Abstract: A CAM circuit utilizes a relatively high operating voltage to control the memory portion of each CAM cell, and a relatively low operating voltage to control at least some of the logic portions of each CAM circuit. The CAM cell memory portion includes a memory (e.g., SRAM) cell controlled by a word line to store data values transmitted on complementary bit lines. The CAM cell logic portion includes a comparator that compares the stored data values with an applied data value transmitted on complementary data lines, and discharges a match line when the stored data value differs from the applied data value. The memory cell is driven using the relatively high memory operating voltage (e.g., 2.5 Volts) such that the stored charge resists soft errors. The complementary data lines and match line used to operate the comparator are driven using the relatively low logic operating voltage (e.g., 1.2 Volts) to conserve power.

Abstract: Content addressable memory (CAM) devices provide improved reliability by inhibiting disabled CAM cells within defective (or unused redundant columns) from contributing to either sustained or intermittent look-up errors when the CAM device is operated in an intended application. The improved reliability may be achieved in volatile CAM devices by configuring (e.g., programming) each column driver that is associated with a CAM array having a defective column therein to preserve intentionally written data and/or mask values of the disabled CAM cells across repeated power reset events.

Abstract: Content addressable memory (CAM) devices provide improved reliability by inhibiting disabled CAM cells within defective (or unused redundant columns) from contributing to either sustained or intermittent look-up errors when the CAM device is operated in an intended application. The improved reliability may be achieved in volatile CAM devices by configuring (e.g., programming) each column driver that is associated with a CAM array having a defective column therein to preserve intentionally written data and/or mask values of the disabled CAM cells across repeated power reset events.

Abstract: A first insulating layer (12) overlying semiconductor substrate (10) has a plurality of conductive paths (14, 16) disposed thereon. Each of the plurality of conductive paths has at least a major portion thereof overlied with a second insulating layer (20). A third insulating layer (26), having air gap ports (28) formed therein, overlies adjacent conductive paths and extends from one to another such that an air gap (34) is formed. A passivation layer (30) overlies third insulating layer and seals the plurality of air gaps ports to form an insulation structure (40) for a semiconductor integrated circuit, and method thereof.

Abstract: Integrated output driver circuits have sourcing and sinking current characteristics that reduce power (Vdd) and ground (Vss) bounce effects by making the dl/dt characteristic of the sourcing current to a load and/or sinking current from the load more nearly uniform during a pull-up or pull-down driving event. Improved speed characteristics can also be achieved using capacitive bootstrapping to quickly turn on a NMOS pull-down transistor, which controls the sinking current from the load, and/or PMOS pull-up transistor, which controls the sourcing current to the load.

Abstract: A novel gate structure and a method of forming the same for a self-aligned contact on a semiconductor substrate. The method includes forming a gate oxide layer on the semiconductor substrate. Then a first conductive layer is formed on the gate oxide layer. Next, a second conductive layer, preferably a refractory metal silicide (e.g. WSix), is formed overlying the first conductive layer. A capping layer is formed overlying the second conductive layer. Then the capping layer is etched to form a patterned capping layer having a lower outside corner. An upper portion of the second conductive layer is selectively dry etched laterally to form a lateral recess under the capping layer to increase etch margin. A lower portion of the second conductive layer is then etched anisotropically down to the first conductive layer along a sidewall approximately vertically aligned with the lower outside corner of the patterned capping layer.

Abstract: A DRAM circuit including a first DRAM array used solely for refresh operations, and the second DRAM array for performing logic operations that is refreshed using data read from the first DRAM array. Specifically, data is read only from the first DRAM array during a read phase of the refresh operation, and is written to both the first DRAM array and the second DRAM array during the write phase of the refresh operation. Accordingly, the second DRAM array is able to simultaneously perform any type of logic operation without delay or disturbance caused by accessing the second DRAM array during the read phase. In one embodiment, the second DRAM array includes DRAM CAM cells that perform data matching operations using the data refreshed from the first DRAM array, which includes conventional DRAM memory cells.

Abstract: A CAM circuit including a RAM array, a CAM array, and a control circuit that systematically writes data from the RAM array to the CAM array, thereby preventing soft errors by continually restoring data that has been corrupted by radiation. The RAM and CAM arrays can be formed on the same substrate, but are preferably fabricated on separate substrates and mounted in a single package or on a PCB. Both the CAM and RAM can be formed using any conventional memory type (e.g., SRAM, DRAM, NVRAM), and the CAM array can be a binary, ternary, or quad CAM array. The CAM and RAM arrays can be formed on different substrates, or the same substrate. A system including an SRAM ternary CAM array and a RAM array perform quad CAM functions by performing read functions utilizing only the RAM array, while performing lookup functions using the ternary CAM array.

Abstract: The invented method involves separately etching the P and N gate features in a dual-poly gate using dual masks, thereby permitting the etching recipes to be tuned to the differentially responsive P and N materials that form the gate.

Abstract: A CAM circuit utilizes a relatively high operating voltage to control the memory portion of each CAM cell, and a relatively low operating voltage to control the logic portion of each CAM cell. The CAM cell memory portion includes a memory (e.g., SRAM) cell controlled by a word line to store data values transmitted on complementary bit lines. The CAM cell logic portion includes a comparator that compares the stored data values with an applied data value transmitted on complementary data lines, and discharges a match line when the stored data value differs from the applied data value. The memory cell is driven using the relatively high memory operating voltage (e.g., 2.5 Volts) such that the stored charge resists soft errors. The complementary data lines and match line used to operate the comparator are driven using the relatively low logic operating voltage (e.g., 1.2 Volts) to conserve power.

Abstract: A CAM circuit including a RAM array, a CAM array, a control/interface circuit, and an error detection and correction (EDC) circuit. The control/interface circuit systematically writes data from the RAM array to the CAM array, thereby preventing soft errors by continually refreshing data stored in the CAM array. The RAM array also stores check bits for each data word that can be generated by the EDC circuit when the data words are initially written to the CAM circuit. During the refresh operation, data words and associated check bits are read from the RAM array and transmitted to the EDC circuit. The EDC circuit analyzes each data word and associated check bits to detect errors, and corrects the data word, if necessary, before sending the data word to the CAM array.

Abstract: A method of generating a priority address using a priority encoder that includes the steps of: (1) providing a plurality of match signals from a CAM cell memory array to the priority encoder, (2) generating a most significant address bit of the priority address in response to a first set of the match signals, and (3) generating a least significant address bit of the priority address in response to the most significant address bit and a second set of the match signals. In one embodiment, step (3) is implemented by splitting the determination of the least significant address bit into two separate determinations, and the using the most significant address bit to select the result of one of these two separate determinations. Using the most significant address bit to help determine the least significant address bit significantly increases the speed of determining the least significant address bit, thereby increasing the overall speed of the priority encoder.

Abstract: A CAM circuit including a RAM array, a CAM array, and a control circuit that systematically writes data from the RAM array to the CAM array, thereby preventing soft errors by continually restoring data that has been corrupted by radiation. The RAM and CAM arrays can be formed on the same substrate, but are preferably fabricated on separate substrates and mounted in a single package or on a PCB. Both the CAM and RAM can be formed using any conventional memory type (e.g., SRAM, DRAM, NVRAM), and the CAM array can be a binary, ternary, or quad CAM array. The CAM and RAM arrays can be formed on different substrates, or the same substrate. A system including an SRAM ternary CAM array and a RAM array perform quad CAM functions by performing read functions utilizing only the RAM array, while performing lookup functions using the ternary CAM array.

Abstract: A content addressable memory (CAM) system that includes first and second CAM arrays, which generate first and second sets of match control signals, respectively, having higher and lower priorities, respectively. The first CAM array is enabled during a first memory cycle, and the first set of match control signals are analyzed. If a match exists in the first CAM array, a first priority encoder is enabled to process the first set of match control signals. If no match exists, the first priority encoder is not enabled, and a second memory cycle is initiated. The second CAM array is enabled during the second memory cycle, and the second set of signals is analyzed. If a match exists in the second CAM array, a second priority encoder is enabled to process the second set of match control signals. If no match exists, the second priority encoder is not enabled.

Abstract: An integrated circuit having an electrostatic discharge (ESD) protection circuit, a core protection circuit, a sensitive core circuit and peripheral circuitry is provided. The ESD protection circuit is coupled between the VDD voltage supply terminal and the VSS voltage supply terminal, and is capable of providing protection to the peripheral circuitry. The ESD protection circuitry requires help from core protection circuit to protect the sensitive core circuit. The core protection circuit and the sensitive core circuit are coupled in series between the VDD and VSS voltage supply terminals, with the core protection circuit coupled to the VDD voltage supply terminal. The sensitive core circuit has a VCC voltage supply terminal coupled to receive a VCC supply voltage from the core protection circuit. The core protection circuit is configured to cause the VCC supply voltage to rise slowly with respect to a rising voltage on the VDD voltage supply terminal during power-on of the integrated circuit.

Abstract: An input buffer for use in an integrated circuit having a VCC voltage supply and a VSS voltage supply. The input buffer includes a p-channel field effect transistor (FET) having a source region coupled to the VCC voltage supply, a drain region coupled to a bias circuit, and a gate electrode coupled to an input terminal. The bias circuit maintains a voltage at the drain region of the p-channel FET which is slightly greater than the VSS supply voltage when a logic high voltage is applied to the input terminal. In an alternate embodiment, the input buffer includes an n-channel FET having a drain region coupled to the VCC voltage supply, a source region coupled to the output terminal and a gate electrode coupled to the input terminal. The bias circuit maintains a voltage at the source of the n-channel FET which is greater than the VSS supply voltage when a logic low voltage is applied to the input terminal.

Abstract: A CAM cell including three-transistor (3T) or four-transistor (4T) DRAM cells. Data is stored using intrinsic capacitance of each 3T or 4T DRAM cell, and is applied to the gate terminal of a pull-down transistor. Read operations are performed in the 3T and 4T DRAM cells without disturbing the stored data value by applying the stored data value to the gate terminal of a pull-down transistor and detecting the operating state (i.e., turned on or turned off) of a pull-down transistor, thereby avoiding the charge sharing problems associated with 1T DRAM cells.

Abstract: A ternary CAM cell including a binary SRAM CAM cell connected in series with a mask transistor between a match line and a discharge line, and a DRAM mask circuit for applying a mask (care/don't care) value to the gate terminal of the mask transistor. The binary CAM cell stores a data value that is compared with an applied data value, and opens the first portion of a discharge path between the match line and the discharge line when the applied data value fails to match the stored data value. The mask transistor is controlled by the DRAM mask circuit, which includes two associated DRAM memory cells that are connected by a bit line to a sense amplifier. The DRAM mask circuit is refreshed such that, during a read phase of the refresh operation, a data value is read only from the first DRAM memory cell and registered (refreshed) by the sense amplifier circuit. In the subsequent write phase of the refresh operation, the data value is written to the second DRAM memory cell.

Abstract: A four-state (quad) CAM cell that stores one of four logic values: a logic high value, a logic low value, a logic high don't care value, and a logic low don't care value. Each quad CAM cell includes a first memory cell, a second memory cell, a comparator circuit, and a control switch. The first memory cell stores a data value (i.e., logic high value or logic low value), and transmits this stored data value to the comparator circuit. The second memory cell stores a care/don't care data value that is transmitted to the control switch. Portions of the comparator circuit and the control switch form a discharge path between a match line and a discharge line connected to the quad CAM cell. The control switch is controlled by the care/don't care value to open/close a first part of the discharge path. The comparator circuit is controlled to open a second part of the discharge path when, for example, the stored data value is equal to an applied data value.

Abstract: A self-aligned via between interconnect layers in an integrated circuit, and a process for forming such a via which allows a less precise masking alignment to be used to fabricate an integrated circuit with increased packing density.