Abstract: A memory system comprising memory modules including memory chips including integrated switching circuits. A memory controller coupled to the memory modules is configured to initiate memory accesses. When a switching circuit within a memory chip detects the memory access, the switching circuit routes the access to another memory module if the access is not directed to a memory chip of the receiving memory module, or processes the access locally if the access is directed to a memory chip of the receiving memory module. The memory controller and memory modules are coupled via bi-directional serial links. Each memory module may include multiple switching circuits, each of which may be coupled to fewer than all of the memory chips within the memory module. Switching circuits further include circuitry configured to de-serialize data prior to conveyance to a memory chip, and serialize data received from a DRAM chip prior to transmitting the received data.

Abstract: A memory system comprising memory modules including memory chips stacked with switching circuits. A memory controller coupled to the memory modules is configured to initiate memory accesses. When a stacked switching circuit detects the memory access, the switching circuit routes the access to another memory module if the access is not directed to a memory chip of the receiving memory module, or processes the access locally if the access is directed to a memory chip of the receiving memory module. The memory controller and memory modules are coupled via bi-directional serial links. Each memory module may include multiple stacked switching circuits, each of which may be coupled to fewer than all of the memory chips within the memory module. Switching circuits further include circuitry configured to de-serialize data prior to conveyance to a memory chip, and serialize data received from a DRAM chip prior to transmitting the received data.

Abstract: A data strobe receiver that includes a first comparator. The first comparator has a first input that is coupled to a first reference voltage. The first comparator has a second input that is coupled to a data strobe. The first comparator also has an output. The data strobe receiver also includes a delay element. The delay element has an input that is coupled to the output of the first comparator. The delay element also has an enable input and an output. The data strobe receiver also includes a second comparator. The second comparator has a first input that is coupled to a second voltage reference. The second comparator has a second input that is coupled to the data strobe. The second comparator also has an output. The data strobe receiver also includes a divide-by-X-counter, where X is an integer greater than 1 and less than 129. The divide-by-X-counter has an input that is coupled to the output of the second comparator.

Abstract: One embodiment of the present invention provides a system for detecting a valid clock signal at a clock receiver. The system operates by receiving a clock signal at the clock receiver, and directing the clock signal into a control input of a voltage-controlled variable resistor. Next, the system uses the voltage-controlled variable resistor to control a first current. A current mirror is then employed to create a second current from the first current. This second current passes through a resistor to produce a control voltage, which is amplified to produce a validity signal indicating whether or not the clock signal is valid. In one embodiment of the present invention, the system additionally uses at least one capacitor to filter out periodic fluctuations in the validity signal.

Abstract: One embodiment of the present invention provides a system for detecting a valid clock signal at a clock receiver. The system operates by receiving a clock signal at the clock receiver, and directing the clock signal into a control input of a voltage-controlled variable resistor. Next, the system uses the voltage-controlled variable resistor to control a first current. A current mirror is then employed to create a second current from the first current. This second current passes through a resistor to produce a control voltage, which is amplified to produce a validity signal indicating whether or not the clock signal is valid. In one embodiment of the present invention, the system additionally uses at least one capacitor to filter out periodic fluctuations in the validity signal.