A low-distortion GaAs variable attenuator IC for digital mobile communication system

This GaAs variable RF attenuator IC shows extremely low distortion with a single positive control voltage. The low-distortion characteristic is realized by employing octal-gate MESFET structures as the voltage-variable resistors. The measured results at 1 GHz show insertion loss lower than 2.5 dB, maximum attenuation over 20 dB and the 3rd order intermodulation distortion (IM3) lower than -50 dBc at 0 dBm input power. The return loss is lower than -30 dB in the whole attenuation range. The present GaAs variable attenuator IC is suitable for transmitting receiving power control for a variety of digital mobile communication systems such as TDMA or CDMA.