Output Driver Swing Timing Alignment in Semiconductor Memory
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Solution Overview
Problem
Conventional semiconductor devices with fixed replica driver swing capability experience timing skew when the output driver's swing capability is changed, as they cannot accurately adjust to varying load conditions, leading to asynchronous data transitions with respect to the desired timing.
Innovation Solution
A semiconductor device with a DLL circuit, output driver, and mode register that allows for variable swing capability of the replica driver, adjusting the delay line based on phase determination to synchronize the internal clock signal with the external clock signal, ensuring the transition start timing of the read data coincides with the desired timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the swing capability of the output driver is changed to adapt to varying load conditions, then the adaptability is improved, but timing skew occurs because the replica driver cannot synchronize with the output driver
Solution Approach 1:
The patent applies dynamics by making the replica driver's swing capability variable rather than fixed. The control circuit dynamically adjusts the swing capability of the replica driver to match the output driver's swing capability, ensuring that both drivers operate at the same swing level and maintain proper timing synchronization despite varying load conditions.
Solution Approach 2:
The patent implements feedback through the control circuit that monitors the output driver's swing capability and uses this information to adjust the replica driver's swing capability accordingly. This feedback mechanism ensures that the replica driver continuously adapts to match the output driver, maintaining timing synchronization.
2Power
If the swing capability of the output driver is increased to improve signal strength, then the power is improved, but the timing skew increases because the data transition timing becomes earlier than desired
Solution Approach 1:
The patent makes the replica driver's swing capability dynamic by allowing it to be adjusted to match the output driver's swing capability. When the output driver operates at high swing capability for strong signal transmission, the replica driver is simultaneously adjusted to the same high swing level, ensuring that the timing characteristics remain consistent and synchronization is maintained.
3Use of energy by moving object
If the swing capability of the output driver is decreased to reduce power consumption, then the energy efficiency is improved, but the timing skew increases because the data transition timing becomes later than desired
Solution Approach 1:
The patent enables the replica driver's swing capability to be dynamically adjusted to match the output driver's swing capability. When the output driver operates at low swing capability for reduced power consumption, the replica driver is simultaneously adjusted to the same low swing level, ensuring that timing characteristics remain consistent and synchronization is maintained even at lower power levels.
4Measurement precision
If a variable delay circuit is added to the clock tree to adjust timing, then the timing accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent uses the output driver as a template to create the replica driver, which is a simplified copy of the output driver structure. By copying the essential characteristics and making the swing capability variable, the system achieves timing accuracy without requiring complex variable delay circuits in the clock tree.
Solution Approach 2:
The patent achieves timing accuracy by changing the swing capability parameter of the replica driver rather than adding complex delay adjustment circuits. By adjusting the swing capability to match the output driver, the timing characteristics are automatically aligned, providing accurate timing with simpler circuitry.
Data Source
AI summary
To provide an output driver that outputs read data to outside and a mode register that sets a swing capability of the output driver. A transition start timing of the read data driven by the output driver is made relatively earlier when a swing capability of the output driver set by the mode register is set to be relatively large, and the transition start timing is relatively delayed when the swing capability of the output driver set by the mode register is set to be relatively small. With this configuration, a timing when the read data exceeds a threshold level can be caused to coincide with a desired timing regardless of the swing capability of the output driver.