Official Blog of Silicon Labs

      • Webinar: Enhance Home and Building Automation with Multiprotocol Wireless Connectivity

        LeighPankonien | 12/354/2017 | 05:15 PM

        Title: Webinar: Enhance Home and Building Automation with Multiprotocol Wireless Connectivity

        Date: February 7 & 8, 2018

        Duration: 1 hour

        Speaker: Øyvind Borgan, Strategic Marketing Manager at Silicon Labs

        Smart lighting has experienced notable success in home and building automation thanks to a wide selection of application-specific wireless protocols. During this webinar, we’ll discuss the wireless technologies that best serve smart lighting, homes, and buildings and consider the benefits of enabling simultaneous operation of Zigbee and Bluetooth low energy (LE) on a single device. We’ll also review key considerations related to multiprotocol implementation and outline advanced functionality that can be achieved such as beaconing and smartphone direct control of smart lamps and connected luminaires.

        Join our hour-long webinar and get your questions answered by our experts during our Live Q&A session at the end.

        Register Now

      • Timing 101: The Case of the PLL’s VCO High Pass Transfer Function

        Lance Looper | 12/353/2017 | 12:04 PM

        Welcome to another edition of the Timing 101 blog from Silicon Labs' Kevin Smith.

        We have been doing some internal training recently and a common question that comes up is how and why a Phase Locked Loop (PLL) treats phase noise differently depending on whether it comes from the input clock or the VCO (Voltage Controlled Oscillator). Most everyone understands that input clock phase noise is jitter attenuated, i.e. the PLL acts like a low pass filter to input phase noise. However, it is not as readily apparent why a PLL should act like a high pass filter to VCO phase noise. This is the Case of the PLL’s VCO High Pass Transfer Function and the subject of this month’s post.

        First, I will review the basic feedback loop and its transfer function. Next, I will generalize the process for signals injected at different locations around the loop. I will then generate and compare the transfer functions for a PLL both from the input clock and the VCO perspective. Finally, I’ll wrap up by offering some intuition and discussing the application considerations.

        Feedback Review

        Consider the basic feedback diagram in the figure below where the variables and blocks are functions of the Laplace complex frequency variable ‘s’. The intermediate variable S representing  error should be considered likewise. The forward gain is G(s) and the feedback gain H(s). I(s) and O(s) are the input and output signals respectively.

        The closed loop transfer function TF for O(s)/I(s) is derived as follows.

        Now what happens if we break up the forward path gain G(s) in to two separate blocks, G1(s) and G2(s) and inject a new signal X(s) as illustrated below? X(s) is additive as with noise.


        By linearity, the transfer function TF for O(s)/x(s) is derived as follows where I(s) is set to 0.

        It turns out we can generalize for any X(s) injection point anywhere around the feedback loop as follows. The term “Loop Gain” refers to the multiplication of all the gain elements going around the closed loop. In this particular example, the Loop Gain = G1(s)*G2(s)*H(s).

        We can now apply these developments to the basic PLL.


        Input Clock Phase Noise Transfer Function

        Consider the basic linear “small signal” PLL diagram below.


        Going clockwise around the loop, the components in the diagram are as follows.

        • Kp represents the gain of the phase detector, usually a PFD (Phase Frequency Detector).
        • F(s) is the low pass filter as a function of complex frequency ‘s’.
        • Kv is the gain of the VCO and the 1/s term represents the integration action of the VCO. That is, the Laplace transform of the integral of Kv*phase is Kv/s.
        • 1/N is the gain of the feedback divider.

        We can now generate the TF for Theta_o(s)/ Theta_i(s) almost by inspection by noting that the forward gain is KpF(s)Kv/s and the loop gain is [KpF(s)Kv/s]/N.

        For reasons of stability F(s) is always a low pass filter so its value is either constant in value or rolls off with increasing frequency. In either case the overall closed loop behavior for the PLL is itself a low pass filter.

        This PLL transfer function is covered in many textbooks and articles but a more detailed and recent discussion on this topic is contained in the article “Phase Locked Loop Noise Transfer Functions” by Peter Delos published in High Frequency Electronics, January, 2016.


        VCO Phase Noise Transfer Function

        Now consider the basic PLL diagram modified below to also inject VCO phase noise via variable Theta_v(s).

         We can generate the TF for Theta_o(s)/ Theta_v(s) by noting that the forward gain from the VCO phase noise injection point is simply unity and the loop gain is [KpF(s)Kv/s]/N as before.

        Again, F(s) is a low pass filter so it is either constant in value or rolls off. Unlike the transfer function for the input clock, the numerator here has a zero at the origin. In this case the overall closed loop behavior for the PLL is now a high pass filter.

        Some Intuition

        OK, I know some of you may be saying, I get the math but I don’t really, intuitively, understand why the PLL acts as a high pass filter to VCO phase noise. Let me offer some food for thought that may provide some intuition.

        Consider the expected difference in behavior for a phase step at Theta_i versus Theta_v:

        • We know that a phase step at Theta_i is not immediately output at Theta_o. Rather, it will take some time, depending on the loop bandwidth, for the PLL to respond and properly step the output phase to track the change in the input clock’s phase. This is analogous to a voltage step applied to a low pass filter.
        • By contrast, a phase step at the output due to Theta_v must be immediately output at Theta_o. There is nothing to prevent this.  The loop then has to put things right in order to correctly track the input clock again. Depending on the loop bandwidth, it will take time for the output clock to lose the excess phase. This behavior is analogous to a voltage step applied to a high pass filter.

        Application Considerations

        The 2 dominant sources of phase noise in a PLL are typically the input clock and the VCO. As we have seen, the PLL treats each source's noise differently, i.e. as a low pass and a high pass filter respectively.

        The application consequences are as follows:

        1. If an input clock has relatively low phase noise versus the VCO, one typically uses a relatively wide bandwidth (BW) PLL in order to attenuate the VCO's phase noise. In this context, a wide bandwidth typically means something on the order of 100s of kHz to MHz. This is how clock generators or clock multipliers are designed. (Note that BW cannot be arbitrarily large for reasons related to stability and the need to suppress phase detector spurs.)

        2. On the other hand, if an input clock has relatively high phase noise versus the VCO, one typically uses a relatively narrow bandwidth PLL in order to attenuate the input clock's phase noise. In this context, a narrow bandwidth means something on the order of kHz or less, usually much less. This is how jitter attenuators are designed.

        Understanding this tradeoff and the ability to adjust the bandwidth "knob" is a key to troubleshooting PLLs and optimizing their application.



        This month I’ve reviewed how a PLL's VCO phase noise transfer function arises and its unique high pass behavior. I’ve also offered some intuition and discussed the application considerations.

        I hope you have enjoyed this Timing 101 article. It’s the last post for 2017. Happy Holidays and

        Happy New Year to all of you!

        As always, if you have topic suggestions, or there are questions you would like answered, appropriate for this blog, please send them to with the words Timing 101 in the subject line. I will give them consideration and see if I can fit them in. Thanks for reading.

        Keep calm and clock on.




      • A Letter to our Customers and Partners

        Lance Looper | 12/341/2017 | 05:30 PM

        Silicon Labs Announces Definitive Agreement to Acquire Z-Wave

        Silicon Labs has entered into a definitive agreement to acquire Sigma Designs and its Z-Wave business and technology. Silicon Labs and the Z-Wave team have a shared vision of a secure, interoperable connected home. Adding Z-Wave to Silicon Labs’ wireless technologies enhances our ability to give you choice of connectivity protocols for your application needs. Silicon Labs intends to work in collaboration with the Z-Wave Alliance to drive the road map and adoption of Z-Wave technology.

        Z-Wave is a popular, mesh networking technology for home automation and security, supplying some of the world’s largest ecosystems of smart home IoT products. There are more than 2,100 certified, interoperable Z-Wave devices available from a thriving alliance of more than 600 manufacturers. Z-Wave will extend our portfolio for wireless connectivity, which features Zigbee®, Thread, Bluetooth®, and proprietary protocols today.

        As a valued customer, we want to thank you for putting your trust in us to deliver quality products for the IoT. The acquisition of Z-Wave will further our mission of providing outstanding, secure and interoperable connectivity solutions for the connected home and beyond.  For more information, please refer to today’s release


        Forward-Looking Statements

        This announcement contains forward-looking statements (including within the meaning of Section 21E of the United States Securities Exchange Act of 1934, as amended, and Section 27A of the United States Securities Act of 1933, as amended) concerning Silicon Labs (“Silicon Labs”) and its proposed acquisition (the “Acquisition”) of Sigma Designs (“Sigma Designs”) or the Z-Wave business and related matters. These statements include, but are not limited to, statements that address Silicon Labs’ expected future business and financial performance and statements about (i) the timing, completion and expected benefits of the Acquisition, (ii) plans, objectives and intentions with respect to future operations and products, (iii) competitive position and opportunities, (iv) the impact of the Acquisition on the market for Silicon Labs products, (vi) the impact of the Acquisition on non-GAAP EPS, (vi) other information relating to the Acquisition and (vii) other statements identified by words such as “will”, “expect”, “intends”, “believe”, “anticipate”, “estimate”, “should”, “intend”, “plan”, “potential”, “predict” “project”, “aim”, and similar words, phrases or expressions. These forward-looking statements are based on current expectations and beliefs of the management of Silicon Labs and Sigma Designs, as well as assumptions made by, and information currently available to, such management, current market trends and market conditions and involve risks and uncertainties, many of which are outside the companies’ and management’s control, and which may cause actual results to differ materially from those contained in forward-looking statements. Accordingly, you should not place undue reliance on such statements.

        Particular uncertainties that could materially affect future results include any risks associated with the Acquisition such as: (1) the risk that the conditions to the closing of the transaction are not satisfied, including the risk that required approvals from the stockholders of Sigma Designs for the transactions or regulatory approvals are not obtained; (2) litigation relating to the transaction; (3) uncertainties as to the timing of the consummation of the transaction and the ability of each party to consummate the transaction; (4) risks that the proposed transaction disrupts the current plans and operations of Sigma Designs and Silicon Labs; (5) the ability of Sigma Designs and Silicon Labs to retain and hire key personnel; (6) competitive responses to the proposed transaction; (7) unexpected costs, charges or expenses resulting from the transaction; (8) potential adverse reactions or changes to business relationships resulting from the announcement or completion of the transaction; (9) the ability to divest or wind down Sigma Designs’ Smart TV business; (10) the ability to divest Sigma Designs’ Media Connectivity business; (11) Sigma Designs’ ability to amend or terminate certain contracts; (12) Sigma Designs’ ability to maintain sufficient cash to satisfy the minimum cash condition; (13) Silicon Labs’ ability to achieve the growth prospects and synergies expected from the transaction, as well as delays, challenges and expenses associated with integrating Sigma Designs into Silicon Labs’ existing businesses and the indebtedness planned to be incurred in connection with the transaction; and (14) legislative, regulatory and economic developments.

        The foregoing review of important factors that could cause actual events to differ from expectations should not be construed as exhaustive and should be read in conjunction with Silicon Labs’ and Sigma Designs’ filings with the Securities and Exchange Commission (“SEC”), which you may obtain for free at the SEC’s website at, and which discuss additional important risk factors that may affect their respective businesses, results of operations and financial conditions. Silicon Labs and Sigma Designs undertake no intent or obligation to publicly update or revise any of these forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.

        Additional Information and Where to Find It

        Sigma Designs intends to file the applicable proxy statement(s) in connection with the Acquisition. Investors and security holders of Sigma Designs are urged to read such proxy statement(s) (including any amendments or supplements thereto) and any other relevant documents in connection with the Acquisition that Sigma Designs will file with the SEC upon such documents becoming available because they will contain important information about Sigma Designs and the Acquisition. Such materials filed by Sigma Designs with the SEC may be obtained free of charge at the SEC’s website ( or at the Investor Relations page on Sigma Designs’ website at or by writing to Sigma Designs’ Secretary at 47467 Fremont Blvd. Fremont, CA 94538 USA.

        Sigma Designs and its directors and executive officers may be deemed to be participants in the solicitation of proxies from Sigma Designs’ stockholders with respect to the Acquisition. Additional information about Sigma Designs’ directors and executive officers is set forth in Sigma Designs’ proxy statement on Schedule 14A filed with the SEC on July 17, 2017 and Annual Report on Forms 10-K and 10-K/A for the fiscal year ended January 28, 2017. Information regarding their direct or indirect interests in the Acquisition will be set forth in the proxy statement and other materials to be filed with SEC.




      • IoT Hero Snooz Moves Air to Lull People to Sleep

        Lance Looper | 12/339/2017 | 10:27 AM

        Silicon Labs recently had the chance to talk with sleep-enthusiast Eli Lazar, co-founder of Snooz, a start-up company that created a white noise sleep machine that strives to turn people’s bedrooms into a sleep haven. A Kickstarter and angel-funded innovation that has only been on the market since April, Eli gave us a behind the scenes glimpse of how the product came about and how he and his partner successfully brought the Snooz machine to market.

        How did you come up with the idea?

        I used a fan to sleep in college and would pack a fan in my suitcase when I traveled to ensure I got a good night’s rest. When I was in college studying mechanical engineering, I started noticing that just about everybody I knew would sleep with a fan pointed at the wall, because they wanted the sound, without the cold air blowing on them. Later on, I also found a study from the University of Michigan that showed about half of their student population used sound to help them sleep. Fans are made to drive a lot of air and do it quietly, but we realized people were trying to use them in the opposite way and extract the noise from them and have no air. So we thought maybe we should make a special fan for sleeping. We found one other company that had made a white noise machine – a real fan, but it started in 1960 and the design hadn’t changed much since. I know there are apps and electronics on the market that mimicked the sound of moving air, but they weren’t real fans.

        So how did you go about to make that happen?

        The first thing we did was a lot of tinkering – experiential engineering. How do you make a “shh” sound?  I didn’t know. There are no books on that. So I literally ordered 10 CPU desktop computer fans. I ordered a box of CD spindles. We just started playing around with stuff. We ended up buying a cheap 3D printer and printed out a bunch of different designs. We eventually got to the point where people actually wanted to sleep with it, which took a full year of experimenting.

        Then we started the painful process of fundraising. We did a Kickstarter campaign to test the market and raised a half million dollars in 49 days. We also attended angel pitch events and eventually got to an investor who had his own VC firm. He told us we were too small for the firm, but I gave him a fan prototype and his wife ended up loving it. He still told us we were still not well-suited for his firm, but he wrote us a personal check.

        The next phase was production. Probably the hardest thing to figure out was the fabric, which seems like it would be the easiest thing. But there are only a niche group of people that understand fabric, and when you have a metal surface, it becomes an even smaller group.

        Eventually we got to a place where we produced the first batch of 10,000 units and we shipped 7,000 on Kickstarter and the rest sold on Amazon or our website. We’re still very much trying to figure out how to bring costs down and those sorts of things. We don’t take a salary - we haven’t taken one penny since we started.

        What was the most surprising thing that you have learned so far?

        Everything moves slowly, it’s really true. Nobody is in a hurry except you. You go to an investor, and months will go by before you hear from them. Even now, we’ll produce something, and it’ll be 20 weeks before we see the product. It has taught me a lot about patience. But the most surprising thing is you kind of lay out how people are going to see the product, but then it’s totally different. For example, you might write out instructions for the device, but people will interpret what you say a lot differently. The other thing I learned is you have to have a thick skin. I mean, you put a lot of time into the product and you end up being very close to it, and people can be brutal. The vast majority of our reviews are very positive, but you do get some people that pick one little thing on the product they don’t like, such as the power cord, something little, and those things can really tear into you if you let it. I never thought I’d be as sensitive to customer feedback as I am.

        Do you have any favorite stories from users?

        We get quite a few emails from people that would really blow you away. People will say they’ve had bad nightmares their entire life, but since using Snooz, they sleep perfectly. We get a lot of people telling us they haven’t been able to sleep for long periods of time or they had to take medication to sleep and now they sleep fine.

        Sleep is everything to people, if you can’t have it, you’re messed up.

        Yes, and I think it’s an issue getting more attention. Last year at CES was the first time the conference included an entire section of devices devoted to sleep.

        What were some of your design challenges with this product?

        We had pretty tight constraints for what we wanted. We brought prototypes to the design firm and laid out our guidelines. They came up with 8 or 9 designs and we were really drawn to the fabric design because it allows sound to go through it unobstructed. We liked the idea of combining fabric and electronics.

        Our original vision was the device would be a beautiful product that sits in your room and you don’t interact with it – you don’t even have to touch it. That’s why we decided to use the Bluetooth chip from Silicon Labs because it gave us the ability to program its schedule or turn on remotely.

        The fabric was a real challenge. They make the fabric wraps automated, but there’s still some manual work to sew the seams. We did a lot to make sure the fabric isn’t toxic, as well.

        Creating the right packaging was another challenge. One thing a design professional asked us right when we were starting was, “Why do people buy products?” And we said for functionality. And he said, “No, no, people don’t buy products for function – they buy them for the emotional connection.” So just having the right package feel, the look to the box – was important to us.

        What product did you use from Silicon Labs?

        Initially, we used the BLE113, but then we switched recently to the new BGM113. I was already familiar with Silicon Labs, but the decision stemmed from our connection with a design firm in Chicago. The firm highly recommended Silicon Labs products and they had a lot of experience with your company and said the technology always pretty much works – it’s really rock solid. They explained that you can always find other dirt cheap chips out there, but you’re going to have all kinds of issues.

        Where do you see IoT going in the next 5-8 years?

        We have definitely encountered two crowds that we sell to. One group loves the app, loves the Bluetooth and loves everything connected. But then the other group is like, I don’t want any of that – I want it old-school simple. We keep trying to figure out the right balance, where we make things connected but not so connected that they become a nuisance to people. My impression is it’s probably going to be a fight about what things should be connected and what shouldn’t be.

        One of the things about Kickstarter is we had 6,000 backers – it’s like having 6,000 bosses. People were telling us to add this and add that, but we didn’t want it to be this super connected device. I don’t think the bedroom should have a ton of connected devices – it should be a place where it’s free of that. I hope IoT’s pace doesn’t go so fast that people try to connect everything, because then people will learn to hate it. But it can be useful if it goes at the right pace, because with some things it just makes sense.

        I don’t like when things get too complicated. I’d rather the whole company flop and stick to the vision that we are going to do what’s right for people, not the company. Because I know if we start adding all kinds of new features, the product might sell more, but I don’t think people will sleep better because of it and it’ll cause them more frustration. My partner and I really just want to do what will help people sleep better. 




      • IoT Gift Guide: For Those Beyond the Early-Adopter

        Lance Looper | 12/335/2017 | 05:08 PM

        2017 was a big year for the Internet of Things (IoT), with more and more devices bringing new levels of usefulness thanks to the power of connectivity. With the holidays quickly approaching, it’s time to start shopping for the perfect gifts for your loved ones. This year you can find more IoT gifts for just about everyone on your list, from teens to grandma. Gifting connected devices can make people’s lives more efficient, safe, healthy and fun. Instead of sticking to people’s wish lists, give them something they can’t live without, but they don’t even know it yet.

        We’ve taken the guess work out of holiday shopping by curating our favorite Silicon Labs-powered products we have featured over the past year in our IoT Hero blog. Below are some popular giftable IoT devices, ranging from smart lighting to high-fashion wearables to personal transportation.


        Electric Skateboard

        For those in your family seeking alternative transportation options, look no further than the Inboard M1Electric Skateboard. Powered by a Silicon Labs BLE113 Bluetooth module in both the board and the remote control, the M1 skateboard keeps rider’s feet on the board while mapping streets, detecting road conditions, and keeping the rider in perpetual motion. 

        The Inboard M1 blends sharp industrial design and functional wireless technology. 


        Beautifying Decor

        After creating the most energy-efficient lightbulb on the market, Nanoleaf started merging art with light and ended up creating unprecedented lighting systems for the home. Powered by Zigbee SoCs and a communications stack from Silicon Labs, Nanoleaf Aurora lighting systems allow people to customize their lights entirely based on their color, mood and timing preferences. The system was largely inspired by the idea of recreating natural light, so people could experience the same warm, soothing qualities indoors as well—especially during winter when there’s less sunlight hours.

        The Aurora lighting system from Nanoleaf offers smart, customizable lighting.


        The Pulse integrates speakers and lighting.

        Another one of our customers, Sengled, has taken lighting to a new dimension by adding a multi-channel music speaker within an actual lightbulb. The Pulse lighting system is a synchronous multi-channel speaker light and the world's first one that can play with a mobile phone. Pulse, powered by a Silicon Labs Zigbee solution, can support up to eight lights simultaneously while playing music and can adjust each light to the sound and volume for each speaker, making it the perfect gift for people in your life looking for gadgets to enhance the home entertainment experience.


        Ice Fishing Gear

        Granted, ice fishing is a highly regional sport, but for those anglers in your life living near ice, how about a device that allows them to stay warm indoors while they wait to get a fish on the line? Deep Freeze Fishing sells Blue Tipz fishing alerts that provide an alert system for fishing lines, freeing the angler to monitor catches from afar. The product uses the Bluegiga BLE121LR Bluetooth module from Silicon Labs to transmit a fish strike from the flag on the line to the phone of the fisher, giving them the freedom to stay indoors while they fish.


        Safety Accessories

        It’s easy to find friends and family among your loved ones who A) like jewelry, and/or B) wouldn’t mind an extra safety net if they run into danger. Two Silicon Labs customers, Wisewear and Revolar, have tapped into the safety wearables trend after creating modern connected IoT jewelry to keep people safe.

        Wisewear built a wellness wearable product in the form of an exquisite gold or silver bracelet or ring, serving as a panic button, fitness tracker and notification device. The founder of Wisewear created the jewelry solution after his grandfather fell down the stairs at home and no one was there to help him. Wisewear is one the first jewelry products on the market to integrate sensors and electronics with metal jewelry, tapping the Silicon Labs Wonder Gecko 32-bit MCU to make the fusion of fashion and technology successful.

        Wisewear brings the benefits of connectivity to superbly designed jewelry.


        Another safety device worth considering for loved ones is Revolar’s Instant Personal Safety device, which hooks onto your clothing, key chain, handbag, etc. and connects to your phone via Bluetooth. If the carrier ever feels threatened or in danger, all the user has to do is press an indiscreet button to send one of three alert levels to their pre-selected loved ones, including a “hey, I’m home or I’m safe” alert, a yellow alert for uncomfortable situations, and a third alert for serious emergencies. 

        Revolar's personal safety devices keep users safe simply, and discreetly.


        Enjoy the holiday season, and happy shopping!