Patents Represented by Attorney E. Eric Hoffman
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Patent number: 7061271Abstract: A 6-input LUT architecture includes 64 memory cells, which store 64 corresponding data values. A set of 64 transmission gates is configured to receive the 64 four data values. A first input signal is applied to the set of 64 transmission gates, thereby routing 32 of the 64 data values. A set of 32 transmission gates is coupled to receive the 32 data values routed by the set of 64 transmission gates. A second input signal is applied to the set of 32 transmission gates, thereby routing 16 of the 32 data values. A 16:1 multiplexer receives the sixteen data values routed by the set of 32 transmission gates. Third, fourth, fifth and sixth input signals are applied to the 16:1 multiplexer, thereby routing one of the 16 data values as the output of the LUT.Type: GrantFiled: June 8, 2004Date of Patent: June 13, 2006Assignee: Xilinx, Inc.Inventors: Steven P. Young, Venu M. Kondapalli, Ramakrishna K. Tanikella
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Patent number: 7046052Abstract: A phase matched clock divider includes a first feed-through flip-flop that receives a first input clock signal, and in response, provides a first output clock signal having the same frequency. The first feed-through flip-flop is enabled and disabled in response to a first reset signal. A plurality of series-connected flip-flops each receives the first input clock signal, and in response, provides a divided output clock signal. Each of the series-connected flip-flops is enabled and disabled in response to a second reset signal. The first and second release signals asynchronously disable the associated flip-flops in response to a third reset signal. The first release signal synchronously enables the first feed-through flip-flop in response to the third reset signal and a release clock signal. The second release signal enables the series-connected flip-flops in response to the third reset signal and a release control signal.Type: GrantFiled: April 30, 2004Date of Patent: May 16, 2006Assignee: Xilinx, Inc.Inventors: Andrew K. Percey, Raymond C. Pang
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Patent number: 7038519Abstract: A digital clock manager having differential clock signal paths is provided. The differential clock signal paths are provided by replacing single-ended circuit elements of a conventional digital clock manager with symmetrical cascade voltage switch logic (CVSL) circuit elements, including CVSL delay buffers, CVSL multiplexers, CVSL AND gates, CVSL OR gates and CVSL set-reset latches. These symmetrical CVSL AND gates, CVSL OR gates and CVSL set-reset latches represent new circuit elements.Type: GrantFiled: April 30, 2004Date of Patent: May 2, 2006Assignee: Xilinx, Inc.Inventors: Raymond C. Pang, Jennifer Wong
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Patent number: 7026692Abstract: A p-channel non-volatile memory (NVM) transistor is programmed by shifting the threshold voltage of the transistor. The threshold voltage is shifted by introducing a programming current to the gate electrode of the transistor, and simultaneously introducing a negative bias to the transistor. The threshold voltage of the p-channel NVM transistor is shifted in response to the negative bias condition and the heat generated by the programming current. The high temperature accelerates the threshold voltage shift. The threshold voltage shift is accompanied by an agglomeration of material in the gate electrode. The agglomeration of material in the gate electrode is an indication of the high temperature reached during programming. The threshold voltage shift of the p-channel NVM transistor is permanent.Type: GrantFiled: November 12, 2003Date of Patent: April 11, 2006Assignee: Xilinx, Inc.Inventor: Kevin T. Look
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Patent number: 7010014Abstract: The frequency of a skew clock signal is dithered around a base frequency, thereby enabling this clock signal to comply with FCC requirements for electromagnetic emissions within a specified window. Delay is introduced such that the clock signals exhibits slightly different frequencies in successive periods. For example, the frequency of a 100 MHz clock signal can be adjusted to have frequencies of approximately 98, 98.5, 99, 99.5, 100, 100.5, 101, 101.5, and 102 MHz during different periods. Because the frequencies are spread in 0.5 MHz increments, only three frequencies are included in any 1 MHz window. As a result, ? of the energy of the clock signal is not included when determining whether the clock signal meets the FCC electromagnetic emission requirements. By spreading the frequencies above and below the base frequency in a regular manner, the average frequency of the clock signal becomes equal to the base frequency.Type: GrantFiled: October 6, 2000Date of Patent: March 7, 2006Assignee: Xilinx, Inc.Inventors: Andrew K. Percey, John D. Logue, F. Erich Goetting, Paul G. Hyland
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Patent number: 6963219Abstract: A configurable low voltage differential signal (LVDS) system is located on a chip, such as a programmable logic device. The configurable LVDS system includes a pair of I/O pads, an LVDS transmitter for driving a differential output signal onto the I/O pads, an LVDS receiver for receiving a differential input signal from the I/O pads, and a termination resistor coupled across the pair of I/O pads, wherein the termination resistance can be enabled for use with either the LVDS transmitter or the LVDS receiver. Control circuitry is provided to control the selective enabling and disabling of the LVDS transmitter, the LVDS receiver and the termination resistance. This control circuitry can be configured in response to configuration data values stored on the chip.Type: GrantFiled: April 8, 2003Date of Patent: November 8, 2005Assignee: Xilinx, Inc.Inventors: Atul V. Ghia, Ketan Sodha
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Patent number: 6963222Abstract: A non-volatile product term cell is provided having a first floating gate located over a first p-channel transistor and a first n-channel transistor, and a second floating gate located over a second p-channel transistor and a second n-channel transistor. A control gate is located over the first and second floating gates. A first tunnel oxide capacitor is coupled to the first floating gate and a second tunnel oxide capacitor is coupled to the second floating gate. A first transistor pair is coupled between the first p-channel transistor and the second n-channel transistor, and a second transistor pair is coupled between the second p-channel transistor and the first n-channel transistor. The first and second floating gates are programmed and/or erased. Complementary input signals are applied to the first and second transistor pairs. An output signal is provided in response to the programmed/erased states of the first and second floating gates.Type: GrantFiled: December 16, 2003Date of Patent: November 8, 2005Assignee: Xilinx, Inc.Inventor: Thomas J. Davies, Jr.
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Patent number: 6956390Abstract: An test block includes a box-like body and four rails extending from side edges of the body. During thermal testing, the test block is mounted between a test head and a test socket such that the rails provide a thermal path between the test block body and contact pads formed on the test socket. In this manner the rails emulate the thermal path formed by the metal leads extending from a conventional Quad Flat Pack Integrated Circuit (QFP IC), thereby reliably duplicating the actual thermal path of the QFP IC. The test block is mounted on the test system and its temperature is measured before and after testing QFP IC devices. Confirming that the test block is within test temperature specifications before and after the QFP-IC test procedure provides a highly reliable verification that the QFP-IC's actual test temperature is within the test temperature specifications.Type: GrantFiled: August 29, 2003Date of Patent: October 18, 2005Assignee: Xilinx, Inc.Inventors: Thomas A. Feltner, James S. Aylett, John C. Marley, Thomas A. Gallagher
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Patent number: 6946870Abstract: Output switch noise resulting from simultaneous switching is reduced by time multiplexing the output switching operation. A plurality of phase-shifted clock signals are generated such that each of the phase-shifted clock signals exhibits an active (e.g., rising) edge during a single period of the reference clock signal. Different groups of input/output blocks are switched in response to the various phase-shifted clock signals, such that output switching occurs at various times during the period of the reference clock signal. The phase-shifted clock signals can be generated with predetermined phase differences or with dynamically determined phase differences.Type: GrantFiled: October 21, 2003Date of Patent: September 20, 2005Assignee: Xilinx, Inc.Inventor: Austin H. Lesea
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Patent number: 6911842Abstract: A programmable logic device (PLD) is provided that supports multi-gigabit transceivers (MGTs). The PLD includes one or more pairs of shared clock pads for receiving one or more high-quality differential clock signals. Dedicated clock traces couple each pair of shared clock pads to one or more MGTs on the PLD. Each MGT includes a clock multiplexer circuit, which allows one of the high-quality differential clock signals to be routed as a reference clock signal for the MGT. The clock multiplexer circuits are designed such that no significant jitter is added to the high-quality clock signals. The clock multiplexer circuits can also route general-purpose clock signals received by the PLD as lower quality reference clock signals for the MGTs. The reference clock signal routed by the clock multiplexer circuit can be stepped down to provide a reference clock for a physical coding sublayer of the MGT.Type: GrantFiled: March 1, 2002Date of Patent: June 28, 2005Assignee: Xilinx, Inc.Inventors: Atul V. Ghia, Vasisht M. Vadi, Adebabay M. Bekele, Philip D. Costello, Hare K. Verma
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Patent number: 6907595Abstract: A programmable logic device, such as a field programmable gate array, is partially reconfigured using a read-modify-write scheme that is controlled by a processor. The partial reconfiguration includes (1) loading a base set of configuration data values into a configuration memory array of the programmable logic device, thereby configuring the programmable logic device; (2) reading a first frame of configuration data values from the configuration memory array; (3) modifying a subset of the configuration data values in the first frame of configuration data values, thereby creating a first modified frame of configuration data values; and (4) overwriting the first frame of configuration data values in the configuration memory array with the first modified frame of configuration data values, thereby partially reconfiguring the programmable logic device. The steps of reading, modifying and overwriting are performed under the control of a processor.Type: GrantFiled: December 13, 2002Date of Patent: June 14, 2005Assignee: Xilinx, Inc.Inventors: Derek R. Curd, Punit S. Kalra, Richard J. LeBlanc, Vincent P. Eck, Stephen W. Trynosky, Jeffrey V. Lindholm, Trevor J. Bauer
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Patent number: 6861895Abstract: A resistive divider for a voltage multiplier circuit minimizes output voltage overshoot by capacitively coupling the tap point of the resistive divider to the output terminal of the voltage multiplier circuit via the parasitic capacitance of the resistive divider. For a resistive divider that includes a resistive structure formed over a dielectric layer formed on a doped well, this capacitive coupling can be performed by connecting the well to the output terminal of the voltage multiplier circuit. This capacitive coupling improves the response time of the resistive divider, so that a scaled test voltage read from the tap point varies more rapidly than the elevated output voltage of the voltage multiplier circuit. Therefore, the scaled test voltage provides charging control that increases the elevated output voltage in gradual increments that prevent the elevated output voltage from exceeding a target output voltage.Type: GrantFiled: June 17, 2003Date of Patent: March 1, 2005Inventors: Ping-Chen Liu, Asim A. Bajwa
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Patent number: 6847228Abstract: A configurable logic block (CLB) slice is provided that includes a single path for a carry input signal to propagate through the CLB slice as a carry output signal. This single path includes a multiplexer that is configured to receive the input signals (including the carry input signal) and provides an output signal that can be routed as the carry output signal. A driver circuit can be coupled to the output terminal of the multiplexer, thereby improving the drive of the single path. A separate path is provided in parallel with the first multiplexer path, thereby enabling the carry input signal to be applied to exclusive OR gates within the CLB slice, or to be provided as an intermediate carry output signal. The single path provides a relatively fast and consistent manner of routing the carry input signal through the CLB slice as the carry output signal. The first and second paths accommodate a carry initialization signal as well as an intermediate carry input signal.Type: GrantFiled: November 19, 2002Date of Patent: January 25, 2005Assignee: Xilinx, Inc.Inventors: Patrick J. Crotty, Tao Pi, Steven P. Young
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Patent number: 6836443Abstract: A sensing system for a memory cell in a memory array includes a current integrator circuit configured to integrate a read current through the memory cell and a reference current through a reference memory cell. The integration process creates a set of differential measurement voltages that can be used to determine the state of the memory cell. By integrating the read current to obtain a measurement voltage, rather than directly comparing the read current to a reference current, the sensing system can use lower supply voltages than conventional sensing systems. In addition, because the measurement voltages are generated by integrating the read current over time, sensing operations are less sensitive to supply voltage fluctuations and the accuracy. Also, for memory cells that exhibit small read currents, the accuracy of sensing operations can be increased by increasing the period of integration.Type: GrantFiled: January 14, 2003Date of Patent: December 28, 2004Assignee: Tower Semiconductor Ltd.Inventor: Oleg Dadashev
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Patent number: 6836142Abstract: A system and method are provided for replacing dedicated external termination resistors typically used to implement an asymmetrical unidirectional bus I/O standard with programmable resistances that are dynamically selected by programming output driver circuits having digitally controlled impedances.Type: GrantFiled: July 12, 2002Date of Patent: December 28, 2004Assignee: Xilinx, Inc.Inventors: Austin H. Lesea, Atul V. Ghia
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Patent number: 6815998Abstract: A voltage generation circuit for generating a read-back voltage in response to a supply voltage and a reference voltage. The voltage generation circuit includes a comparator configured to receive the supply voltage and the reference voltage. The voltage generation circuit activates a select signal if the supply voltage has a predetermined relationship with respect to the reference voltage, and de-activates the select signal if the supply voltage does not exhibit the predetermined relationship with respect to the reference voltage. An adjustable voltage divider circuit is coupled to receive the supply voltage and the select signal. The adjustable voltage divider circuit is configured in response to the select signal to provide an output voltage that is a first percentage of the supply voltage if the select signal is activated, and provide an output voltage that is a second percentage of the supply voltage if the select signal is de-activated.Type: GrantFiled: October 22, 2002Date of Patent: November 9, 2004Assignee: Xilinx, Inc.Inventor: Maheen A. Samad
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Patent number: 6808169Abstract: A non-volatile memory (NVM) system includes a NVM cell having: a semiconductor region having a first conductivity type; a gate dielectric layer located over the semiconductor region; a gate electrode located over the gate dielectric layer; a source region and a drain region of a second conductivity type, opposite the first conductivity type, located in the semiconductor region and aligned with the gate electrode; a crown electrode having a base that contacts the gate electrode and walls that extend vertically from the base region, away from the gate electrode; a dielectric layer located over the crown electrode, wherein the dielectric layer extends over at least interior surfaces of the walls; and a plate electrode located over the dielectric layer, wherein the plate electrode extends over at least interior surfaces of the walls.Type: GrantFiled: September 6, 2001Date of Patent: October 26, 2004Assignee: Monolithic System Technology, Inc.Inventors: Fu-Chieh Hsu, Wingyu Leung
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Patent number: 6809948Abstract: A multi-bit programmable memory cell is provided that includes an access transistor and a plurality of N anti-fuse elements. The access transistor has a source coupled to a source line and a gate coupled to a word line. Each of the anti-fuse elements has a first terminal coupled to a drain of the access transistor, and a second terminal coupled to a corresponding bit line. At most, only one of the anti-fuse elements is programmed. The memory cell is capable of storing M bits, wherein N=2M−1. A method is provided for both programming and reading the memory cell. In another embodiment, the anti-fuse elements can be replaced with mask-programmable elements.Type: GrantFiled: May 6, 2003Date of Patent: October 26, 2004Assignee: Tower Semiconductor, Ltd.Inventors: Ishai Nachumovsky, Yaov Nissan-Cohen, Robert J. Strain
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Patent number: 6795364Abstract: An array of memory cells that require periodic refresh is operated in a single-cell mode during normal operating conditions. Upon receiving an asserted standby control signal from an accessing memory client, the array enters a standby mode from the normal operating conditions. The standby mode can be specified as a differential-cell mode, a single-cell mode or a non-retentive mode. To enter the differential-cell standby mode, data stored in the single-cell mode is converted to a differential-cell mode. In this conversion, half of the data stored in the single-cell mode is saved, while the other half is discarded. In the differential-cell standby mode, refresh operations are performed less frequently than in the normal operating mode, thereby conserving power. The external clock signal provided by the accessing memory client can be disabled during the differential-cell standby mode, as a local clock signal is provided to implement the refresh operations during standby mode.Type: GrantFiled: February 28, 2003Date of Patent: September 21, 2004Assignee: Monolithic System Technology, Inc.Inventors: Wingyu Leung, Jae-Hong Jeong
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Patent number: 6784048Abstract: A memory system that includes a DRAM cell that includes an access transistor and a storage capacitor. The storage capacitor is fabricated by forming a polysilicon crown electrode, a dielectric layer overlying the polysilicon crown, and a polysilicon plate electrode overlying the dielectric layer. A first set of thermal cycles are performed during the formation of the storage capacitor to form and anneal the elements of the capacitor structure. Subsequently, shallow P+ and/or N+ regions are formed by ion implantation, and metal salicide is formed. As a result, the relatively high first set of thermal cycles required to form the capacitor structure does not adversely affect the shallow P+ and N+ regions or the metal salicide. A second set of thermal cycles, which are comparable to or less than the first set of thermal cycles, are performed during the formation of the shallow regions and the metal salicide.Type: GrantFiled: August 28, 2002Date of Patent: August 31, 2004Assignee: Monolithic Systems Technology, Inc.Inventors: Wingyu Leung, Fu-Chieh Hsu