Isolation Effect between DC supply Voltage Signal Lines in Wireless LAN Module

A compact RF front-end module (FEM) for Wireless LAN (WLAN) application was proposed by merging DC supply voltage lines. The proposed module had one DC supply voltage line and one external shunt capacitor. This paper approached the aspect of isolation among DC supply voltage signal lines instead of using RF chokes or external shunt capacitors. Three types of module were designed and fabricated to verify the effect corresponding to isolation. A tested FEM consists of a SiGe Power Amplifier (PA), DPDT switch, a BPF for Rx, a LPF for Tx, a matching circuit for PA, and a structure for merging DC supply voltage signal lines. The performance of PA was improved along with large isolation. Measured results of the module using a proposed approach showed a P1dB 24 dBm with a 3.3 V supply. The measured adjacent-channel power ratios (ACPR) at first side-lobe and second side-lobe are -32.4 dBc and -57.9 dBc at an 18 dBm output power, respectively.