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ADG904 (2)

Question asked by FreddyS on Mar 12, 2014
Latest reply on Mar 12, 2014 by EricC

Hi Eric

I am facing problems to reply to you in my last post. Your answer was: 

 

I think there are a few things to consider here in this crystal switching application.  It sounds like your shunt load conditions for the TCXO are up to 10pF-10kohm (in parallel) followed by a high impedance input IC.  If my assumption is wrong let me know.  In the high impedance IC termination case the ADG904 switch will have an attenuating effect on your sine-wave signal.  Added in some large value series resistors to the switch should help e.g. 10k+. 

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My answer is:

I am not sure I understand why the switch will attenuate the sine-wave of the TCXO?

If I understand the switch correctly, it is a pair of CMOS transistors with very low capacitance to ground (3pF according to data sheet).

The RDSON should be very low, according application note http://www.analog.com/static/imported-files/application_notes/AN_952.pdf

It should be below 8 Ohm for signal levels below 1V.

Please clarify.

Thanks

 

 

 

 

 

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