PhotoDiode Amplifier with Data Compression Explained
Вставка
- Опубліковано 29 лют 2024
- An Example implementation of Avalanche PhotoDiode Amplifier with Data Compression is discussed in this video. This Log compression transimpedance amplifier is designed with three Op Amps, two matched NPN Bipolar Junction Transistors, a Zener Diode and a Temperature Compensating Tempco resistor with positive temperature coefficient. The Tempco resistor compensates the BJT thermal voltage linear dependency on temperature. If temperature compensation is not required, then instead of TempCo resistor, a nominal 1kohm resistor with small tolerance (for example less than or equal 1%) can be used. A combination of OpAmp virtual short and negative feedback, Shockley PN junction equation and Kirchhoff Circuit Laws (KCL and KVL) are used to analyze this Log amplifier circuit and to prove that it is operating as a Transimpedance amplifier with an out put voltage Vo=Log10(1mA/Ipd) where Ipd is photodiode current that varies from 100 nano ampere to 1 mA in this design. For more examples see @STEMprof Analog playlist • Electrical Engineering... . Notice that both Zener Diode and Avalanche Photo Diode are properly reversed biased in this analog circuit.
- Наука та технологія
I loved this analysis, it's so beautiful. Love working with op-amps, because the calculations involving them are so simple, however my hat goes off to the person who came up with this circuit. Thank you professor for making the circuit understandable. I appreciate your work a lot!
You're very welcome! Glad that you liked this circuit analysis. This is my design variant based on the core matched BJT log amplifier ua-cam.com/video/RpKEq5WyoLg/v-deo.html . Thank you!
Thank you
You're welcome. Glad that you liked this video.
Great! I might need this soon for a measurement setup whereby we would like to do a relative measurements (start with exposing the diode to the maximal light intensity and then put the sample in between to determine the total relative transmittance). As I was thinking about the setup I figure it out that the difference (the dynamic range) would be quite big, and that regular linear circuit would probably not suffice. Maybe if you use opamp with higher supply voltage so you have more room for the output. But this is very nice circuit worth looking at more closely. But for sure not an simple circuit 😀 Very nice explanation and the analysis. The photo diode current could then be calculated as Ipd = 1mA / 10^(Vo)
What I don't understand very well is how the transistor T2 can conduct current if it's base is on the ground? Mawybe therefore the output of the first opamp would need to provide negative voltage?
...and of course there are 'ready to go' logarithmic amplifier. But this is good as an exercise and learning circuit design and analysis of course.
Glad that you liked this circuit analysis. Thank you for sharing your thoughts and experiences. And yes, the photo diode current is Ipd = Iref / 10^(Vo). This is my design variant based on the core matched BJT log amplifier discussed in ua-cam.com/video/RpKEq5WyoLg/v-deo.html video.
@@ernestb.2377 That is a good question. And you answered it correctly as well :) Op Amps are supplied with negative and positive voltages. OpAmp output will provide the required negative voltage as also discussed in the matched BJT log amplifier ua-cam.com/video/RpKEq5WyoLg/v-deo.html circuit.
@@ernestb.2377 Thank you. Glad that this Log amplifier video is useful. Log and Exponential amplifiers can be used to design very interesting circuits including an Analog Computer Raises signal to the Power signal ua-cam.com/video/Qe3cY9JSzYg/v-deo.html (Analog Power Raiser with OpAmp & Transistor). 👍
Useful video, thanks prof!
You're welcome. Glad that this Log amplifier video is useful. Log and Exponential amplifiers can be used to design very interesting circuits including an Analog Computer Raises signal to the Power signal ua-cam.com/video/Qe3cY9JSzYg/v-deo.html (Analog Power Raiser with OpAmp & Transistor).
thank you sir
My pleasure. Glad that you like this photodiode amplifier video. For more sensor videos pls see the Sensors Amplifiers playlist ua-cam.com/play/PLrwXF7N522y7Ut9bm8TXAOhIWqL__FGlj.html
An implementation of PhotoDiode Amplifier with Data Compression is discussed in this video. For more analog circuit videos see: PhotoDiode Amplifier with Op Amp and MOSFET Explained ua-cam.com/video/1c3EJ2d4pVI/v-deo.html
PhotoDiode Amplifier with Howland Current Inverter ua-cam.com/video/ILK6rakvJc8/v-deo.html
Analog Computer Raises signal to the Power signal ua-cam.com/video/Qe3cY9JSzYg/v-deo.html
Amplifier with -25 to 55 dB Attenuation-Gain range ua-cam.com/video/oyz6lTGd2Xo/v-deo.html
Electronic Gain Control for Op Amp Amplifier ua-cam.com/video/NoNgQpbj77Y/v-deo.html
Thermometer Circuit Design with Op Amp & BJT transistor ua-cam.com/video/55YsraFE0rg/v-deo.html
Instrumentation Amplifier with Electronic Gain Control ua-cam.com/video/C4tghZ-q6Zs/v-deo.html
Power Amplifier Design (Class A) with Transformer ua-cam.com/video/gKlJrqGqeCI/v-deo.html
VCA Electronic Gain Control (Part 1): Voltage-Controlled Attenuator Overview ua-cam.com/video/cFzYZsPEtP0/v-deo.html
Analog Multiplier Circuit ua-cam.com/video/VP53A2zpVMQ/v-deo.html
Push-Pull Power Amplifier Design with Op Amp, Sziklai Darlington Transistors ua-cam.com/video/8BFzsi7-Vbs/v-deo.html
Analog Vector Summer Circuit Design with Op Amp and BJT Transistors ua-cam.com/video/PIAsa0QNVns/v-deo.html
Op Amp Analog Computer Differential Equation Solver ua-cam.com/video/ENq39EesfPw/v-deo.html
Push-Pull Power Amplifier with Darlington Transistors ua-cam.com/video/866MYibo8yE/v-deo.html
And the Analog Circuits Video playlist: ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html I hope these Circuit design and analysis videos are interesting.