Design of a Broadband HEMT Mixer for UWB Applications

Background/Objectives: Microwave mixer is a crucial element in virtually all transmits and receives systems. Methods/Statistical analysis: In this paper, a novel distributed HEMT mixer with three layers is designed for Ultrawide-Band (UWB) receivers. We employ external capacitors in the proposed circuit to adjust the output phase shift between stages to equal the input phase shift. Findings: The simulation results show that the proposed structure, achieves vary broadband performances in Converstion Gain, Power Consumption and LO-RF Isolation, comparable to the recent reported cascode or dual-gate distributed mixers. With a local oscillator power of 12 dBm and RF power of -20 dBm, our mixer has a Conversion Gain of 0 ~ 4 dB (without IF signal amplification), LO-to-RF isolation better than 32 dB and 130 mW DC power consumption over bandwith 5-25 GHz. Applications/Improvements: In our scheme, an intermediate layer is considered to increase LO-RF Isolation and improve the Converstion Gain criterion. Moreover, Microstrip lines are used to form the artificial gate and drain transmission lines as well as phase equalization of the signal on drain transmission line.