Abstract: A synchronous double-data-rate semiconductor memory device is adapted to receive write data on both the rising and falling edges of a data strobe signal derived from an externally-applied system clock. In the write path circuitry for each data pin of the device, adjustable delay elements are provided to enable the adjustment of the setup and hold times of write data applied to the data pin relative to the data strobe signal. The delays are separately adjustable for data present during the rising edge of the data strobe signal and for data present during the falling edge of the data strobe signal. The setup and hold window for write data is thus optimizable on a per-bit basis rather than a per-cycle basis. In one embodiment, a delay circuit is provided for generating delaying the rising edge data and the falling edge data by different delay intervals.

Abstract: A memory device including a circuit for actively driving a reference voltage in a memory device is disclosed. A circuit integrated in a memory device and coupled to an external voltage source substantially eliminates fluctuations in the reference voltage of the memory device caused by power supply changes and noise occurring in the memory device by generating a constant voltage and good current drive from the external voltage source.

Abstract: An integrated semiconductor memory chip includes hardwired presence detect data which can be accessed for transmission to a location external to the memory chip as well as logic allowing additional presence detect data to be programmed in the memory chip after fabrication of the memory chip. Storing the presence detect data on the memory chip rather than on a separate integrated circuit can help reduce the number of integrated chips required for a memory module, which may include multiple DRAM or other memory chips. Hardwiring at least some of the presence detect data during fabrication of the chip can reduce the number of programming errors as well as the number of mismatches that might otherwise occur if a separate presence detect data chip were used. On the other hand, the capability of programming presence detect data after fabrication of the memory chip provides additional flexibility, allowing the foregoing techniques to be used with a wide variety of memory chips and modules.

Abstract: A synchronous double-data-rate semiconductor memory device is adapted to receive write data on both the rising and falling edges of a data strobe signal derived from an externally-applied system clock. In the write path circuitry for each data pin of the device, adjustable delay elements are provided to enable the adjustment of the setup and hold times of write data applied to the data pin relative to the data strobe signal. The delays are separately adjustable for data present during the rising edge of the data strobe signal and for data present during the falling edge of the data strobe signal. The setup and hold window for write data is thus optimizable on a per-bit basis rather than a per-cycle basis. In one embodiment, a delay circuit is provided for generating delaying the rising edge data and the falling edge data by different delay intervals.

Abstract: A selector circuit (12) for placing a memory device (10) in test mode. The selector circuit (12) uses a logic circuit (26) to determine when a control signal provided to a pin of the memory device (10) maintains a first logic level for a period of time exceeding the specification for the control signal in normal operation. A multiplexer (24) receives the control signal and a substitute control signal at an alternate pin of the memory device. The substitute control signal is used in place of the control signal during the test. The output of the logic circuit (26) is coupled to control the multiplexer (24) to select the control signal for use in addressing a cell of the memory device (10) in normal operation and to select the substitute control signal for use in addressing a cell of the memory device (10) in test mode.

Abstract: A selector circuit (12) for placing a memory device (10) in test mode. The selector circuit (12) uses a logic circuit (26) to determine when a control signal provided to a pin of the memory device (10) maintains a first logic level for a period of time exceeding the specification for the control signal in normal operation. A multiplexer (24) receives the control signal and a substitute control signal at an alternate pin of the memory device. The substitute control signal is used in place of the control signal during the test. The output of the logic circuit (26) is coupled to control the multiplexer (24) to select the control signal for use in addressing a cell of the memory device (10) in normal operation and to select the substitute control signal for use in addressing a cell of the memory device (10) in test mode.