Limitations and Implementation Strategies of Interstage Matching in a 6-W, 28–38-GHz GaN Power Amplifier MMIC

Abstract

In this article, we summarize the theoretical matching boundaries and show the limitations they implicate for real-world amplifier design. Starting with a common schematic prototype, we investigate the question of how to realize its electrical response in a densely routed, massively parallelized layout. To that end, we develop a comprehensive study on the application of space-mapping techniques toward the design of high-power amplifiers (HPAs). We derive three reference design procedures and compare their performance in terms of convergence, speed, and practicality when laying out a densely routed HPA interstage matching network. Subsequently, we demonstrate the usefulness of the study by designing the networks of a compact three-stage eight-way wideband HPA in the Ka-band. The processed monolithic microwave integrated circuit features a 1-dB large-signal bandwidth of more than 11 GHz (a fractional bandwidth of 32.8%) and thus covers most of the Ka-band with an output power exceeding 6 W in 3 dB of gain compression. This demonstrates the highest combination of power and bandwidth to date using a reactively matched topology in the Ka-band.

670-GHz Cascode Circuits Based on InGaAs Metamorphic High-Electron-Mobility Transistors

“…To account coupling effects between the densely routed elements of the matching networks-such as T-junctions and thin-film capacitors-the actual circuit behavior can only be described with the 3D-EM models. Thus, a simplified space mapping approach is used as described in [27]. This permits the implementation of scalable schematic models of the passive matching networks in Keysight ADS and a time efficient optimization of the required impedance transformations.…”

Broadband 100-W Ka-Band SSPA Based on GaN Power Amplifiers

“…As a result, the translation of the prototype networks to a layout first yielded poor electromagnetic (EM) responses. To improve this, spacemapping techniques [10], [11] were used extensively for each of the networks, which resulted in significantly improved EMsimulated matching bandwidth.…”

High efficiency 35 GHz MMICs based on 0.2 μm AlGaN/GaN HEMT technology

“…The performance of GaN HEMTs for Ka-band has been developed over the years, and many monolithic microwave integrated circuits (MMICs) are designed with AlGaN/GaN and InAlGaN/GaN HEMT structures [1][2][3][4][5][6][7][8][9][10][11][12]. At 35 GHz, a saturated power density of 4 W/mm is achieved for an AlGaN/GaN device with 0.18 mm gate length in [1].…”

“…Another InAlGaN/GaN HEMT work with AlGaN back-barrier introduces an improved epitaxial structure for the reduced recovery time of drain current, which would be favorable, especially for low noise amplifiers in transceivers for radar applications [10]. The limitations of design for large bandwidths at Ka-band frequencies are discussed in [11] which shows a design example with 26% PAE using 15 V operating voltage and 50 W/mm drain current. A large bandwidth is obtained in [12] with 15.5 W output power and 16% PAE over 15.6% bandwidth from 26.5 to 31 GHz.…”