A filter circuit that secures the steepness from a pass range to an attenuation range while maintaining a wide-band transmission characteristic and a filter device including this filter circuit are formed. A filter circuit includes a first filter and a second filter. The first filter is a filter including an LC circuit in which a first frequency band is a pass band and a frequency band not higher than the first frequency band is an attenuation band. The second filter is a filter that attenuates a second frequency band within the first frequency band by using an attenuation pole produced by a resonance or an antiresonance of an acoustic wave resonator. Further, the first filter is placed closer to an antenna terminal than the second filter.

A diplexer includes a first filter circuit including a first loop inductor defining a first loop plane and a second loop inductor defining a second loop plane, a second filter circuit adjacent to the first filter circuit, and a first via hole conductor that electrically connects an input/output terminal, the first filter circuit and the second filter circuit to each other. The first loop plane faces the second loop plane while protruding beyond the second loop plane in a first direction. The first via hole conductor is provided relative to the first loop inductor in a second direction from the first loop plane toward the second loop plane, and is superposed with a portion of the first loop plane that protrudes beyond the second loop plane when viewed in the second direction.

Tunable filters, cancellers, and duplexers based on passive mixers. A tunable delay cell includes passive mixers electrically coupled together for receiving an input signal and outputting a delayed signal, each passive mixer comprising a plurality of mixer switches. The tunable delay includes a control circuit for providing, to each passive mixer, a respective plurality of local oscillator (LO) signals, one to each mixer switch of each passive mixer. The control circuit is configured to vary the LO signals to cause a target frequency band of the input signal to be delayed by a target delay time in propagating through the passive mixers.

A filter circuit comprises in a signal line a band filter (BF) allowing to let pass a useful frequency band and a notch filter (NF) circuited in series to the band filter for filtering out a stop band frequency. The notch filter comprises a series circuit of a number of parallel shunt elements (SE1 . . . SE6) wherein each shunt element is shifted infrequency against the other shunt elements that the frequencies thereof are distributed (f1 . . . F6) over a notch band. All shunt elements may be realized as a SAW one-port resonator (TR.sub.NF) including regions with different pitches.

A power amplification circuit can include an input impedance matching circuit associated with one or more frequency bands of a plurality of frequency bands. The power amplification circuit can include a transistor with respective input coupled to an output of the input impedance matching circuit. The power amplification circuit can include a plurality of output impedance matching circuits. Each output impedance matching circuit can be associated with a respective frequency band of the plurality of frequency bands. The power amplification circuit can include a single pole multi-throw (SPMT) switch having an input terminal connected to an output of the transistor and a plurality of output terminals. Each output terminal of the SPMT switch can be connected to a corresponding output impedance matching circuit of the plurality of output impedance matching circuits.

A branching filter includes a common port, a first signal port, a second signal port, a first filter, which is provided between the common port and the first signal port, that selectively passes a signal of a frequency within a first passband, a second filter, which is provided between the common port and the second signal port, that selectively passes a signal of a frequency within a second passband different from the first passband, and a capacitor that has a first end and a second end and connects the first filter and the second filter.

A transmission and reception module includes a substrate including a transmission signal input terminal, a reception signal output terminal, and an antenna terminal, a duplexer that is provided on the substrate, outputs a transmission signal input from the transmission signal input terminal to the antenna terminal, and outputs a reception signal input from the antenna terminal to the reception signal output terminal, a first inductor included in a first matching circuit provided between the duplexer and the antenna terminal, and a second inductor included in a second matching circuit provided between the duplexer and the reception signal output terminal. On the substrate, a winding axis direction of a conductor of the first inductor and a winding axis direction of a conductor of the second inductor are different from each other.

Disclosed is a semiconductor device including a semiconductor die, a base member, a side wall, first and second conductive films, and first and second conductive leads. The base member has a conductive main surface including a region that mounts the semiconductor die. The side wall surrounds the region and is made of a dielectric. The side wall includes first and second portions. The first and second conductive films are provided on the first and second portions, respectively and are electrically connected to the semiconductor die. The first and second conductive leads are conductively bonded to the first and second conductive films, respectively. At least one of the first and second portions includes a recess on its back surface facing the base member, and the recess defines a gap between the at least one of the first and second portions below the corresponding conductive film and the base member.

A filter includes an input terminal, an output terminal, a ground terminal, a first capacitor and a second capacitor that are connected in series between the input terminal and the output terminal, a capacitive element that is connected in parallel to the first capacitor and the second capacitor between the input terminal and the output terminal, and has a Q factor that is smaller than a Q factor of the first capacitor and is smaller than a Q factor of the second capacitor, and an inductor that has a first end and a second end, the first end being coupled to a node that is provided between the first capacitor and the second capacitor and that is coupled to the capacitive element through the first capacitor and the second capacitor, the second end being coupled to the ground terminal.

A filter includes an input terminal, an output terminal, a first ground terminal, a second ground terminal, a first inductor having a first end coupled to a first node in a path between the input terminal and the output terminal and a second end coupled to a second node, a second inductor having a first end coupled to the second node and a second end coupled to the first ground terminal, and a third inductor having a first end coupled to the second node and a second end coupled to the second ground terminal.