Optimized low-power RF transceivers, a key differentiator in IoT applications

In any modern wireless communication device, the physical layer (PHY) is responsible for the information exchange over the air and as such requires to be designed with high quality constraints.

Its custom design represents a key differentiator in Internet of Things (IoT) applications where the trade-off between extended battery-life and high performance must be carefully optimized.

CSEM expertise and capabilities cover the whole radio transceiver IC design process from the system definition, architecture and requirements to the IC design and layout flow in most advanced technology nodes:

IC architecture
RF front-end design
Frequency synthesis
Analog design (including power management)
Digital design
Digital signal processing algorithms
IC Prototype characterization
Production test preparation

CSEM's integrated low-power RF transceiver design and IP solutions

Since 1998, CSEM has been an active and leading actor in the design of ultra-low power radio Intellectual Property (IP) blocks, with a proven capability to create strong partnerships with strategic players and collaborate fruitfully with leading industrial companies all over the world. CSEM has a proven record of (co-)development successfully answering customer requirements. Numerous ICs on the market integrate CSEM radio IP, examples include RSL10 by onsemi, EM9304 by EM Microelectronics, hearing aids by Oticon or a ranging solution from 3db Access (now Infineon Technologies Switzerland AG).

CSEM developments cover diverse radio standards, frequency bands and applications, such as, Bluetooth®, Ultra-Wide Band, RADAR, sub-GHz, positioning, and localization (e.g. GNSS, AoA, AoD).

icyTRX- best-in-class Bluetooth Low Energy transceiver

Bluetooth Low Energy and Dual-Mode Transceiver IPs

icyTRX and icyTRX-DM are CSEM’s flagship IPs that cover, respectively, Bluetooth Low Energy (LE) and dual mode by adding Bluetooth legacy modulation schemes (also known as Bluetooth Classic).

These two products are available in different technology nodes and foundries, in various metal stack flavors, and are compatible with multiple packaging options. Their compatibility with different hardware and/or software protocol stack implementations allows seamless integration in a complete system on chip. Their programmability and flexibility in icyTRX-DM, due to the software-defined radio (SDR) approach used, make it possible not only to run custom wireless communication protocols with higher throughput and data-rates, but also to address other communication standards (e.g., IEEE 802.15.4, basis for Matter and Thread standards).

CSEM is also very proactive in implementing the most advanced features released and announced by the Bluetooth SIG, with continuous updating of its product portfolio, e.g., Direction Finding, Channel Sounding, Wake-Up Receiver, High-Data Throughput, and higher RF frequency bands.

icyTRX block diagram

icyTRX: Bluetooth Low Energy

The icyTRX ultra-low-power RF transceiver is designed to meet standards such as Bluetooth Low Energy (Bluetooth Smart), 802.15.4 PHY Layer (e.g. ZigBee), and proprietary standards with data-rates from 62.5 kbit/s up to 4 Mbit/s. icyTRX offers 5.3 mW consumption in receive mode from a 1.0 V supply. icyTRX is a complete transceiver that is designed for miniaturization, yielding an analog/RF area of less than 1 mm² in 55 nm CMOS and, requiring minimal external components thanks to its high degree of integration. icyTRX is designed for easy integration into ASICs and Systems-on-Chips (SoCs) and can be used in applications such as wearable sensors, wireless sensor networks, smart watches, fitness bands and indoor positioning.

icyTRX-DM block diagram

icyTRX-DM: Bluetooth Dual Mode

The icyTRX-DM ultra-low-power RF transceiver IP is designed to meet 2.4 GHz standards like Bluetooth Classic (BR/EDR), Bluetooth Low Energy, 802.15.4 PHY Layer (e.g. ZigBee), and other proprietary standards. The icyTRX-DM IP offers best-in-class i.e. lowest power consumption together with state-of-the-art performances (sensitivity, interferers rejection) and atminimal cost. Thanks to its built-in LDOs, its fully programmable modem and its interface compatible with leading Bluetooth baseband controllers, the icyTRX-DM IP is optimized for easy integration into ASICs and SoCs. The average power consumption for stereo audio streaming is 1.1mW in Bluetooth EDR mode and only 0.6mW in Bluetooth Low Energy mode. The best-in-class sensitivity level is –98dBm in 1Mbps LE mode and –94dBm in 3Mbps EDR mode. The output power can be controlled in the range from –20 dBm to 10 dBm. IcyTRX-DM is designed for applications like hearing aids, true wireless stereo (TWS) earbuds & headsets, wearables, connected sports equipment, indoor positioning, asset tracking, beacons, wireless sensor networks and alarms, and security systems.

Die micrograph of 4-Transmitter and 4-Receiver MIMO Radar

60 GHz Radar on Chip

Numerous applications based on close-range RADAR are emerging: in-cabin monitoring systems, man-machine interfaces with gesture or posture recognition, vital-sign monitoring for healthcare, wellness or sleepiness detection, imaging, and various detections systems in different contexts, from home to urban environments.

Convenient RADAR-on-Chip solutions now exist on the market, embedding not only the RF part, but also the signal processing. They tend to be associated with automotive anti-collision market legacy, with long-range detection capability, which are associated with power consumption of several Watts. This level of power consumption is not compatible with portable or long-autonomy miniature sensors.

CSEM’s approach is to leverage its Ultra-Low-Power (ULP) expertise in design and integration of RF CMOS SoCs, to develop a Low-Cost Low-Power 60 GHz Multiple-Input-Multiple-Out (MIMO) Frequency Modulated Continuous Wave (FMCW) RADAR-on-Chip Front-End (MIMO FMCW RADAR).

This 2 mm² RADAR-on-Chip, integrated into GlobalFoundries® 22FDX FDSOI 22nm, includes:

57-66 GHz swept quadrature Digitally Controlled Oscillator,
Crystal oscillator and fully integrated All Digital Phase Locked Loop (ADPLL),
Scalable Local Oscillator (LO) distribution to facilitate addition of Transmitter & Receiver channels (Tx & Rx),
4-Transmitter with orthogonal Biphase Shift Keying (BPSK) modulations,
4-Receiver mixer-first with quadrature down-mixing,
Digital control including frequency modulation,
Tunable current and voltage references and distributed voltage regulators.

From 1T1R to 4T4R, power consumption goes from 40 to 100 mW, possibly reduced by duty-cycling the minimum 0.5 ms sweeps.

With integration of analog baseband and digital processing, external components will be limited to a quartz crystal, a pair of supply decoupling capacitors and 50 Ω single-ended antennas.

Module with 3dB Access UWB chip (integrating CSEM’s RF transceiver Front-End)

Ultra-Wideband (UWB) transceiver

Ultra-wideband technology uses a two-way time of flight to calculate distance between two devices. It combines unparalleled ranging precision with low power consumption and secure connectivity. As such, it has already been adopted in smartphones, allowing to localize different smart devices, and is slowly paving its way towards other real-time localization applications.

Together with CSEM, 3db Access AG (now Infineon Technologies Switzerland AG) has brought to market one of the first commercial UWB chips. It is currently in use in keyless car access systems. The implemented chip, whose RF transceiver front-end was completely designed by CSEM, operates in the 6-8 GHz range, provides record low-power consumption, requiring only 10 µJ per distance measurement, as well as accuracy better than 10 cm.

CSEM is now oriented towards the High-Rate Pulse (HRP) repetition frequency standard, aiming to develop a new transceiver to further push the performance. By leveraging our competencies in the low power IC design domain, we intend to provide a unique solution to the market that enables both widespread connectivity through compatibility with existing devices, and long autonomy for battery-powered applications.

Looking for ultra-low-power radio transceiver solutions?

CSEM is the partner of choice, given our excellent track record in providing ultra-low power radio, both as an IP for SoC integration or as part of an ASIC design. This path to excellence is the achievement of a highly skilled and passionate team which enjoys answering new technical challenges with effective solutions. CSEM is strongly motivated to create high-performance radio for differentiated and long-lasting products while meeting stringent marketing requirements on battery-life and performance trade-off.

To probe further

Explore further the literature published in selected Conferences and Journal Papers

N. Scolari, F. X. Pengg, K. Manetakis, C. A. Salazar, A. Vouilloz, E. Pérez Serna, A. Dissanayake, P. Persechini, V. Kopta, E. Le Roux, F. Chicco, S. Cillo, N. Gerber, C. Barbelenet, F. Epifano, P. A. Dal Fabbro, N. Raemy, “A 1 mm<sup>2</sup> Software-Defined Dual-Mode Bluetooth Transceiver with 10dBm Maximum TX Power and -98.2dBm Sensitivity 2.96mW RX Power at 1Mb/s”, 2024 IEEE International Solid-State Circuits Conference - (ISSCC), San Francisco, CA, USA, 2024. doi: 10.1109/ISSCC49657.2024.10454304.
S. C. Rengifo, F. Chicco, E. Le Roux, C. Enz, "An Ultralow Power Short-Range 60-GHz FMCW Radar in 22-nm FDSOI CMOS," in IEEE Transactions on Microwave Theory and Techniques, doi: 10.1109/TMTT.2023.3348035.
V. Kopta and C. C. Enz, "A 4-GHz Low-Power, Multi-User Approximate Zero-IF FM-UWB Transceiver for IoT," in IEEE Journal of Solid-State Circuits, vol. 54, no. 9, pp. 2462-2474, Sept. 2019, doi: 10.1109/JSSC.2019.2917837.
V. Kopta and C. Enz, "A 100kb/s, 4 GHz, 267 μW fully integrated low power FM-UWB transceiver with multiple channels," 2018 IEEE Custom Integrated Circuits Conference (CICC), San Diego, CA, USA, 2018, pp. 1-4, doi: 10.1109/CICC.2018.8357097.
V. Kopta, D. Barras and C. C. Enz, "An Approximate Zero IF FM-UWB Receiver for High Density Wireless Sensor Networks," in IEEE Transactions on Microwave Theory and Techniques, vol. 65, no. 2, pp. 374-385, Feb. 2017, doi: 10.1109/TMTT.2016.2645568.
E. Le Roux et al., "A 1V RF SoC with an 863-to-928MHz 400kb/s radio and a 32b Dual-MAC DSP core for Wireless Sensor and Body Networks," 2010 IEEE International Solid-State Circuits Conference - (ISSCC), San Francisco, CA, USA, 2010, pp. 464-465, doi: 10.1109/ISSCC.2010.5433848.
M. Contaldo, D. Ruffieux and C. Enz, "A 5.4dBm 42mW 2.4GHz CMOS BAW-based quasi-direct conversion transmitter," 2010 IEEE International Solid-State Circuits Conference - (ISSCC), San Francisco, CA, USA, 2010, pp. 498-499, doi: 10.1109/ISSCC.2010.5433865.