Patent ID: 6985712

Claim:
An RF device comprising: a first substrate made of a material with a lower relative dielectric constant; a first RF circuit for a lower frequency band, which is provided in said first substrate; a second substrate made of a material with a higher relative dielectric constant larger than said lower relative dielectric constant, and a second RF circuit for a higher frequency band, at least a part of which is provided in a vicinity of said second substrate, wherein said first RF circuit and said second RF circuit are connected to each other, said part of said second RF circuit is sandwiched between said first substrate and said second substrate, said second substrate is partially overlaid on said first substrate, a semiconductor device or passive device is provided on a region in the surface of said first substrate on which said second substrate is not overlaid, and a multilayered wiring pattern made of copper or silver is formed in said first substrate, whereby said first RF circuit is formed.