Hybrid signal filter

A signal filter comprising:

• a first filtering unit configured to perform a first specific filtering operation according to a first specific filtering property;
• a second filtering unit configured to perform a second specific filtering operation according to a second specific filtering property including a relatively low quality factor and a relatively high coupling coefficient;
• and
• a substrate supporting the first and the second filtering units, and including a coupling circuit, wherein the first filtering unit is electrically coupled to the second filtering unit through the coupling circuit, wherein:
• the first filter unit is a notch filter, and the second filter unit is a wideband filter
• the signal filter further comprises an impedance matching element;
• the substrate supports the impedance matching element;
• the impedance matching element is electrically coupled to the notch filter and the wideband filter through the coupling circuit;
• and
• the wideband filter is a bandpass filter.

A signal filter comprising:

• a notch filter configured to perform a band-rejection filtering operation according to a band-rejection filtering property;
• and
• a wideband filter coupled to the notch filter, and configured to perform a wideband filtering operation according to a wideband filtering property, wherein:
• the band-rejection filtering property includes a first cutoff frequency and a frequency bandwidth;
• the wideband filtering property includes a second cutoff frequency, a relatively low quality factor and a relatively high coupling coefficient;
• the first and the second cutoff frequencies have a frequency difference therebetween;
• a ratio of the frequency difference to the frequency bandwidth is within a preset ratio range being from 2.5% to 20%;
• the signal filter further comprises a coupling substrate and an impedance matching element;
• the coupling substrate supports the notch filter, the wideband filter and the impedance matching element, and includes a coupling circuit;
• the notch filter is electrically coupled to the wideband filter through the coupling circuit;
• the impedance matching element is electrically coupled to the notch filter and the wideband filter through the coupling circuit;
• and
• the wideband filter is a bandpass filter.