FILTERING APPARATUS AND METHOD FOR MULTIBAND RADIO

摘要

A portable radio provides operation in LTE and LMR radio bands. Improved filtering in the LTE receive path is provided through the use of a linear duplexer and a SAW filter. The SAW filter is implemented as a duplexer with one port terminated to provide a filter for the LTE RX path. The linear duplexer and SAW filter provide filtering for an LMR TX signal and an LTE TX signal which are simultaneously present at an LTE antenna of the radio. The linearity of the linear duplexer which reduces LTE TX and LMR TX signal levels combined with the selectivity of the SAW filter prevents intercept intermodulation in the LTE RX path.

主权项

1. A portable radio, comprising:
a long term evolution (LTE) transceiver having an LTE receive (RX) path and an LTE transmit (TX) path for operation in full duplex mode; a land mobile radio (LMR) transceiver having an LMR transmit (TX) path and an LMR receive (RX) path for operation in half-duplex mode; an LTE antenna; an LMR antenna; a linear duplexer coupled to the LTE antenna; first and second surface acoustic wave (SAW) filters coupled to the linear duplexer, the first SAW filter implemented as a duplexer with one port terminated to provide a filter for the LTE RX path of the portable radio, the second SAW filter implemented as a duplexer with one port terminated to provide a filter in the LTE TX transmit path of the portable radio; and the linear duplexer and first SAW filter for filtering an LMR TX signal and an LTE TX signal which are simultaneously present at the LTE antenna, the linear duplexer and first SAW filter combining to eliminate intermodulation spurs before they are generated in an active LTE RX path.