A front-end module may include an acoustic wave filter with a first and second interdigital transducer electrode, and a low noise amplifier (LNA) that converts a differential input to a single-ended output with respect to ground. The first interdigital transducer electrode may be single-ended with a first input bus bar configured to receive an input signal and a second input bus bar connected to ground. The second interdigital transducer electrode may be differential with a first output bus bar connected to a first output terminal and a second output bus bar connected to a second output terminal. The LNA may have a differential input connected to the acoustic wave filter, a first input transistor that receives a first signal from the first output terminal of the acoustic wave filter, and a second input transistor that receives a second signal from the second output terminal of the acoustic wave filter.

A front-end module may include an acoustic wave filter with a first and second interdigital transducer electrode. The first interdigital transducer electrode may be single-ended with a first input bus bar that receives an input signal and a second input bus bar connected to ground. The second interdigital transducer electrode may be differential with a first output bus bar connected to a first output terminal and a second output bus bar connected to a second output terminal. The front-end module may include a low noise amplifier (LNA) that outputs a differential signal via a differential output and has a differential input connected to the acoustic wave filter. The LNA may include a first input transistor that receives a first signal from the first output terminal of the acoustic wave filter and a second input transistor that receives a second signal from the second output terminal of the acoustic wave filter.

An acoustic wave element includes an IDT electrode includes pluralities of electrode fingers, and reflector electrodes on the two sides of the IDT electrode. The IDT electrode includes a major part and at least one end part which is located between the major part and one of the reflector electrodes and is arranged along a direction of propagation of an acoustic wave together with the major part. the at least one end part includes a pitch of the plurality of electrode fingers substantially the same as a pitch of the plurality of electrode fingers in the major part, is electrically connected in parallel with respect to the major part, and is divided into two or more sections which are electrically connected in series with each other.

A filter device includes a filter chip on a multilayer substrate. The filter chip includes a reception filter chip portion and a transmission filter chip portion, and a reception filter defined by a first bandpass filter includes first and second balanced output terminals. First and second balance wirings connect first and second balanced input pads and first and second balanced output pads provided on a second principal surface of the multilayer substrate. The first and second balance wirings cross each other within the multilayer substrate and are electrically insulated from each other. A portion of a ground conductor is disposed at a region in which the first and second balance wirings overlap, interposed between portions of the first and second balance wirings, and disposed at a different substrate layer.

A radio frequency (RF) switch apparatus includes a signal input terminal; a signal output terminal; a first transistor including a first input terminal connected to the signal input terminal, a first output terminal connected to the signal output terminal, a first gate terminal, and a first body terminal, wherein one of the first input terminal and the first output terminal is a source terminal and another one of the first input terminal and the first output terminal is a drain terminal; a first capacitor circuit connected between the first input terminal and the first body terminal; and a second capacitor circuit connected between the first body terminal and the first output terminal; wherein a first capacitance of the first capacitor circuit is greater than a second capacitance of the second capacitor circuit.

A radio frequency (RF) switch apparatus includes a signal input terminal; a signal output terminal; a first transistor including a first input terminal connected to the signal input terminal, a first output terminal connected to the signal output terminal, a first gate terminal, and a first body terminal, wherein one of the first input terminal and the first output terminal is a source terminal and another one of the first input terminal and the first output terminal is a drain terminal; a first capacitor circuit connected between the first input terminal and the first body terminal; and a second capacitor circuit connected between the first body terminal and the first output terminal; wherein a first capacitance of the first capacitor circuit is greater than a second capacitance of the second capacitor circuit.

A filter device includes a filter chip on a multilayer substrate. The filter chip includes a reception filter chip portion and a transmission filter chip portion, and a reception filter defined by a first bandpass filter includes first and second balanced output terminals. First and second balance wirings connect first and second balanced input pads and first and second balanced output pads provided on a second principal surface of the multilayer substrate. The first and second balance wirings cross each other within the multilayer substrate and are electrically insulated from each other. A portion of a ground conductor is disposed at a region in which the first and second balance wirings overlap, interposed between portions of the first and second balance wirings, and disposed at a different substrate layer.

A duplexer includes a first band-pass filter and a second band-pass filter with a pass-band lower than the first band-pass filter. The first band-pass filter includes an unbalanced surface acoustic wave filter. First, second and third signal wire electrodes and a ground wire electrode are provided on a piezoelectric substrate in the first band-pass filter, and a bridging area is provided where any one of the first, second and third signal wire electrodes bridges the ground wire electrode. A width of a portion of the signal wire electrode that opposes the ground wire electrode with an interlayer insulating film located therebetween is greater than a width of a portion of the signal wire electrode other than the bridging area so that a low-pass filter capacitor is provided.

In a filter device, a first filter and a second filter are connected to a common connection point by a filter connection conductor line including a first conductor line portion, and a parallel connection area with an electrical length shorter than that in a single conductor line is provided in the first conductor line portion.

A front-end module may include an acoustic wave filter with a first and second interdigital transducer electrode, and a low noise amplifier (LNA) that converts a differential input to a single-ended output with respect to ground. The first interdigital transducer electrode may be single-ended with a first input bus bar configured to receive an input signal and a second input bus bar connected to ground. The second interdigital transducer electrode may be differential with a first output bus bar connected to a first output terminal and a second output bus bar connected to a second output terminal. The LNA may have a differential input connected to the acoustic wave filter, a first input transistor that receives a first signal from the first output terminal of the acoustic wave filter, and a second input transistor that receives a second signal from the second output terminal of the acoustic wave filter.