#223

[@kedmark]

Gilbert, Early and Widlar all should have received Nobel prizes. Great video, tyvm for posting.

[@absurdengineering]

Gilbert was a genius. There are several books out there not written by Gilbert where every 10th citation is to a paper of Gilbert. To understand how the Gilbert multiplier cell can be generalized, there’s an excellent book by Evert Seevinck: Analysis and Synthesis of Translinear Integrated Circuits. That’s one of those “10% Gilbert citations” books. Gilbert cell is a basic example of a translinear loop formed by the BE junctions of all 4 transistors.

[@garygrove6643]

Thank you for posting the operation of the "Gilbert Cell" ! Very helpful indeed. 73's / Gary Grove

[@redefined4657]

This channel is a gift to every freshman scratching their head after looking at a semi-complex circuit. And it helps all the way into the final year. I wish I could like and subscribe twice. It baffles me that you're still out here liking comments and explaining little doubts.

[@w2aew]

It’s always nice to hear that my videos are helping people.

[@BM-jy6cb]

Such an incredible teacher. Up there with AppliedScience as the best in KZbin.

[@w2aew]

Wow - that is quite a complement! Thank you!

[@shabbarvejlani]

Thank You for the simplified explanation. Never did much practicals for analog circuits in college. But this practical approach really helps.

[@mab7727]

Bless you man. 8 years ago, yet still so good!

[@keesnuyt8365]

Excellent tutorial, again I learned a lot. What I like especially is that you only repeat key items, because they matter, not because you didn't remember you mentioned them earlier in the video. In other words: no time wasted. Concise. Clear. I wish I could hand out 2 thumbs up ;)

[@nekidzemaili7372]

Thank you for the excellent explanation of the Gilbert cell (and diff pair video aswell). For my wireless class in university I got assigned to build a RF receiver for receiving SSB signals with the help of the NE602. This video has helped me to understand the inner workings of the IC!!!

[@CretaZigman]

I designed a gilbert cell over the summer to learn a little more about mixers and diff pairs, and I am so impressed at how well you described the concepts here! Building up that entire circuit must have been a pain in the fingers, but it is so very much appreciated. Great work!

[@krzysztofwaleska]

Best ever explanation how it works. You have explained to me and I understood. Next: how to build frequency shifter using it and which transistor needs to be similar in characreristics (Ube, Hfe and thermically)? I always wanted to do design thermically stable freq. shifter using discrete transistors.

[@anishjoshi8302]

This is amazing. I always get more intuition and inspiration when I open your channel. Thanks a lot, Alan!

[@anandparalkar]

Without your video, I would have definitely run away from a circuit with so many diff pairs! Great video (once again). May God give you the strength to continue the good work (and benefit people like me ;) ).

[@mrsc1914]

I can't thank you enough for taking the time to do all this ! You have certainly inspired me to share knowledge and help others.

[@kevinobrien8803]

This is great. I been trying to learn how to build a multiplier for an analogue computer. (trying to emulate all the math operations) but got totally stuck trying to understand the working of the Gilbert cell. So this has helped me so much. Bizzare how out of all the operations the multiplier is the hardest to understand. And yet all the others no problem. Many thanks, I read a ton of papers on this and none of them explained it simply like this.

[@rfburns5601]

Your circuit analysis videos are fantastic! Merry Christmas and Happy New Year!

[@w2aew]

+RF Burns Thank you! Merry Christmas and Happy New Year to you too!

[@charlesvoudvill6125]

I have spent months researching into electronics and discovered an awesome resource at Gregs Electro Blog (google it if you are interested)

[@johnwest7993]

Thanks for the clear and simple explanation of the differential pair and the Gilbert Cell. I'm a self-taught tech, and when I first read about the differential pair at a young age I found myself in awe of its simple elegance, the same simple elegance I found when I first learned of LC resonance. It was so amazing that I found myself wanting to run and explain it to my mother and everyone I knew, as if I were some 12 year-old electronics evangelist. The Gilbert Cell expands on that simple elegance, and I find myself wanting to describe it too, to others. I'm pleased to see you doing just that. Thanks.

[@wisehomo]

Very nice explanation thanks very much! I didn't need to read a book to understand it and I love videos showing in practice how circuits perform.

[@ydonl]

This is such an excellent explanation of such a very clever circuit! Mm, mm, mm. Makes me think "wow," every time I rewatch it.

[@stevekim6923]

Your lecture is incredible! I wish you put more time on phase difference.

[@duhbe]

A good example of how complicated things can be explained in a simple way! Thanks a lot!

[@yoramstein]

It is not so complicated two diff amplifiers in parallel.

[@aduedc]

Thank you. You have great way of explaining things. You make things intuitive. I talked with Barrie Gilbert in 2002 ISSCC conference, read many papers about this topology and I have designed mixer chip with this cell, which is in use in many cell phones up to this day. Even I learned new things from this lecture and saw it from different view point. This lecture inspired me to see other Gilbert Cells potential applications. You pointing out Vout= K.V1.V2 is great way of looking at this cell. Thanks again.

[@cuevasarcie1408]

Clear, brief and coherent explanation, I commend your hard work on sharing this video sir!

[@danialmoghaddam8698]

As always , fluent and clear crystal. Most appreciated

[@eternaldoorman5228]

Beautiful explanation and demonstration!

[@ShirazushSalekin]

Pure Gold ❤

[@cooperchaopingzhang5882]

Very useful. Thank you for your video!

[@SatyajitRoy2048]

Really a great explanation and you made the understanding of such thing in proper way. Please keep up the good work that helps a lot. A big thumbs up.

[@MrRObot-bin]

Thank you Sr. it really helped me a lot! I love RF circuits!

[@ancelb9590]

Pleased to see & understand this; didn' t have to pause at all once I reviewed the long tail pair as advised b4! Useful to me as i am just getting into RF and understanding its mysteries. Have my first VNA arriving soon, an 8753D and hope to start building basic Rx and TX, so modulating and AGC wil be key. Mixer IF outputs as well for frequency shifting!

[@im99er85]

The movie of yours is very interesting for me, I'm from Japan and I wanna watch more movies of yours on other famous analog circuits in chronological order. Thank you.

[@m1geo]

Really enjoyed this one, Alan! I'm gonna have a play with one on the bench here!

[@ccsphsc]

I'm working on an automated jig to stress test audio amplifiers and will be using the circuit to measure the delivered power to the speakers. Your content is helping a lot. TKS, from PP5IXD 73

[@lesleypaulvj_TVPM]

This is interesting, the basis of all active RF mixers. Still learning a lot from this video.

[@theovannieuwenhuizen5756]

Again Kudos, very clear explanation of a not so easy topic. Inspiring to go and build / experiment with Gilbert Cell circuits.

[@jansebele1481]

thank you so much for this video

[@stefflus08]

Fantastic. They say "If you are bad at something, teach it", and I think that is too often true. You however are an extraordinary teacher. I'm glad you have a Paypal, but I'm sure you could build more engagement to the channel with a Patreon if you wanted to.

[@w2aew]

Thank you Stephan, and thank you for your PayPal donation. I have considered Patreon, but the main reason that I haven't gone that route is because I feel like I would be "obligated" to produce content on a more regular basis, which is difficult for me to do.

[@stefflus08]

@@w2aew Yes it usually means regular videos. Which I very much understand if you don't want to do. For all I know you are well off as it is, which is probable on account of your skill and knowledge.

[@w2aew]

@@stefflus08 The extra money would always be nice, but my work/life commitments would make it difficult to provide the content that I'd feel obligated to produce.

[@davidwilkinson411]

Fabulous detail and fabulous presentation skills

[@mahmoudtamer3414]

Great great explanation. Thank you

[@movax20h]

This is awesome and so simple explanation, to the point of it being obvious. Nice.

[@artax19999]

very well made and easy to understand! thanks!🙏

[@NoName-ip4tt]

I understand now why we need to add DC off-set to the message signal for the AM modulation --to prevent phase inversion. I have an EE degree and I got all the courses regarding the signal processing along with the communication theory, but non of teachers did not mention this basic detail. Every engineering school should take these videos as the reference teaching materials...

[@jbumstead21]

I've been searching for an analog multiplier and I found your video on the Gilbert Cell. Exactly what I was looking for. I have also watched some of your other videos and they have been equally helpful! Thanks for creating them.

[@JanicekTrnecka]

Excellent explanation!

[@quinten52]

If I viewed this video a few weeks earlier, I could have put a reference of it in my paper on stereo multiplexing! Great video!

[@jeffscaparra6985]

Wow this could not have come at a better time for me. Thanks for your work doing these videos.

[@roelandriemens]

Never heard of these Gilbert Cell's before at school in the eighties. Great explanation. Thanks for this video. Merry Christmas and Happy New year.

[@andrewferg8737]

Building the Gilbert Cell from discrete components was a real education for me. I would love to see an additional video on using the 602 mixer. I haven't had much luck with that chip yet. Any practical tips would be a great help. Thanks again!

[@w2aew]

The trick is usually in getting the biasing and signal levels right. Some resources online: www.lb3hc.net/wp-content/uploads/2019/12/UsingTheNe602.pdf docs.rs-online.com/3cf1/0900766b80027aa2.pdf

[@moustaphamuhammad7013]

You really talking about the real things that matter. As usuall you are unique!

[@pradeepchandran5463]

thats the most simple and usefull circuit analysis i have ever heard

[@w2aew]

+Pradeep Chandran Thank you, I'm glad you enjoyed it.

[@vasiliymansurov1483]

Dear w2aew, thank you so much for this and next video. I wanted to play with mixers and You were the best source of information. Thank you!

[@w2aew]

Be sure to check out my other videos on mixers (diode ring mixers, etc.).

[@pacosoide]

Excellent explanation of the Gilbert cell function. Thanks very much for your efforts to enlighten the rest of us.

[@robertjohansen7482]

Alan, very good circuit explanation, takes some mystery out of the analog circuit design. 73, Bob WB2SRF

[@herbertsusmann986]

Wow, best description I have ever heard of a Gilbert Cell Mixer! You hit it out of the park on this one! 73s de KA2ZOH and happy new year!

[@w2aew]

+Herbert Susmann Thank you!

[@robvegart]

I love the fundamentals of push comes to shove or push comes to pull...? Or is it 'quit pushing me around!!!'? Oh well, love the lesson. Thanks, Brought back memories. Videos make learning this so much quicker.

[@ny6u]

Very Nicely done ! I quickly prototyped this circuit on a simulator and was able to verify it in phase detection mode !

[@renejansen5939]

Thank you for your great video's! Your channel is a "must watch" for everyone who's into electronics! I Was looking around the web for a mixer to be part of a circuit that can shift frequencies from 80 - 86 MHz "up the dial" where a standard FM receiver can handle them (there's a lot of pirate radio activity just below the standard 3 meter "FM" band here in the Netherlands and I don't want to modify and mess up good receivers). I Discovered the double balanced diode mixer, other diode mixers and solid state mixers, but this one seems to be great to use in the circuit I want to build. Thank you!

[@w2aew]

I hope it works out well for you. This mixer is part of the NE602/NE612 - which may make your implementation easier.

[@ETILHK54]

Simple, easy to understand. Masterful explanation.

[@beforebefore]

LIGHT BULB!!! Thumbs-up, and subscribed! Thanks so much... I was familiar with balanced amps, but the double-reversed with balanced gain mixing topology here is really cool. Here's my problem... I'm working on an IQ digital modulator in a piece of avionics test equipment that uses a pair of the UPA101's as Gilbert Cell modulators. They are fed L.O. (120-170MHz) through lead/lag L/C circuits (main balanced inputs), the tails are commoned and static (shunt 5.1V zener regulator, each via its own NPN common-emitter buffer), the differential gain inputs are driven by the I and Q gain circuits (the Q channel has a slightly adjustable gain control circuit to balance them... all via sampled feedback). Then the outputs from each Gilbert Cell IC are summed to create the TX IF. The problem I'm having is that the carrier is not being eliminated, but only reduced by about -10dB, where it should be reduced about -50+dB from the main offset frequency (either upper or lower). It does the same thing regardless of whether the IQ inputs are creating USB or LSB... the carrier leakage is still horribly high. From what you said, it seems the carrier reduction should be happening in this modulator circuit... I kept thinking maybe it was in a TX IF gain-reduction circuit... Thoughts? Each IC has active outputs, but I did notice a DC imbalance on one of them when I was trying to troubleshoot it... and from what you said, they should not have any DC imbalance... right? I have full schematics, but the mfr gives no detailed circuit operational theory... at least not enough to help. Your video gave me FAAAARRR more info than the mfr did!

[@w2aew]

DC imbalance will definitely lead to poor carrier suppression. You may also want to view this video: kzbin.info/www/bejne/iHmpi4inirJrers

[@w2aew]

kzbin.info/www/bejne/iHmpi4inirJrers

[@gtrekiran]

Simple , simplified and understandable explanation. Thank you

[@kevinbyrne4538]

Nice explanation of the Gilbert cell. Many thanks for preparing & posting this presentation.

[@royvanstraeten3215]

Again a more than perfect explanation...i liked it ..clear ..technical and again a working example to show ..thanks

[@kooox]

Those videos are really awesome. My transistor background is really far away (like 10 years away...) yet everything seems intuitive again. Thanks!

[@fer_fdi]

excellent! Thank you so much!

[@DavidLeeMenefee]

Thanks for another good video. Like others, I too have never heard of this GILBERT CELL. I always learn something from your videos. Thumbs up. Thanks

[@GiNodrog]

Brilliant and very informative video.

[@suereed]

Excellent explanation. Helping me understand a four quadrant multiplier module I am building for my modular synth.

[@101blog]

Excellent description of the Gibert cell function ..well executed ..Cheers !

[@dl8cy]

A very big thumbs up!

[@Loundre3]

Thanks for showing how an Gilbert cell works. I finally made an mixer (for mixing 2 square wave oscillators) based on this cell, and it works much better then an OR based one.

[@TheRadioShop]

Outstanding explanation on this Alan.Have a safe and Merry Christmas.

[@EwaldBurger]

And again a great video from a great teacher! Thanks a lot and wish you a merry christmas!

[@souravdokania1929]

This video tops, very clear explanation. Please keep making such videos.

[@robvegart]

Looking at this I think of both the Ne-602 (now Sa-612) and the Ne-599... Both using Gilbert cell configure all except the Ne-602 had an LO implemented of 200 mHz. So cool to remember these things some 25 to 30 years later. I now have closure!

[@robertcalkjr.8325]

Thanks Alan for another superb lesson! Merry Christmas and Happy New Year!

[@bwack]

Oh man. I've been thinking about voltage controlled filters lately, and this video is so right on time for me :D Well explained as always. Thank you.

[@jaydwgtre0]

Great explanation!

[@aleksandartomic5515]

Extremely clever man. Even I can understand :)

[@movax20h]

Awesome video. Would love more about Gilbert Cell, maybe about bandwidth and noise.

[@w2aew]

Will add this to my long list of future topics

[@MichaelLloyd]

Outstanding video (again). Merry Christmas to you and yours Alan

[@everydaywarriors]

Excellent high level description.

[@leventsasmazel6292]

Beautiful circuit analysis. Marry Christmas Alan 73.

[@w2aew]

Thank you, Levent! Nice to hear from you!

[@yoremkastor]

I built up the circuit in ltspice and that magnitude difference you talk about at 13:00 also occurs in ltspice too. So I went on tried different approaches but when base Voltage variations and so are the currents are equal on q5 and q6 I get no voltage at the output. So this voltage difference is a must to have on q5 and q6 transistors? If it is a must to have then will we always see some magnitude difference at the output?

[@waltsailing2009]

Great video, i was curious in this single ended example, could you explain why there is no bypass to ground on base of q6 vs the bypass to ground on the bases of q2 and q3 please. Maybe the biasing is stiff enough, maybe it doesn’t matter, just curious.

[@theoneandonlynobody]

Very interesting explanation and clear demonstration. Very well done. My one want is to see the inputs and outputs in the frequency domain. I suspect that there would be quite a bit of distortion due to the usage of discrete devices, but it would definitely be worth doing if your scope can FFT things fast enough or if you have access to a 4 port SA.

[@stm3252]

Is there a way i can make a million likes at once? Frankly, W2AEW is the best electronics teacher in KZbin hands down.

[@iamswastik]

This is gold. Keep it up. Thank you!

[@afterthought138]

Excellent video, as usual.

[@mr1enrollment]

once again nice video.

[@piotraswys]

Thank You very much for Your videos! You are able to explain a lot of complicated issues. Merry Christmas and Happy New Year! :)

[@___xyz___]

16:32 What is DC offset, and how would you go about applying it to the input frequencies to eliminate phase shift? Could you offset the lower frequency input both negatively and positively?

[@w2aew]

The DC offset is the mid-point voltage of the signal with respect to the bias voltage on the opposite input of the differential pair. The offset can be positive or negative. This is illustrated in the followup video: kzbin.info/www/bejne/o5bNgYGrhaZ7eLs

[@boyscout419]

I really appreciate the work you do to provide such education. Thanks very much and Merry Christmas/Happy New Year

[@okonkwofrankline8871]

Best explanation ever...Thank you. Please what regions of operation are the transistors in, forward or saturation?

[@fpgaguy]

thank you so much for this. Please make more!

[@pablo_costas]

really nice video, amazing content!

[@andrewferg8737]

Another great and informative video! Thanks for sharing again and again...

[@gregfeneis609]

Very neat!

[@mrjohhhnnnyyy5797]

Thank you a lot for uploading such vids, I learn a lot from them. Merry Christmas and Happy New Year to you!

[@jge27455]

Fantastic videos and simple and great explanations!

[@shashvatsinghchouhan4153]

Thank You Sir, it is very informative, helpful and easy to comprehend.

[@arashcrouse2]

Thank you very much for your fantastic explanation.