load 102 of 200 u03c9 the absolute value of patient voltage 610 has a quite flat shape it hits a peak of about 2 kv but remains for nearly the entire impulse at about 1 8 kv as shown in fig6 in practical systems the preference is to deliver substantially constant energy to the patient during a period of time thus if a 200 joule therapeutic shock is desired to be delivered in a 10 msec period the controller circuit 107 is designed or programmed to obtain a current level in the inductor 104 that delivers 20 j msec the controller circuit 107 in connection with the current sensing network 109 the desired current profile 110 and the solid state switch 108 forms a feedback loop that controls and maintains the 20 j msec level or such other level or waveform as desired except for parasitic losses explained below the storage capacitor 103 need only have a rated energy storage capacity of 200 joules since no excess energy is dumped and it is desired to leave no residual energy in the storage capacitor 103 after the therapeutic shock has completed fig7 a f illustrate the manner in which the boost converter circuit 100 of fig1 may be used to control the shape and or phase of the defibrillating waveform applied to the patient as described previously with respect to fig1 current drawn through the switch 108 is measured by the current sensing network 109 compared to a desired current profile 110.