SUBSTRATE BIAS GENERATING DEVICE AND OPERATING METHOD THEREOF

摘要

A substrate bias generating circuit including waveform shaping circuits for producing two signals having different phases on the basis of signals in phase extracted from a ring oscillator and two logic gates using these two signals having large phase difference as inputs is disclosed. A first charge pump circuit is driven with one of outputs of these two logic gates and a second charge pump circuit is driven by the other output. First charge pump circuit and second charge pump circuit are electrically coupled to generate substrate bias alternately. Since the difference in phase of two signals inputted to the two logic gates respectively is so large that a possibility is reduced of occurrence of a period in which both of input potential to charge pump circuit and input potential to charge pump circuit are at a low level even if a rise speed and a fall speed of input potential to charge pump circuit greatly differ from a fall speed and a rise speed of input potential to charge pump circuit, respectively. Operation margin of charge pump circuits thus increases.