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I'm currently working on designing a wideband bias tee and have been using LTSpice to simulate its performance. However, the results I'm obtaining seem too good to be true, and I'm concerned there might be an issue with my simulation setup.

I've attached the LTSpice screenshot for reference. Any advice or suggestions on how to improve the accuracy of this simulation would be greatly appreciated.

enter image description here

enter image description here

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    \$\begingroup\$ Typical inductors have very large parasitics that are relevant in the MHz range, and by 1 GHz most have an impedance dominated by their capacitance and so do not function as inductors. If you want to build GHz frequency filters, you'll need to pay careful attention to the inductor selection and its parasitics. Coilcraft has some white papers on this if you're interested. \$\endgroup\$
    – user1850479
    Commented Aug 7 at 0:43
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    \$\begingroup\$ What components are you using (part number)? Have you set up the models (SPICE or translated s1p file)? I gather you haven't extracted a PCB layout model either, which will be relevant at these frequencies. \$\endgroup\$
    – Tim Williams
    Commented Aug 7 at 0:47
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    \$\begingroup\$ Plot with a logarithmic frequency axis to better see the behavior \$\endgroup\$
    – The Photon
    Commented Aug 7 at 1:13

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Probably the actual performance is limited by all the parasitics that are not included in your model.

By the way, the graph doesn't seem to show anything.

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    \$\begingroup\$ The graph shows exactly what the circuit is: flat frequency response for all frequencies well above cutoff. \$\endgroup\$
    – Tim Williams
    Commented Aug 7 at 0:48

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