Low-cost sub-GHz long-range connectivity to drive IoT markets
Silicon Labs has released its FG23L sub-GHz SoC, the latest addition to the Series 2 portfolio, that will be generally available on September 30, 2025. It balances high performance with secure long-range connectivity at a fraction of the cost. By balancing essential performance with affordability, it opens sub-GHz IoT to broader markets and higher-volume applications.
Developers benefit from streamlined design tools, including Simplicity Studio 5 and the Radio Configurator, which accelerate development and reduce complexity across global sub-GHz bands. The EFR32FG23L wireless SoCs will be generally available on September 30, and supporting development kits are now available worldwide.
eeNews talks to Chad Steider, Senior Wireless Product Marketing Manager at Silicon Labs, about the innovations the FG23L brings to developers.
The FG23L SoC is ideal for simple sensor networks such as home automation, access control, and agriculture. Source: Silicon Labs
eeNews: What differentiates the FG 23L from other ICs in the series?
Over the last few years, the Series 2 portfolio has been focussed on adding features and addressing sub-GHz emerging markets. The FG25 was released in 2023, adding some high data rate PHYs. The F228, released in the fall of 2024, added AI/ML acceleration and some advanced peripherals. The FG23L goes the other direction. So as Silicon Labs has been focussed on new and emerging standards in sub-GHz, there’s still a need for simpler sub-GHz SoCs, to address the legacy proprietary market, which is where the FG23L comes into play.
eeNews: The propriety market still requires scalable processing and RF performance, especially due to the sheer number of devices being deployed. How does the FG23L balance these demands?
The FG23L balances, cost and performance. For example it is ideal for simple sensor and remote access fob applications. If you look at the parts that are addressing this market today, most of them take a different approach than what we implemented in the FG23L. A lot of these parts are based on cortex M3 and M0 type architectures, which limits processing performance. Silicon Labs stayed with the M33 family, which roughly delivers a 50% processor performance advantage over the parts that are currently addressing that space, all with much lower power consumption.
Secondly, there is no compromise on RF performance either. The parts that are addressing this space today are typically limited to +14dBm. The FG23L delivers over +20dBm with a link budget of around 146dB that achieves around one and a half to 2x range improvement over devices currently on offer today.
eeNews: What key market segment does this SoC address and what does it offer IoT developers?
The FG23L addresses the lower end of the IoT market, which is huge. Essentially, developers are having to make a trade off in designing for cost or for performance. The FG23L is a platform that allows developers to find that sweet spot, but also provides a migration path upstream. All developers are being asked to do more, whether it’s using AI/ML or adding more functionality, which requires tradeoffs. The FG23L has enough processing power to run some simple AI/ML at the edge and software. If you need to do more, you can migrate to the F228 family that offers AI/ML acceleration with more advanced features. However, your application code stays the same. So, developers don’t have to completely redesign the application, just pick up the application code and drop it on the new processor.
eeNews: When you look at all the sensors out there, a lot of these are simple use cases, but the number of devices deployed cna be in the millions. How do you address this?.
Being able to scale in these simple applications is really what’s going to drive the growth of IoT. The markets that the FG23L targets is often a wireless link that’s replacing wires — to be able to read a sensor or turn some LEDs on or off. However, parts that have been addressing this segment often lack processing power or RF performance to hit the performance/range sweet spot. The FG23L has 23 GPIOs and a 16-bit DAC to add sensors and can take advantage of the cycles available in the M33 core.
Everybody likes to think about sleep currents when we talk about low power devices, but active current has a large impact when waking up, reading sensors and processing the data. Compared to doing this with an M0 core, the M33 can wake up, act on the data faster, and then go back to sleep. This flattens out that average current that being used as the M33 is awake for less time, and processing for less time — offering some system architecture advantages over what what’s currently available.
Silicon Labs has a wide range of sub-GHz transceivers ranging from simple eight bit devices to transceiver plus type products. The FG23, released in 2021, added features and memory. The new FG23L bridges the gap between legacy transceivers and transceiver plus parts and SOCs.
Simple sensor networks such as home automation, access control, and agriculture can benefit from the IoT by having something that’s simple, low cost and easy to deploy — helping scale these markets. The FG23L delivers the low power performance that Silicon Labs is known for. Compared to other parts in this space today, the 36 microamps per MHz active current is on par with M0 and M3 parts, but with 50% processor improvement.
eeNews: How do you address security?
The FG23L features Secure Vault™ Mid security, which provides mid level security as the name suggests. However, there is a path for customers that need to migrate up the chain. If you deploy with the FG23L and then need to change the security scheme to, for example, CRA or Red or any of future standards, the FG23, which has a secure Vault High, or the FG25 or 28 platform can be used instead as the processor and security architecture across all of those parts is identical.
Silicon Labs has enabled platform migration for developers to start today, invest today, and then the investment becomes much smaller as needs evolve, because there’s so much reuse.
All Series 2 devices are built on basically the same platform, so you have the cortex M33 application core that hosts the stacks and application code, but then there are also two captive cortex M0 cores that provide commonality across the entire platform. One of those runs the radio subsystem and the other one runs the security subsystem. Developers can write application code once to interface with either of those subsystems, and then migrate through the platform. This applies to sub-GHz and 2.4 GHz parts. For example developers, could start with the FG23L and migrate to the BG22 or BG24L or even an MG26 for Matter support.
Source: Silicon Labs
eeNews: Which wireless protocols are you finding the most successful?
Silicon Labs has had a lot of success with Wirepas on FG23 in India in the metering space, recently crossing the 10 million units shipped with Wirepas and is expected to be north of 15 million before the end of the year.
Wi-SUN is also seeing a lot of potential with its history of the deployments in the EU and its growing use in the USA in the metering and smart city space, especially with the release of the FAN 1.1 specification. We are also seeing quite a bit of interest in the Mioty wireless LPWAN protocol as an alternative LoRaWAN. Mioty delivers the same or better point-to-point range while being much more robust in noisy environments and offering much better scaleability than what you see with LoRaWAN.
The FG23L creates an entry point for developers who are being asked to do more with less resources, either by adding more intelligence to the edge in these simple products while ensuring a migration path up the chain. Silcon Labs are also seeing a lot of customers being stretched thin on the software development and the R&D side. The biggest hesitancy to enter into sub-GHz is choosing the right protocol. The FG platform supports a broad array of protocols and enables developers to go from stack to stack, from protocol to protocol as the market evolves.
One of the use cases in the USA is interoperability between Amazon Sidewalk and Z-Wave. In the home space, a customer might have an existing Z-Wave network, so developers want to provide the customer with the ability to operate existing Z-Wave devices. If there is no Z-Wave network the SoC can fall back to Amazon Sidewalk. In another example there is a demand for using Bluetooth for local provisioning and sub-GHz for connectivity, which the FG28 supports. As long as the design supports the required frequencies and the hardware is capable, the stack can always be updated.
eeNews: The IoT is always associated with low power. Besides faster processing and shorter wake times are there any other techniques being used by the FG23L to minimise power consumption?
Yes, the peripheral reflex system (PRS) within our devices basically allows peripherals to autonomously interact while keeping the processor core asleep. So, especially in simple applications targeted by the FG23L, there is no need to wake up the processor core to go and read a sensor or for a push button interaction. Data can be transmitted off a push button press, and leave the processor core asleep. Sensors collect a lot of data. If the processor core has to be woken up every time for a sensor reading to compare it to threshold, for example, battery life is quickly compromised. There are also some low energy sensor interfaces for inductive sensing and capacitive sensing to improve power consumption
eeNews: Could you conceivably move to energy harvesting in some cases?
For energy harvesting we have E versions of the Silicon Labs XG22 platform. Depending on the wake up times required, the FG23L can be used in these applications. When you look at Bluetooth for energy harvesting, the wake up times have to be very quick and some parts need to be optimised for it. However, for something more proprietary without these protocol constraints, developers can leverage the low power and performance of the FG23L in energy harvesting applications.
Silicon Labs has a lot of demos done with partners on the energy harvesting space using the XG22E platform to maintain Bluetooth connections running off a solar panel, or using a button press to capture kinetic energy. Silicon Labs has invested pretty heavily in this space due to the problems associated with deploying large numbers of batteries.
eeNews: What was the rationale for driving up the range so far?
The FG23L range is one and a half to two times over parts that are in a similar application optimised bracket. The RF performance is the same as the FG23 family and similar to the FG28. Silicon Labs quotes a mile and a half range on almost all of our sub-GHz parts, which gives developers flexibility and more overhead. There are some caveats there with OFDM and when using the FG25.
Not many developers are actually broadcasting at +20dBm but the option is there. Having that headroom and the better sensitivity ensures that devices are performing as required in noisy or challenging environments.
eeNews: Which markets are you seeing the most traction for these sub-GHz?
For the FG 233L specifically, the most common use cases are in sensors, fobs and remotes. Expanding across sub-GHz we’re seeing a lot of traction in Smart City and Smart Agriculture and Smart Energy. The design cycles in sub-GHz tend to be longer than those for Bluetooth and Wi-FI and Matter, so adoption takes longer.
Sub-GHz offers many advantages, but the most important is range and the object penetration as many devices are deployed in challenging locations, such as in a basement, between buildings, or in a factory setting surrounded by metal. Putting 2.4 Hz devices in these environments shrinks range dramatically.
In the USA there is move towards standardisation. The big players that have deployed sub-GHz networks historically are adopting a more open approach, instead of the alley garden model. For example, CISCO offers OpenCSMP, an open-source project for managing large-scale, resource-constrained networks. In Europe, there are millions of Wi-Sun devices deployed and in India, WirePass is dominant.
However, whether a protocol is open or closed is not as important as it used to be, as the entire Series 2 platform provides the flexibility to use 2.4 GHz, sub-GHz, Matter, Wirepas, Wi-Sun and other protocols all within the same platform.
Chad Steider is a Senior Wireless Product Marketing Manager at Silicon Labs focused on proprietary, Sub-GHz, and MCU products. He holds a BS in Computer Science from the Rose-Hulman Institute of Technology.
Further reading
Taoglas addresses antenna design in miniature, multi-radio environments
Formal methods are the future of embedded software verification
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