Reversible I/O Delay Line for Shared Input-Output Signal Timing
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Solution Overview
Problem
Integrated circuit devices lack a programmable delay mechanism that can be dynamically shared between input and output paths, limiting their ability to adjust signal delays and synchronize signals effectively across I/O pads.
Innovation Solution
A reversible input/output (I/O) delay line structure that utilizes a single delay element, controlled by a tristate signal, to insert delay in either the input or output path, or both, allowing for dynamic sharing and bypassing, thereby supporting various applications such as clock/data alignment and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate delay elements are provided for input and output paths, then signal delay adjustment capability is improved, but silicon area consumption increases
Solution Approach 1:
The delay element is configured to serve dual purposes by being selectively insertable into either the input path or the output path based on operational mode. When the I/O pad operates as an input pad, the delay element is inserted into the input path; when it operates as an output pad, the delay element is inserted into the output path. This multi-functional design eliminates the need for separate delay elements for each path, thereby reducing silicon area consumption while maintaining full signal delay adjustment capability for both input and output operations.
2Area of stationary object
If a single delay element is shared between input and output paths, then silicon area consumption is reduced, but the complexity of controlling delay insertion increases
Solution Approach 1:
The control mechanism automatically determines the appropriate path for delay element insertion based on the operational state of the I/O pad. The controller receives the operational mode signal and autonomously configures the delay element to be inserted into the correct path (input or output) without requiring external intervention or complex manual control logic. This self-service approach simplifies the overall control architecture while enabling the single delay element to function correctly in both input and output modes.
3Adaptability or versatility
If delay elements are made programmable, then signal synchronization capability is improved, but device complexity increases
Solution Approach 1:
The delay element is implemented as a programmable structure where the delay amount can be dynamically adjusted by modifying internal parameters such as the number of logic levels or the configuration of delay stages. Configuration data stored in memory cells controls the programmable logic elements to adjust the delay characteristic, allowing precise synchronization of signals with different path delays. This parameter-based control approach provides flexible signal synchronization capability while keeping the device complexity manageable through systematic configuration rather than complex hardwired logic.
Data Source
AI summary
An input/output (I/O) structure includes a delay element usable for the input path, the output path, or both input and output paths in a user design. In a first mode, the delay element is included in the input path. In a second mode, the delay element is included in the output path. In a third mode, the I/O structure includes the delay in both outgoing signal paths and incoming signal paths, e.g., by utilizing an output tristate signal to control the direction of the delay line. When the output buffer is driving, the delay is inserted in the output path. When the output buffer is tristated, the delay is inserted in the input path. Thus, a single delay element is dynamically shared by both input and output signals that use the same I/O pad. In an optional fourth mode, the delay element is bypassed by both input and output signals.