No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
A Comparison of AlGaN/GaN HFETs on Si Substrates in Ceramic Air Cavity and Plastic Overmold Packages
Abstract
AlGaN/GaN HFETs on Si substrates have been assembled in ceramic air cavity and plastic overmold packages. Thermal, DC, small and large signal RF and reliability characterization have been performed on both types of devices. Thermal characterization shows that the thermal resistance of the plastic overmolded parts is higher resulting in higher operating temperatures. The higher operating temperature causes parameters such as the peak CW power to be lower than that seen in the ceramic air cavity package. The advantage of the plastic packaging resides in its >10x lower package assembly cost.
... It is very important to note that Cu gate AlGaN/GaN HEMTs are thermally instable. Because the channel temperature of AlGaN/GaN HEMTs can exceed 3008C under normal operation [14], such thermal instability will cause severe problems in practical applications. This should be carefully taken into account when utilising Cu-gate AlGaN/ GaN HEMTs. ...
Thermal reliability of nickel (Ni) and copper (Cu) gate AlGaN/GaN high electron mobility transistors (HEMTs) is investigated. Though the current-voltage characteristics of as-deposited Cu gate AlGaN/GaN HEMTs is superior to those of Ni gate AlGaN/GaN HEMTs, severe degradation was observed after aging at 220°C. This instability problem should be carefully taken into account in practical applications of Cu gate AlGaN/GaN HEMTs.
A high density packaged integrated circuit (IC) was found to be permanently abnormal due to its bonding wire short when the spacecraft equipment in which it was used was subjected to a mechanical shock. The IC is packaged in CPGA391 with an outline size of 47mm×47mm and has up to 492 internal bonding wires. Through the experiments, we found that the bonding wire short was caused by the collision between the two adjacent bonding wires when the IC was subjected to mechanical vibration. As the internal layout of the IC package cavity could not be further adjusted due to its functional requirements, a vacuum coating process was proposed for the bonding wire. The Parylene-N thin film was deposited on the surface of the bonding wire to form an insulating layer. It can improve the mechanical strength of the bonding wire and change the natural frequency of the bonding wire, which then makes the vibration amplitude of the bonding wire not too large and does not cause collision of adjacent bonding wires. Some tests were carried out to verify the method and the results show that it solves the problem of the bonding wire short under the condition of mechanical vibrations.
Wide-band power amplifiers (PAs) are considered the most expensive and critical component for RF and microwave applications. New power systems, including those for radars, transmitters, electronic warfare (EW) jammers, and electromagnetic compatibility (EMC) testers, require the latest, state-of-the-art semiconductor technologies for power, linearity, and bandwidth [1], [2]. In addition, wide bandwidth is essential for high-speed communication and high resolution in radar, imagers, and sensors [2], [3]. In modern electronic vehicles, complexity is rapidly increasing and imposing strict EMC regulations, which often require very high 1-dB compression point (P1dB) power [to kilowatt, continuous wave (CW)] across an ultrawide bandwidth (decade) with high linearity, good reliability, and long life [4], [5].
A plastic packaged GaN HEMT is presented for 3.5-GHz-band LTE small-cell base-station applications. A pair of GaN HEMT dies and MIM capacitors is assembled in the package for Doherty amplifier use. Optimized drain bonding wire length enhances high efficiency operation. The input prematching with the MIM capacitors suppresses insertion loss and improves power gain. Measurements of a single-chain amplifier using the GaN HEMT show a high drain efficiency of 66.3% and a high power gain of 16.2 dB at 3.5 GHz, regardless of plastic packaging. A Doherty amplifier demonstration with the GaN HEMT shows a drain efficiency as high as 51.2% and an output power of 36.0 dBm at ACLR of −50 dBc. This is the first demonstration of a plastic packaged GaN HEMT Doherty amplifier in the 3.5-GHz band.
Al<sub>0.26</sub>Ga<sub>0.74</sub>N-GaN heterojunction field-effect transistors were grown by metal-organic chemical vapor deposition on high-resistivity 100-mm Si (111) substrates. Van der Pauw sheet resistance of the two-dimensional electron gas was 300 Ω/square with a standard deviation of 10 Ω/square. Maximum drain current density of ∼1 A/mm was achieved with a three-terminal breakdown voltage of ∼200 V. The cutoff frequency and maximum frequency of oscillation were 18 and 31 GHz, respectively, for 0.7-μm gate-length devices. When biased at 50 V, a 2.14-GHz continuous wave power density of 12 W/mm was achieved with associated large-signal gain of 15.3 dB and a power-added efficiency of 52.7%. This is the highest power density ever reported from a GaN-based device grown on a silicon substrate, and is competitive with the best results obtained from conventional device designs on any substrate.
High performance and low cost LDMOS for 3G base stations
- Z Xie
- A Shibib
- Deskoj
- P Gammel
- I C Kizilyalli