High-frequency component

A high-frequency component, comprising:

• a diplexer including a high-frequency-band filter and a low-frequency-band filter connected in parallel to an antenna port, the high-frequency-band filter being arranged to pass a transmission/reception signal in a high-frequency band and attenuate a transmission/reception signal in a low-frequency band among transmission/reception signals of a plurality of communications systems each having a different frequency band, and the low-frequency-band filter being arranged to pass a transmission/reception signal in the low-frequency band and attenuate a transmission/reception signal in the high-frequency band, among the transmission/reception signals of the plurality of communications systems;
• a high-frequency-band circuit serially connected to the high-frequency-band filter of the diplexer;
• and
• a low-frequency-band circuit serially connected to the low-frequency-band filter of the diplexer;
• wherein
• the high-frequency-band filter includes a first series resonant circuit, one end of which is connected to a connection node between the antenna port and the high-frequency-band circuit and the other end of which is grounded, and a second series resonant circuit including a reactance element connected serially between the antenna port and the high-frequency-band circuit and including the first series resonant circuit;
• a resonance frequency of the first series resonant circuit is a trap frequency of a transmission/reception signal in the low-frequency band, in the frequency characteristic of the high-frequency-band filter;
• and
• a resonance frequency of the second series resonant circuit is substantially the same as a frequency of a predetermined attenuation pole in the frequency characteristic of the low-frequency-band filter.