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I'm looking for a circuit topology that has unity gain, a 50 Ohm resistive input impedance, a 50 Ohm resistive output impedance, and here is the kicker, at least 60 dBm OIP3 over a 2 - 30 MHz HF bandwidth. I have tried a VMOS FET in a common gate configuration, and by adjusting the drain current to give a Gm of 20 mmhos, I get my 50 Ohm input impedance, but I only see 47 dBm of IP3. This circuit will terminate a Norton HF LNA preamp. Thanks for any suggestions - W6DSR

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    $\begingroup$ Why wouldn't a non-inductive resistor work as a terminator? $\endgroup$ – Mike Waters Nov 20 '19 at 21:42
  • $\begingroup$ Because the following appliance would also have a 50 Ohm input impedance and thus present a 25 Ohm impedance to the source. My circuit needs two ports, an input of 50 + j0, an output = 50 +j0, and a gain from the input port to the output port of 1. (or some gain would be great as long as IP3 is > 60 dBm.) $\endgroup$ – W6DSR Nov 21 '19 at 22:43

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