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a question about ADC
Hi flyingsky:
At first, thank you for applying.
But I still puzzled.
What mean's DCged? Is it DCgnd?
If I connect "inp" to "com" derictly, what shortcoming would be come? after all, If that is feasible, the '"Cp" would do not needed again.
a question about ADC
As the operation of SAR-ADC, In sample mode, the capacitor Cp is connected to AC gnd "com" by close the switch; in redistribution mode, the switches is opened, the voltage of plus port of comparator is hold by Cp.
My question is why we use Cp to hold the voltage of plus...
Bandgap Problem!!
The answers of above two posts are very well, I want to say a little more:
for issue 4, I always use POLY resistors, for the sake of small Voltage Coef.
as diffusion resistors or well resistors, you must connect substrate to proper bias, that will intruduce some mismatch as...
For bandgap or other references, you need do this:
1. do .op analysis to ensure the devices been properly biased.
2. do DC sweep to check output voltage vs. power, temperature. process.
3. do ac ayalysis to the the loop stable.
4. check psrr.
If I need low-power application with the parallel structure, then, the resistors would consume much area. that will be unfeasible.
Is there any else way?
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