A highly linear mixer design with a schottky diode linearizer for WiMAX applications

2.6 GHz mixers are designed and implemented in hybrid microwave circuits (HMCs) using the GaAs pseudomorphic high electron mobility transistors (pHEMTs). A crucial goal for the design is to achieve the high linearity required in WiMAX systems. The proposed design is based on a commonly used Gilbert mixer with a Schottky diode linearizer to enhance the linearity. The input 1 dB compression point (IP_1dB) and the third-order intercept point (IIP₃) of the proposed design achieve -3 dBm and 6.8 dBm, respectively. A Schottky diode linearizer has improved the IP_1dB by 3 dB and the IIP₃ by 3.8 dB without the reduction in conversion gain when compared to the conventional Gilbert mixer. Comparison between simulation and measurement shows good agreement in compensation of gain compression and IIP₃ due to a Schottky diode linearizer.