Patents Assigned to T-Ram, Inc.
  • Patent number: 7135745
    Abstract: A semiconductor device having a thyristor-based device and a pass device exhibits characteristics that may include, for example, resistance to short channel effects that occur when conventional MOSFET devices are scaled smaller in connection with advancing technology. According to an example embodiment of the present invention, the semiconductor device includes a pass device having a channel in a fin portion over a semiconductor substrate, and a thyristor device coupled to the pass device. The fin has a top portion and a side portion and extends over the semiconductor substrate. The pass device includes source/drain regions separated by the channel and a gate facing and capacitively coupled to the side portion of the fin that includes the channel. The thyristor device includes anode and cathode end portions, each end portion having base and emitter regions, where one of the emitter regions is coupled to one of the source/drain regions of the pass device.
    Type: Grant
    Filed: September 9, 2002
    Date of Patent: November 14, 2006
    Assignee: T-Ram, Inc.
    Inventors: Andrew Horch, Scott Robins
  • Patent number: 7123508
    Abstract: A reference cell produces a reference current that is about half of the current produced by a memory cell. The reference cell is essentially the same as the memory cell with an additional current reduction device that can be a transistor. Adjusting a reference voltage applied to the transistor allows the reference current to be varied. A control circuit to produce the reference voltage includes dedicated memory and reference cells and a feedback circuit that compares the two cells' currents. The feedback circuit applies the reference voltage to the reference cell of the control circuit and adjusts the reference voltage until the current from the reference cell is about half of the current from the memory cell. The reference voltage is then applied to other reference cells in a memory array.
    Type: Grant
    Filed: August 17, 2004
    Date of Patent: October 17, 2006
    Assignee: T-RAM, Inc.
    Inventors: Andrew Horch, Tapan Samaddar
  • Patent number: 7096144
    Abstract: A sampling circuit for testing an integrated circuit receives several signals from points of interest in the integrated circuit, digitizes them, and determines whether the digitized signal is above or below a threshold. By sampling the signal at different phases of a system clock signal, a determination can be made of when during the system clock signal the signal at a point of interest changed state. Circuits are provided for making minimal impact on the circuit being observed. Circuits are also provided for clocking the observed signal so that it can be compared to other observed signals.
    Type: Grant
    Filed: August 9, 2004
    Date of Patent: August 22, 2006
    Assignee: T-RAM, Inc.
    Inventor: Bruce L. Bateman
  • Patent number: 7089439
    Abstract: An output clock for a memory device having a read latency more than one clock cycle includes a clock generator at a central location on the device. A clock channel couples the clock generator to output structures. A timing path emulates the address/data paths in the memory, and is responsive to an address emulation signal produced by the clock generator to provide dummy data near the output structures. An output clock signal with an adjustable phase and a dummy data reference clock signal on the input of the clock channel are generated. A phase detector near the output structures, determines whether the output clock is early, late or on time with respect to the dummy data. Logic signals are produced at the phase detector, and returned to the clock generator for adjusting the relative phase of the output clock signal.
    Type: Grant
    Filed: September 3, 2003
    Date of Patent: August 8, 2006
    Assignee: T-RAM, Inc.
    Inventors: Shahram Abdollahi-Alibeik, Chaofeng Huang
  • Patent number: 7064977
    Abstract: A reference cell produces a reference current that is about half of the current produced by a memory cell. The reference cell is essentially the same as the memory cell with an additional current reduction device that can be a transistor. Adjusting a reference voltage applied to the transistor allows the reference current to be varied. A control circuit to produce the reference voltage includes dedicated memory and reference cells and a feedback circuit that compares the two cells' currents. The feedback circuit applies the reference voltage to the reference cell of the control circuit and adjusts the reference voltage until the current from the reference cell is about half of the current from the memory cell. The reference voltage is then applied to other reference cells in a memory array.
    Type: Grant
    Filed: May 20, 2005
    Date of Patent: June 20, 2006
    Assignee: T-RAM, Inc.
    Inventors: Andrew Horch, Tapan Samaddar, Scott Robins
  • Patent number: 7054191
    Abstract: A first and a second set of memory cells are connected to the same first word line and second word line. At the commencement of data writing, the first word line is set up. The first set of memory cells is read and temporarily stored into a buffer. At about the same time, the bit lines of the second set of memory cells is set up. After completion of reading of the first set of memory cells, the bit lines of this set of memory cells are set up (while the setting up of the bit lines of the second set of memory cells continues). After the bit lines of both sets of memory cells are set up, the second word line is pulsed. At this time, written into both sets of memory cells begins, which comprises data previously read from the first set of memory cells and new data to be written into the second set of memory cells. It is found that this method reduces the overall write time.
    Type: Grant
    Filed: June 3, 2004
    Date of Patent: May 30, 2006
    Assignee: T-Ram, Inc.
    Inventors: Rajesh Narendra Gupta, Scott Robins
  • Patent number: 7053423
    Abstract: A thyristor-based semiconductor device exhibits a relatively increased base-emitter capacitance. According to an example embodiment of the present invention, a base region and an adjacent emitter region of a thyristor are doped such that the emitter region has a lightly-doped portion having a light dopant concentration, relative to the base region. In one embodiment, the thyristor is implemented in a memory circuit, wherein the emitter region is coupled to a reference voltage line and a control port is arranged for capacitively coupling to the thyristor for controlling current flow therein. In another implementation, the thyristor is formed on a buried insulator layer of a silicon-on-insulator (SOI) structure. With these approaches, current flow in the thyristor, e.g., for data storage therein, can be tightly controlled.
    Type: Grant
    Filed: November 5, 2004
    Date of Patent: May 30, 2006
    Assignee: T-RAM, Inc.
    Inventors: Farid Nemati, Scott Robins, Andrew Horch
  • Patent number: 7049182
    Abstract: A semiconductor device is formed having a thyristor, a pass device and a conductive shunt that electrically connects an emitter region of the thyristor with a node near an upper surface of the substrate. In one example embodiment of the present invention, the conductive shunt is formed in a trench in a substrate and extending from an upper surface of the substrate to an emitter region of a vertical thyristor, with the emitter region being in the substrate and below the upper surface. In one implementation, the thyristor includes a thyristor body and a control port, with an N+ emitter region of the thyristor body being in the substrate and below and upper surface thereof. A pass device is formed adjacent to the thyristor, and the conductive shunt is formed in a trench extending from the N+ emitter region to a source/drain region of the pass device.
    Type: Grant
    Filed: October 9, 2003
    Date of Patent: May 23, 2006
    Assignee: T-RAM, Inc.
    Inventors: Andrew Horch, Scott Robins
  • Patent number: 7015077
    Abstract: A semiconductor device is formed having a thyristor and trench arranged to electrically insulate an emitter region of the thyristor from another circuit structure. In one example embodiment of the present invention, a trench having a bottom portion with two different trench depths is etched in the substrate. A thyristor is formed having a control port in a trench and having an emitter region adjacent to the trench and below an upper surface of the substrate. A deeper portion of the trench electrically insulates the emitter region from the other circuit structure. The control port is capacitively coupled to the thyristor and to the other circuit structure (e.g., in response to at least one edge of a voltage pulse applied thereto). In one implementation, the trench further includes an emitter-access connector extending from the emitter region to an upper surface of the substrate.
    Type: Grant
    Filed: October 21, 2004
    Date of Patent: March 21, 2006
    Assignee: T-RAM, Inc.
    Inventors: Andrew Horch, Scott Robins
  • Patent number: 7006398
    Abstract: A sensing circuit including a sense amplifier to resolve a data signal generated by a memory cell is disclosed herein. The sensing circuit includes a bit line to receive the data signal, a first pre-charge device coupled to the bit line and configured to pre-charge the bit line, a device for providing a bias coupled to the bit line and configured to provide a bias to the bit line, and a reference node configured to be at least one pre-determined level. In one embodiment the pre-determined level is equal to a low potential such as ground and in another embodiment equal to a high potential such as VDD. One or more switching devices allows for the activation or deactivation of the pre-charge device allowing to pre-charge the bit line to a certain potential and the sensing circuit quickly and accurately determines whether a logical state of ‘1’ or ‘0’ is being applied to the bit line.
    Type: Grant
    Filed: October 29, 2004
    Date of Patent: February 28, 2006
    Assignee: T-RAM, Inc.
    Inventors: Sei-Seung Yoon, Jin-Man Han, Seong-Ook Jung
  • Patent number: 6998652
    Abstract: A semiconductor device includes a thyristor body having at least one region in a substrate. According to an example embodiment of the present invention, a trench is in a substrate and adjacent to a thyristor body region in the substrate. The trench is lined with an insulative material and further includes conductive material that is insulated from the thyristor body region in the substrate by the liner material. A conductive thyristor control port is located in the trench and adapted for capacitively coupling to the thyristor body region in the substrate and to control current in the thyristor body by causing an outflow of minority carriers in the thyristor. With this approach, conductive material can be used to fill a portion of the trench while using the trench portion including the conductive material to electrically isolate a portion of the thyristor body in the substrate.
    Type: Grant
    Filed: October 1, 2002
    Date of Patent: February 14, 2006
    Assignee: T-Ram, Inc.
    Inventors: Andrew Horch, Scott Robins
  • Patent number: 6980457
    Abstract: A thyristor-based semiconductor device is formed having a thyristor, a pass device and an emitter region buried in a substrate and below at least one other vertically-arranged contiguous region of the thyristor that is at least partially below an upper surface of the substrate. According to an example embodiment of the present invention, a conductor, such as a polysilicon pillar formed in a trench, extends through the substrate and to the buried emitter region of the thyristor. In one implementation, a portion of the conductor includes a reduced-resistance material, such as a salicide, that is adapted to reduce the resistance of an electrical connection made to the buried emitter region via the conductor. This is particularly useful, for example, in connecting the buried emitter region to a power supply at a reduced resistance (e.g., as compared to the resistance that would be exhibited, were the reduced-resistance material not present).
    Type: Grant
    Filed: November 6, 2002
    Date of Patent: December 27, 2005
    Assignee: T-RAM, Inc.
    Inventors: Andrew Horch, Scott Robins
  • Patent number: 6979602
    Abstract: A semiconductor device is formed including a substrate having an upper surface, a thyristor region in the substrate and a control port adapted for capacitively coupling to at least a portion of the thyristor region via a dielectric material. According to an example embodiment of the present invention, a trench is formed in the substrate and subsequently filled with materials including dielectric material and a control port. The control port is adapted for capacitively coupling to the thyristor via the dielectric material for controlling current flow in the thyristor (e.g., for causing an outflow of minority carriers from a portion of the thyristor for switching the thyristor from conducting state to a blocking state). A portion of the substrate adjacent to the upper surface is implanted with a species of ions, and the dielectric material via which the control port capacitively couples to the thyristor does not include the species of ions.
    Type: Grant
    Filed: December 8, 2003
    Date of Patent: December 27, 2005
    Assignee: T-RAM, Inc.
    Inventors: Andrew Horch, Scott Robins
  • Patent number: 6975260
    Abstract: A geometric DAC architecture includes a series of substantially identical sub-DACs, each sub-DAC having n taps. The sub-DACs are fed from a bias-DAC having m=(total number of taps needed)/n taps. The output of each of the m taps is increased geometrically at a rate of kn. The geometric DAC architecture control lines desirably require only (m+n) taps compared with (m×n) taps for the simpler more conventional approach. Further, the geometric DAC architecture requires less real estate than the simpler more conventional approach, is easy to expand because it is modular, and generates an output current that is always monotonic, regardless of errors in transistor sizes and PVT variations. The n tap control lines are coded by alternately inverting n control line inputs between sub-DACs such that any state transition associated with the geometric DAC occurs with only one bit change in each of the control lines.
    Type: Grant
    Filed: November 12, 2004
    Date of Patent: December 13, 2005
    Assignee: T-RAM, Inc.
    Inventors: Shahram Abdollahi-Alibeik, Chaofeng Huang
  • Patent number: 6965129
    Abstract: Switching operations, such as those used in memory devices, are enhanced using a thyristor-based semiconductor device adapted to switch between a blocking state and a conducting state. According to an example embodiment of the present invention, a thyristor-based semiconductor device includes a thyristor having first and second base regions coupled between first and second emitter regions, respectively. A first control port capacitively couples a first signal to the first base region, and a second control port capacitively couples a second signal to the second base region. Each of the first and second signals have a charge that is opposite in polarity, and the opposite polarity signals effect the switching of the thyristor at a lower power, relative to the power that would be required to switch the thyristor having only one control port.
    Type: Grant
    Filed: November 6, 2002
    Date of Patent: November 15, 2005
    Assignee: T-Ram, Inc.
    Inventors: Andrew Horch, Scott Robins, Farid Nemati
  • Patent number: 6958931
    Abstract: A circuit and a method are provided for facilitating control of bit lines in preparation for, or during, sense amplification of data signals from thinly capacitively-coupled thyristor (“TCCT”)-based memory cells. In accordance with a specific embodiment, a circuit and method are designed, among other things, to effectively minimize power consumption by memory cells and to increase speed and reliability of sense amplification. In another specific embodiment, the circuit and method are directed to TCCT-based memory cells.
    Type: Grant
    Filed: July 30, 2002
    Date of Patent: October 25, 2005
    Assignee: T-RAM, Inc.
    Inventors: Sei-Seung Yoon, Seong-Ook Jung
  • Patent number: 6953953
    Abstract: A thyristor-based semiconductor device includes a filled trench separating and electrically insulating adjacent thyristor control ports. According to an example embodiment of the present invention, the filled trench is formed in a substrate adjacent to at least one thyristor body region. The filled trench includes a conductive filler material, an insulative material formed on the conductive filler material and at least two laterally-adjacent thyristor control ports separated from one another by the conductive filler material and the insulative material. One of the control ports is adapted for capacitively coupling to the thyristor body region for controlling current in the thyristor. With this approach, two or more control ports can be formed in a single filled trench and electrically isolated by the conductive filler material/insulative material combination.
    Type: Grant
    Filed: October 1, 2002
    Date of Patent: October 11, 2005
    Assignee: T-RAM, Inc.
    Inventor: Andrew Horch
  • Patent number: 6947349
    Abstract: A method and apparatus generates output clock pulses, having leading and trailing edges that are adjusted in a pulse forming processor, according to the relative phase of an output clock and output data. Dynamic adjustment of the leading and trailing edges of output clock pulses improves the performance of high-speed devices significantly.
    Type: Grant
    Filed: September 3, 2003
    Date of Patent: September 20, 2005
    Assignee: T-RAM, Inc.
    Inventors: Shahram Abdollahi-Alibeik, Chaofeng Huang
  • Patent number: 6944051
    Abstract: In a thyristor based memory cell, one end of a reversed-biased diode is connected to the cathode of the thyristor. During standby, the second end of the diode is biased at a voltage that is higher than that at the cathode of the thyristor. During restore operation, the second end is pulled down to zero or even a negative value. If the cell is storing a “1,” the voltage at the thyristor cathode can be approximately 0.6 volt at the time of the pull down. The large forward-bias across the diode pulls down the thryistor cathode. This causes the thyristor to be restored. If the cell is storing a “0,” the voltage at the thyristor cathode can be approximately zero volt. The small or zero forward-bias across the diode is unable to disturb the “0” state. As a result, the memory cell is restored to its original state.
    Type: Grant
    Filed: October 29, 2003
    Date of Patent: September 13, 2005
    Assignee: T-Ram, Inc.
    Inventors: Zachary K. Lee, Farid Nemati, Scott Robins
  • Patent number: 6937085
    Abstract: The voltage comparator of the present invention comprises a sense amplifier connected to a latch. The sense amplifier has a first input terminal for connecting to the input voltage under consideration and a second input terminal for connecting to the reference voltage. The sense amplifier generates two voltages of opposite logic values (i.e., high or low). A latch accepts these two voltages and generates an output voltage that is indicative of whether the voltage under consideration is higher or lower than the reference voltage. In another embodiment, a signal conditioning circuit is used to reduce the transients in the input voltage under consideration and perform level shifting function.
    Type: Grant
    Filed: April 25, 2003
    Date of Patent: August 30, 2005
    Assignee: T-Ram, Inc.
    Inventor: Tapan Samaddar