My line buffer preamp
 

Hello

I've done, with Ltspice, a line buffer preamp with a gain of 1.4x , any opinions about it ?

Any improvements suggestions ?

I include the schematic and the asc file.

Thank

Bye

Gaetan

Looks a bit too much like an opamp :p Why not try single ended input?

Hello

Like that one ?

Bye

Gaetan

Yeah then instead of voltage feedback to the gate, how about current feedback to the source? Then a passive RF filter on the input, series L shunt C?

Hello

You mean moving it to between R10 and V3 ?

Thank

Bye

Gaetan

Between R10 and J3. J3's source.

Hello

I've just simulated the circuit with feedback between R10 and J3, the result are very bad.

Thank

Bye

Gaetan

It might be because of the 2nF (C4) capacitor - can't use a capacitor with CFB. Also the value of the feedback resistor probably needs reducing as its critical with CFB, unlike with VFB.

Hello

Your right, I've take out the capacitor and reduced the feedback resistor by half, but it may need more experiment since the thd is higher at -60db.

Thank

Bye

Gaetan

Hello

Here's the asc file of that last circuit with current feedback.

Thank

Bye

Gaaetan