 Hello, my name is Laurent. I am an application engineer and I am part of the ST Microelectronics RF Support Lab. During this video we will discuss about hardware and RF design when using our new STM32 WBA5 series. We will first look at documentation available to develop your own schematics and layouts. In a second step we will look at all material available to test your own PCBs, what are the main points to focus on. And finally we will discuss about certification as we know this is a very important topic when dealing with RF products. So I hope you will enjoy this video and let's start. So let's start by how designing your schematics and layout when using STM32 WBA5. A complete set of documentation is available on ST.com. The main entry documentation when starting as design will be the application node 5948. This application node will give you RF basis generalities, will provide a guideline selection for the components and will also provide you guidelines regarding layouts with a very useful layout checklist. Of course after reading this doc you will find on ST.com the different CAD resources depending the package you will have selected and you will find associated symbol or footprint directly on ST.com. Then multiple reference schematics and layout are or will be available on ST.com. This table shows you the difference reference design depending the part number you will have selected. On top of those reference design you will be able to order two evaluation kits for prototyping and evaluation. The first one is composed of the MB1A01, the Medzadin board, which plug on top the MB1A03 meaning the mini board composed of the STM32 WBA55 into a FN48 package. The second orderable kit is focusing on BLE audio. Now let's look at the main points to pay attention when starting your design. We will look at 32 MHz crystal requirements, then we will look at low-speed clock requirements if considering LSE with an external 32 kHz crystal or if using the internal LSI. We will look at RF design recommendation especially required RF matching and filtering. We will look at power management requirements with a focus on SMPS implementation if using STM32 WBA55. And finally we will look at key points regarding layout design. So first let's look at the HSE. HSE is a mandatory clock. It will come through a 32 MHz crystal or an external clock sources. Then about 32 MHz crystal selection. Please keep in mind the STM32 WBA includes internal programmable capacitance to trim the crystal frequency. But in order to do so, you should use a 8 picofarad load cap crystal. If so, no external load caps are needed and no HSE frequency trimming is needed in production. We will go through on the next slide. So 8 picofarad load cap crystal is the right value. We have provided here the recommended part we are using on our evaluation kit. You may choose, of course, an equivalent part number with a focus on this 8 picofarad load cap crystal. In terms of layouts, basically, we should try to set this crystal as close as possible from the STM32 WBA5X. Now let's talk about LSE or LSI selection. While in the previous case, a 32 MHz crystal is mandatory, for the low-speed clock it is optional. We can use either the LSE, so use an external 32 kHz crystal. Either we can use the LSI. The choice is basically a matter of cost versus power consumption. So if we need to get the best current consumption performances, we should use the LSE. We should try to use a crystal having low load cap crystal and low ESR, meaning equivalent series resistor. We will go in more details on the next slide, but having low load cap crystal and low ESR ensure we can use the lowest drive for STM32 WBA, meaning we can ensure the minimum current consumption performances. Here we do provide a recommended part number, which is the one we do use on our evaluation kit. And in terms of layout, if we use an LSE, we should again try to put this crystal as close as possible from the STM32 WBA and minimize the track lengths. In case we want to focus on bill of material and cost of our product versus the current consumption, we can decide to use the LSI. In that case, we will simply let the two dedicated pins open if we don't use them, or we can use them as standard GPIO. So LSE versus LSI is really a matter of bill of material versus current consumption. Let's now look at RF matching and filtering requirements. STM32 WBA is having an integrated balloon, so that's why you will find a single ended RF output pin. Very limited number of discrete components are needed to ensure the matching and filtering function. This matching and filtering function will allow to get the best takes power performances, the best sensitivity, and ensure a good harmonic rejection. Please note that we do propose a kind of plug-and-play solution with the IPD components called MLPFWB04D3. These components will allow to replace all those discrete components. On top of this STM32 WBA matching and filtering, you may have to add a few discrete to match the antenna, but we will go more in details in the next slide. We have discussed RF matching and filtering of the STM32 WBA 5x, but let's go more in details regarding the possibility to reduce the components count here. So the first picture on top left is the one we shown on the previous slides, means we do have few components for STM32 WBA matching and filtering, and we do have also few components for antenna matching. If you look at our reference design, here I am mentioning for example the MB1803 where we have set not an SMA but directly a printed antenna. You will notice that we have improved the components count. It means we have merged the function of matching and filtering of STM32 WBA and the antenna matching into a single matching here. So those components will act both to match and filter the STM32 WBA 5 and ensure a proper antenna matching. So of course this let's say optimization will improve the components count but is a bit more complex in term of tuning versus reusing our matching filtering recommended or using our IPD filter and separate the function of the antenna matching. We as ST are also working on a further improvement here and try to reduce again the components count in case we use reduced X power. So stay tuned, this may come very soon. After RF matching and filtering let's discuss now about power management. Again here the recommendation is to refer the dedicated hardware application node the 5948 and also to be as close as possible than our difference reference evaluation kit. So what we may mention here is that we will need few decoupling caps on each power supply pins as we can see here and you should simply replicate those decoupling caps on your own design. We have added here some optional coil for the VDDA pin that can eventually ensure a better noise rejection and ensure that your ADC will get the best behavior as possible. Let's now have a focus on the S MPS which is proposed on the STM32 WBA 55 version. So of course this S MPS will allow you to get the best current consumption with STM32 WBA 55. So the main components of the S MPS are the three components shown here. The S MPS is running 3 MHz on the STM32 WBA 55 and the main component is this 2.2 micro on record. Having a low equivalent series resistor for this coil will ensure the best efficiency of the S MPS. You should also dimension here to sustain some very short and high current peaks such as I would say 100 mA here. We will have then this 4.7 micro Farad decoupling capacitor and you may notice here this 10 nano hundred coil. This one is optional. This one allows to filter the S MPS period and achieve the best sensitivity. So in case you want to ensure the best RF sensitivity performances we do recommend this coil. If not this can be avoided. I have also mentioned on this slide some optional current filter here this one I mentioned already and those filters maybe added depending your schematics and layout. In any case the recommendation is to follow as usual our application note and our reference schematics and documentation. Still about this STM32 WBA 55 and S MPS one point very important here. You may see on our reference design those two options so that the S MPS can supply or not our VDD RFPA pin. So either this VDD RFPA pin will be supplied directly by S MPS or will be supplied by the VDD here. Please keep in mind that if you are willing to get the maximum output power so up to 10 dBm you must connect the VDD RFPA pin directly to VDD. If you can sustain a takes power up to 4 dBm then you can take benefits of the S MPS to supply directly this VDD RFPA pin. So pay attention to these specificities and properly connect VDD RFPA pin depending your targeted output power. Let's complete this first part about schematics and layouts with general layout recommendation. So again please refer to the application note and you can find full Gerber and Altium reference layouts on ST.com. Some key points I would like to highlight here. Our recommendation for all RF product is always to route your power supply lines in star configuration as shown here and each line will supply the different VDD pin of the WBA so that the decoupling will be more efficient. Of course let's try to put the decoupling cap as close as possible from the pads. Let's try to get solid ground plane and enough ground vias to ensure minimum current return pass. I mentioned already let's try to have the crystal as close as possible from the STM32 WBA and of course for the RF line let's ensure some 50 ohms transmission line and many tools are available to design 50 ohms Coplanar lines. Four layer stack up are recommended. You may consider some lower stack up of course especially for the lowest package. As ST support is available to help you in reviewing your schematics and Gerber so don't hesitate coming back to us so that we will review your schematics and your layout to ensure the best performances. Now after having discussed schematics and layout design let's imagine you have received now your PCB and here we will discuss what are our recommendations in regards of test and tuning your PCBs. Again we will have a focus on main below items. The first one will be about tuning of the HSE. The second will be about tuning of the LSE if used and also regarding the setting the drive of the oscillator and finally we will discuss about RF performances and RF matching optimization. Again please keep in mind ST support is available here to help you in bring up in RF pretesting or antenna matching. So let's discuss HSE tuning. Why do we need HSE tuning? We need HSE tuning to ensure all your product will respect regulation requirements. For example the Bluetooth requires all your products will be inside the plus minus 60 ppm limit. So if your HSE is not properly centered it may lead to some connection problems. So we need during the development phase of your product to tune your HSE and define the programmable capacitance value called HSE tune parameter and this value will be applied for all your production. Again no tuning in production you will define this value during the development phase. How doing it? We've got a dedicated application note the AN-5042 that will provide you multiple ways to calibrate the HSE clock for our entire STM32 wireless MCU portfolio. Now we will propose here what I think is the easiest and recommended method to really easily tune your HSE. We will see it in details. The idea is to flash the STM32 WBA with a dedicated firmware called the transparent firmware. This firmware and the associated project is available in STM32 cube package. We will also download a package called xcube clock trim on ST.com. You will see on the next slides. And finally we will also use a nice PC tool called Q monitor RF available on ST.com. Basic idea is that we will simply generate RF tone. We will check how centered it is and there will be a direct correlation between the RF tone centering and the HSE centering. We will simply then tune this parameter with the dedicated scripts. So let's do it. So the idea is as I said to flash your product having the STM32 WBA with the BLE transparent firmware. You will then be able to control your product with a cube monitor RF PC tool through USB to UART converter for example. You will output your RF on a spectrum analyzer to check if your RF is properly centered or not. Thanks to the script available in the xcube clock trim package we will be able to modify this HSE tune value. We will modify it till we are able to get a perfect centered tone. A script is also available to directly raise this value at the end in OTP. So let's do it practically. So let's do it practically here. In this setup I do have my STM32 WBA flashed with transparent firmware and I am able to connect my STM32 WBA with my cube monitor RF PC tool. So let's do it. Okay I am now connected to my board and I am able to generate a tone thanks to this RF test panel. As we can see on the spectrum analyzer we have this tone generated at 2.402 GHz but we can observe this tone is shifted by around 40 kHz. So the ID here will be to modify the HSE tune register to shift back the tone. So I will then open the dedicated script you can find in the xcube clock trim package. So this HSE tuning text file will be modified and for example I will apply the value 1A for the HSE tune register. I will go to the cube monitor RF panel and launch this script. I have just edited and launch it. Back now to the RF test panel I am able to send back the tone and I can confirm now my tone is effectively centered at 2.402 GHz with no shift so that the right value for HSE tune if using the crystal I am using is 1A. So after HSE let's now discuss LSE tuning. If LSE is used you must tune it and you must tune its frequency thanks to external load caps. So you saw those two caps here on each side of the crystal and you must also define the proper drive to ensure the oscillator will behave properly. What could be the impact? If the gain and the drive is not set properly you may have boot issues and if it is not properly centered if you get inaccuracy for LSE this is typically what could lead to disconnection issue after a while. So we must ensure to properly tune the frequency of the LSE and properly set its drive and gain. Regarding frequency centering of the LSE again there is a very good application not available on ST.com the 2867. Basically we will simply output the LSE frequency on some dedicated pins MCU or LSEO pins of the STM32WBA. Multiple software examples propose to demonstrate this capability and when you have output the LSE frequency you will be able to read it with a frequency meter and the idea is simply to adjust the right capacitor so that you will get a perfect 32.768 kHz frequency on those pins. So after you have done this during your development phase you will have defined the right capacitor values according to the crystal you have selected. But this is not over, you must do a second job during your development and when having your PCBs. Based on this you must also define the LSE gain needed. How doing it? You will simply define what is called a GM criteria so here is a formula to be used and you will use here the crystal parameters crystal equivalent series resistor, crystal C0 and crystal load caps. Thanks to this formula you will define then this GM criteria and depending on this GM criteria you will be able to define the proper gain. Let's imagine for example we use a crystal that will give us thanks to this formula a GM criteria of 0.75. If it is below 0.75 it means you are able to use the low drive capability and you will define in your software this low drive capability. Of course the lower is the drive the lower will be the current consumption of your overall product. So please ensure to properly center the LSE frequency and properly define the drive needed according to the crystal you have selected. Let's talk about now RF testing. Here the ID is and we discussed this previously to use two things available on ST.com. The first one is the STM cube monitor RF PC tool that will allow you to control directly the RF of the STM32WBA and set it in the right mode transmit or receive the right power the right channel in a very easy way. To do so you must also flash in your STM32WBA the dedicated firmware called the transparent mode firmware. When this is done you will be able to control your product set it in the right mode the right power the right frequency and thanks to a dedicated spectrum analyzer or other RF tool confirm and improve your RF matching and filtering. When all those tasks are completed and your product is fully tested and aligned with requirements it's time to move to certification. So let's discuss it. STM32WBA5 is a certified solution. It means it is compliant in regard of regional requirements. Red, European, CE, FCC for America etc. But also in regards of Bluetooth low energy requirements. So we do provide a complete set of documentation of firmware and tools to certify your product. The first thing and we will go through on the next slide is about the certification guideline. We have a dedicated wiki page where we do provide very useful information and very technical details and step by step how to to ease your understanding of certification requirement and ease your understanding of all the tools we do provide. So please have a look at this wiki webpage. Again our two main material we will consider for certification will be again the Q monitor RF PC tool and again this transparent mode that will allow this PC tool to control the STM32WBA5x. So in regards of Bluetooth certification STM32WBA5x is having some reference QDIDs for components and for stack. We are dealing here with a chipset so it means you are due to perform fee testing and declare your product at Bluetooth SIG organization. In short this graph explains it. Okay you must move at Bluetooth website and start qualification by entering your project name enter our QDIDs we will see this on the next part so you will use our QDID for the fee and for our stack and then here there are two paths. We are dealing here with an STM32WBA chipset so we must move through fee testing and at the end to declaration. Only in case of using a module a module meaning a full hardware integration not only a chipset but also the associated crystal and so on only in the case of module the fee testing can be skipped so that you save around 10k dollars and you can move directly to the declaration here. No software testing are required at SIG except if you are using adopted profile. If you are using your own proprietary profile no software testing are required. So here on this table we are for example mentioning the fee QDID of the STM32WBA 52 in QFN48 package so you will find here the reference fee QDID and for the stack you will find also a reference QDID as mentioned here. So again all this is described in a certification wiki page and let's have a look at it. Okay let's have a look at this dedicated wiki web page about certification so you will find it on st.com and you will see we will have two dedicated pages. The first one is really about the guideline while the second web page is really a step-by-step example when using the launch studio tool from Bluetooth SIG Alliance. Let's have a look at the guideline. Here you will find different chapters. First you will find what we discussed previously meaning what are the tools we do provide in regards of certification. It is again a matter of transparent mode firmware and cube monitor RFPC tool. Then you will find two different chapters. The first one is about the Bluetooth certification and the other part is about regional certification. So in Bluetooth certification you will get details about what is needed in terms of testing, how to do it, how to prepare your board, how to use launch studio process flow tool and you will find as well all the reference QDIDs of our different products. Okay you will find the fee QDID as well as the host stack QDID so you should simply go there to find the needed information in order to certify your product in regard of Bluetooth. Same concept for regional certification you will find many details in this wiki regarding what is needed, how to do it and what you should prepare in terms of hardware and software to go for regional certification in some dedicated labs. So please have a look, enjoy it and try to find all needed information on this wiki webpage. It is now the end of this presentation I hope this video has been useful for you and you get a better understanding of documentation tools we do provide for helping you in designing your PCB, in testing your PCB and in certifying your product. I also hope you get a better view about the key points to focus on when tuning your PCB. In any case RF support team in ST is available for helping you so please contact us and stay tuned. Thank you!