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The top plane has small parasitic capacitor.
1 The parasitic capacitor at input end will decrease the feedback factor, increase the op's bandwidth requirement.
2 top plane far from substrate, they give little niose to OP's input.
The top plane has small parasitic capacitor.
1 The parasitic capacitor at input end will decrease the feedback factor, increase the op's bandwidth requirement.
2 top plane far from substrate, they give little niose to OP's input.
Thanks very much.
My sample and hold is used the SAR adc. I have three question.
1.This adc is 5 bits. ENOB is bigger than 4.5. But I run the cornor of FF , the ENOB is less than 4. But my sample and hold's output's SFDR is larger than 40dB.
Why?
2.How do I simulate my comparator?
3.In the cornor of TT, my sample and hold's output's SFDR is larger than 55dB. But through the comparator , theo adc's SFDR is less than 40 dB but larger than 30 dB. Why? Is it architecture of SAR ADC? or why?
If you have some informations about SAR ADC, please let me know. Thanks.
Why use such a sample/hold in SAR ADC? Did you want to change single input to differential?
If only 5 bit SAR, The comparator can share the S/H op. But the S/H needn't like your architecture.
The ENOB relate to SNDR.
SFDR only the signal power to max tone(Noise or harmonic) ratio.
SNDR is signal to noise and total harmonic distortion ratio.
About comparator: check the speed and resolution and input range, noise, offset.
Why use such a sample/hold in SAR ADC? Did you want to change single input to differential?
If only 5 bit SAR, The comparator can share the S/H op. But the S/H needn't like your architecture.
The ENOB relate to SNDR.
SFDR only the signal power to max tone(Noise or harmonic) ratio.
SNDR is signal to noise and total harmonic distortion ratio.
About comparator: check the speed and resolution and input range, noise, offset.
Check the op state in FF. Is the gain enough in FF corner. The 1/ βA + exp(-t/τ) <1/2LSB. t is settling time. ω0=1/τ ω0 is hold state close loop -3dB bandwidth. β is feedback factor.
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