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VOLTAGE MULTIPLICATION AND DIVISION EMPLOYING ACTIVE SWITCHING

IP.com Disclosure Number: IPCOM000006121D
Original Publication Date: 1991-Apr-01
Included in the Prior Art Database: 2001-Dec-05
Document File: 2 page(s) / 92K

Publishing Venue

Motorola

Related People

Homer Webb: AUTHOR

Abstract

Charging capacitors in parallel followed by switching them in series for voltage multiplication and conversely for voltage division usually requires the switching signal to power the charging path. This process is generally suitable only for low power applications as a result.

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MOTOROLA INC. Technical Developments Volume 12 April 1991

VOLTAGE MULTIPLICATION AND DIVISION EMPLOYING ACTIVE SWITCHING

by Homer Webb

   Charging capacitors in parallel followed by switching them in series for voltage multiplication and conversely for voltage division usually requires the switching signal to power the charging path. This process is generally suitable only for low power applications as a result.

  Increased power and utility can be obtained through the use of active switches, such as MOSFETs, to control the parallel and series connection of the voltage-multiplying capacitors. By using active switches, a voltage doubler circuit can be designed; the voltage doubler can then be replicated using series connections for greater voltage outputs or parallel connections for greater current outputs. Phase switching, e.g., for reduced noise, can be achieved by connecting several voltage doubler circuits in parallel and phase shifting the associated gate driver clocks.

  Two voltage doubler circuits that utilize high- speed switching diodes and high current MOSFET transistors are illustrated. Other active devices such as bipolar transistors or solid state relays can also be utilized to design voltage multipliers. The first circuit shown consists of two N-channel MOSFET transistors, one capacitor for voltage doubling, one capacitor for output filtering, and two switching diodes. A two-phase gate driver clock circuit, which can be derived from on-board counters or delay circuits, is required to counteract the switch-off and switch-on times of the MOSFET transistors. Voltage regulation surge circuits can be added, if desired. Note that single gate clock driver circuits can be implemented by using complementary MOSFET transistors as long as turn-on and turn-off parameters of the MOSFETs are observed. The clock circuit in

the drawing shows the phase overlap requirements of the gate driver clocks required by...