A Universal GaAs HBT PA with Active Bias Circuitry, Covering 4.9-6 GHz

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  • Author: Andrew Dearn1 , Tony Richards , Liam Devlin , Wing Yau , Owen Wu
This paper describes the design, fabrication and measured performance of a 4.9 to 6GHz Power Amplifier IC developed on a commercially available InGaP HBT process. It can address a number of applications including U-NII (US FCC), 802.11a, HiperLAN2, Japanese WLAN and cordless telephony. The amplifier was designed to operate from a 3.3V supply in either linear mode (backed off several dB from gain compression) or saturated mode (at an output power level of 0.5W). The quiescent current is kept low by an active bias circuit, and rises with increased input power to yield optimum efficiency in all modes. The active bias circuit also serves to extend the region of linear gain by appropriate dynamic control of the transistor’s base voltages. The amplifier requires a simple off-chip output matching network that can be tailored to satisf