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Hi,
I have seen many youtube videos of the current return path from FEDEVEL academy that shows how the return current of high frequency and low frequency are. But in all of them, the current is high enough, for example, 1-10 A, to simulate and show the current flow. In this regard, I am really interested in answering these two questions:
1) different types of return paths: reference to power, reference to GND. for example, consider that we have an LED that one the side is connected to VCC and the other side connect to the LED1_DRIVING_PIN. In this condition, what is the return path? Is that the power plane is the return path? Is that the putting power plane is working as a return path. Then the current goes to GND through decoupling capacitors? or consider that we have Photo Diodes connected to PDREF and ADC_INPUT. is that the return current of Photo Diodes is PDREF? Putting PDREF is working or not? We do not have a decoupling capacitor on PDREF. So the return current is inside the IC?
2) about the current value. Consider that the current for Photo Diodes is about 100nA-50uA. What happened about the signal integrity of such this signal? We should be concerned about the cross-talk of another part of this signal, or we should have specific consideration about the return path.
In the end, working with the simulator is so difficult, and in many cases, the results are not as in the real. But if we can see some practical topics in case of mixed-signal systems with low frequency and low voltage and digital part and other hands with some power signals, such as some nice discussion of FEDEVEL that is really expert on describing, is valuable.
Thank you so much.
Best Regards,
Mostafa
I have seen many youtube videos of the current return path from FEDEVEL academy that shows how the return current of high frequency and low frequency are. But in all of them, the current is high enough, for example, 1-10 A, to simulate and show the current flow. In this regard, I am really interested in answering these two questions:
1) different types of return paths: reference to power, reference to GND. for example, consider that we have an LED that one the side is connected to VCC and the other side connect to the LED1_DRIVING_PIN. In this condition, what is the return path? Is that the power plane is the return path? Is that the putting power plane is working as a return path. Then the current goes to GND through decoupling capacitors? or consider that we have Photo Diodes connected to PDREF and ADC_INPUT. is that the return current of Photo Diodes is PDREF? Putting PDREF is working or not? We do not have a decoupling capacitor on PDREF. So the return current is inside the IC?
2) about the current value. Consider that the current for Photo Diodes is about 100nA-50uA. What happened about the signal integrity of such this signal? We should be concerned about the cross-talk of another part of this signal, or we should have specific consideration about the return path.
In the end, working with the simulator is so difficult, and in many cases, the results are not as in the real. But if we can see some practical topics in case of mixed-signal systems with low frequency and low voltage and digital part and other hands with some power signals, such as some nice discussion of FEDEVEL that is really expert on describing, is valuable.
Thank you so much.
Best Regards,
Mostafa
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