Monolithically Integrated GaN Gate Drivers- A Design Guide

In recent years, an increasing trend towards GaN integration can be observed, enabled by the lateral structure of the GaN technology. A key improvement over a discrete implementation is the integration of a monolithic gate driver. This tutorial-style article aims to give insight into the design flow. It starts with the possibilities of GaN technologies in terms of IC design followed by basic driving principles of GaN HEMTs. Gate loop requirements and recommendations for the gate driver output stage are explained. A flowchart for the design of integrated gate drivers is presented with the boundary constraints from the technology, topology research, and selection using a step-by-step guide. The design flow is run through with an example scenario and the realized gate driver design is optimized for low power consumption and fast switching, which is verified with simulations and measurements. Thus, a guide is given for the design of a monolithically integrated GaN gate driver to further advance, promote, and accelerate integration in GaN

Broadband low-noise GaN HEMT TWAs using an active distributed drain bias circuit

Modern communication and radar systems show an increasing demand for robust ultra-broadband amplifiers for low-noise applications. A set of three different 0.5 GHz to 20 GHz MMIC LNAs using a GaN HEMT technology with a gate length of 0.25 μm was designed and fabricated, each with a noise figure between 3 dB and 7 dB over frequency. Two designs with four and five FET cells feature approx. 10 dB and 11 dB broadband gain, while a third MMIC with a chain connection of both figures more than 20 dB of gain. A distributed active drain bias circuit substitutes large area or off-chip inductor structures and enables a full-MMIC chain connection of both TWA stages

Monolithically integrated GaN power stage for more sustainable 48 V DC-DC converters

In this article, a fully monolithically integrated GaN power stage with a half-bridge, driver, level shifter, dead time and voltage mode control for 48 V DC-DC converters is proposed and analyzed. The design of the GaN IC is presented in detail, and measurements of the single function blocks and the DC–DC converter up to 48 V are shown. Finally, considerations are given on a life cycle assessment with regard to the GaN power integration. This GaN power IC or stage demonstrates a higher level of integration, resulting in a reduced bill of materials and therefore lower climate impact.This research was partly funded the German Federal Ministry of Education and Research (BMBF) through the project GreenICT@FMD (FKZ: 16ME0496).German Federal Ministry of Education and Research (BMBF

Noise degradation of cascodes in broadband power amplifiers

This paper compares the noise performance of the common-source and the cascode topology. Although the cascade topology has several advantages over the common-source stage, the noise performance degrades due to the channel noise and the induced gate noise of the common-gate stage. To underline the theory two multi-decade GaN feedback power amplifiers were designed in common-source and cascode topology, using a submicron AlGaN/GaN MMIC technology on SiC substrate. Both designs achieve 13 dB gain and simultaneously good input and output matching. The 3 dB cutoff frequency of the common-source design is 12 GHz and the cascode feedback amplifier achieves even 17 GHz. At mid-band the common-source and the cascode design achieve a moderate noise figure of 3 dB and 4 dB while maintaining an output power over the complete frequency range of 28dBm and 29dBm respectively

Investigation of processing modules to establish a mm-wave foundry process for space applications

GaN is a breakthrough material offering huge enhancements in power amplifier performance. Favourable material properties like a combination of a wide band gap, high breakdown field and operating voltage, high thermal conductivity, high temperature operation and inherent radiation hardness enable very high RF output powers at high frequencies up to at least 130 GHz. GaN devices find and will find applications in several space segments: earth observation, navigation, telecommunications, mobile communications and multimedia. It has to be expected that GaN devices will replace a fraction of the GaAs devices in the power amplification and SSPA market segment. With the publication of the 0.15 μm process by Triquint in 2013 the stage was set for the industrial development of GaN-devices for space application. In parallel strong programs have been carried out in the US. This paper presents activities in the frame of the ESAmmWGaNproject (ESA-Tender T123-401QT “Investigation and preliminary characterization of component building blocks needed to establish a European mm-wave GaN foundry process”) for Ka-Band up to V-Band operation

Industrial Application of Heterostructure Device Simulation,”

Abstract-We give an overview of the state-of-the-art of heterostructure RF-device simulation for industrial application based on III-V compound semiconductors. The work includes a detailed comparison of device simulators and current transport models to be used, and addresses critical modeling issues. Results from two-dimensional hydrodynamic simulations of heterojunction bipolar transistors (HBTs) and high electron mobility transistors (HEMTs) with MINIMOS-NT are presented in good agreement with measured data. The simulation examples are chosen to demonstrate technologically important issues which can be addressed and solved by device simulation

Enhancement of the broadband efficiency of a class-j power amplifier with varactor-based dynamic load modulation

A broadband Class-J power amplifier (PA) with dynamic load modulation (DLM) is presented. It is theoretically shown that a PA with judicious variation of the load resistance and a purely reactive load modulation can maintain 70% drain efficiency over 73% fractional bandwidth and 8.5 dB dynamic range. The theory is verified by a demonstrator PA based on a gallium nitride (GaN) device and a varactor as the tuneable element. The load modulation shows good results from 1.7 GHz to 2.3 GHz and up to 50% of power added efficiency (PAE) is obtained. It is shown that the average PAE for a modulated signal with 7 dB peak-to-average ratio is improved by 15%

Riemann-pump based RF-power DACs in GaN technology for 5G base stations

This paper introduces two realizations of a Riemann-Pump based digital transmitter geared towards software defined radio in 5G systems. In contrast to traditional digital-to-analog converter (DAC) concepts, the Riemann Pump exhibits a higher signal-to-noise ratio (SNR). Since the used 0.25 m gallium nitride (GaN) technology has a transit frequency of 30 GHz, an oversampling ratio (OSR) of five for the targeted frequency range from DC to 6 GHz is enabled. As the Riemann Pump serves as a digital driver, a co-integration with a suitable wide bandpower amplifier is possible to reach high power levels. A hybrid assembly is compared to the fully integrated Riemann Pump circuit in GaN technology. The world’s first measurement data of a two bit resolution Riemann Pump in GaN technology are discussed. Radio frequency (RF) power in the watt level range is measured for frequencies between 0.5 GHz - 12GHz into a capacitive load representing the input capacitance of a power amplifier