• ADA4937-1的问题

    我的电路图如上图所示,其中ADA4937-1输出端的电阻应该是0欧姆。

    两个运放电路一模一样。

    我现在的问题是,不供任何信号,就这样的电路,加上电后,频谱仪设置为0-100MHz,幅度为-120~-20dB。

    这个时候就可以看到,70MHz附近会有个一些信号抬起来。大概比噪底-70dB提高5dB左右。

    实在找不到原因。

    另外还有一个问题。调制器IQ数据的滤波电容改成560pF对100MHz带宽数据有没有影响?

  • Request the schematic review with AD9251-80 and ADA4937-1

    Hi,

    My customer wnats to get your advice about their schematic with AD9251-80 and ADA4937-1.

    They used AD9251-65 and ADA4937-1 in their system, but now they will change the sampling frequency of their system.

    So they need your help.

    The sampling frequency…

  • Request Schematic Review about AD9258-125 and ADA4937-1

    Hello,

    My customer request your confirmation about their schematic.

    They used AD9251-65 and ADA4937-1 to LTE ICS Repeater.

    But now they want to change ADC from AD9251-65 to AD9258-125.

    As you know, these two devices are pin compatible, so they want…

  • ADA4937-1 drive AD9284

    Hi there,

    My customer is designing ADA4937-1 to drive AD9284 for his project. He follow AD9284-250EBZ schematic design, however there are some questions.

    1) In EVB circuit, ADA4937-1 IN+ & IN- are swapped compared to Fig19 in AD9284 DS. Is there any…

  • Inquiry about the design of the AD9258 and the ADA4937-1

    Hello,

    My customer will use ADA4937-1 and AD9258 at repeater application.

    1. Input voltage range of the Vocm pin in the ADA4937-1 is min 1.2V to max 3.8V. However, the VCM output of the AD9258 is 0.9V.

        The voltage ranges between the Vocm pin and the…

  • ADA4937 Gain resistors

    Hi,

    I'd like to know if there is any problem in using resistors of some kOhms as RF and RG for ADA4937 fully differential amplifier: I need a 2kOhms input impedance.

    Thanks.

  • Driver AD9253 using ADA4937

    Hi,

    I have designed a circuit by using an ADA4937-1. I used it to drive ad AD9253-125.

    As shown in the picture attached, the input is a single ended Vpp = 1,6V.

    The Vcm of the ADC is qual to 0,9V but, using this voltage as Vocm for ADA4937, the signal…

  • ADA4937 Load

    Hi,

    I'm simulating the ADA4937 Differential Ampliifier that I will use as ADC driver for the AD9255, with and without output filter.

    It seems that adding the output filter at tha ADA4937 leads to a huge distortion of the output signal.

  • ADA4937 Output series Resistor

    I'll drive the 14-bit AD9255 ADC, sampling a 35MHz signal at 88MHz, with a ADA4937.

    I read a couple of application notes, like AN742.

    So, "the key is to make the input look as "real" as possible to achieve a good impedance match".…

  • Correct layout of ADA4937-2

    Hello,

    The ADA4937-2 datasheet states that the ground and power planes should be cleared near the summing nodes and gives an example for the ADA4938-1:

    This is a bit confusing to me because it only looks like the polygon pour on the top layer is removed…