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reg interconnecting two chips

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I am working on a project where we have to interface a sensor and an A/D converter. the sensor output is differential centered around common mode of 1.5V (this is designed for the ADC). the sensor specs say nominal output impedance is 100 ohm and max load capacitance is 20 pf. also the ADC spec says the input cap is 7pf. Now i think these can be interconnected without any signal drivers inbetween but not sure of the impedance matching/transmission line considerations ? how do i go about finding out the series/parallel resistance and cap to be added while interfacing these two components.
 

I don't think you need to use any additional R or C inbetween this sensor and the A/D converter. The sensor can easily handle 7pF and the ADC input impedance will not present to high load comparing with 100Ω.
If the ADC doesn't have differential inputs you may consider would be changing differential output into single ended using an opamp .. this will give you full output from the sensor, not just half ..
 

@IanP thanks for your reply. The ADC takes in differential input and it gives max performance when the common mode on the voltage is 1.5V. So I can just go ahead and interface the two components directly.

I was worried if any low pass filter is required before the ADC. In my system the same clock is provided to ADC and sensor and so should I think about a Low pass filter to filter out anything above the desired frequency ?

Also I wanted to ask this. the same clock is provided to the ADC and sensor through an external BNC connector(max 20 MHz). Can I route the signals directly and how do I make sure there is no delay between them ? Thanks in advance
 

LPF will not hurt .. but if you want to add one you will need to use a buffer ..
As far as delay is concerned, you can use couple of gates on the path to ADC, which I presume is shorter than the truck to the sensor. This will give you option of adding some ns .. if you need them ..
 

Thanks. So If I am routing them manually from an external connector and I can make them run the same distance, then I dont need to have any gates since the delay is going to be the same ?
 

Similar length - similar delay ..
 

    C

    circuit

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cool thanks. so I dont have to worry about any impedances while interfacing the two components ie just connect them directly ?

I have a few more questions. I am providing different power supplies to the board 2.4V(DVDD) 3.5V (AVDD) 1V (ref) for sensor and 3V (AVDD and DVDD) for ADC. Now how do I go about providing power connectors ? Can I use regulators for 1V reference or use voltage divider from 3.5V ? I can create a power connector in Capture CIS as a new part and then how do I add the footprint ....generally for any part I create ?
 

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