Collaborative Research: High-frequency, High-power Amplifier Based on Distributed Coupling of GaN HEMTs Through a SiC Substrate-integrated Waveguide

Abstract Nontechnical

High-frequency, high-power sources are critical to exploiting the electromagnetic spectrum. The project may enable the next generation of millimeter-wave electronics with unprecedented bandwidth and power, while minimizing their size, weight, power consumption, cost, and failure rate. The methodologies developed to design, integrate, and fabricate high-power sources above 110 GHz, and to characterize these devices in terms of electromagnetic coupling, millimeter-wave performance, and thermal metrology can be used in the future to further improve the bandwidth and power of monolithically integrated power amplifiers to cover not only the entire millimeter-wave frequency range, but also terahertz frequencies that are not widely exploited.

The substrate-integrated waveguide (SIW) platform may enable other electronic components such as high-quality filters and antennas to be monolithically integrated on a single chip, which has been difficult with conventional integrated circuits. The project directly impacts Future of Work by facilitating ubiquitous wireless communications, smart man-machine interfaces, and Internet of Things (IoT).

It is estimated that wireless communications currently cover approximately 60% of the Earth surface, making Internet accessible to only about half of the world's population. 6G wireless communications enabled by millimeter-wave sources that are small, light, powerful, low cost, and reliable can extend the coverage to 100% of the Earth surface, making Internet accessible to everyone.

Technical

Based on an ultra-low-loss SiC SIW, a novel traveling-wave amplifier (TWA) is used to combine high-electron-mobility transistors (HEMTs) in a distributed manner for overcoming the power combining and impedance matching challenges of conventional monolithic millimeter-wave integrated circuits. Distributed and synchronous coupling between a quasi-transverse-electromagnetic wave on a grounded coplanar waveguide and a transverse-electric wave on an SIW is new, as is monolithic integration of SIW with transistors.

This approach takes advantage of high-quality GaN grown epitaxially on SiC to achieve high-frequency, high-power performance through monolithic integration. This monolithic integration allows unprecedented precision and field strength in a distributed geometry, which is impossible to realize with conventional split-block machined parts or hybrid integration on a printed circuit board.

This provides a path to high-frequency circuits with power and efficiency performance that is not otherwise attainable. As a proof-of-concept test vehicle, TWAs capable of 1-W output power at the D band (110-170 GHz) are designed, fabricated, and characterized. If successful, similar approaches can be used to generate higher powers at higher frequencies, or be implemented in other semiconductor technologies.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.