Semiconductor Memory I/O Pad Sharing for Multi-Mode Operation
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Solution Overview
Problem
Conventional semiconductor memory devices supporting multi-operation modes have an increased number of pads, leading to a larger device size and operational limitations due to the need for non-overlapping lines, which complicates the disposition of lines and deteriorates operation characteristics.
Innovation Solution
The semiconductor memory device shares pads for signals used in different operation modes, such as the read data strobe signal and data mask signal in the X8 mode, and the inverted read data strobe signal and upper data mask signal in the X16 mode, using a control signal generator and input/output units to manage these signals based on extended mode register settings and operation mode signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of pads is increased to support multi-operation modes, then the device can support more operation modes, but the device size increases and line disposition becomes more complex
Solution Approach 1:
The patent applies multi-functionality by enabling pads to serve different purposes depending on the operation mode. Specifically, the first selection pad can function as a data mask signal input pad in X16 mode or as a read data strobe signal output pad in X8 mode. Similarly, the second selection pad can serve as an inverted data mask signal pad or an inverted read data strobe signal pad. This universal design allows the device to support multiple operation modes without proportionally increasing the number of pads, thereby reducing device size while maintaining adaptability.
2Adaptability or versatility
If the number of pads is increased to support multi-operation modes, then the device can support more operation modes, but line disposition becomes more complex
Solution Approach 1:
The patent reduces line disposition complexity by implementing universal pads that can be configured for different functions. The control signal generator receives operation mode signals and generates appropriate control signals to route data mask signals, inverted data mask signals, read data strobe signals, and inverted read data strobe signals through the same physical pads based on the selected operation mode. This approach minimizes the number of required signal lines and simplifies the overall device architecture while maintaining support for multiple operation modes.
3Reliability
If separate pads are allocated for read data strobe signal and data mask signal, then signal integrity is maintained, but the number of pads increases
Solution Approach 1:
The patent applies dynamics by making pad functions configurable rather than fixed. The control signal generator dynamically assigns different functions to the same physical pads based on the operation mode. In X16 mode, the first selection pad receives data mask signals and the second selection pad receives inverted data mask signals. In X8 mode, the first selection pad outputs read data strobe signals and the second selection pad outputs inverted read data strobe signals. This dynamic reconfiguration maintains signal integrity through proper routing while reducing the total number of pads required.
Data Source
AI summary
A semiconductor memory input/output device includes selection pads used to input and output signals for multiple operation modes and having multiple functions, a control signal generator for outputting setting signals and a mask control signal, a lower input/output unit including a lower output buffer for outputting a read data strobe signal to a selection pad and a lower input buffer for receiving a lower data mask signal from the selection pad, and selecting one operation of the lower output buffer and the lower input buffer, and an upper input/output unit including an upper output buffer for outputting an inverted read data strobe signal to the second selection pad and an upper input buffer for receiving an upper data mask signal from the second selection pad, and selecting one operation of the upper output buffer and the upper input buffer.