Radio-frequency filter, radio-frequency front-end circuit, and communication device

A radio-frequency filter comprising:

• a series arm circuit located in a path that connects a first input/output terminal and a second input/output terminal;
• and
• a parallel arm circuit connected between ground and a node on the path, wherein:
• the series arm circuit comprises:
• a first series arm resonator in the path, and
• a first variable frequency circuit connected in parallel with the first series arm resonator,
• the first variable frequency circuit comprises:
• a second series arm resonator, and
• a first switch connected in series with the second series arm resonator,
• the first variable frequency circuit is configured to change a resonant frequency or an anti-resonant frequency of the radio-frequency filter, a pass band of the radio-frequency filter being based on the resonant frequency and an attenuation pole of the radio-frequency circuit being based on the anti-resonant frequency, and
• a resonant frequency of the second series arm resonator is different from a resonant frequency of the first series arm resonator.