Author(s)

Bai Yuhui, Ren Jiatai, Chen Jianming, Chu Hequn, Wang Rui, Cheng Pengguang

Corresponding Author

Chen Jianming

ABSTRACT

The performance of RF resonant circuit is improved by adding inductor in the circuit. Firstly, according to the equivalent circuit of a single lossless film bulk acoustic resonator (FBAR), the resonant frequency and anti-resonant frequency formulas of the resonator are derived. According to the expressions, the principle of improving circuit performance by series parallel inductors is studied. Secondly, considering that too large inductor will bring great challenges to the subsequent process, the inductor size is optimized through Π-T transformation principle. Based on this research, another mobile duplexer is designed for umts-1 band (transmitting band: 1920-1980mhz, receiving band: 2110- 2170MHz). The insertion loss of transmitting filter and receiving filter is better than 2dB, and the isolation of transmitting filter and receiving filter is greater than 58db and 77db respectively.

KEYWORDS

Thin film bulk acoustic resonator, resonant frequency, duplexer, Π-T transformation