Memory Command Decoder Reduces Signal Terminals
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Solution Overview
Problem
Memory devices, such as DRAM, require a large number of signal terminals for command, address, and write data signals, making it impractical to reduce the number of command signals due to the necessity of maintaining all desired functionality.
Innovation Solution
A memory device that eliminates the need for a chip select signal CS# and clock enable signal CKE#, using a command decoder to perform operations typically handled by these signals, reducing the number of command signals by decoding RAS, CAS, and WE signals along with address signals to preserve functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of command signals is reduced, then the number of signal terminals is reduced, but the functionality of the memory device is compromised
Solution Approach 1:
The command decoder is designed to perform multiple functions that were previously handled by separate command signals. Specifically, it decodes RAS#, CAS#, and WE# signals in combination with address signals to generate all necessary control signals for memory operations, including power down mode transitions, thereby eliminating the need for dedicated CKE# and CS# signals.
Solution Approach 2:
The patent merges the functionality of multiple command signals (CKE#, CS#, RAS#, CAS#, WE#) into a unified decoding mechanism that processes RAS#, CAS#, WE#, and address signals together. This consolidation allows the memory device to maintain full functionality while using fewer physical signal terminals.
2Device complexity
If CKE# and CS# signals are eliminated, then the number of command signals is reduced, but control over power down modes and device selection is lost
Solution Approach 1:
The command decoder acts as an intermediary that translates the simplified set of input signals (RAS#, CAS#, WE#, and address signals) into the comprehensive set of control signals needed for reliable memory operation. It mediates between the reduced signal interface and the complex internal requirements for power management and device control.
Solution Approach 2:
The command decoder performs preliminary decoding and analysis of the incoming RAS#, CAS#, WE#, and address signals to determine the intended operation before generating the appropriate control signals. This preliminary action ensures that power down mode transitions and other control functions are executed reliably without requiring separate CKE# or CS# signals.
3Ease of operation
If command signals are simplified, then ease of operation is improved, but risk of spurious operations and data loss increases
Solution Approach 1:
The command decoder incorporates feedback mechanisms that monitor the decoded signals and ensure proper sequencing of memory operations. This feedback control prevents spurious operations by verifying that read, write, and power down commands are executed in the correct sequence, thereby maintaining data integrity despite the simplified command interface.
Solution Approach 2:
The decoder logic is designed with built-in protection mechanisms that anticipate and prevent potential errors before they occur. By analyzing the combination of RAS#, CAS#, WE#, and address signals in advance, the decoder ensures that only valid operation sequences are executed, cushioning against spurious operations and data loss.
Data Source
AI summary
Systems, devices and methods are disclosed. In an embodiment of one such method, a method of decoding received command signals, the method comprises decoding the received command signals in combination with a signal provided to a memory address node at a first clock edge of a clock signal to generate a plurality of memory control signals. The received command signals, in combination with the signal provided to the memory address node at the first clock edge of the clock signal, represent a memory command. Furthermore, the signal provided to the memory address node at a second clock edge of the clock signal is not decoded in combination with the received command signals. The memory command may be a reduced power command and/or a no operation command.