Apparatus and methods to control an electron beam of an x-ray tube are provided. One apparatus includes at least one of (i) a first switching unit having a voltage source and a pair of switches connected in series and configured to switch between open and closed positions to change an output voltage to engage or bypass the voltage source or (ii) a second switching unit connected to a voltage source and having a first pair of switches connected in series and a second pair of switches connected in series, wherein the first and second pair of switches are connected in parallel, and wherein the first and second pairs of switches are configured to switch between open and closed position to change an output voltage generated from the voltage source. The first and second switching units are connected in series and a third switching unit provided that is amplitude controllable.