Scalable Multi-Stage CMOS OTAs With a Wide C<sub>L</sub>-Drivability Range Using Low-Frequency Zeros
Bibliographic record
Abstract
This work introduces a multi-stage CMOS OTA design technique that allows cascading identical gain stages (for arbitrarily scalable high DC gain) while driving an ultra-wide range of capacitive loads ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{C}_{\text {L}}\text{s}$ </tex-math></inline-formula> ). At the heart of the proposed design is a new frequency compensation technique (FCT) that relies on low-frequency left-half-plane zeros to allow the proposed OTA to operate for a desired closed-loop behavior. In this work, classical gain-stages (i.e., differential pair and common source transistors) are used to design fully-differential 2-, 3-, 4- and 5-stage CMOS OTAs. The proposed 2-to-4-stage designs have been fabricated in TSMC 65 nm CMOS process and the measurement results show that the 2-stage OTA is achieving a DC gain of 50 dB with a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{C}_{\text {L}}$ </tex-math></inline-formula> -drivability ratio (i.e., <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{C}_{\text {L,max}}/\text{C}_{\text {L,min}}$ </tex-math></inline-formula> ) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10,000\times $ </tex-math></inline-formula> , the 3-stage OTA is achieving a DC gain of 70 dB with a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{C}_{\text {L}}$ </tex-math></inline-formula> -drivability of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1,000,000\times $ </tex-math></inline-formula> , and the 4-stage OTA is achieving a DC gain of 90 dB with a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{C}_{\text {L}}$ </tex-math></inline-formula> -drivability of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1,000,000\times $ </tex-math></inline-formula> . This is a 10-to-1000-time improvement in the state-of-the-art, as the highest <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{C}_{\text {L}}$ </tex-math></inline-formula> -drivability reported to date is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1000\times $ </tex-math></inline-formula> . Accordingly, the proposed OTAs can cover a wider range of applications than any other reported works.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".