A novel size reduction of a MMIC I/Q direct down converter in uniplanar technology at 20 GHz using CPW and ACPS stubs loading for an EHF satcom terminal phased array size
Bibliographic record
Abstract
This paper proposes a novel compact uniplanar 20 GHz/baseband I/Q direct downconverter GaAs MMIC. It uses previously developed ACPS and CPW structures for capacitive and inductive loading techniques to drastically reduce its size. The proposed I/Q down converter uses direct analog extraction of the baseband in-phase and quadrature (I and Q) signals from the 20 GHz RF signal. Two pairs of antiparallel diodes achieve frequency translation by mixing the RF signal with the fundamental local oscillator (LO) pump while novel ACPS reduced size magic T, provide high local oscillator (LO)-to-RF isolation and good spurious suppression. The circuit was fabricated using OMMIC's ED02AH foundry process and contains two pairs of 0.18 µm PHEMT based diodes, each having two 15-µm cathode fingers. This 3.15 × 4.1 mm2 chip uses a previously developed, reduced size Wilkinson divider as an RF divider and a previously developed, reduced size 90° coupler. The I/Q down converter conversion gain was measured to be - 15.5dB ±1dB over the RF frequency range of 20.2 to 21.2 GHz with the IF fixed at 1 MHz. The amplitude imbalance between the I&Q channels was under 0.8dB and the quadrature phase error was less than 4°over the frequency range. The circuit also does not require any dc bias. Compared to the conventional microstrip I/Q direct down converter a 40% reduction in circuit area was achieved with better performance.
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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 | 0.000 |
| 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 | 0.001 | 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".