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circuit diagram

Thread Summary

The user inquires about the AD8307 log response circuit. The final answer provides specific values for C1, C2, and Rt in Figure 32, describes the 100 MHz log response data, confirms that following Table 5 and Fig 35 increases the gain, and states that the eval-board schematic matches Figure 32 with the noted values. Consider using AD8310 for a buffered output and faster response.
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Category: Hardware
Product Number: AD8307

Hello

My customer  want to start their design using AD8307.

But  would you please let us know ?

Please allow us such a basic questions.

Q1)

We understand the "basic connection" of the test circuit of Log responce; Fig 33 is Fig32.


But Could you please give us know the specific circuit schematic ? 


Q2)

Do you have Log Response Data in case 100 MHz whose circuit diagram is Table 5 and Fig 35 ?

Q3)

If customer followed Table5 and Fig 35 diagram, gain of Log responce will be increased instead of Fig 33 responce? 

Q4)

If you had  some Eval-board schematic of AD8307, it will be helpful for us

Best Regards

  • Answers are below. Note that you should consider using AD8310. It has similar sensitivity to AD8307 but it has a buffered output and a faster output response (which may or not matter to you). 

     

    Q1)

    We understand the "basic connection" of the test circuit of Log response; Fig 33 is Fig32. But Could you please give us know the specific circuit schematic ? 

     

    A1). Figure 32 is the exact schematic with the following values:

    C1=C2=10 nf

    Rt=52.3 ohms


    Q2)

    Do you have Log Response Data in case 100 MHz whose circuit diagram is Table 5 and Fig 35 ?

     

    A2) 

    We do not have that plot on hand. However I can describe it. Take the 100 MHz curve in Figure 33 and move it 13.3 dB to the left. So with the matching circuit, you will get the following output voltages.

    Pin                 Vout

    -43.3 dBm     1.5 V

    -23.3 dBm     2 V

    -3.3 dBm        2.5V

     

    Q3)

    If customer followed Table5 and Fig 35 diagram, gain of Log responce will be increased instead of Fig 33 responce? 

     

    A3) That is correct. The intercept will move to the left. The slope will not change

     

    Q4)

    If you had  some Eval-board schematic of AD8307, it will be helpful for us

     

    A4) The schematic of the evaluation board is the same as I described above, that is Figure 32 with the values noted above. 

     

  • Dear Mr Enash

    Thank you for your quick answer! 

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