A modulated Class E transmitter is disclosed. In one embodiment of the invention,
the modulated Class E oscillator achieves high coil currents (1 A) and voltages
(500V) with low power components by precisely timed injection of current
when the oscillating current in the inductor passes through zero. A detector circuit
is used to trigger the current injection at the appropriate instant regardless
of changes in the resonant frequency of the system. Its phase can be adjusted to
compensate for propagation delays in the drive circuitry, while amplitude modulation
is accomplished by switching in additional reactive conductance to increase the
current injected into the tank circuit. Frequency modulation is accomplished in
an alternate embodiment.
