playing with a design. feedback from the coupled inductor is given to the differential amplifier on the left. one side is bootstrapped to get the gain high enough
output from the differential amplifier goes to the inverter pair. I couldn't get the gain high enough here to saturate it into full swing, will have to play with it.
a complementary pair then drives the series resonant circuit output. the pair have to switch source and sink right when the current on the main tank crosses zero to get maximum resonance out of the tank.
the 90° phase shift is coming from the shunt resistor across the secondary winds of the coupled inductor. increasing this resistance makes the oscillator easier to start but reduces the maximum voltage as the phase shifts too far away from the optimal 90°.
