Radio frequency filter, radio frequency circuit, antenna duplexer and radio terminal

A radio frequency filter comprising:

• a ladder-type resonator filter in which a plurality of first surface acoustic wave resonators or first film bulk acoustic resonators are connected in a ladder circuit configuration;
• a first terminal and a second terminal;
• a serial inductance and a parallel capacitance connected between said ladder-type resonator filter and said first terminal;
• and
• a serial capacitance and a parallel inductance connected between said ladder-type resonator filter and said second terminal;
• wherein at least one of said serial inductance and said parallel inductance is a second surface acoustic wave resonator or a second film bulk acoustic resonator having an impedance characteristic as an inductance equivalently in a pass band frequency f0 of said radio frequency filter, and formed on a chip on which said first surface acoustic wave resonators or said first film bulk acoustic resonators are formed.

A radio frequency filter comprising:

• a ladder-type resonator filter in which a plurality of first surface acoustic wave resonators or first film bulk acoustic resonators are connected in a ladder circuit configuration;
• a first terminal and a second terminal;
• a serial inductance and a parallel capacitance connected between said ladder-type resonator filter and said first terminal;
• and
• a serial capacitance and a parallel inductance connected between said ladder-type resonator filter and said second terminal;
• wherein an output signal of said radio frequency filter passing through said radio frequency filter to be thereby formed in a pass band frequency f0 has an amplitude deviation of not higher than ±1 dB and a phase deviation of not higher than ±10° with respect to 180° between said first terminal and said second terminal.

A radio frequency filter comprising:

• a ladder-type resonator filter in which a plurality of first surface acoustic wave resonators or first film bulk acoustic resonators are connected in a ladder circuit configuration;
• a first terminal and a second terminal;
• a serial inductance and a parallel capacitance connected between said ladder-type resonator filter and said first terminal;
• and
• a serial capacitance and a parallel inductance connected between said ladder-type resonator filter and said second terminal;
• wherein said first terminal and said second terminal are connected to differential terminals of a differential amplifier or a differential mixer respectively.