Selective application of voltages for testing storage cells in semiconductor memory arrangements

• US 5,157,629 A
• Filed: 04/10/1989
• Issued: 10/20/1992
• Est. Priority Date: 11/22/1985
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kawamoto, Hiroshi, Yanagisawa, Kazumasa, Sato, Katsuyuki
• Primary Examiner(s): Bowler, Alyssa H.
• Application Number:
  US07/336,345
• Time in Patent Office: 1,289 Days
• Field of Search: 365/149, 365/189.09, 365/226, 365/201, 371/21
• US Class Current: 365/201
• CPC Class Codes: G11C 11/401 forming cells needing refreshing or charge regeneration, i.e. dynamic cells
• CPC Class Codes: G11C 11/4074 Power supply or voltage generation circuits, e.g. bias voltage generators, substrate voltage generators, back-up power, power control circuits
• CPC Class Codes: G11C 2029/5004 Voltage
• CPC Class Codes: G11C 29/50 Marginal testing, e.g. race, voltage or current testing
• CPC Class Codes: G11C 29/50016 of retention

Abstract

A dynamic RAM is provided with a plurality of 1-MOSFET memory cells, each having a storage capacitor and a switching MOSFET coupled to one electrode of the storage capacitor. The other electrode of each of the storage capacitors is coupled to a switching circuit which controls the voltage which is applied to the capacitor. The switching circuit is, in turn, coupled to both a voltage generating circuit (which preferably provides a voltage of 1/2 Vcc) and a voltage supply circuit which is set to provide predetermined test voltages. Thus, by operating the switching circuit, a voltage of 1/2 Vcc can be applied to the memory cell capacitors during normal operation of the dynamic RAM, and the predetermined test voltages can be applied to the memory cell capacitors during a testing operation.

Claims

1. A semiconductor memory comprising:

a memory cell including a data storage capacitor, having a pair of electrodes, and a MISFET coupled in series with said capacitor; and

a voltage generating circuit, powered by a power source voltage, for providing a voltage of about a half of said power source voltage to one of said pair of electrodes, the other of said pair of electrodes being coupled to said MISFET;

wherein said voltage generating circuit comprises a voltage dividing circuit which has a first resistor means having one end coupled to said power source voltage, a second resistor means having one end coupled to a predetermined voltage, a first node, a first MISFET of a first channel conductivity type, configured to operate as a diode, coupled between a second end of said first resistor means and said first node, and a second MISFET of a second channel conductivity type, configured to operate as a diode, coupled between a second end of said second resistor means and said first node, a first output MISFET of said first channel conductivity type having a gate coupled to the common connection of said first MISFET and said first resistor means, and a second output MISFET of said second channel conductivity type having a gate coupled to the common connection of said second MISFET and said second resistor means and having its source connected to the source of said first output MISFET, and wherein said first and second MISFETs have threshold voltage levels of absolute value smaller than that of the corresponding first and second output MISFETs, respectively, and wherein an output voltage of about a half of said power source voltage is obtained from said common source connection of said first and second output MISFETs.

2. A semiconductor memory according to claim 1, wherein said first and second resistor means comprise a third MISFET of said second channel conductivity type and a fourth MISFET of said first channel conductivity type, respectively, and wherein the gate of said third MISFET is coupled to the gate of said fourth MISFET and to said first node.