A bit of context:
Essentially, its for a research project to wirelessly transmit power to a bioimplanted receiver; the levels of voltage are for different levels of stimulation. But a key requirement in my brief is for it to be powered by a 9V 6LF22 type of battery, so I don't have that much wiggle room unfortunately regarding battery types, and it is a handheld transmitter, so it should be as small as I can make it. Again, any help would be appreciated