Researchers at Tokyo Tech have designed a very small 28 GHz transceiver that integrates beamforming with dual-polarized multiple-input and multiple-output (MIMO) technology.

Measuring just 3 mm by 4 mm, this tiny transceiver could help improve performances of fifth-generation cellular network (5G) and Internet of Things (IoT) devices.

The proposed chip, fabricated in a standard 65-nanometer CMOS process, takes up a total area of just 12 mm2.

A team of researchers led by Kenichi Okada at Tokyo Tech's Department of Electrical and Electronic Engineering has devised a strategy with a clear eye on supporting high-speed mobile data access using the millimeter-wave spectrum for 5G.

Their proposed 28-GHz transceiver combines beamforming, a very efficient signal processing method, with dual-polarized MIMO capabilities, meaning that its array of antennas can respond to both horizontal and vertical radio waves at the same time.

Preliminary testing showed that the maximum data rate achieved was 15 gigabits per second (Gb/s) in the 64-QAM format. This data rate is 25 percent higher than that achieved by previous comparable models.

The researchers achieved a design that fits into an area measuring just 3 mm by 4 mm, which is around half the size achieved to date. The smaller the chip, the better for 5G, owing to the anticipated demand for high-performance, area-efficient transceivers for use in tiny and portable sensors and devices.

The transceiver consists of a total of four horizontal (H1–4) and four vertical (V1–4) array orientations.

"Compared with the conventional switch-based bi-directional approach, our bi-directional amplifier completely shares the inter-stage matching networks between the transceiver and the receiver. Thus, the required on-chip area is further minimized," Okada explains.

Japan is currently stepping up efforts to prepare for 5G ahead of the Tokyo 2020 Olympic and Paralympic Games.

Further details of the study are being presented as part of the 4G/5G Transceivers Session at the 2019 International Solid-State Circuits Conferenceouter (ISSCC) held in San Francisco from 17 to 21 February 2019.