Gallium Nitride Power Devices Research Articles

Transmit/Receive (T/R) Modules – Key Elements for Phased Array Antennas

Modern Active Electronically Steered Antennas (AESA) are operating in different platforms and systems. Inside EADS/CASSIDIAN the focus on X-Band antennas today is in airborne and fighter nose radars, in satellite based SAR antennas (Synthetic Aperture Radar) for earth observation and ground surveillance and security radars. Active antennas are assembled with hundreds or even thousands of T/R modules. This paper will describe an example of a so called standardized module solution based on LTCC package technology. State-of-the-art modules are assembled with active components like MMICs realized in GaAs technology, e.g. Low Noise Amplifier (LNA) and High Power Amplifier (HPA), Silicon based devices and passives. Assembly technologies are optimized for high yield series production inside CASSIDIAN MicroWave Factory. New semiconductor technologies, like GaN (Gallium Nitride) are enablers for a new T/R module generation. GaN/SiC based MMICs with higher power density compared with GaAs based devices are technological challenges for innovative thermal management solutions and assembly alternatives. GaN power devices are soldered on modern heatsink materials with high thermal conductivity and matched CTE (between MMIC and heatsink). Results of thermal simulations comparing different heatsink materials in combination with soldering techniques will be discussed and an optimized solution will be shown. Another type of T/R Module technology based on RF-PCB and packaged MMICs will be discussed. Future applications of ground-based security radars, active antenna products with a one-dimensional array and needs for cost-effective solutions seem to be SMD-based products. Different packages, e.g. QFN (Quad Flat Pack no Lead) and ceramic based (HTCC), mainly for power devices will be shown and compared.

Voltage Switching Limits of Lateral GaN Power Devices

The dv/dt switching limitations of power semiconductor devices are evaluated in a boost (PFC) power converter using circuit simulations. State-of-the-art commercial silicon CoolMOS devices, commercial Silicon Carbide (SiC) Junction Barrier Schottky (JBS) diodes, and emerging Gallium Nitride (GaN) lateral power transistors are considered. It is shown that although SiC and GaN power devices have low stored charge and small capacitances, they experience high switching dv/dt stresses which may pose serious switching limitations especially in high-frequency power converters. This problem is likely to be further exacerbated by the presence of a high density of crystal defects in SiC and GaN materials which will manifest in the form of poor field-reliability. Specific guidelines for device selection are recommended in order to optimize both performance and field-reliability.

Transmit/Receive (T/R) Modules—Key Elements for Phased Array Antennas

Modern active electronically steered antennas (AESA) operate in different platforms and systems. Inside EADS/CASSIDIAN, the focus on X-band antennas today is on airborne and fighter nose radars, in satellite based SAR antennas (synthetic aperture radar) for earth observation, and ground surveillance and security radars. Active antennas are assembled with hundreds or even thousands of transmit/receive modules. This paper will describe an example of a so-called standardized module solution based on LTCC package technology. State-of-the-art modules are assembled with active components such as MMICs realized in GaAs technology, for example, the low noise amplifier (LNA) and the high power amplifier (HPA), silicon based devices, and passives. Assembly technologies are optimized for high yield series production inside CASSIDIAN MicroWave Factory. New semiconductor technologies, such as GaN (gallium nitride) are enablers for a new transmit/receive module generation. GaN/SiC based MMICs with higher power density compared with GaAs-based devices are technological challenges for innovative thermal management solutions and assembly alternatives. GaN power devices are soldered on modern heat sink materials with high thermal conductivity and matched CTE (between the MMIC and the heat sink). The results of thermal simulations comparing different heat sink materials in combination with soldering techniques will be discussed and an optimized solution will be shown. Another type of transmit/receive module technology based on RF-PCB and packaged MMICs will be discussed. Future applications of ground-based security radars, active antenna products with a one-dimensional array, and the need for cost-effective solutions seem to be a good fit for SMD-based products. Different packages, for example, QFN (quad flat pack no lead) and ceramic based (HTCC), mainly for power devices will be shown and compared.