Successive-approximation and sigma-delta architectures dominate this corpus, which is classified almost entirely under H03M (coding and code conversion) — 2,156 of 2,271 records. That concentration means claim space around core conversion techniques, calibration schemes and quantization is already densely occupied. Anyone drafting a new architecture claim in this space should expect to find substantial prior art and should search H03M first before assuming an idea is novel.

Filings rose from 59 in 2017 to a peak of 108 in 2021, held near that level at 105 in 2022, and the visible trend afterward reads flat to declining. However, patent publication typically lags filing by around eighteen months, so the 2025 and 2026 figures in this dataset are understated and should not be read as a genuine collapse in R&D activity. The honest read is a mature, plateaued filing rate rather than either strong growth or a real decline.

The recent-year momentum data tracks assignees including Texas Instruments alongside several others, most of which show flat or zero filings in the latest recorded year. That pattern is consistent across the tracked set and most likely reflects publication lag rather than an actual exit from the field. A representative early filing worth reviewing for calibration claim scope is US6924755B1, assigned to Analog Devices, which covers multi-channel offset and gain calibration.

The clearest under-claimed territory sits adjacent to the dominant H03M core: time-interleaved ADC skew calibration, power-efficiency figure-of-merit optimisation circuits, and cross-domain ADC-filter co-design touching H03H all show materially thinner filing density than the core coding and conversion claims. These branches are still tied to the same commercial architectures, which makes them a more realistic filing target than an entirely new conversion technique. A first claim there would typically need to tie a specific calibration or efficiency metric to a concrete circuit implementation rather than claim the metric in the abstract.

The US receiving office accounts for 1,219 of the records in this corpus, more than four times the EPO's 288 and close to six times China's 208. This likely reflects where the major semiconductor design houses in this field are headquartered and where they first seek protection before extending coverage via WIPO/PCT routes, which account for 166 records. For competitive monitoring or clearance work, the US office should be the first jurisdiction searched, not a secondary check after Europe or China.