A New GaN HEMT Small-Signal Model Considering Source via Effects for 5G Millimeter-Wave Power Amplifier Design

Jihoon Kim

doi:10.3390/app11199120

Abstract

A new gallium nitride (GaN) high electron mobile transistor (HEMT) small-signal model is proposed considering source via effects. In general, GaN HEMTs adopt a source via structure to reduce device degradation due to self-heating. In this paper, the modified drain-source capacitance (Cds) circuit considering the source via structure is proposed. GaN HEMTs fabricated using a commercial 0.15 μm GaN HEMT process are measured with a 67 GHz vector network analyzer (VNA). The fabricated device is an individual source via (ISV) type. As a result, it is difficult to predict the measured S12 in the conventional small-signal model equivalent circuit. This causes errors in maximum stable gain/maximum available gain (MSG/MAG) and stability factor (K), which are important for circuit design. This paper proposes a small-signal equivalent circuit that adds the drain-source inductance to the drain-source capacitance considering the source via structure. The proposed equivalent circuit better reproduces the measured S12 without compromising the accuracy of other S-parameters up to 67 GHz and improves the accuracy of MSG/MAG and K. It is expected that the proposed model can be utilized in a large-signal model for 5G millimeter-wave GaN HEMT power amplifier design in the future.

Highlights

Gallium nitride (GaN) semiconductors have a high breakdown voltage due to inherent wide-bandgap and high current density, which is advantageous for use as power semiconductors [1,2]
Since GaN high electron mobility transistor (HEMT) exhibit high power density but have a self-heating effect, a source via structure that can dissipate heat well to substrates is widely used in transistor layouts
The. Theproposed proposedsmall-signal small-signalmodel modelcan canbe be applied applied to to Gallium nitride (GaN) GaN high electron mobility transistor (HEMT). HEMTs with with other other quencies

Summary

Introduction

Gallium nitride (GaN) semiconductors have a high breakdown voltage due to inherent wide-bandgap and high current density, which is advantageous for use as power semiconductors [1,2]. Since the high electron mobility transistor (HEMT) structure has high electron mobility due to the generation of its unique 2-D electron gas (2-DEG), GaN. HEMTs have been widely studied and utilized in high-frequency power amplifiers [3,4,5,6,7]. Since GaN HEMTs exhibit high power density but have a self-heating effect, a source via structure that can dissipate heat well to substrates is widely used in transistor layouts. With the commercialization of 5G communication, research on millimeter-wave power amplifiers using GaN HEMTs is being actively conducted [12,13,14,15].

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Results

Conclusion