Rolf Bombach has proposed the following circuit to increase the input impedance of a source follower with bip. Trans. And Bootstrapping:
The real part of the input impedance at 100 MHz is now 2.57 kOhm.
The input capacitance at the gate is only1 / (608.55883 kOhm * 2 * Pi * 2 MHz) = 131 fF.
wow - awesome for some applications