Hairpin band pass filter and related frequency down converter
A band pass filter includes a first micro-strip port for receiving a radio-frequency signal, a second micro-strip port for outputting a filtered radio-frequency signal and comprising at least one resonating cavity formed for enhancing rejecting effect of image frequency corresponding to the filtered radio-frequency signal, and a plurality of resonators arranged between the first micro-strip port and the second micro-strip port for performing band pass filtering on the radio-frequency signal to generate the filtered radio-frequency signal.
1. A frequency down converter for enhancing rejecting effect of image frequency, the frequency down converter comprising:
a receiver end for receiving a radio-frequency signal;
a mixer for transforming a frequency of a filtered radio-frequency signal to a preset frequency according to a local oscillation signal, so as to outputting an intermediate frequency signal; and
a band pass filter coupled between the receiver end and the mixer, the band pass filter comprising:
a first micro-strip port for receiving a radio-frequency signal;
a second micro-strip port for outputting a filtered radio-frequency signal, the second micro-strip port comprising at least one resonating cavity formed for enhancing rejecting effect of image frequency corresponding to the filtered radio-frequency signal; and
a plurality of resonators arranged between the first micro-strip port and the second micro-strip port for performing band pass filtering on the radio-frequency signal to generate the filtered radio-frequency signal.
2. The frequency down converter of claim 1 , wherein each of the at least one resonating cavity is in a form of U-shape.
3. The frequency down converter of claim 1 , wherein a length of each of the at least one resonating cavity is half of a wavelength corresponding to the filtered radio-frequency signal.
4. The frequency down converter of claim 1 , wherein the at least one resonating cavity is formed in the second micro-strip port by an etching process.
5. The frequency down converter of claim 1 , wherein each of the plurality of resonators is in a form of U-shape.
6. The frequency down converter of claim 1 , wherein a length of each of the plurality of resonators is half of a wavelength corresponding to the filtered radio-frequency signal.
7. The frequency down converter of claim 1 being utilized in a super heterodyne receiver.
8. The frequency down converter of claim 1 , wherein the band pass filter is a hairpin band pass filter.
9. The frequency down converter of claim 1 , wherein the band pass filter is a parallel-coupled strip filter.
10. A band pass filter comprising:
a first micro-strip port for receiving a radio-frequency signal;
a second micro-strip port for outputting a filtered radio-frequency signal, the second micro-strip port comprising at least one resonating cavity formed for enhancing rejecting effect of image frequency corresponding to the filtered radio-frequency signal; and
a plurality of resonators arranged between the first micro-strip port and the second micro-strip port for performing band pass filtering on the radio-frequency signal to generate the filtered radio-frequency signal.
11. The band pass filter of claim 10 , wherein each of the at least one resonating cavity is in a form of U-shape.
12. The band pass filter of claim 10 , wherein a length of each of the at least one resonating cavity is half of a wavelength corresponding to the filtered radio-frequency signal.
13. The band pass filter of claim 10 , wherein the at least one resonating cavity is formed in the second micro-strip port by an etching process.
14. The band pass filter of claim 10 , wherein each of the plurality of resonators is in a form of U-shape.
15. The band pass filter of claim 10 , wherein a length of each of the plurality of resonators is half of a wavelength corresponding to the filtered radio-frequency signal.
16. The band pass filter of claim 10 , wherein the band pass filter is a hairpin band pass filter.
17. The band pass filter of claim 10 , wherein the band pass filter is a parallel-coupled strip filter.