Patents Assigned to Monolithic System Technology, Inc.
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Patent number: 5829026Abstract: A method and structure for implementing a DRAM memory array as a second level cache memory in a computer system. The computer system includes a central processing unit (CPU), a first level SRAM cache memory, a CPU bus coupled to the CPU, and a second level cache memory which includes a DRAM array coupled to the CPU bus. When accessing the DRAM array, row access and column decoding operations are performed in a self-timed asynchronous manner. Predetermined sequences of column select operations are then performed in a synchronous manner with respect to a clock signal. The DRAM array is operated at a higher frequency than the frequency of the CPU bus clock signal, thereby reducing the access latency of the DRAM array. By operating the DRAM array at a higher frequency than the CPU bus, additional time is provided for precharging the DRAM array. As a result, the precharging of the DRAM array is transparent to the CPU bus.Type: GrantFiled: March 5, 1997Date of Patent: October 27, 1998Assignee: Monolithic System Technology, Inc.Inventors: Wingyu Leung, Fu-Chieh Hsu
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Patent number: 5805509Abstract: A method and structure for generating a boosted word line voltage for a memory array, such as a DRAM array. To ensure that an adequate voltage is applied to the word line of the memory array during write operations, the word line driver circuit is connected to a boost voltage generator which provides a substantially constant, regulated voltage which is boosted to a level which is approximately equal to the V.sub.cc supply voltage plus the threshold voltage of the memory cell pass transistor. A bias voltage generator provides a negative voltage which is used to bias the substrate of the memory array. The boosted voltage generator and the bias voltage generator can be operated in response to the same clock signal used to operate the memory array. A latch-up prevention circuit is provided to ensure that the word line driver circuit does not latch-up during power-on before an adequate boost voltage has been established.Type: GrantFiled: July 10, 1997Date of Patent: September 8, 1998Assignee: Monolithic System Technology, Inc.Inventors: Wingyu Leung, Jeffrey J. Lin
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Patent number: 5790138Abstract: A computer unified memory architecture (UMA) system and method which includes a unified memory which is partitioned into a main memory and a main frame buffer memory, as well as a separate expansion frame buffer memory. Together, the main frame buffer memory and the expansion frame buffer memory form an entire frame buffer memory. The UMA system performs a display refresh operation by alternately accessing the main frame buffer memory and the expansion frame buffer memory. Because the display data bandwidth is split between the main frame buffer memory and the expansion frame buffer memory, the data bandwidth of the unified memory is effectively increased, thereby enabling higher system performance. The expansion frame buffer memory has a relatively small capacity, thereby retaining much of the cost benefit of a UMA system.Type: GrantFiled: January 16, 1996Date of Patent: August 4, 1998Assignee: Monolithic System Technology, Inc.Inventor: Fu-Chieh Hsu
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Patent number: 5787267Abstract: A structure and method of implementing a cache memory for a multi-processor system. The cache memory includes a main memory which is coupled to a main memory bus. A plurality of processors can also be coupled to the main memory bus. The main memory includes a plurality of RAM circuit module memory banks. The sense amplifiers of a predetermined number of banks are used as cache memory (i.e., sense amplifier cache lines). The number of banks used with sense amplifiers activated is substantially less than the total number of banks. The banks which are not used as cache memory are kept in a precharged state.Type: GrantFiled: June 7, 1995Date of Patent: July 28, 1998Assignee: Monolithic System Technology, Inc.Inventors: Wingyu Leung, Kit Sang Tam
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Patent number: 5737587Abstract: A memory system having several memory devices coupled to a memory controller through an I/O bus, each memory device including multiple memory modules coupled to a chip I/O interface through an internal bus. The system includes a circuit for driving the I/O bus with a reduced CMOS-swing, a circuit for driving the internal bus with a full CMOS-swing in one bus direction and with a reduced CMOS-swing in the other bus direction, a column address generation circuit for allowing sequentially addressed data to be accessed with the decoder delay being eliminated, and a circuit for re-synchronizing data from a source clock to a destination clock with reduced access latency penalty. Simultaneously writing data into multiple circuit modules significantly increases the write bandwidth of the memory. Also included are a dynamic base-address mapping into an address space, a read or write operation across multiple memory modules, a novel I/O bus format, and a protocol and test mode for testing redundant memory sub-arrays.Type: GrantFiled: June 6, 1995Date of Patent: April 7, 1998Assignee: Monolithic System Technology, Inc.Inventors: Wingyu Leung, Winston Lee, Fu-Chieh Hsu
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Patent number: 5729152Abstract: A memory device which utilizes a plurality of memory modules coupled in parallel to a master I/O module through a single directional asymmetrical signal swing (DASS) bus. This structure provides an I/O scheme having symmetrical swing around half the supply voltage, high through-put, high data bandwidth, short access time, low latency and high noise immunity. The memory device utilizes improved column access circuitry including an improved address sequencing circuit and a data amplifier within each memory module. The memory device includes a resynchronization circuit which allows the device to operate either synchronously and asynchronously using the same pins. Each memory module has independent address and command decoders to enable independent operation. Thus, each memory module is activated by commands on the DASS bus only when a memory access operation is performed within the particular memory module. The memory device includes redundant memory modules to replace defective memory modules.Type: GrantFiled: October 27, 1995Date of Patent: March 17, 1998Assignee: Monolithic System Technology, Inc.Inventors: Wingyu Leung, Winston Lee, Fu-Chieh Hsu
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Patent number: 5708624Abstract: A method and structure for controlling the timing of an access to a DRAM array in response to a row access (RAS#) signal and the rising and/or falling edges of a clock signal. Row address decoding and the deactivation of equalization circuits are initiated when the row access signal is received and a first transition of the clock signal is detected. The row address decoding and the deactivation of the equalization circuits are completed before a second transition of the clock signal occurs. The second transition is then used to initiate the turning on of the sense amplifiers of the DRAM array. The sense amplifiers are turned on before a third transition of the clock signal. The third transition of the clock signal is then used to initiate the column address decoding operation of the DRAM array. In an alternative embodiment, the column address decoding is initiated when a column access (CAS#) signal is asserted and the clock signal undergoes the third transition.Type: GrantFiled: November 27, 1996Date of Patent: January 13, 1998Assignee: Monolithic System Technology, Inc.Inventor: Wingyu Leung
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Patent number: 5703827Abstract: A method and structure for generating a boosted word line voltage for a memory array, such as a DRAM array. To ensure that an adequate voltage is applied to the word line of the memory array during write operations, the word line driver circuit is connected to a boost voltage generator which provides a substantially constant, regulated voltage which is boosted to a level which is approximately equal to the V.sub.CC supply voltage plus the threshold voltage of the memory cell pass transistor. A bias voltage generator provides a negative voltage which is used to bias the substrate of the memory array. The boosted voltage generator and the bias voltage generator can be operated in response to the same clock signal used to operate the memory array. A latch-up prevention circuit is provided to ensure that the word line driver circuit does not latch-up during power-on before an adequate boost voltage has been established.Type: GrantFiled: February 29, 1996Date of Patent: December 30, 1997Assignee: Monolithic System Technology, Inc.Inventors: Wingyu Leung, Jeffrey J. Lin
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Patent number: 5666480Abstract: A fault-tolerant, high-speed wafer scale system comprises a plurality of functional modules, a parallel hierarchical bus which is fault-tolerant to defects in an interconnect network, and one or more bus masters. This bus includes a plurality of bus lines segmented into sections and linked together by programmable bus switches and bus transceivers or repeaters in an interconnect network.Type: GrantFiled: June 6, 1995Date of Patent: September 9, 1997Assignee: Monolithic System Technology, Inc.Inventors: Wingyu Leung, Fu-Chieh Hsu
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Patent number: 5655113Abstract: A resynchronization circuit for processing a stream of data values read from a memory system, and a method of operating the same. The resynchronization circuit includes a first in, first out (FIFO) memory device, a phase locked loop circuit and a latency control circuit. The FIFO memory device receives a stream of data values and a first clock signal from the memory system. The data values are sequentially read into the FIFO memory device in response to the first clock signal. The phase locked loop circuit receives a second clock signal, and in response generates an output clock signal which leads in phase the second clock signal. The output clock signal is provided to the FIFO memory device to cause the data values to be sequentially read from the FIFO memory device. As a result, a stream of data values is generated which is synchronized with the second clock signal.Type: GrantFiled: July 5, 1994Date of Patent: August 5, 1997Assignee: Monolithic System Technology, Inc.Inventors: Wingyu Leung, Winston Lee, Fu-Chieh Hsu
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Patent number: 5615169Abstract: A method and structure for controlling the timing of an access to a DRAM array in response to a row access (RAS#) signal and the rising and falling edges of a clock signal. Row address decoding and the deactivation of equalization circuits are initiated when the row access signal is received and a rising edge of the clock signal is detected. The row address decoding and the deactivation of the equalization circuits are completed before the falling edge of the clock signal occurs. The falling edge is then used to initiate the turning on of the sense amplifiers of the DRAM array. The sense amplifiers are turned on before the subsequent rising edge of the clock signal. The subsequent rising edge is then used to initiate the column address decoding operation of the DRAM array. A test mode is included which allows the DRAM array to be operated asynchronously for testing purposes.Type: GrantFiled: August 31, 1995Date of Patent: March 25, 1997Assignee: Monolithic System Technology, Inc.Inventor: Wingyu Leung
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Patent number: 5613077Abstract: A fault-tolerant, high-speed wafer scale system comprises a plurality of functional modules, a parallel hierarchical bus which is fault-tolerant to defects in an interconnect network, and one or more bus masters. This bus includes a plurality of bus lines segmented into sections and linked together by programmable bus switches and bus transceivers or repeaters in an interconnect network.Type: GrantFiled: September 14, 1994Date of Patent: March 18, 1997Assignee: Monolithic System Technology, Inc.Inventors: Wing Y. Leung, Fu-Chieh Hsu
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Patent number: 5592632Abstract: A fault-tolerant, high-speed wafer scale system comprises a plurality of functional modules, a parallel hierarchical bus which is fault-tolerant to defects in an interconnect network, and one or more bus masters. This bus includes a plurality of bus lines segmented into sections and linked together by programmable bus switches and bus transceivers or repeaters in an interconnect network.Type: GrantFiled: June 6, 1995Date of Patent: January 7, 1997Assignee: Monolithic System Technology, Inc.Inventors: Wing Y. Leung, Fu-Chieh Hsu
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Patent number: 5576554Abstract: A system for substrate scale integration by interconnecting a large number of separate memory (or other circuit) modules on a semiconductor substrate so as to electrically exclude both defective modules and defective interconnect/power segments, and include operative modules and interconnect/power segments. A set of discretionary connections are associated with each of the separate modules and interconnect/power segments and such connections are made (or broken) after a module or interconnect or power segment is tested. A power supply network is set up by combining operative power segments. A bidirectional bus is set up by combining operative interconnect segments to connect to each operative modules. This bidirectional bus consists of one or more hierarchies for speed, power and yield considerations. Each module is assigned an identity code using discretionary connections.Type: GrantFiled: December 10, 1993Date of Patent: November 19, 1996Assignee: Monolithic System Technology, Inc.Inventor: Fu-Chieh Hsu
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Patent number: 5511020Abstract: A pseudo nonvolatile memory cell which may be operated in a pseudo-nonvolatile mode is achieved by utilizing a thin direct tunneling dielectric adjacent to the charge retaining region in a traditional nonvolatile memory cell such as an EPROM, EEPROM, flash EPROM, or flash EEPROM cell. The use of the direct tunneling dielectric allows for greatly enhanced write/erase cycles (exceeding 100 gigacycles) and reduced data write/erase time (under 1 microsecond). The direct tunneling dielectric also results in a reduced data retention period. Consequently, refresh circuitry is provided to maintain the non-volatility of the memory cell. A back-up battery is used to power the refresh circuitry when the system power is removed. This mode of operation provides an effectively nonvolatile memory system that is suitable for replacing traditional nonvolatile memory devices.Type: GrantFiled: November 23, 1993Date of Patent: April 23, 1996Assignee: Monolithic System Technology, Inc.Inventors: Chenming Hu, Fu-Chieh Hsu
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Patent number: 5498886Abstract: A system and method for wafer scale integration optimized for medium die size integrated circuits by interconnecting a large number of separate memory (or other circuit) modules on a semiconductor wafer so as to electrically exclude both defective modules and defective interconnect/power segments, and include operative modules and interconnect/power segments. A set of discretionary connections are associated with each of the separate modules and interconnect/power segments and such connections are made (or broken) after a module or interconnect or power segment is tested. A power supply network is set up by combining operative power segments. A bidirectional bus is set up by combining operative interconnect segments to connect to each operative modules. This bidirectional bus consists of one or more hierarchies for speed, power and yield considerations. Each module is assigned an identity code using discretionary connections.Type: GrantFiled: May 20, 1994Date of Patent: March 12, 1996Assignee: Monolithic System Technology, Inc.Inventors: Fu-Chieh Hsu, Wingyu Leung
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Patent number: 5498990Abstract: A memory system having several memory devices coupled to a memory controller through an I/O bus, each memory device including multiple memory modules coupled to a chip I/O interface through an internal bus. The system includes a circuit for driving the I/O bus with a reduced CMOS-swing, a circuit for driving the internal bus with a full CMOS-swing in one bus direction and with a reduced CMOS-swing in the other bus direction, a column address generation circuit for allowing sequentially addressed data to be accessed with the decoder delay being eliminated, and a circuit for re-synchronizing data from a source clock to a destination clock with reduced access latency penalty. Simultaneously writing data into multiple circuit modules significantly increases the write bandwidth of the memory. Also included are a dynamic base-address mapping into an address space, a read or write operation across multiple memory modules, a novel I/O bus format, and a protocol and test mode for testing redundant memory sub-arrays.Type: GrantFiled: April 5, 1995Date of Patent: March 12, 1996Assignee: Monolithic System Technology, Inc.Inventors: Wingyu Leung, Winston Lee, Fu-Chieh Hsu