| US 7,579,929 B2 | ||
| Transmission circuit, antenna duplexer, and radio-frequency switch circuit | ||
| Osamu Hikino, Yokohama (Japan); Masashi Ohki, Kawasaki (Japan); and Hideaki Sunayama, Sagamihara (Japan) | ||
| Assigned to Hitachi Media Electronics Co., Ltd., Iwate-Ken (Japan) | ||
| Filed on Feb. 27, 2006, as Appl. No. 11/362,518. | ||
| Claims priority of application No. 2005-181402 (JP), filed on Jun. 22, 2005. | ||
| Prior Publication US 2006/0290447 A1, Dec. 28, 2006 | ||
| Int. Cl. H01P 1/213 (2006.01); H01P 5/12 (2006.01) | ||
| U.S. Cl. 333—134 [333/128; 333/129] | 8 Claims |
| 1. A transmission circuit, comprising:
a dielectric substrate;
a spiral-shaped transmission line disposed in said dielectric substrate;
a first shield layer, being a first ground electrode, facing a top face of said spiral-shaped transmission line;
a second shield layer, being a second ground electrode, facing a bottom face of said spiral-shaped transmission line;
a first terminal part disposed at an inner circumference of said spiral-shaped transmission line;
a second terminal part disposed at an outer circumference of said spiral-shaped transmission line;
a third terminal part which lies above said first shield layer; and
a fourth terminal part disposed on said dielectric substrate,
wherein said first terminal part and said third terminal part are connected,
wherein said second terminal part and said fourth terminal part are connected, and
wherein said third terminal part is exposed to outside and so disposed that said first shield layer is between said third
terminal part and a spiral part of said spiral-shaped transmission line.
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