A quadrature bandpass ΣΔ modulator for digital radio
Bibliographic record
Abstract
In a bandpass /spl Sigma//spl Delta/ modulator, bandpass filtering and feedback around a low-resolution quantizer shape the noise spectrum, facilitating accurate A/D conversion on narrow-band input signals. This is extended to the quadrature, or complex, case if a complex filter - having complex-valued coefficients and thus not restricted to a symmetrical frequency response - is placed in a /spl Sigma//spl Delta/ loop. The modulator performs a "complex" A/D conversion on the pair of analog inputs, that are in phase-quadrature, and it has two high-speed bit stream outputs: one represents the real output; the other the imaginary output. When combined, these outputs form a complex signal that accurately represents the complex input within a narrow frequency band. This quadrature modulator is useful in architectures for a single-chip digital-radio receiver. The receiver ideally has no image response, and thus the bulky narrow-band image-rejection filter in the RF stage of a single-path receiver can be replaced with a broadband one. The architecture alleviates many problems of the direct-conversion receiver, often considered for single-chip implementations, since the input signal is mixed to a non-zero IF where 1/f noise and DC offsets cause no problem and self-interference is not an issue because oscillator frequency is offset from the carrier frequency. The quadrature modulator IC uses standard fully-differential switched-capacitor circuit techniques and is implemented in 0.8 /spl mu/m CMOS technology.
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How this classification was reachedexpand
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) | 0.000 | 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".