A Compact Low-Loss High-Selectivity Excellent-Isolation FBAR Duplexer Integrated Chip for LTE Band-3 Industrial Applications

This brief presents a complete design flow for a compact low-loss high-selectivity excellent-isolation LTE Band3 (B3) duplexer (TX: 1710 MHz-1785 MHz, RX: 1805 MHz-1880 MHz). The proposed chip duplexer is based on the thin film bulk acoustic resonator (FBAR). In addition to the general design method, the effects of temperature drift, resonator performance distribution on wafer, the quality factor of inductance, device yield, and dissipated power density distribution on the design flow are described. These aspects are of great significance for the batch production of FBAR duplexers in the industry. Samples that pass the above industrial process are selected for testing. Measured results show reasonable consistency with the co-simulation results. 1.2/1.0-dB minimum IL in TX /RX band, 20-dB rejection in 3.5 GHz (second harmonic of TX), and more than 50 dB isolation in both TX and RX frequency are achieved with less massload simultaneously.