Grounding circuit question

Thread Starter

Conor_b

Joined Nov 22, 2016
2
The question
Q1.jpgQ2.jpg Q3.jpg Q4.jpg

The attempt
For the first set of questions:
part1.jpg

part2.jpg

part3.jpg
part4.jpg
I've worked through to part 6), at which is I encountered my first problem. I'm not entirely sure what the question is asking. Is it as if there would be a capacitor between Q1 and X1? Is the voltage to be reduced the one calculated in part 5)?

part5.jpg

Moving on from that

AnswerSheet2.jpg

I am also unsure about part 9) and 10). We haven't really covered MOSFETs in lectures so these two questions are a bit lost on me. Do I use the frequency, current and resistance to get the average value?

For the second answer sheet for I haven't worked out 5), 7), 9), 12) However I am working on this right now. I will probably have questions later on this

I don't want the answers, but rather help on what methods I should be doing or perhaps pointers to resources that would help

Also, I'm not even certain what I have done is correct

I appreciate any help

Thanks in advance,
 

wayneh

Joined Sep 9, 2010
16,129
I've worked through to part 6), at which is I encountered my first problem. I'm not entirely sure what the question is asking. Is it as if there would be a capacitor between Q1 and X1? Is the voltage to be reduced the one calculated in part 5)?
Not between, but in parallel with them and the power supply. The purpose of the cap is to compensate for the fact that the power supply isn’t ideal.
 

Thread Starter

Conor_b

Joined Nov 22, 2016
2
Not between, but in parallel with them and the power supply. The purpose of the cap is to compensate for the fact that the power supply isn’t ideal.
OK, so in this case, can I use C = I/(Vripple x f), with Vripple being 0.8057 (LSB voltage for ADC) and f being 1.6 MHz). I have seen that in forums before. Or do I need to calculate the impedance of a capacitor in parallel with the PCB track, such that a 100 mA current flowing through them gives a voltage less that 0.8057 (LSB voltage for ADC)?
 
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