Patent ID: 7586361

Claim:
A semiconductor device comprising: a charge pump portion being inputted with first clock signals to output a boosted voltage; and converter portions being inputted with second clock signals to output the first clock signals, the converter portions comprising n boosting stages each of which includes a second capacitor element and comprising a plurality of boosting switch elements each of which is provided at least between adjacent ones of the boosting stages to connect and disconnect the second capacitor elements in series between a first voltage source and an output node of the converter portions in response to the second clock signals, wherein when at least one of the second capacitor elements is disconnected from other second capacitor elements, the at least one of the second capacitor elements is charged on the basis of a voltage difference between a second voltage source and a reference voltage, and the number of the second capacitor elements connected in series from the output node of the converter portions is controlled to each one of m and n (n>m>0) or to each one of 0, m, and n (n>m>0) according to the voltages of the first and the second voltage sources when the boosting switch elements conduct connecting operation.