Pseudo Double Clock Memory Interface for DDR2 Compatibility
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Solution Overview
Problem
The transition from DDR SDRAM to DDR2 SDRAM requires significant redesign of memory controller and circuit components, making it costly and time-consuming, and using a DDR2 SDRAM device when a DDR SDRAM suffices is not cost-effective, due to the need for doubling the clock rate.
Innovation Solution
A memory device with pseudo double clock signals is designed, generating an even clock signal and an odd clock signal, both at half the rate of the input clock signal, allowing a DDR SDRAM device to operate at DDR2 SDRAM clock rates by selectively applying these signals based on control triggers, thus avoiding the need for redesign.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the clock rate is doubled to meet DDR2 SDRAM requirements, then the bandwidth and performance are improved, but the device complexity and redesign cost increase significantly
Solution Approach 1:
The clock signal is segmented into two separate clock phases (even clock phase and odd clock phase), each operating at half the frequency of the original DDR2 clock rate. This segmentation allows the memory device to achieve DDR2 bandwidth by processing data in two half-speed phases, avoiding the need to redesign circuits for full DDR2 clock rates.
Solution Approach 2:
The memory device dynamically switches between even and odd clock phases to handle different data transfer operations. By dynamically alternating between two half-speed clock phases, the system achieves the effective bandwidth of a full-speed DDR2 interface without requiring circuits designed for the higher clock rate.
2Speed
If a DDR2 SDRAM device is used to meet clock rate requirements, then the performance specification is satisfied, but the cost increases due to abandonment of existing DDR SDRAM designs
Solution Approach 1:
The patent creates a universal interface that allows DDR SDRAM devices to function in DDR2 SDRAM slots. By implementing the pseudo-double clock rate interface, existing DDR SDRAM designs can be adapted to work with DDR2 memory controllers, making the system multi-functional and eliminating the need to abandon proven DDR SDRAM designs.
Solution Approach 2:
The invention creates a virtual copy of the DDR2 interface functionality by implementing two half-speed clock phases that together replicate the behavior of a single full-speed DDR2 clock. This allows DDR SDRAM devices to emulate DDR2 performance characteristics without requiring actual DDR2 hardware, reducing manufacturing costs.
3Speed
If the clock rate is doubled, then the data transfer speed is improved, but the time and resources required for redesign increase
Solution Approach 1:
The patent implements preliminary action by pre-defining the even and odd clock phase generation logic within the memory device. This preliminary structuring of clock phases allows the device to achieve DDR2 data transfer speeds without requiring time-consuming redesign of the entire memory system, as the clock phase management is built into the device architecture.
Data Source
AI summary
A method for operating a memory device with pseudo double clock signals comprises the steps of: generating an even clock signal and an odd clock signal, wherein the clock rates of both the even clock signal and the odd clock signal are half that of the input clock signal, and the even clock signal is the inverse signal of the odd clock signal; if the logic level of the even clock signal is 1 when receiving a trigger of a control signal, applying the even clock signal to a memory device; and if the logic level of the odd clock signal is 1 when receiving another trigger of the control signal, applying the odd clock signal to the memory device.