Siemens Aktiengesellschaft

Burkhard Giebel

Lothar Schrader

Hans Moormann

Adolf Scheibe

Reprogrammable semiconductor read-only memory with memory cells of the floating-gate type, including an additional potential carrier for each memory cell for capacitively coupling a further potential to the floating gate.

Reprogrammable semiconductor read-only memory of the floating-gate type

Circuit arrangement for checking memory cells of programmable MOS-integrated semiconductor memories, especially non-volatile semiconductor memories of the floating-gate type, has an active programming and read mode of operation wherein all word lines of the semiconductor memory with the exception of one selected word line are at a low level. The circuit arrangement also has an inactive power-down mode of operation, wherein all word lines at a high level. Both of the modes of operation are represented by a signal having a first level for the active mode of operation and a second level for the inactive mode of operation. The circuit arrangement further includes a single circuit in the semiconductor memory switchable via a first signal indicating the operating mode for the memory cell test, wherein all of the word lines are addressed by a voltage corresponding to the programming voltage, as a function of a single second signal fed into the semiconductor memory from the outside, from the level indicating the active mode of operation to the level indicating the inactive mode of operation, so that all the word lines can be switched simultaneously to the level required for programming.

Circuit for checking memory cells of programmable MOS-integrated

Circuit arrangement for a read-only memory organized in rows and columns, including bit lines having potentials applied thereto, and selection circuits being connected to the bit lines, being addressed by a bit line decoder and containing at least one selection transistor having a cut-off voltage and a gate potential, for preventing bit line potentials from dropping below a given value at which the selection circuits become conducting without having been selected by the bit line decoder, including current-feed lines each being connected to a different one of the bit lines for feeding current to the bit lines and for ensuring that for each of the selection circuits not selected by the bit line decoder the difference between at least one gate potential of the participating selection transistors and the respective bit line potential is smaller than the cut-off voltage of the respective selection transistors.

Circuit for a read-only memory organized in rows and columns to prevent

Circuit having MOS-transistors for the rapid evaluation of the logic state of a sampling node, including a circuit input connected to the sampling node, a circuit output, a supply voltage source, an inverter being connected to the circuit input and having an output, a first transistor being connected between the circuit input and the circuit output and having a gate connected to the output of the inverter, a second transistor being connected between the supply voltage source and the circuit output and having a gate connected to the output of the inverter, and a third transistor shunted across the second transistor as a load resistor.

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Munich, Germany

Burkhard Giebel