Constrained clock shifting for field programmable gate arrays
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
Circuits implemented in FPGAs have delays that are dominated by its programmable interconnect. This interconnect provides the ability to implement arbitrary connections. However, it contains both highly capacitive and resistive elements. The delay encountered by any connection depends strongly on the number of interconnect elements used to route the connection. These delays are only completely known after the place and route phase of the CAD flow. We propose the use of Clock Shifting optimization techniques to improve the clock frequency as a post place and route step.Clock Shifting Optimization is a technique first formalized in [4]. It is a cycle-stealing algorithm that allows one to reduce the critical path delay of a synchronous circuit by shifting the clock signals at each register. This technique allows late arriving signals to be sampled at a later point in time by intentionally introducing a skew on the clock input of the sampling register. Typical FPGAs contain a number of special purpose global clock networks that distribute clock signals to every register in the chip. Unused global clock lines in FPGAs can be used to distribute a finite set of clock skews to the entire circuit. We propose an efficient integer programming method to find the optimal circuit improvement for a finite set of clock skews. This technique is modified to consider inherent uncertainties present in the timing models. The uncertainty controls the aggressiveness of the optimizations as we must take great care in ensuring functionality for any range of possible timing characteristics.Our results confirm intuition that more aggressive speed optimizations can be performed as timing models become more accurate. We also show that providing 4 skewed versions of the nominal clock signal results in the best delay--area tradeoff. This result is evocative as it may suggest future FPGA architectures that contain greater numbers of global clock lines, as we tradeoff gains in speed for greater power requirements from increased clock network flexibility.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it