Simulation Modeling and Analysis of FBAR RF Filters Considering Different Configurations of Grounding Bond-wires

Wire bonding is widely used for the interconnection of film bulk acoustic resonator (FBAR) radio frequency (RF) devices and the electrical performance of the FBAR filter is related to the grounding bond-wire configuration. This paper presents simulation modeling and analysis of FBAR filters considering different configurations of grounding bond-wires. When the shunt resonators in the FBAR filter based on the ladder structure are connected to the electrical ground, the parasitic parameters of the grounding pads and the bond-wires will affect the electrical performance of the resonators. To optimize the filter performance, an equivalent model of the FBAR filter considering parasitic inductance and capacitance was established and the filters with different configurations of grounding bond-wires were simulated. In the modeling procedure, the simulation of the resonant frequency of the grounding pads and the bond-wires was implemented to extract the parasitic parameters. The simulation results of the filter show that the transmission zeros at the low frequency edge move to higher frequencies as the number of the bond-wires increases (i.e., the parasitic inductance decreases). To verify the validity, two filter samples were assembled and measured, which were with one and two bond-wires on each grounding pads, respectively. The measurement results of S21 curves show that the shifting of the filter's transmission zero at the low frequency edge is related to the ground bond-wire configuration, which is accordance with the simulation results.