The Supertex HV440 is used for implementing a pulse width modulated high voltage ring generator for telecommunication applications. The HV440 can operate in both closed-loop or open-loop. A closed-loop design is more complex but provides better load regulation and lower THD compared to an open-loop design [...]
Source: http://www.supertex.com/pdf/app_notes/AN-H37.pdf

If you need a simple high voltage generator circuit here is your.The peak output voltage will be approximately 15,000 to 20,000 volts, but this will vary with the ignition coil type and the voltage at which the MOV starts conducting. Do not touch any part of the 555 circuit including any leads of the timing [...]

High-voltage drive is useful for driving electrodes in many applications. The challenge is to boost the output of a conventional op amp to high voltages.This Design Idea presents a simplified ac high-voltage amplifier that uses complementary, cascaded NMOS and PMOS transistors [...]
Source: http://www.edn.com/index.asp?layout=article&articleid=CA468423