Patents Represented by Attorney Larry D. Cutter
  • Patent number: 5949723
    Abstract: For high-speed single-ended sensing of the signal from a (multi-port) SRAM cell, a configurable half-latch with 2 PFET feedback pathes is proposed, which can be set up either as a bleeder device in the system mode or as keeper devices in the test modes, controlled by a DC signal (TEST). The bleeder and keepers are attached to the bit line and gated by a small ratioed inverter serving as sense amplifier. In case of system mode, a low control signal is applied to the source of the bleeder to limit the bit line up-level to a threshold below the supply voltage Vdd. Thus, discharging the bit line when reading a `0` is fast. Reading a `1` is also fast by skewing the inverter to a PFET/NFET ratio below 1. For chip testing, the control signal is set high to enable the keepers which restore the bit line close to the supply voltage, even when large subthreshold currents try to discharge it via the unselected cells. This turns off the PFET of the inverter, thereby minimizing the DC current.
    Type: Grant
    Filed: July 30, 1998
    Date of Patent: September 7, 1999
    Assignee: International Business Machines Corporation
    Inventors: Rainer Clemen, Herald Mielich, Jurgen Pille