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ADL5513 back-terminating resistor of evaluation board

Hi,

I am basing my design of a log detector using the schematic of the evaluation board of the  ADL5513.

My question is about the value of the resistor R3. It is necesary to have that output impedance? It can be greater?

If I use no CL nor RL, the value of R3 afect the behavior of the detector?

I am using R4=0Ω and R5=R10=R2=RL=CL=Open

Here is the schematic extracted from the data sheet:

Already thankfull, Santiago

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  • Hi Santiago,

    Even when the location for CL is not populated, there is always some parasitic load capacitance, for example the input capacitance of the next stage, or input capacitance of a voltmeter connected to the output. Resistor R3 is there to help when driving highly capacitive loads, or to help integrate the eval board into the system design (datasheet page 24). There's no rule that R3 must equal 1k.

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  • Hi Santiago,

    Even when the location for CL is not populated, there is always some parasitic load capacitance, for example the input capacitance of the next stage, or input capacitance of a voltmeter connected to the output. Resistor R3 is there to help when driving highly capacitive loads, or to help integrate the eval board into the system design (datasheet page 24). There's no rule that R3 must equal 1k.

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