, a voltage signal for the effective pre-charging of the bit line and, secondly, a pre-charging voltage reference signal. So long as the effective pre-charging has not reached the assigned value, the differential amplifier delivers a command signal to a power transistor that pre-charges the bit lines. As soon as the assigned pre-charging value is reached, the power transistor goes off, and the circuit of the amplifier is itself uncoupled.

Abstract: Electrically programmable memories often include an internal circuit for establishing a programming voltage Vpp higher than the supply voltage. This circuit is formed by a charge pump followed by a voltage regulator. Previously, an analog circuit was usually provided behind the regulator to convert the level of voltage Vpp, set up by the charge pump, into a signal with a slow-rising edge (to reduce the constraints on the programmed cells and increase their lifetime). Instead of such analog circuit, the present invention provides a digital control circuit to control the regulator to set up a regulation voltage that rises gradually from a low value up to the desired value Vpp. The digital control circuit comprises counter with k outputs which enables the gradual short-circuiting and unshort-circuiting of the various series-mounted transistors constituting the regulator, thus making the regulation voltage increase slowly.

Abstract: The disclosure concerns integrated circuits. More particularly, a method is disclosed for making a constant current source, in these circuits, that is stable as a function of the temperature and the supply voltage of the integrated circuit. It is proposed to make a stable current source in using two parallel-mounted transistors, one of which is controlled by a bandgap type of reference voltage while the other is controlled by a Wilson mirror. The addition of the currents of the two transistors gives a current that is far more stable as a function of temperature than the individual currents in each of the transistors.