Patent ID: 8222976

Claim:
A multilayer dielectric substrate having a cavity formed on a dielectric substrate and in which a semiconductor device is incorporated within the cavity, the multilayer dielectric substrate comprising a cavity-resonance suppressing circuit that includes: an opening formed in a surface-layer ground conductor arranged on the dielectric substrate within the cavity; an impedance transformer that is formed in the dielectric substrate, electrically connected via the opening to the cavity, and has a length of an odd multiple of about ¼ of in-substrate effective wavelength of a signal wave; a tip-short-circuited dielectric transmission line that is formed in the dielectric substrate and has a length of an odd multiple of about ¼ of in-substrate effective wavelength of a signal wave; a coupling aperture formed at a part of an inner-layer ground conductor where the impedance transformer is connected to the dielectric transmission line; and a resistor formed in the coupling aperture, wherein the multilayer dielectric substrate comprises: a first cavity-resonance suppressing circuit that suppresses cavity resonance of a first signal wave; and a second cavity-resonance suppressing circuit that suppresses cavity resonance of a second signal wave, a frequency thereof being different from that of the first signal wave.