Band-Gap Voltage Reference Diode [Temperature Compensated Circuit]
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- Опубліковано 24 сер 2024
- How does a Band-gap voltage reference diode work? What is the value of output voltage? What should be the choice of circuit components to ensure near zero temperature coefficient for this reference diode so that generated output voltage doesn't change with temperature? These questions are discussed and answered in this bandgap reference voltage design example and tutorial. There are many practical applications for Band-gap circuits that are effectively Zener diodes with practically zero temperature coefficient. Example application is stable reference voltage in chip design including the wireless transceiver chips in cell phones. The example band-gap circuit discussed in this video is implemented with five NPN BJT and one PNP bipolar junction transistors. Three of the NPN BJT transistors are required to be matched transistors (sharing the same process, junction and thermal properties) in order to have the same saturation current (Is) and same thermal voltage (VT) which is roughly 26mV when PN junction is at 300 kelvin room temperature. Using a combination of KVL and Shockley equation of PN junction of BJT transistor, it is proven that the output generated voltage of this reference diode is 1.28V with near zero thermal sensitivity. Analog Devices LM313 from Texas Instruments REF54 0.8ppm/°C drift precision voltage reference are examples of voltage references that can be purchased from circuit component suppliers Digikey or Mouser. At the end of this video, an example of component selection for the value of resistors is provided.
This was a high level and top quality explanation. Thank you for your videos. 😊
You are very welcome. Glad that my circuit videos are useful. Here are a few related videos:
Bandgap Voltage with Op Amp & Widlar Current Mirror Circuit ua-cam.com/video/esMlNx5w9Jw/v-deo.html
Voltage Regulator Design with BJT Darlington Transistors and Zener Diodes ua-cam.com/video/ArisQp7V0Ac/v-deo.html
I hope these videos are interesting as well. 🙏
Excellent explanation. Keep up with the good work.
My pleasure. Glad that you liked this bandgap circuit video. Here are a few related videos:
Bandgap Voltage with Op Amp & Widlar Current Mirror Circuit ua-cam.com/video/esMlNx5w9Jw/v-deo.html
Voltage Regulator Design with BJT Darlington Transistors and Zener Diodes ua-cam.com/video/ArisQp7V0Ac/v-deo.html
I hope these videos are interesting as well. 🙏
Nice presentation. It would be nicer if you could carry the literals up to the end of the derivation of the actual result(s), and then replacing the values. The analysis of a particular result and pre-requisites/simplifications (betas, and so on) could be carried out with a separate annotation and be left somewhere until the presentation's end.
I would point out that the actual diode bandgap is also a function of temperature (eg. Varshni semiempirical formulation), possibly out of the scope of the presentation.
Thanks for your time.
@_nemo174 Glad that you liked this BandGap video. And thanks for your suggestion and for pointing out the fact that actual PN junction band-gap is not absolutely independent of junction temperature. I would say, practically speaking, it is safe to neglect its thermal dependency at least for the range of practical applications that matter in this context. For example, a bandgap voltage reference Diode with coefficient temperature of say +/- 0.003% per degree kelvin is at least an order of magnitude less temperature sensitive than Zener diodes. If nominal bandgap voltage is ~1.28 volt, then such a small temperature coefficient translates to a mere 0.00003*1.28 volt ~= 38.4 micro volt change per degree which means ~1mV change (practically negligible) even if junction temperature changes 30 degree Celsius. For more related circuit examples please see:
Bandgap Voltage with Op Amp & BJT Widlar Current Mirror Circuit ua-cam.com/video/esMlNx5w9Jw/v-deo.html
Voltage Regulator Design with BJT Darlington Transistors and Zener Diodes ua-cam.com/video/ArisQp7V0Ac/v-deo.html
I hope these circuit examples are interesting as well. Thanks again for your comment. 🙏
How does a Bandgap voltage reference diode work? What is the value of output voltage? What should be the choice of circuit components to ensure near zero temperature coefficient for this reference diode so that generated output voltage doesn't change with temperature? These questions are discussed and answered in this bandgap reference voltage design example and tutorial. For additional circuit examples see: 5v Charger Voltage Regulator with MOSFET, JFET & Temperature Compensation ua-cam.com/video/NdfyHoxjKrY/v-deo.html
Voltage Regulator Design with BJT Darlington Transistors and Zener Diodes ua-cam.com/video/ArisQp7V0Ac/v-deo.html
More example are posted in the Analog Circuits video playlist ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html. I hope these analog examples are useful and interesting. Thanks for watching.
Interesting
@uvx508 Glad that you liked this bandgap voltage reference diode. For more related circuit examples please see:
Bandgap Voltage with Op Amp & BJT Widlar Current Mirror Circuit ua-cam.com/video/esMlNx5w9Jw/v-deo.html