Thank you for these videos, I never get tired or lost. back in school it was easy to drift away from the lecture, now I know it wasn't me, rather it was the lecturer... thank you
Hi, I am actually a new college graduate who is now working as a analog designer and your videos are really helpful. At 30:53 minutes you have shown a Sub 1V BGR and mentioned that will be discussed in a different video. Can you please upload a video on that particular circuit. It would be really helpful.
At 21:17 why only R1 is considered ? That path current should be decided by both R1 and R2 ,rt? Vt ln(n) is the voltage at + input ,so ideally current through R2 should be drain voltage of MP2 - Vt ln(n) divided by R2,rt? or am I missing something here?
vtln(n)/R2 is the current in R2. That same current current comes from the current source MP2. So.. The drop across R1 is current flowing in R1 X resistance R1.... current flowing in R1 is nothing but current flowing in R2...which is Vtln(n)/R2...substituting it we get that equation... Current in the MP2 is set by the loop thru its gate... hope I answered...why we dont take voltage across MP2 is because its current source... current source can have any voltage across it..still current in it is same...we cant apply KVL across current source..hope this answers
Nicely explained...👍...All ur videos are very informative and explained well....helped a lot in clearly understanding so many concepts... Would like to see more videos in coming days...keep up the good work..All the very best for ur channel 👍👍
Here we could have used Diode connected MOSFET instead of Diode connected BJT, since both have same IV characteristics. Is there any specific reason for choosing BJT? Thanks for the video, It was really helpful
ya..we can generate MOSFET based BGR, but there would be a need of two transistors with different Vt.we will need one extra Threshold adjust implant layer....it comes at a cost..... that becomes a hard constraint. on the other hand, we dont need anything extra when we use BJT based diode.... this bjt diode is parasitic bjt....substrate PNP... so doesnt impose any requirement on fabrication.
Hello sir.. It is a wonderful video which helped me a lot to understand.... Thank you .. could you please share the LDO and VCO videos also... that may help us ...
Thanks For the video. At 9:00 what is the Thermal voltage of the BJP, How it will increase when temperature increases, is it the junction potential ? if we connected BJTs in parallel how the PTAT voltage will become M times VT ?
Good Explanation, Can u please provide a link to reach you? If there is a simulation assistance for each Analog block in this channel, it will be helpful. As soon as possible. The content of this lecture is good.
I didn't give much thought for why it is called BGR. The reason explained in the video is that Band-Gap voltage is 1.2eV and it is similar to Band-Gap reference voltage we get which is usually 1.2V.
Sir !! Please! please! .. ...Send ur mail id to mine.... vegyarapumanideep@gmail.com Plz sir i wont distub u much... I 'll list out and ping u once in a while..
Thermal runaway happens when the BJT is biased for amplification(Ic=Beta times IB) and also there is substantially high current. Here we are using it as diode, secondly this is not a actual BJT. its parasitic substrate BJT. so the beta of this BJT will be only 5 or 10 unlike 100 of an actual BJT. Also the current that flows in will be in less than 10uA. the package will be able to quench the heat generated by such kind of temperature rise due to such small current. Hope this answers.
@@rajasekharnallamekala4950 Hi Rajasekhar , Diode current will have proportional temperature coefficient PTAT we can tell. Here Bjt are used as diodes, compare to actual diodes BJT created diodes will give better diode action. If we connect as diode collector and base tied here beta Ic/Ib =1 here always. If any change in beta due to external parameters. If beta increases is there any impact is my question. As beta increases temp increases and vice versa is thermal runway. Hope I answered your question.
Here bjt is diode cncted device ( collector and base shorted ) . IC equal to beta into Ib .. if beta value increses temperature Increses and thermal runway Increses ok . But in above msg sir mentioned beta Value is 5 to 10 only and IC equal to just 10 micro amp. Small amount of current can handle. Finally I am expecting in simple one word purpose of bjt in BGR is ?
Thank you for the explanation sir. I tried to simulate bandgap voltage reference using hspice, unfortunately the operation region of the two pmos that I added in my op-amp to produce a bandgap reference is in cutoff region. Can you enlighten me as to why it operated in cutoff region?
I generally advice to check BGR using ideal error amp.. So that u can check if circuit is working. Separately design opamp and check if that's working for the reqd range. Then replace ideal opamp with actual... This is my approach.. Think abt it..
@@analoglayoutdesign2342 hello sir. can you check what's wrong with the values of the elements of my bgr? q1 gnd gnd vin- pnp10 area=5 q2 gnd gnd vr2 pnp10 area=5 mp1 vr1 vout vdd vdd pch w=20u l=1u mp2 vbg vout vdd vdd pch w=20u l=1u r1 vr1 vin- 100k r2 vbg vin+ 100k r3 vin+ vr2 1k vdd is 1.8v and i also used my own constant gm current circuit with 20uA.
Hi Dennis, Bjt area will be 1:8 generally. R2:R3 ratio will be 10-12. Are u using ideal opamp? Please go thru the calculation Also look into example circuits and simulate them
are there any designs where bjt ratio is different from 1:8? Could you please point me to those designs? Overall very informative video. Thank you so much for sharing your knowledge. May I know which company do you work for?
what is the value for equation VBE2+VT ln(n)(1+r2/r1) here ln(n)=2 , (1+r2/r1)=11 , VT= 0.087mv/c. so what is the final ans? please explain calculation
Hi Sir. I really enjoy watching your lectures. Thank you. The content is very helpful to me to understand the concept of the analog design. I am sorry to say this, the content of this slide is very good and understood, but the audio is very poor compared to other lectures (video). I am looking forward to watching your next lectures with good quality audio. Thank you and Thumb up!!
When I calculate the output Bandgap voltage with respect to VBE1 then it will be only R2/R1.. but when I calculate the Bandgap voltage with respect to VBE2, then its (1+R2/R1)... just check if I am wright...
please sir do a video of current mirror 2 and apamp ckt with different layout matching techniques and how to do a perfect floorplan for any analog layout becease of these stuffs i didnt get a job please sir help to get a job
Video is superb, however I cannot interpret some of the words you are saying. Would love it if you could remake the video speaking much slower. Thanks.
Thank you for these videos, I never get tired or lost. back in school it was easy to drift away from the lecture, now I know it wasn't me, rather it was the lecturer... thank you
Thanks for the feedback
Learning all these practical aspects of analog engineering while studying in prefinal year of college. I'm loving it.
This is the best video on BGR
This is a great lecture, thank you so much, Professor!
The content of the lecture is very helpful for me.
Thanks for the feedback
Thank you really MUCH! In the script from my university it was explained horribly, but thatks to this video I got it ! Thanks
Thanks for the feedback.
Very complex concept explained in very to understand language and that too in depth 🙏🙏🙌🙌 Thank you so much sir😇
Thanks for the feedback
Ur really great sir....i get clear understanding
thanks for all the knowledge u share with the world
Very clear explanation. Thanks for the education.
Thanks for the feedback
Thank you ! Can you please add a video on how to integrate the opamp in CMOS and discuss the startup circuit ?
Ok will do.. thanks for the feedback
Hi, I am actually a new college graduate who is now working as a analog designer and your videos are really helpful. At 30:53 minutes you have shown a Sub 1V BGR and mentioned that will be discussed in a different video. Can you please upload a video on that particular circuit. It would be really helpful.
Thanks for the feedback. Will make video on sub1v bgr
Yes pls make one.
Very nicely explained sir. Please share the two stage opamp video of this part. Thanks
At 21:17 why only R1 is considered ?
That path current should be decided by both R1 and R2 ,rt?
Vt ln(n) is the voltage at + input ,so ideally current through R2 should be drain voltage of MP2 - Vt ln(n) divided by R2,rt?
or am I missing something here?
vtln(n)/R2 is the current in R2. That same current current comes from the current source MP2. So.. The drop across R1 is current flowing in R1 X resistance R1.... current flowing in R1 is nothing but current flowing in R2...which is Vtln(n)/R2...substituting it we get that equation... Current in the MP2 is set by the loop thru its gate... hope I answered...why we dont take voltage across MP2 is because its current source... current source can have any voltage across it..still current in it is same...we cant apply KVL across current source..hope this answers
Do you have the video for the start up circuit and also how to generate the IPTAT? can you please share the link?
Startup circuits can be found easily in search engines.. IPTAT is nothing but the current source that is for the bjt .. a mirrored one of that
For ptat ckt. Generation are we taking beta of the bjt as infinite because only then base current is negligible....?
Here bjt used as diode.. it’s now variation of vbe as pn junction
Nicely explained...👍...All ur videos are very informative and explained well....helped a lot in clearly understanding so many concepts... Would like to see more videos in coming days...keep up the good work..All the very best for ur channel 👍👍
Nicely explained...
Here we could have used Diode connected MOSFET instead of Diode connected BJT, since both have same IV characteristics. Is there any specific reason for choosing BJT? Thanks for the video, It was really helpful
ya..we can generate MOSFET based BGR, but there would be a need of two transistors with different Vt.we will need one extra Threshold adjust implant layer....it comes at a cost..... that becomes a hard constraint.
on the other hand, we dont need anything extra when we use BJT based diode.... this bjt diode is parasitic bjt....substrate PNP... so doesnt impose any requirement on fabrication.
so bjt diode is ubiquitously used...
@@analoglayoutdesign2342 Thankyou
Only it provides constant ouput v or i respective of temperature variations? It is not if voltage supplay varies will not vontrol,
This architecture provides constant voltage and ptat current. Sub 1v architecture provides constant voltage and ztat current
good explanation 👍
Thank you so much sir, you are my king
Thanks
Well said Sir 👌
Hello sir.. It is a wonderful video which helped me a lot to understand.... Thank you .. could you please share the LDO and VCO videos also... that may help us ...
sure..first ldo maybe later vco
Analog Layout & Design Thank you
I am not able to find 2nd video can u provide
In the making
Hi can you give link of second part.. i could not find it
Its still not there.. Should record and upload.
Thanks For the video. At 9:00 what is the Thermal voltage of the BJP, How it will increase when temperature increases, is it the junction potential ? if we connected BJTs in parallel how the PTAT voltage will become M times VT ?
Thermal voltage is KT/q... Where T is temperature. This will be around 26mV typically. Its directly proportional to temp.
Good Explanation, Can u please provide a link to reach you? If there is a simulation assistance for each Analog block in this channel, it will be helpful. As soon as possible. The content of this lecture is good.
You can reach me on jt.analog@gmail.com
Regarding simulation, even I have similar thought… but will see how to make that available.. thanks for feedback
NICE ONE SIR
Need of matching also to vary the Pvt variations ? Correct .?
yes...matching is basically to counter gradients in fabrication...please watch semiconductor resistors video...
I didn't give much thought for why it is called BGR. The reason explained in the video is that Band-Gap voltage is 1.2eV and it is similar to Band-Gap reference voltage we get which is usually 1.2V.
When calculated, Vref becomes Eg/q in case of T=0K. Read chapter Bandgap References in Design of Analog CMOS Integrated Circuit by Razavi.
what an explanation!
very nice and informative video thanks
Hello sir your explanation is very good, can you please mention better book names which is helpful for analog layout
thankyou in advance
Majority of the content is from internet search..
You are an excellent teacher! Could you please explain MOS comparator / op amplifier in similar manner?
thanks...plan is there for 5transistor OTA..soon..
@@analoglayoutdesign2342 Thank you Sir!
Sir !! Please! please! .. ...Send ur mail id to mine.... vegyarapumanideep@gmail.com
Plz sir i wont distub u much... I 'll list out and ping u once in a while..
jt.analog@gmail.com
God You Saved me✨✨
Good luck
We have any thermal runaway effect due to BJT ??
Thermal runaway happens when the BJT is biased for amplification(Ic=Beta times IB) and also there is substantially high current. Here we are using it as diode, secondly this is not a actual BJT. its parasitic substrate BJT. so the beta of this BJT will be only 5 or 10 unlike 100 of an actual BJT. Also the current that flows in will be in less than 10uA. the package will be able to quench the heat generated by such kind of temperature rise due to such small current. Hope this answers.
@@analoglayoutdesign2342 Thanks
Hi Sanjay ,in BGR ckt what is the purpose of bjt ? If u know tell me your answer
@@rajasekharnallamekala4950 Hi Rajasekhar ,
Diode current will have proportional temperature coefficient PTAT we can tell.
Here Bjt are used as diodes, compare to actual diodes BJT created diodes will give better diode action.
If we connect as diode collector and base tied here beta Ic/Ib =1 here always. If any change in beta due to external parameters. If beta increases is there any impact is my question. As beta increases temp increases and vice versa is thermal runway.
Hope I answered your question.
Here bjt is diode cncted device ( collector and base shorted ) . IC equal to beta into Ib .. if beta value increses temperature Increses and thermal runway Increses ok . But in above msg sir mentioned beta Value is 5 to 10 only and IC equal to just 10 micro amp. Small amount of current can handle. Finally I am expecting in simple one word purpose of bjt in BGR is ?
we take 8 bjt's for layout matching only ?
8 and 1: together 9 bjts
Thank you! Is there any way I can get these slides ?
explanations will not be there in slides...I write it while recording the video...so slides alone will not be useful
Thank you for the explanation sir. I tried to simulate bandgap voltage reference using hspice, unfortunately the operation region of the two pmos that I added in my op-amp to produce a bandgap reference is in cutoff region. Can you enlighten me as to why it operated in cutoff region?
You mean the input diff pmos pair of the opamp?what is supply voltage , vt and technology?
I generally advice to check BGR using ideal error amp.. So that u can check if circuit is working. Separately design opamp and check if that's working for the reqd range.
Then replace ideal opamp with actual...
This is my approach.. Think abt it..
@@analoglayoutdesign2342 hello sir. can you check what's wrong with the values of the elements of my bgr?
q1 gnd gnd vin- pnp10 area=5
q2 gnd gnd vr2 pnp10 area=5
mp1 vr1 vout vdd vdd pch w=20u l=1u
mp2 vbg vout vdd vdd pch w=20u l=1u
r1 vr1 vin- 100k
r2 vbg vin+ 100k
r3 vin+ vr2 1k
vdd is 1.8v
and i also used my own constant gm current circuit with 20uA.
Hi Dennis,
Bjt area will be 1:8 generally.
R2:R3 ratio will be 10-12.
Are u using ideal opamp?
Please go thru the calculation
Also look into example circuits and simulate them
They will help u a lot
are there any designs where bjt ratio is different from 1:8? Could you please point me to those designs?
Overall very informative video. Thank you so much for sharing your knowledge.
May I know which company do you work for?
yes sometimes they use more...if unit size of bjt is small...it will be more than twenty devices...
what is the value for equation VBE2+VT ln(n)(1+r2/r1) here ln(n)=2 , (1+r2/r1)=11 , VT= 0.087mv/c. so what is the final ans?
please explain calculation
yes..all put together will be your bandgap voltage~1.2V.
Any link for sub 1v architecture?
I will be posting one more video on that..kindly wait
Hi Sir. I really enjoy watching your lectures. Thank you. The content is very helpful to me to understand the concept of the analog design. I am sorry to say this, the content of this slide is very good and understood, but the audio is very poor compared to other lectures (video). I am looking forward to watching your next lectures with good quality audio. Thank you and Thumb up!!
sorry for the poor audio...will ensure that audio will be clear hereafter
In BGR ckt what is the purpose of bjt
bjt will produce CTAT. please go thru the video again
@@analoglayoutdesign2342 ok
Nice explanation but in cmos also we use npn
That’s BiCMOS process or BCDMOS process
Good lecture but too many ads!
Thanks Sir for these lectures,
Can we have some lectures on Impedance matching and Tuning circuits used in SERDES.
those are advanced topics....let me plan for those...
can you guide us how to used mod gen efficiently
i didnt get you
I mean to say that modgen tool which is used for matching and some other purpose so can you make a video on modgen tool
@@hemantpise3414 ok got it..
It's my humble request to make one video
👌👌👍👍
Hello sir,
At 36:0, In Vbg equation 1 Plus is not mention with Resistor ratio.
When I calculate the output Bandgap voltage with respect to VBE1 then it will be only R2/R1.. but when I calculate the Bandgap voltage with respect to VBE2, then its (1+R2/R1)... just check if I am wright...
why we used only parasitic pnp why not npn
easy to construct...basically its diode that we need...for vbe
please sir do a video of current mirror 2 and apamp ckt with different layout matching techniques and how to do a perfect floorplan for any analog layout becease of these stuffs i didnt get a job please sir help to get a job
sure...I will... just need time..
Video is superb, however I cannot interpret some of the words you are saying. Would love it if you could remake the video speaking much slower. Thanks.
To remake video is a huge effort.. however I will take care in future. Thanks for feedback
Please use a pop filter for your microphone
Thanks for the feedback. Will do.
Good explanation but the sound is very bad
My apologies for bad audio..its rectified in other videos
I got rejected in interviews after learning this design of BGR.
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