Page 48 - Chip Scale Review_January-February_2024-digital

Scaling up GaN- and InP-based technologies for 5G

and 6G wireless communication

By Nadine Collaert [imec]
Y ear after year, more and fraction of transmitted energy reaches power and efficiency at high operating

m o r e d a t a a r e b e i n g
transmitted wirelessly by the intended receiver. frequencies. GaN, for example, has
a high current density, high electron
The advent of higher frequencies,
an ever-growing group of users. To however, comes at a price. Today, mobility, and large breakdown voltage.
keep up with this trend and make data c o m p l e me n t a r y me t a l - o x i d e - The high power density also allows for
transfer faster and more efficiently, semiconductor (CMOS) is the preferred a small form factor and, therefore, a
the fifth generation (5G) of mobile technology for building the critical reduction in overall system size at the
communication is being rolled out, and component s of t r a n sm it te r s a nd same performance.
the industry is already looking at what receivers. These include the power
lies beyond. While 5G enables peak amplifiers within the front-end modules GaN and InP outclass CMOS at
data rates of 10Gbit/s, 6G is projected that send the radio frequency signals higher operating frequencies
to operate at 100Gbit/s from 2030 to and from the antennas. The higher In a modeling exercise, researchers
onwards. In addition to coping with the operating frequency, the more the at imec compared the performance
more data and connections, researchers CMOS-based power amplifiers struggle of three different power amplifier
a r e i nve s t ig a t i ng how t h e n e x t to deliver the required output power implementations at 140GHz operating
generation of wireless communication with sufficiently high efficiency. And frequency: a full CMOS implementation,
can support new use cases such as that’s where technologies such as GaN a CMOS be a m for me r w it h SiGe
autonomous driving and holographic and InP come into play. Because of heterojunction bipolar t ransistor
presence, among others. To enable their outstanding material properties, (HBT), and an InP HBT (Figure 1)
these exceedingly high data rates, the these III/V semiconductors are more [1]. InP was the clear winner in terms
telecom industry has been pushing up likely to provide the required output
the frequencies of wireless signals.
While 5G initially uses sub-6GHz
frequency bands, products targeting
28/39GHz are already showcased.
Additionally, there is a growing interest
in using FR3 (6-20GHz) frequency
bands for 5G networks because of
their ability to balance coverage and
capacity. For 6G, frequencies above
100GHz are being discussed.
Moving toward higher frequencies
has several advantages: new frequency
bands can be used—thereby solving the
spectrum scarcity issue within existing
bands. Also, the higher the operating
frequency, the easier it is to obtain
wider bandwidths. Frequencies above
100GHz and bandwidths up to 30GHz
allow telecom operators, in principle,
to use lower-order modulation schemes
within the wireless data links, which
reduces power consumption. Higher
frequencies are also associated with
smaller wavelengths (λ). As the antenna
2
array size scales with λ , antenna arrays
can be packed more densely. This
contributes to better beamforming, a
technique that ensures that a larger Figure 1: Comparing the power consumption of CMOS, SiGe, and InP devices in transmitter architectures as a
function of the number of antennas [1].
46 Chip Scale Review January • February • 2024 [ChipScaleReview.com]
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