A GaN MMIC Stacked Doherty Power Amplifier For Space Applications

Abstract

This paper presents the design and the experimental results of a Monolithic Microwave Integrated Circuit Power Amplifier in which the FET-Stacking approach is combined with the Doherty architecture in order to maximize the achievable performance. In particular, the Stacked cell is realized by splitting the common source device in two smaller devices leading to a very compact and symmetric structure, whereas the Doherty idea is exploited to fulfil high efficiency at back-off. The chip is implemented on a 100 nm gate length Gallium Nitride on Silicon technology targeting the downlink satellite Ka-band. The two stage amplifier was carried out to satisfy not only the power requirements but also to meet the thermal constraints for space use. In the frequency range from 17.3 GHz to 20.3 GHz, measurement results have shown a linear gain of about 25 dB with a peak power of 38 dBm and a power added efficiency larger than 35%.

An Optimized Control System for the Independent Control of the Inputs of the Doherty Power Amplifier

“…Significant research endeavors have been conducted to assess and validate the technical potential of GaN HEMT. The requirement for robust equipment capable of operating effectively in challenging conditions, like for radio communication systems where temperature constraints are present, has led to the necessity of addressing reliability concerns [35]. The power amplifier used to implement this Doherty and parallel-connected amplifier structure is a commercial component, Qorvo QPD0005, as shown in Figure 3.…”

“…This manuscript's comparisons are established by considering the control systems' technique and performance, focusing on improving the DPA, regardless of the amplifiers and other devices employed. In the prior works [35,39,40], the system is designed for fixed PAs, which does not give the flexibility of characterizing the other amplifiers. In both the previous studies and the current work, the inputs and outputs are different due to the integration of distinct control systems with varying amplifier types, each with its unique biasing prerequisites.…”