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A narrow available voltage range on AVDD in ADCs JESD20B I/F inside

Question asked by ahata Employee on Oct 8, 2015
Latest reply on Oct 15, 2015 by ahata

Hi,

 

I have a question about JESD204B interfaced ADCs.

ADCs which has JESD204B requires very precise and low noise powers.

 

For example, AD9680 (14bit 500MSPS to 1GSPS dual ADC) has 7 kind of different power.

 

     AVDD1     1.22 / 1.25 / 1.28 (min/typ/max) [V]

     AVDD2     2.44 / 2.50 / 2.56  

     AVDD3     3.2 / 3.3 / 3.4

     AVDD1_SR     1.22 / 1.25 / 1.28

     DVDD     1.22 / 1.25 / 1.28

     DRVDD     1.22 / 1.25 / 1.28

     SPIVDD     1.7 / 1.8 / 3.4

 

But I feel like LVDS I/F ADCs don't have such a strict rule.

I want to take an example of AD9643 (14bit 170MSPS to 250MSPS dual ADC).

 

     AVDD     1.7 / 1.8 / 1.9

     DRVDD     1.7 / 1.8 / 1.9

 

 

I imagine power supply for digital should be accurate, otherwise sometimes the link with a digital component is possible to break down.

But I still wonder why power supply for analog also have a narrow range...

 

This is my question.

1. Is it correct that digital power supply has strict rule because of keeping JESD204B connection with a digital component?

2. Why is analog supply for JESD204B ADC also required such a narrow acceptable voltage range? What is happened if it is wobbling within spec? Does that affects to linearity or other specs of ADC?

 

Could you give me your advice?

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