RF Design-6: Smith Chart and Impedance Matching Fundamentals

[@yaoyucao9601]

Extremely good videoed, watched several times since the videos were published, now I have finished my PhD and still watching them to enhance my skills

[@BhargavaAnurag]

Glad to know that videos are helpful...👍

[@babaelectromagnetism07]

I was stuck with textbooks like radmanesh and pozar for almost 6 months this one video and watched it only one time and every thing is clear in one go...your videos are really helpfull

[@BhargavaAnurag]

Big words....thanks for the feedback and happy to know it was of help to you...🙏

[@PrantikDutta-r8r]

Extremely exhaustive and comprehensive explanations. Really wonderful!

[@BhargavaAnurag]

Glad you liked it!

[@wazieal-qadri5718]

very good explanation I want you to upload more vedio on designing the RF power amplifiers. thhanks for your efforts

[@FirasMAli]

Thank you so much for these interesting ADS tutorials.

[@BhargavaAnurag]

You're most welcome!

[@dbharathi2003]

Great vedio. Thank you so much. Clear voice

[@BhargavaAnurag]

Glad it was helpful!

[@krutomerfrog11]

fynally, i've found a great explanation of using Smith's chart for mathcing circuits. Thank You very much!

[@BhargavaAnurag]

Glad it was helpful!

[@ajithsrighakollapu3569]

its really a nice video and great information , thanks alot for this

[@BhargavaAnurag]

You are most welcome

[@praesche]

Very nice and helpful tutorial. Thanks a lot for sharing!

[@BhargavaAnurag]

Glad it was helpful!

[@namratamarigoudar7123]

Very good clear explanation given. This is one of the best vedio to understand matching network design. Sir I want you to upload more vedio on designing RF active circuits mainly oscillator and mixer.

[@BhargavaAnurag]

Sure I will

[@nasirullah3579]

Hi Anurag, very well explained. I have a query if I am designing a dual band matching circuit, should I need to design two circuit and combine them through a 50 ohm TL or how it`s possible to design a single circuit for both freq as we can put a single freq while doing matching through smith chart?

[@BhargavaAnurag]

You can design a single matching network that is dual band but this can't be done using Smith Chart tool as explained in the video. You will need to use traditional schematic and data display for the same.

[@sofiafenni7324]

Very helpful video, thanks a lot So grateful

[@BhargavaAnurag]

Glad it was helpful!

[@pangsuilingeh6134]

wonderful piece of work Anurag. How do I perform impedance matching with the load being a diode and source being 50 ohm. How do I know the impedance of the diode. A typical application is designing impedacne matching network for a rectenna.

[@BhargavaAnurag]

Process remains same. You need to find input impedance of the diode network, you can see video on S-Parameter simulation of Active Circuits to find how to find the input impedance of any device.

[@pangsuilingeh6134]

thanks a lot Anurag. I got it from the video of S-Parameter simulation of active circuits video

[@wasihaiderawan341]

@@pangsuilingeh6134 kindly mention the video link

[@murattsenn]

Thank you, sir. It was a very clean and understandable narrative. I was going to have a question. Should the line impedance we use when connecting Zs-Zl-coil-capacitors in PCB design be 50ohm?

[@BhargavaAnurag]

Ideally Yes if want to go by text book logic but in reality you can change it as per your own design requirements and its usually the case to reduce size of the line/layout section.

[@MrRijubratapal]

Extremely important topic. Thanks for explaining in detail.

[@BhargavaAnurag]

Glad it was helpful!

[@hamzaahmed2556]

its really great job I like your videos. keep it up

[@BhargavaAnurag]

Glad that you liked it...👍

[@SIAT2023]

thanks a lot for an excellent explanation , and helpful video could you please upload videos about matching but this time using short stub and double stub for all shape (as straight or radial, etc.) and when need for straight or radial ? and i need guide to understand deal with Smith chart in CST to extract length and distance for stub from source ,because the smith chart tools in CST not like in your software (ADS) what you Were used , if you have guide(as video) for clear explanation like all your videos (using CST ) please help me with it , thanks in advance

[@BhargavaAnurag]

My apologies but I don't have expertise or access to CST hence can't help here.

[@chrisflello5587]

Great video, thanks Anurag.

[@BhargavaAnurag]

My pleasure...Happy learning....👍

[@hariwi39]

clear and easy to understand, great explanation , thank you

[@BhargavaAnurag]

Glad it was helpful!

[@markustheil7119]

Great video. What literature did you use as a guide when you created the video? In the classic RF literature, such as Pozar, broadband matching is not discussed.

[@BhargavaAnurag]

Hi Markus, The details shared in the video doesn't come out from a single book but multiple references + working design experience of many years in RF/MW field.

[@mohammadkhalvati9599]

Awesome! Thank you so much.

[@BhargavaAnurag]

Glad it was helpful!

[@peymandehghanzadeh2884]

Hello I am new to ADS. Can you tell me how did You extract impedance from S11 in this video? Thank you!

[@BhargavaAnurag]

You can plot S11 on Smith Chart, place a marker, double click on Marker Readout/Text and from Format change the Zo from Normalized to 50Ohm and it will show you the impedance directly....👍

[@peymandehghanzadeh2884]

@@BhargavaAnurag Thank you very much Anurag. you are really an expert in ADS.

[@mkfhnt1]

Wow. Thank you Sir. For your efforts

[@BhargavaAnurag]

Most welcome

[@surendramanoharrakshit7255]

Very Good Explanation! Could you help me in finding the value of rf choke while doing transistor biasing? Plz if possible help me.

[@BhargavaAnurag]

Hi Surendra, I am not sure what frequency range you are working with but if it is @UHF or lower GHz range then you could look at the Inductor value that has SRF on your desired operating frequency so that it provides max possible rejection at your desired frequency to isolate DC and RF Frequency. Other key considerations are as below: 1. Make sure the DC current capability matches the required bias current. 2. Select a sufficiently high inductance value. (Z = 2 * pi * f * L) Select an impedance (Z) that is much larger than the load resistance. 3. Decide the maximum allowable DC resistance so that the voltage drop on the inductor is small compared to the voltage swing of the amplifier stage. A resistance of between 1 and 10 Ohms is usually OK. 4. Select a small package size. Look for a low Q inductor (High L and small physical size usually means Low Q). 5. Make sure the core material is useable in the frequency range of interest.

[@surendramanoharrakshit7255]

@@BhargavaAnurag thank you Sir, If I get your mail id then I will share you ckt. And details. Or send me test mail on [e-mail].

[@mohdzainal5303]

@@BhargavaAnurag This so helpful. Thank you

[@abrahamcraig7626]

Hi Anurag, Why would it be necessary to transform between series matching networks and parallel matching networks? Can you give examples that would require this transformation?

[@BhargavaAnurag]

Hi Abraham, I couldn't understand what do you mean by transform series & parallel networks? We are not transforming anything here as far as I remember, choice is between LowPass and HighPass topology and you do that when you have specific preference or depending upon which network gives you more reasonable component values.

[@abrahamcraig7626]

@@BhargavaAnurag Hi Anurag, I understand that you didn't cover this specific topic in your video. In the textbooks and courses that I have read and or attended pertaining to impedance matching, the topic of converting series resonant circuits to parallel resonant circuits and vice versa is always covered. However, reasons or examples that would require these transformations to be performed are never given. This material is usually presented in conjunction with impedance matching techniques. I just thought you might be able to provide some insight into why these transformations might be needed when performing impedance matching.

[@BhargavaAnurag]

Probably I am or we are missing some point here because I personally never used resonant circuits for matching, its always L & C connected in series or parallel and each component has its own trajectory and you use the combination based on the impedance transformation you require for your network. I would always recommend to keep things simple and it takes you to your destination....😊

[@chutichxomtb]

Thank you Sir. for your video. My design is in Complex Source to 50 Ohm Load case, but I don't know the Zsource, so How can calculate the Zsource? Thanks for your time.

[@BhargavaAnurag]

Hi, You could use SP_Probe component and insert it in your design's appropriate node and that probe will report S11 looking into left and right direction by which you could find corresponding impedance as explained in the video: kzbin.info/www/bejne/ZpPOg6yjdrR5qdk

[@hamidk4772]

Outstanding job 👍.

[@BhargavaAnurag]

Thank you! Cheers!

[@neo419]

Can you please make a tutorial on rectenna design?

[@evangelinepersis9169]

Thanks for the videos sir. Could you please tell how to build a matching circuit that operates at multiband frequency

[@BhargavaAnurag]

I would recommend you to look at relevant reference paper available to understand it better...

[@peymandehghanzadeh2884]

Hello Dear Anurag, I have a high Q coil which is 75+i1800. When I plug this value into Smith chart utility, it will be change to smaller value automatically. Can I ask how can fix that? Thank you for your time and help!

[@BhargavaAnurag]

Hi Peyman, You can work with your local Keysight tech support team to look into it but I would suggest to directly use a Termination in the schematic with that value and simply optimize the matching network...😊

[@mekaladevi1422]

HELLO SIR, Your lecture is really helpful for beginners. how to incorporate the matching circuit into hfss software

[@BhargavaAnurag]

I don't support HFSS, kindly contact Ansys tech support team for help

[@dmitry.shpakov]

Thank you!

[@BhargavaAnurag]

You're welcome!

[@rjrodrig]

I measured a BT antenna with a VNA, I tried following these steps, I perform the matching L match and when I measure again the antenna return loss measured does not match the simulation. I am not sure what I am doing wrong with the measurement vs. sim. I calibrate the VNA up to the SMA to U.FL connector Open short load. I have a flat response in the vna, but I can't match the antenna. what could I be doing wrong?

[@BhargavaAnurag]

Hi, Its difficult to see what are you are simulating and what are you measuring. As long as you have modeled all aspects you should get close matching e.g. EM analysis of your matching PCB, vendor component models for L & C etc You can consult your local tech support team for more help and they help you over live session.

[@daniyelyahunemerem7220]

Thank you very much, Sir. I am having a challenge matching a wideband antenna to my Greinacher voltage doubler circuit. I had tried using the smith chart and also bandpass filter, however, from the results I got, I am not doing a good work. Please, how best can I use to make my matching a reality?

[@BhargavaAnurag]

Its difficult to support queries like on YT. I would recommend you to contact your local/regional ADS tech support team.

[@daniyelyahunemerem7220]

@@BhargavaAnurag Alright. Thank you, Sir

[@yians12345]

I've shut down the component palette in the smith chart utility, any idea on how to get this back?

[@BhargavaAnurag]

You can right click in the empty area of the Smith Chart toolbar area (on the top of Chart UI) and activate Palette to get it back....😊

[@dungle-ck8xp]

May I ask what should we do if the impedance of the Load is outside of the Q circle. Thank you sir.

[@BhargavaAnurag]

Only thing you could do is to add a component to bring it inside Q-circle and then add components such that it doesn't go outside Q-circle.

[@alirezajafarieh226]

Thank you, sir. It was very understandable

[@BhargavaAnurag]

Glad to hear that

[@emmanuelmuganza3426]

thank you sir

[@BhargavaAnurag]

Most welcome

[@peimanparand]

awsome thanks so much

[@BhargavaAnurag]

You bet!

[@chenitimohamed4141]

Sir, I need to find the z output of RF circuit before doing matching, please tell me the methode to find out Z output of RF circuit before matching with 50 ohm of the antenna

[@BhargavaAnurag]

Hi, You can use SmZ2 component available under Simulation-S_Parameter library palette, place it on your schematic and run simulation. This component measures the output impedance of your circuit when you connect Termination2. There are other measurements also available that you can use to find respective impedance for matching.

[@chenitimohamed4141]

@@BhargavaAnurag thank you very much.

[@renne4200]

Thank sir. I think when the load is 5-5*j, the value of load in smith chart matching should be 5+5*j. Why we don't need to change to conjugate？（since when I finish the matching network and try to combine the circuit, the S11 is quite low）

[@renne4200]

Oh the impedance I choose is from source pull, did I change the impedance to conjugate when I do matching? thanks sir~~ :)

[@BhargavaAnurag]

As per the Smith Chart tool architecture, it expects you to only use complex conjugate for Zs and ZL is to be entered as it is so no confusions please...😊

[@yaoyucao9601]

This is a very good question, basically, whenever we match a load to a source, when matched, the impedance looking into the matching network from the source side is always the conjugate of the source impedance. This simply means that if we want to match a load to a source, we actually should move from the load impedance to the conjugate of the source impedance.

[@waqasahmedmir3319]

Sir can you solve this Design a two-element impedance match network on a Smith Chart so to match a 10 ohm source to a 50 ohm load at 60 MHz. The matching network must also act as low-pass filter between spurs and the load.

[@BhargavaAnurag]

It should be easy, simply use LPF topology ie. L in series and C in shunt while doing the design as I mentioned in the video.

[@waqasahmedmir3319]

@@BhargavaAnurag Sir i am new and I did not know how to solve please can you make a video for me i shall be very thankful to you

[@BhargavaAnurag]

@@waqasahmedmir3319 It's difficult for me to create a video for this. You need to look at Learn ADS in 5mins tutorial playlist to learn the basics of ADS and then simply do it yourself.

[@diegoram0499]

Trying to do a problem like this for my class, but I dont know what is going on and I get this error: (smithdg.ael line 11175, column 13) Parameter1 of fputs is NULL. Expected "file".

[@BhargavaAnurag]

Hi Diego, You might have corrupted your config folder. Kindly do following and see if this helps: 1. Close ADS 2. Go to your HOME folder (where ADS creates workspaces by default), rename "hpeesof" folder to something like "hpeesof_old" 3. Start ADS and try creating the design which you were trying earlier.

[@diegoram0499]

@@BhargavaAnurag I tried renaming the folder and still get the same error. Oh and on the Message List it says: WARNING: /home/linux/.../itemdef.ael AEL file not found

[@BhargavaAnurag]

@@diegoram0499 I would suggest you to contact ADS tech support for help.

[@wajidalikhan7933]

If you have used any dot(.) etc in your schematic name, remove that...

[@user-nt4nm4fb3u]

Sir! please put the full video about how to do load/source pull simulation for obtain the optimum source and load impedance of a RF power transistor for designing purpose of a power amplifier for wide band application.

[@BhargavaAnurag]

Will upload soon...👍

[@bhimireddybhavana6077]

@@BhargavaAnurag sir can you please upload a video of gallium nitride on silicon carbide FET in ads software

[@noahballou6350]

17:40 When I "push into hierarchy" I find nothing there. Also when I try to simulate, I get the error message "There is no corresponding terminal for `P1' in the netlisted view ". I feel like I have copied everything that you have done up to this point, why is it not working?? Thank you for your help.

[@BhargavaAnurag]

Hi Noah, If you don't see anything inside Smith Chart component subcircuit then it means you haven't yet created the schematic by clicking on the appropriate button from Smith Chart Utility and hence the error.

[@debabrata2137]

Sir, Can we simulate LNA for cryogenic temperature in ADS?

[@BhargavaAnurag]

Sure, as long as you have all the components that respect temp variations

[@naimulhasan4712]

THANK U SIR

[@utkarshkumar7476]

sir I have query in regarding impedance matching through cadence.

[@BhargavaAnurag]

Sorry, I don't have much idea on Cadence and you need to contact them to get required help.

[@pujapriya4671]

very nice

[@BhargavaAnurag]

Thanks

[@ltteogoali7251]

what is the name of the software you use to create your video?

[@BhargavaAnurag]

Hi, I use Camtasia from techsmith.com

[@shibasishprusty3148]

which software is this

[@BhargavaAnurag]

This is Keysight Advanced Design System (ADS) software.

[@UzairKhan-mu7pw]

Please provide your email sir

[@BhargavaAnurag]

Hi Uzair, You can post your queries here and I will try my best to answer them