US Patent No. 10,038,423

NOTCH FILTER


Patent No. 10,038,423
Issue Date July 31, 2018
Title Notch Filter
Inventorship Takahiro Ishikawa, Saitama (JP)
Assignee NIHON DEMPA KOGYO CO., LTD., Tokyo (JP)

Claim of US Patent No. 10,038,423

1. A high-pass notch filter having a pass band on a high frequency side with respect to an attenuation band, the high-pass notch filter comprising:an input port configured to receive an input signal;
an output port configured to output an output signal;
a first SAW resonator and a second SAW resonator arranged between the input port and the output port, the first SAW resonator being configured to resonate in parallel at a first frequency corresponding to the attenuation band, the second SAW resonator being configured to resonate in parallel at a second frequency corresponding to the attenuation band;
a third SAW resonator having one end and another end, the one end of the third SAW resonator being connected between the first SAW resonator and the second SAW resonator, and the another end of the third SAW resonator being grounded, and the third SAW resonator being configured to resonate in parallel at a third frequency corresponding to the attenuation band;
a first inductor element having one end and another end, the one end of the first inductor element being connected between the first SAW resonator and the third SAW resonator, and the another end of the first inductor element being grounded; and
a second inductor element having one end and another end, the one end of the second inductor element being connected between the second SAW resonator and the third SAW resonator, and the another end of the second inductor element being grounded.