Abstract

Variable attenuator circuits are essential system blocks in millimetre wave radio links. Two novel variable attenuator MMICs have been realized and tested: One with continuous i.e. analog control (VVA) and the other with three bit digital control (DA). Circuits operate in a very broad frequency range of 15 GHz – 45 GHz and they have been fabricated with commercially available GaAs pHEMT processes: VVA utilizing OMMIC 0.2 µm process and DA with TriQuint 0.25 µm process. The digital attenuator circuit reached an input 1 dB compression (or expansion) point of + 16 dBm at all attenuation states and an extremely low minimum insertion loss of 0.9 dB at 15 GHz and 2.5 dB at 45GHz. The dynamic range of attenuation was 35 dB at 40 GHz. The input 1 dB compression point of the voltage variable attenuator circuit was better than + 13 dBm at all levels of attenuation.