To further improve LTE B3 diplexer interband isolation, a high-isolation SAW duplexer module is designedusing SIP technology in this study. The module is composed of two SAW duplexers and three couplers. Itapplies the phase cancellation of the TX-RX path and the isolation of the couplers to improve the isolation betweenthe uplink and downlink of a single SAW duplexer. An impedance-element filter architecture is used to achieve an isolationdegree of 51 dB for the proposed module. A broadside stripline multilayer helical coupler-line architecture isadopted to achieve miniaturized integrated 3 dB couplers with a wide operating bandwidth. The results of the developedmodule show that in the B3 band, for a SAW duplexer measuring 8.0 mm×8.0 mm×2.0 mm, the insertionloss is less than 3.2 dB, the return loss exceeds 13 dB, and the isolation degree exceeds 65 dB; furthermore, it canwithstand instantaneous power levels up to 34 dBm.