An ultra broadband upconverter MMIC has been designed; realized and measured using a 0.25 Âµm PHEMT process on GaAs . It contains a switch; amplifiers; a step attenuator; filters; and mixer. The input frequency band is 2 - 12 GHz and the output frequency band is 8-18 GHz. The input signal; selectable using a switch; is amplified and converted from 2-12 GHz to 18-8 GHz. An attenuator is used to increase the dynamic range of the circuit. Measured performance shows full functionality with an overall gain better than 30 dB and with a noise figure of 5 dB. The work was part of a CEPA project.