Exploration of the integration of a passive coplanar isolator based on thin magnetic films

✍ Scribed by S. Capraro; T. Rouiller; M. Le Berre; J. P. Chatelon; B. Bayard; D. Barbier; J. J. Rousseau

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 141 KB
• Volume: 46
• Category: Article
• ISSN: 0895-2477
• DOI: 10.1002/mop.21009

✦ Synopsis

As an example, the helix-pitch profile of the considered tube was modified for improving the yield (Table 1), maintaining similar small-signal gain (62.6-dB average gain and 5% flatness). In particularly, according to the previously exposed theory, the helix pitch in the lower helix-pitch section (section 4) was incremented to 0.064 cm. The yield for the original and improved tubes was compared for both the cases of random (independent random variation of the helix pitch of each section) error and systematic (same helix-pitch variation for all the sections) error [5]. A maximum helix-pitch tolerance of 3% was considered. Three hundred different tubes were simulated for each value of helix-pitch error.

For the purpose of this study, a tube was considered acceptable if the average gain was included in the Ϯ1.5% range with respect to the nominal value and the flatness was lower than 6%. A remarkable yield improvement is obtained for both random (Fig. 2) and systematic (Fig. 3) errors. The small histograms included in the figures show that the percentage increment of the yield obtained for the different helix-pitch error values is, in some cases, higher than 25%.

CONCLUSION

TWT yield degradation in case of small-signal gain, caused by the tube sections with lower helix pitch, has been studied. The analysis of the small-signal gain per unit length of a helix slow-wave structure provides useful information for predicting the yield behaviour. It was demonstrated that a suitable adjustment of the helix-pitch profile, hence maintaining similar small-signal gain performance, significantly improves the yield.