Compact High-Output Millimeter-Wave Transceiver Module

In addition, because the occurrence of signal loss tends to increase in internal module terminal connector components at higher frequencies, reaching millimeter-wave operations has proved to be challenging.

The new high-output millimeter-wave transceiver module developed by Fujitsu Laboratories uses a heat sink embedded with multilayer ceramic technology capable of efficiently dissipating heat. Through its unique architecture that reduces signal loss occurring in internal terminal connector components, the transceiver module can achieve millimeter-wave operations. With dimensions of 12 mm × 36 mm × 3.3 mm, the new module measures less than 1/20 the size of conventional combined unit.

Using the new technology, it is possible to combine multiple chips within a single unit, thereby enabling the development of more compact radar devices and wireless communications equipment.

Details of the new technology will be presented at the IEEE MTT 2013 International Microwave Symposium, in Seattle, Washington.

GaN HEMT

Gallium nitride is used as a material in blue LEDs. Compared to the conventional semiconductor materials of silicon and gallium arsenide, GaN features a high electron transfer rate and relative resistance to the breakdown caused by voltage. Given these characteristics, GaN HEMTs—or transistors that use GaN—show promise for high-output, exceptionally efficient operations.

Background

In line with the advancement of a network-based society, radio wave demand in a variety of wireless systems is expected to increase even further. For example, in the field of smartphones and other wireless communications, there is a shortage of available frequencies. Using millimeter waves to accommodate　this increase in demand is being given consideration. Likewise, aircraft currently employ the 10 GHz frequency band, but a move toward usage of higher frequencies is expected to take place in the future.

Current generations of high-output millimeter-wave transceiver modules consist of separately packaged transmitter and receiver components. Being able to integrate both functions in a single unit, however, will enable equipment to become more compact.

Technical Issues

Transceiver modules, needed for millimeter-wave communications and radar, must possess wideband capabilities for operating in the millimeter-wave band, as well as high-output performance sufficient enough to cover wide geographic areas. When developing a transceiver module with 10 W-class high-output power, it is critical to improve the transceiver module's heat dissipation characteristics, as heat generation intensifies in tandem with higher output levels.

Moreover, it is also necessary to reduce signal loss in connector components. This is because, at higher frequencies, loss increases in the components connecting the chip and the wiring that transmits a signal.

Newly Developed Technology

Fujitsu Laboratories has developed a compact, high-output transceiver module that uses GaN-HEMT and operates in the millimeter-wave band. The key features of the technology are as follows:

1. Improved heat dissipation with a new heat sink structure
Fujitsu Laboratories developed an embedded heat sink structure that efficiently dissipates the heat generated at high output levels. The heat sink is built into the transceiver module's multilayer ceramic substrate. Compared to previous designs, heat dissipation improved by a factor of five times, enabling 10 W-class output levels.

2. Lower signal losses in the signal input/output connector components
Fujitsu Laboratories devised a wideband connector structure that reduces loss at higher frequencies in the heat sink. With the new connector structure, high frequency signals passing through the module can be transmitted at up to 40 GHz, two times the frequency levels of previous designs.

Using the newly developed technology, it was possible to shrink the size of the millimeter-wave transceiver module to 12 mm × 36 mm × 3.3 mm, measuring less than 1/20 the size of previous combined unit configurations.


Figure 1: Diagram of the millimeter-wave GaN transceiver module


Figure 2: Photo and structure of the millimeter-wave GaN transceiver module

Results

This new technology will make it possible to achieve high-output transceiver functionality with a single unit, thereby leading to improved performance and more compact and lighter equipment for wideband communications and radar systems.

Future Developments

Fujitsu Laboratories plans to put this technology to use in a wide range of applications that require compact modules with high output across wide bandwidths, including wireless devices and radar systems.