RF Transceivers for Wireless Connectivity in 5G and IoT Devices

The internet of things (IoT) is only enabled by interconnectivity between devices using wireless communication technology as a medium of connecting people, objects, locations, and even animals to the internet. A major advantage of using IoT devices is direct transmission and continuous sharing of digital data. Likewise, it has a substantial impact on different sectors such as traffic, health, weather, and environmental monitoring.

When it comes to internet connectivity, there are some devices that quickly come to mind; our smartphones, personal computers, tablets, desktops, and others. They’ve been built with the capability to connect to the internet, and by so doing, exchange data and information. But there are other smart devices that were not originally intended to have interconnectivity. RF components provide wireless connectivity to these devices and allows them to communicate and work remotely just like computers and smartphones.

Frequency and Protocol

The frequency and wireless communication protocol will determine the relevant components required in any IoT device. These two factors work hand-in-hand to provide wireless communication within a certain frequency band. Any wireless device requires a wireless transceiver chip in order to operate and function as intended. Many IoT devices communicate via Wifi, ZigBee, Bluetooth, or some other protocol in the GHz frequency range.

Some transceivers can be digitally reconfigured to support different protocols as needed within a single device. With upcoming 5G-enabled devices, transceivers must be complemented with an antenna tuning switch in order to provide beamforming for directional transmission. Amplifiers and filters are other RF components that are crucial in a variety of devices, including IoT devices. Power amplifiers and weak-signal amplifiers are primarily used in IoT devices. Weak-signal amplifiers are used on the receiver side of a wireless transceiver, while power amplifiers find their home in the transmit side of a transceiver.

It Starts With Your Transceiver

Your transceiver will form the cornerstone of your IoT device’s wireless communication capabilities. What used to be separated into transmitters, receivers, and other supporting components, an integrated transceiver IC provides signal conditioning, modulation, and transmit/receive functions in a single package. Here are some excellent options for wireless transceivers that operate in various frequency bands:

Semtech, SX1211I084TRT

This SX1211I084TRT transceiver from Semtech is a lower frequency transceiver that operates in the 863-870, 902-928, or 950-960 MHz bands with FSK or OOK modulation. The data rate for this transceiver only reaches 25 kbps with FSK or 2 Kbps with OOK, so its use is limited to applications that involve lower throughput. A great example is periodic data transmission from a small wireless sensor array. However, the highly integrated nature of this package helps reduce overall component count, making it ideal for use in wearables that communicate at lower RF frequencies:

The SX1211...highly integrated architecture allows for minimum external component count whilst maintaining design flexibility. All major RF communication parameters are programmable and most of them may be dynamically set. It complies with European (ETSI EN 300-220 V2.1.1) and North American (FCC part 15.247 and 15.249) regulatory standards.

Typical application circuit, from the SX1211 datasheet

Infineon, BGT24MTR12

For upcoming 5G applications, the BGT24MTR12 transceiver from Infineon is an excellent choice for wireless communication in the 24 to 24.25 GHz frequency range. The RF input terminals are single-ended, meaning some care will need to be taken to provide EMI suppression at the PCB level. This device is flexible enough to interface with a variety of MCUs through SPI communication, and the device has reasonable power consumption of 690 mW in continuous operating mode with 11 dBm maximum output power. Finally, this device includes a temperature sensor and power detector as part of an overall power regulation scheme:

Monitoring of the chip temperature is provided by the on-chip temperature sensor which delivers temperature proportional voltage...For RF power indication, peak voltage detectors are connected to the output of the TX power amplifier and to the LO medium power amplifier.

Top and bottom images of the BGT24MTR12 RF transceiver from Infineon

Maxim Integrated, MAX2829ETN+

The MAX2829ETN+ RF transceiver from Maxim Integrated provides single or dual-band wireless communication via 802.11a/g world-bands from 2.4 to 2.5 GHz, and from 4.9 to 5.875 GHz in a surface mount package. This transceiver is ideal for IoT devices that operate over Wifi and Bluetooth. On-chip filters provide signal conditioning with good noise rejection at a variety of baseband frequencies, and the maximum data rate depends on the modulation scheme used to transmit data:

Each IC completely eliminates the need for external SAW filters by implementing on-chip monolithic filters for both the receiver and transmitter. The baseband filtering and the Rx/Tx signal paths are optimized to meet the 802.11a/g IEEE standards and cover the full range of the required data rates (6, 9, 12, 18, 24, 36, 48, and 54Mbps for OFDM; 1, 2, 5.5, and 11Mbps for CCK/DSSS)

Example 5 GHz application circuit with the MAX2829ETN+ RF transceiver, found in the datasheet from Maxim Integrated

Ever since IoT devices came into the limelight some years back, they have continued to evolve. The latest protocols and technologies have helped these devices become more accessible, energy-efficient, cost-effective, and secure. New products with wireless connectivity are expanding beyond consumer electronics; expect further applications in manufacturing, as well as in connected autonomous vehicles and 5G-enabled devices in the years ahead.

Using the right combination of embedded processing and accurate sensors can ensure accurate data acquisition while supporting graphics display on a touch screen. The devices we’ve presented here are only a portion of the sensing options available for use in wearable devices and sensor networks. In the realm of wearable sensors, many ICs that can interface with a touch screen and multiple sensors are packaged on evaluation boards, giving you some level of freedom to prototype your next wearable product.

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