Low-loss non-adjacent-band rejection topologies using baw resonators

A wireless communication device comprising:

• a baseband processor;
• and
• transmit circuitry configured to receive encoded data from the baseband processor and to modulate a carrier signal with the encoded data, wherein the transmit circuitry comprises:
• a passband filter configured to pass a desired frequency band;
• and
• a filter coupled to the passband filter, wherein the filter comprises at least one acoustic wave resonator configured to attenuate an undesired frequency band that is nonadjacent to the desired frequency band, wherein a gap between the undesired frequency band that is nonadjacent to the desired frequency band has a gap percentage that is equal to a gap that is a difference between the desired frequency band and the undesired frequency band divided by a lowest frequency of the gap.

A method of filtering radio frequency signals comprising:

• determining a gap percentage, where the gap percentage is equal to a gap that is a difference between a desired frequency band and the undesired frequency band divided by a lowest frequency of the gap, and setting the gap percentage to be between 0.8% and at least 23%;
• filtering the desired frequency band using a passband filter;
• and
• attenuating the undesired frequency band that is nonadjacent to the desired frequency band using at least one acoustic wave resonator, the acoustic wave resonator being coupled to the passband filter.