Charge pump circuit

Abstract

There is provided a charge pump circuit which can prevent EMI noise of a frequency component independent of an operation clock frequency from occurring at the time of a change from a disable state to an enable state. The charge pump circuit includes a detection signal synchronization circuit which outputs a synchronization detection signal generated by synchronizing a detection signal outputted from a level detection circuit to a clock signal outputted from an oscillator circuit. The synchronization detection signal is used as a pump enable signal, and a first pump capacitance and a second pump capacitance in a pump circuit body are charged and discharged in response to the synchronization detection signal and the clock signal outputted from the oscillator circuit.

1 - 3 . (canceled) 
     
     
         4 . A charge pump circuit comprising:
 a plurality of charge pump circuit bodies, including a plurality of charge transfer elements coupled in series and a plurality of capacitive elements each coupled to a coupling path between adjacent charge transfer elements, which boost an external power supply voltage supplied from an external power supply to the charge transfer elements by charging and discharging adjacent capacitive elements alternately and output a boosted voltage higher than the external power supply voltage;   a level detection circuit which compares the boosted voltage outputted from the charge pump circuit bodies with a predetermined reference voltage and outputs a level detection signal according to a comparison result;   an oscillator circuit which outputs respective clock signals to the charge pump circuit bodies in response to the level detection signal outputted from the level detection circuit;   a plurality of detection signal synchronization circuits which one-to-one correspond to the charge pump circuit bodies, the number of detection signal synchronization circuits being the same as the number of charge pump circuit bodies, and output synchronization detection signals generated by synchronizing the level detection signal outputted from the level detection circuit to the respective clock signals outputted from the oscillator circuit to the charge pump circuit bodies,   wherein the capacitive elements in the charge pump circuit bodies are charged and discharged in response to the clock signals outputted from the oscillator circuit and the synchronization detection signals outputted from the detection signal synchronization circuits.