Input Impeadance of AD9200 ( General Input Impedance of Unbuffered Switched Cap Input ADC's)

Discussion created by ChrisH Employee on May 5, 2011

For most UNBUFFERED switched-capacitor input ADC's the input impedance is


Zin =   1/(Ch * Fs)


(-- for example see "Design Of Analog Integrated Circuits And Systems", Laker & Sansen, p. 661. )


Ch is switched capacitance = 5pf for the AD9200.  Fs is sample rate.


Zin for the AD9200 running at 20Mhz fs is 10k ohms