Implementation of the front-end module with a power amplifier for dual-band wireless LAN

This paper presents a compact RF front-end module (FEM) with the power amplifier module (PAM) for dual band Wireless LAN (W-LAN). The FEM is composed of a single-pole-double-throw (SPDT) IC, a PAM, two Tx LPFs, two matching circuits for 802.11 b/g (low band) and 802.11 a (high band), two Rx BPFs, Tx diplexer for low/high band, and Rx diplexer for low/high band. Tx diplexer, Rx diplexer, two LPFs, two BPFs, and two matching circuits are fully integrated in the low temperature co-fire ceramic (LTCC) substrate. The optimal impedance of the matching circuit is obtained by using load pull equipment. The matching circuit and the Tx LPF for high band employ the geometry of strip line by using parasitic capacitance and inductance in the high frequency instead of avoiding these effects. Two diplexers apply conjugate matching method. The size of implemented module is given as 7.0 mm × 6.0 mm × 1.2 mm. The implemented module was measured as two parts. One is Rx part which includes the SPDT switch, Rx diplexer and two BPFs, the other is Tx Part which includes the SPDT switch, the Tx diplexer and two LPFs. In case of Rx, the insertion loss is less than 3.3 dB and the return loss is more than 15.5 dB in low/high pass band. In case of Tx, the insertion loss is less than 2.6 dB and the return loss is more than 11.3 dB. The measured adjacent-channel ratios (ACPRs) at first and second side-lobe in low band are −30.2 dBc and −50.0 dBc, respectively. In case of high band, ACPRs at first, second, and third side-lobe are −24.3 dBc, −35.4 dBc and −56.3dBc, respectively.