Integrated multiple-input multiple-output multi-band bandpass filter bank

A multi-band radio frequency (RF) communication device, comprising:

• a multi-band antenna,
• a band selection switch coupled to the multi-band antenna,
• a plurality of multi-band RF transceiver circuits for RF signal transmission, and
• an integrated multi-band bandpass filter bank including a plurality of RF input ports coupled to the band selection switch and a plurality of RF output ports coupled to the plurality of multi-band RF transceiver circuit,
• wherein the integrated multi-band bandpass filter bank comprises:
• a plurality of transmission line structures for transmitting and receiving RF signals;
• and
• a plurality of concentric ring resonators with different sizes and different resonant frequencies electromagnetically coupled to the plurality of transmission line structures,
• wherein each ring resonator of the plurality of concentric ring resonators is a single-band bandpass filter to generate a designed bandpass signal having a central frequency, and
• wherein at least one of the plurality of concentric ring resonator is a composite ring resonator composed of a plurality of vertically-stacked layered resonator elements having resonant frequencies in operational band of the bandpass filter.

A method for filtering multi-band RF signals within a multi-band RF communication device, comprising:

• receiving RF signals by a plurality of multi-band transmission lines;
• coupling the RF signals to an integrated multi-band bandpass filter bank comprising a plurality of concentric ring resonators, wherein each ring resonator of the plurality of concentric ring resonators operates at a separately desired frequency;
• and
• filtering, at the integrated multi-band bandpass filter, the RF signals into desired passband signals, wherein at least one of the plurality of ring resonator is a composite ring resonator composed of a plurality of vertically-stacked layered resonator elements having resonant frequencies in operational band of the bandpass filter.