An issue about AD831

Dear Sir/Madam,

I wonder the  value for C1  C2  L1  Rr   Cc for below schematic, and how to calculate them.  Do you have any principle for the calculation.


  • 0
    •  Analog Employees 
    on Oct 21, 2015 1:32 AM

    Hi, Peng,

        The L & C's are generic placeholders for matching components, whose types and values depend on the application -- frequency, gain, noise figure, and input level capacity.  Assuming the source impedance is 50 ohm, you can choose to simply terminate the device's input with a 50 ohm resistor to ground (i.e., use a resistor in place of L1), and use C1 & C2 as DC block capacitors.

        Alternatively, if high sensitivity (high gain) over a narrow frequency range is desired, then you can use the L-C network to match the 50 ohm source to the device's input impedance (equivalent R & shunt C values vs. frequency are shown on TPC 15 on the datasheet (p. 6).  There are a number of tools on the web for calculating the needed component values.  E.g.,

    Impedance Matching Network Designer

    L-Match | Electronics and Electrical Engineering Tools | EEWeb Community

        The attached example shows calculated L-C values for a high-pass and a low-pass matching network for a 50 ohm source at 150 MHz.


  • 0
    •  Analog Employees 
    on Aug 2, 2018 3:14 PM
    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

    Thank you,
    EZ Admin