Staas & Halsey
DC-DC converter
 A DC-DC converter includes first and second MOS transistors which selectively connect a first capacitor to a DC power supply so as to charge the first capacitor, and third and fourth MOS transistors which selectively connect the first capacitor to a second capacitor so as to charge the second capacitor by electric charges stored in the first capacitor. A predetermined output voltage is produced at a lead of the second capacitor serving as an output terminal, based on the charge/discharge operations of the first and second capacitors in response to the switching operations of the four MOS transistors. A variable voltage is applied to a back gate of one MOS transistor selected from the first to fourth MOS transistors. When the selected MOS transistor is on, a first control transistor in the converter forms a connection between a source and a back gate of the selected MOS transistor, to reduce the resistance value of the selected MOS transistor when turned on. When the selected MOS transistor is off, a second control transistor in the converter applies a voltage, selected from the predetermined output voltage and the supply voltages of the first and second DC power supplies, to the back gate of the selected MOS transistor. This prevents a parasitic bipolar transistor, inherently formed in the selected MOS transistor, from turning on. 
Fujitsu Limited
H H
H03K H02M
additional inventional
Hidenobu Hiroko
Ito Mizuno