At the IEEE RFIC Symposium, Imec unveiled a CMOS-based beamforming transmitter for D-band wireless applications with exceptional output power, energy efficiency, and support for data rates up to 56Gb/s per channel. This is a key component of a 4-way beamforming transceiver chip being developed by Imec’s researchers to support the deployment of next-generation, short-range wireless services at frequencies above 100 GHz.
These chips will be a great deal of development for data centers in search of wireless fail-safe mechanisms, fixed wireless access (FWA) deployments, or wireless hotspots enabling extended reality (XR) experiences, as they are all converging on the sub-THz bands between 100 and 300GHz.
The ample bandwidth offered by these frequencies is just one of the essential features. In addition, their shorter wavelengths allow for smaller antennas, enabling increasingly compact access points and handheld devices. Finally, the high sensing resolution will prove invaluable in future applications (gaming, smart buildings, Industry 5.0, ...) where communication and sensing are intertwined.
“Yet, when CMOS technology ventures into the realm of 100GHz and beyond, it encounters various obstacles. The first challenge is to achieve sufficient output power to overcome the higher pathloss at these frequencies. It’s also much more difficult to realize wideband circuitry with good dynamic range and acceptable power consumption. These challenges are at the heart of our novel CMOS-based D-band beamforming transmitter,” explained Joris Van Driessche, program manager at Imec.
Imec’s transmitter, part of a 4-way beamforming transceiver architecture, operates in the 120-145GHz frequency range. Designed using a 22nm FD-SOI process, each transmitter channel occupies an area of 1.17x0.3mm² and consumes 232mW of power. And with a Pout of 3dBm for 16QAM modulation and 2dBm for 64QAM modulation, Imec’s implementation stands out as a top performer among CMOS D-band transceivers in terms of transmitted output power.
By incorporating beamforming in the local oscillator circuit to steer high-gain narrow beams in specific directions, along with a zero-IF transceiver architecture, Imec's transmitter reduces the number of components in the signal path. This preservation of the dynamic range, coupled with a wide RF bandwidth, ensures high data rates across a broad frequency range. Additionally, the design features a wideband analog baseband section covering channel bandwidths up to 14GHz.
Joris Van Driessche: “And yet another unique feature of our chip is its completeness. Unlike competing solutions, ours seamlessly integrates LO beamforming and a full analog baseband section across all four channels, along with the complete RF chain and beamforming functionality. To our knowledge, this is a significant first.”
The paper presented at the IEEE RFIC Symposium outlines the impressive results of Imec’s new beamforming transmitter. Further research has led to the development of a complete 4-way beamforming transceiver chip, currently undergoing further characterization. This chip aims to build a D-band wireless system, allowing experiment with beamforming technology, joint communication and sensing (JC&S) applications, and more. It demonstrates the viability of CMOS technology for next-generation, short-range wireless applications at frequencies above 100 GHz.
Imec’s Advanced RF program spearheads this research, aiming to enable next-generation, high-data-rate wireless and high-resolution sensing applications by addressing challenges from the device level to the system level. Click here to learn more about the program and to enquire about collaboration opportunities.
