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https://designers-guide.org/forum/YaBB.pl Design >> Mixed-Signal Design >> Substrate connection in a pipelined ADC https://designers-guide.org/forum/YaBB.pl?num=1118713275 Message started by Stan on Jun 13th, 2005, 6:41pm |
Title: Substrate connection in a pipelined ADC Post by Stan on Jun 13th, 2005, 6:41pm Hi, Where should I connect the substrate in a pipelined ADC? To the analog ground or the digital ground? I have checked several books but got inconsistent answers. Thank you! Stan |
Title: Re: Substrate connection in a pipelined ADC Post by sheldon on Jun 21st, 2005, 9:10pm Stan, First it would help to know more about the application? Are you putting the ADC in the middle of 1,000,000 noisy gates? Or is it standalone? Also why does your Pipeline ADC macro have only one ground? Wouldn't it be better to separate the grounds into analog and digital to prevent crosstalk? Does all your digital logic run off the same supplies as the analog or is there high and low voltage digital, that is do you need three ground lines analog, high voltage digital, and low voltage digital? When the design was simulated was it simulated with package parasitics? If not probably need to do this simulation to understand how to partition the power supllies. Best Regards, Sheldon |
Title: Re: Substrate connection in a pipelined ADC Post by sheldon on Jun 21st, 2005, 9:18pm Stan, Sorry got off the topic, it depends on a lot of factors. In general, the answer is neither, give it an isolated supply to an isolated pin with really low impedance to ground. The goal is to minimize noise injection from the subtrate by shorting the local substrate to ground. Sheldon |
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