A broadband high linearity voltage variable attenuator MMIC

This paper discusses design and development of a 9–15 GHz high linearity voltage variable attenuator (VVA) realized using 0.25µm GaAs/InGaAs/AlGaAs pHEMT MMIC process. A cascade of Pi- and T-attenuator topologies provides necessary attenuation range and improves the linearity. Further linearity enhancement is achieved using stacked transistor structure in shunt arms. The simulated insertion loss of this VVA MMIC is less than 6dB over 9–15GHz. Dynamic range is over 12dB with third order input intercept point more than +20dBm at all attenuation values. Balanced structure provides return losses better than 15dB over entire frequency range. The chip area is 3.8×3 mm².