Patent attributes
In a charge pump circuit provided with a positive electric potential generating charge pump circuit that generates a positive electric potential and a negative electric potential generating charge pump circuit that generates a negative electric potential, a parasitic bipolar transistor is prevented from turning on so that the charge pump circuit performs normal voltage boosting operation. First, the negative electric potential generating charge pump circuit is put into operation to generate −VDD as an output electric potential LV. Since the output electric potential LV is applied to a P-type semiconductor substrate, an electric potential of the P-type semiconductor substrate becomes −VDD. After that, the positive electric potential generating charge pump circuit is put into operation while the negative electric potential generating charge pump circuit continues its operation. The positive electric potential generating charge pump circuit performs the normal operation, because the electric potential of the P-type semiconductor substrate is −VDD. After the output electric potential HV of the positive electric potential generating charge pump circuit reaches 2VDD, the negative electric potential generating charge pump circuit is put into a second operation mode (inverting HV).
