A Compact Wideband Inductorless Cascadable Tunable True Time Delay
Bibliographic record
Abstract
We present a compact inductorless cascadable gigahertz-frequency true time delay (TTD) circuit implemented as a gm-C all-pass filter (APF) cell having poles and zeros prescribed by the Padé approximation. The proposed APF cell not only overcomes the large chip areas required by lumped-LC and transmission-line delay circuits, but it also maintains wide bandwidths by eliminating the need for dc-blocking capacitors or buffers, which are often necessary when cascading active APFs. In this article, we develop design equations and propose techniques to enhance bandwidth, improve phase linearity, and minimize delay variation across the bandwidth. Results were obtained using a 65-nm CMOS delay circuit containing four cascaded APF cells closely agreed with those of the postlayout simulations, achieving a delay tuning range of 300–500 ps over a 0.1–4-GHz bandwidth. Furthermore, the delay can be tuned to 550 ps, causing the bandwidth to drop to 3.55 GHz while still maintaining the delay-bandwidth product (DBW) of 1.95. The filter exhibited a worst case input of 1-dB compression point (IP1dB) of −21 dBm, while occupying an active area of 0.04 mm2 and dissipating 6.2 mW/cell from a 1.3-V supply. The APF demonstrated a delay-per-area metric at least 1.6 times higher than what was realized with prior gm-C APFs while also operating over a wider bandwidth, exhibiting a high DBW of 1.95, and maintaining a 3.3 dB gain.
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.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".