A 5GHz WLAN amplifier with novel on-chip positive voltage switchable bias implemented in a D-pHEMT process

This paper presents the RF characterization of a 4.9-5.9 GHz microwave amplifier for WLAN applications with a novel on-chip positive voltage switchable bias implemented in a depletion p-HEMT process. In order to assess the impact of the novel bias network on the amplifier´s RF performance, a second amplifier without DC switch has also been designed and tested. Both amplifiers are biased at the same collector current value. Full characterization of both designs has been carried out vs. frequency, bias conditions and control voltage V_C for the DC switchable amplifier at room temperature. The results demonstrate that the DC switch does not degrade the linear gain and return loss. The switch impact on the linearity performance is limited and still allows for a highly linear design. To the authors´ knowledge, DC switching capability driven by a positive voltage has never been reported in normally on, D-FET based, monolithic microwave integrated circuits.