TUNABLE RADIO FREQUENCY FILTERING CIRCUITRY

摘要

Radio frequency (RF) filtering circuitry includes transmit signal filtering circuitry and receive signal filtering circuitry. The RF filtering circuitry is configured to separate RF transmit signals within a transmit signal frequency band from RF receive signals within a receive signal frequency band. A tunable impedance is coupled to the transmit signal filtering circuitry and adjusted such that the attenuation of the RF transmit signals is greater in a first portion of the receive signal frequency band than in a second portion of the receive signal frequency band in a first mode of operation, and greater in the second portion of the receive signal frequency band than in the first portion of the receive signal frequency band in a second mode of operation.

主权项

1. Radio frequency (RF) filtering circuitry comprising:
a common node, a transmit signal node, and a receive signal node; transmit signal filtering circuitry coupled between the transmit signal node and the common node and configured to pass RF transmit signals within a transmit signal frequency band between the transmit signal node and the common node while attenuating signals outside of the transmit signal frequency band, the transmit signal filtering circuitry comprising:
a series transmit signal filter path coupled between the transmit signal node and the common node and comprising at least one transmit signal series resonator;a shunt transmit signal filter path comprising a transmit signal shunt resonator and a shunt impedance coupled in series between the series transmit signal filter path and a fixed voltage such that the connection between the transmit signal shunt resonator and the shunt impedance provides a shunt intermediate node; anda tuning impedance coupled between the transmit signal node and the shunt intermediate node; and receive signal filtering circuitry coupled between the receive signal node and the common node and configured to pass RF receive signals within a receive signal frequency band while attenuating signals outside the receive signal frequency band.