Data Buffer Latency Measurement Using Fill-Level Clock Adjustment
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Solution Overview
Problem
Existing methods for measuring the latency of data buffers in communication systems, particularly in integrated circuits, face limitations in precision due to unknown phase relationships between clock and control signals, leading to incomplete measurement of latency to a fraction of a cycle, and require specialized hardware or complex clocking structures that are not universally applicable.
Innovation Solution
A latency measurement circuit is implemented in an integrated circuit that configures data buffers to specific fill levels, adjusts read clock signals based on fill level status signals, and uses phase interpolators to achieve high-resolution latency measurements without real-time access to FIFO reading and writing pointers, allowing for continuous direct measurement of latency variations without affecting the operating transmitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If write and read pointers are used to determine data buffer latency, then latency can be measured in terms of pointer positions, but measurement precision is limited to integer cycles and cannot achieve fraction of a cycle resolution
Solution Approach 1:
The patent introduces an intermediary measurement approach by using fill level status signals and clock signal adjustments as mediators between the write/read pointers and the latency measurement. Instead of directly measuring pointer positions, the system uses these intermediaries to achieve fraction-of-cycle precision without requiring direct access to pointer values, thereby resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The patent changes the measurement parameter from discrete pointer positions to continuous fill level status combined with clock phase adjustments. By transitioning from integer-cycle pointer-based measurement to fraction-of-cycle fill level and clock phase measurement, the system achieves higher precision without proportionally increasing complexity.
2Measurement precision
If clock signals are adjusted to achieve high-resolution latency measurement, then measurement precision improves beyond unit interval resolution, but the operating transmitter may be affected or manipulated
Solution Approach 1:
The patent segments the measurement function from the transmitter operation by using dedicated fill level status signals and separate clock adjustment mechanisms. The measurement circuit operates independently on copy or status signals rather than directly on the transmitter's critical data paths, allowing high-resolution measurement without compromising transmitter reliability.
Solution Approach 2:
The patent performs preliminary actions by pre-configuring data buffers to specific fill levels and pre-adjusting read clock signals based on fill level status before actual latency measurement begins. This preliminary setup establishes a stable baseline that enables subsequent measurements without disrupting normal transmitter operation, thus maintaining reliability while achieving precision.
3Measurement precision
If specialized hardware or complex clocking structures are used to achieve precise latency measurement, then measurement capability improves, but device complexity and hardware requirements increase
Solution Approach 1:
The patent uses copying by creating fill level status signals that represent the state of data buffers without requiring direct access to the buffers themselves. By measuring latency through these copied status signals and clock phase relationships rather than through complex direct pointer interrogation, the system achieves high precision with reduced hardware complexity.
Solution Approach 2:
The patent implements a universal measurement approach that can be applied to different data buffer configurations and transmitter architectures using the same basic principles of fill level monitoring and clock adjustment. This multi-functional methodology avoids the need for specialized hardware for each specific application, thereby reducing overall device complexity while maintaining measurement precision.
Data Source
AI summary
An integrated circuit (IC) includes a first device and a second device. A latency measurement circuit is configured to determine a first latency of the first device; and determine a second latency of the second device based on the first latency.