Output Enable Timing Circuit for Multi-Chip Data Path Latency
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Solution Overview
Problem
Conventional multi-chip packages face challenges in ensuring stable data output due to longer data paths for slave chips, leading to delayed data output timing as the enable timing of the output enable signal is set based on the longest data path, causing inefficiencies in data output speed.
Innovation Solution
An output enable signal generation circuit that includes a latency decoder, latch unit, latency multiplexer, and enable setting unit to generate and set latency signals based on individual chip select signals, allowing for tailored enable timing for each chip, optimizing data output speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the enable timing of the output enable signal is set based on the longest data path of the third slave chip, then stable data output is ensured for all chips, but the data output speed is reduced because data from chips with shorter data paths is outputted later than necessary
Solution Approach 1:
The patent segments the data output control by chip type, creating separate control paths for master chip, first slave chip, second slave chip, and third slave chip. Each chip type has its own dedicated output enable signal (OE0, OE1, OE2, OE3) with timing optimized for its specific data path length, eliminating the need to use a unified conservative timing for all chips.
Solution Approach 2:
The patent implements dynamic timing adjustment by generating different enable timings based on the specific chip being accessed. The system dynamically selects appropriate latency values (CL3, CL3.5, CL4, CL4.5) and corresponding enable signals based on whether the master chip or specific slave chips are being read, optimizing the output timing for each scenario rather than using a fixed conservative timing.
2Reliability
If the column address strobe latency is increased for slave chips with longer data paths, then stable operation is achieved, but the data output timing is delayed beyond what is actually needed for chips with shorter data paths
Solution Approach 1:
The patent applies local quality by assigning different latency characteristics to different chips based on their specific data path requirements. The master chip uses CL3, the first slave chip uses CL3.5, the second slave chip uses CL4, and the third slave chip uses CL4.5. Each chip receives the quality (latency timing) appropriate to its local needs rather than a uniform timing for all chips.
Solution Approach 2:
The patent changes the latency parameter dynamically based on which chip is being accessed. The system modifies the CL parameter value according to the chip select signal, selecting from multiple predefined latency values to match the data path length of the active chip, thereby optimizing timing without sacrificing stability.
3Device complexity
If a single output enable signal timing is used for all chips in the multi-chip package, then the circuit control is simplified, but the data output speed is limited by the longest data path
Solution Approach 1:
The patent creates a universal control mechanism that handles multiple chip types with different timing requirements through a unified output enable signal generation circuit. The circuit universally supports master chip and multiple slave chips with different data path lengths, generating appropriate enable timings for each chip type while maintaining a single integrated control structure.
Data Source
AI summary
An output enable signal generation circuit includes a latency decoder, a latch unit, a latency multiplexer, and an enable setting unit. The latency decoder is configured to decode a mode register set code and generate first and second CAS latency information. The latch unit is configured to output the latched first and second latency information as first and second latency signals. The latency multiplexer is configured to output the first or second latency signal as an output CAS latency signal in response to a chip select signal. The enable setting unit is configured to set an enable timing of an output enable signal.