Band-pass filter and branching filter

A branching filter comprising:

• a common port;
• a first signal port;
• a second signal port;
• a first filter provided between the common port and the first signal port, and configured to selectively pass a signal of a frequency within a first passband;
• and
• a second filter provided between the common port and the second signal port, and configured to selectively pass a signal of a frequency within a second passband higher than the first passband, wherein
• the first filter is a first band-pass filter,
• the first passband is a frequency band that is not lower than a first low-band cut-off frequency and not higher than a first high-band cut-off frequency,
• the first band-pass filter includes a first resonant circuit section provided between the common port and the first signal port, and a first LC resonant circuit connected to the first resonant circuit section,
• the first resonant circuit section includes at least one acoustic wave resonator, and
• the first resonant circuit section has a resonant frequency within the first passband and at least one anti-resonant frequency higher than the first high-band cut-off frequency.

A branching filter comprising:

• a common port;
• a first signal port;
• a second signal port;
• a first filter provided between the common port and the first signal port, and configured to selectively pass a signal of a frequency within a first passband;
• and
• a second filter provided between the common port and the second signal port, and configured to selectively pass a signal of a frequency within a second passband higher than the first passband, wherein
• the second filter is a second band-pass filter,
• the second passband is a frequency band that is not lower than a second low-band cut-off frequency and not higher than a second high-band cut-off frequency,
• the second band-pass filter includes a second resonant circuit section provided between the common port and the second signal port, and a second LC resonant circuit connected to the second resonant circuit section,
• the second resonant circuit section includes at least one acoustic wave resonator, and at least one inductor connected in parallel to the at least one acoustic wave resonator, and
• the second resonant circuit section has a resonant frequency within the second passband, an anti-resonant frequency lower than the second low-band cut-off frequency, and an anti-resonant frequency higher than the second high-band cut-off frequency.

A branching filter comprising:

• a common port;
• a first signal port;
• a second signal port;
• a first filter provided between the common port and the first signal port, and configured to selectively pass a signal of a frequency within a first passband;
• and
• a second filter provided between the common port and the second signal port, and configured to selectively pass a signal of a frequency within a second passband higher than the first passband, wherein
• the first filter is a first band-pass filter,
• the first passband is a frequency band that is not lower than a first low-band cut-off frequency and not higher than a first high-band cut-off frequency,
• the first band-pass filter includes a first resonant circuit section provided between the common port and the first signal port, and a first LC resonant circuit connected to the first resonant circuit section,
• the first resonant circuit section includes at least one first acoustic wave resonator,
• the first resonant circuit section has a resonant frequency within the first passband and at least one anti-resonant frequency higher than the first high-band cut-off frequency,
• the second filter is a second band-pass filter,
• the second passband is a frequency band that is not lower than a second low-band cut-off frequency and not higher than a second high-band cut-off frequency,
• the second band-pass filter includes a second resonant circuit section provided between the common port and the second signal port, and a second LC resonant circuit connected to the second resonant circuit section,
• the second resonant circuit section includes at least one second acoustic wave resonator, and at least one inductor connected in parallel to the at least one second acoustic wave resonator, and
• the second resonant circuit section has a resonant frequency within the second passband, an anti-resonant frequency lower than the second low-band cut-off frequency, and an anti-resonant frequency higher than the second high-band cut-off frequency.