Dramatically increasing voltage in a circuit
The current source must ideally be stored into a battery cell with 0.8V  or a suitable Cap before it is converted and kept about 0.8V within a 10% tolerance for acceptable MPT using half bridge.  This is how MPPT converters store energy.

If you use a transformer, the load impedance requires 5 to 10% of max current to couple energy to the secondary. Thus when you determine these parameters for max source energy, and equivalent source impedance who can decide if there is a suitable reactance to upconvert or use sub-threshold CMOS to transfer current with 0.8V Vgs and a suitable high inductance flyback coil.