Design and performance of a single band 1X2 RF front end module for mobile WiMAX applications

Abstract

This paper describes the design and performances of the first single band (2.6 GHz) dual receive and single transmit 50 Ohm front end module (FEM) for WiMAX applications. The module is designed to meet error vector magnitude, adjacent channel power ratio, channel power and all 802.16 e uplink requirements. The transmit chain is made up of a narrowband balun, an inductively coupled pseudo-elliptic band pass filter, a three stage amplifier, a matching network and a SPDT switch. The FEM is characterized with a 16QAM 3/4, 10MHz BW 5ms frame uplink burst at 3.6V VCC and +23 dBm output power. The transmit path achieves an EVM of 3%, gain of approximately 29dB, gain flatness of 0.3dB, rejection of 51, 25, 32, 57dB at 1.9, 2.2, 3.3, 4 GHz respectively, and a low current drain. The dual line up receive path is designed to optimize RF performance and minimize preceding baseband sensitivity. The receive path is made up of a RF switch and pre select filters with insertion loss of 2.4 dB across the band, rejections of −53, −45, −25, −24 and −40 dB at 0.96, 1.9, 2.17, 3.3, and 4 GHz respectively. The front end module is integrated in a 7X7mm 40 pad LGA package, resulting in the first and smallest 1X2 802.16e FEM.