A 4th-Order 4-Bit Continuous-Time ΔΣ ADC Based on Active–Passive Integrators With a Resistance Feedback DAC
Bibliographic record
Abstract
This article reports a fourth-order continuous-time (CT) delta–sigma modulator (DSM) that features a single-amplifier biquad, a passive integrator, and an active integrator. This simplifies the circuit to only two op-amps in comparison to four power-hungry op-amps used in a conventional fourth-order DSM. In addition to improving the power consumption, the proposed design also has more relaxed requirements for the gain–bandwidth product and the loop gain. A 4-bit flash analog-to-digital converter (ADC) and two feedback digital-to-analog converters (DACs) are employed in this design to implement a fully integrated CT DSM. By incorporating the passive network in front of the last active integrator, this design gives a better attenuation at high frequency, which decreases the possibility of instability caused by out-of-band high-frequency signals. The proposed design has a measured bandwidth of 2 MHz with a power consumption of only around 3 mW. The effective number of bits (ENOB) of the proposed CT-DSM is approximately 12.7 bits with a peak signal-to-noise and distortion ratio (SNDR) around 78 dB, and it also exhibits a good Schreier figure of merit on the order of 166 dB compared to the existing state of the art.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".