High Voltage, High Efficiency Sine Wave Generator That Prevents Spikes During Amplitude Adjustments and Switching of Channels

An apparatus for generating AC electrical signals for application to a first pair of electrodes and a second pair of electrodes, the apparatus comprising:

• an AC voltage generator having an output;
• an electronic switch having an input that receives the output of the AC voltage generator, a first power output, and a second power output, wherein the electronic switch is configured to (a) operate in a first mode that routes the output of the AC voltage generator to the first power output, and (b) operate in a second mode that routes the output of the AC voltage generator to the second power output, and wherein the electronic switch is further configured to cycle through a repeating sequence that includes the first mode and the second mode;
• and
• a controller configured to synchronize the operation of the AC voltage generator and the electronic switch such that whenever the electronic switch switches to either the first mode or the second mode, the instantaneous output of the AC voltage generator has a magnitude that is below a threshold at which a subject being treated begins to experience a perceptible sensation,
• wherein, within 20 ms after the electronic switch switches to either the first mode or the second mode, the AC voltage generator's output voltage is at least 80% of the AC voltage generator's steady-state output voltage.