Part Number: LMH32401
Champs:
Please help to comment those 2 questions from my cust.
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Please see the below posted pic.
Q1. "Is the impedance configuration in Figure 8-3 designed to match the RACDIN of the ADC in Figure 8-1?"
Q2. "The 1uF capacitor in Figure 8-3 is intended to form an AC coupling circuit with the (50 ohn impedance.
If I replace the 50 ohm) resistor with a 1M ohm resistor, would it be feasible?
Please comment, thanks.
BR Rio
"
Hello Rio,
Q1
The 20Ohm differential output impedance is an intended characteristic of the device. The finite output impedance helps isolate the reactance which would be expected on the PCB. Traditionally, we see many customers place similar value resistors close to the device on the PCB. This architecture lends itself to further performance through integrating the resistors directly on die. This resistance however needs to be factored into the transfer function, as shown here:
Q2:
The 1uF plus 25Ohm network is being used to convert the differential output to be 50Ohm single ended reference.
What is the goal for the high input impedance connection? 1MOhm is possible, though the impedance mismatch will likely introduce reflection in a transmission line.
Thanks,
Jacob
