Patent ID: 6294950
Filing Date: 2001-09-25
Classification: H02M,Y02B

Abstract:
A charge pump circuit having a variable oscillation period, comprising:a voltage divider for dividing a boosting voltage to a predetermined level;a voltage level sensing unit for sensing a voltage difference between a divided voltage from the voltage divider and a reference voltage, and for outputting a control voltage corresponding to the sensed voltage difference;an oscillator circuit for varying an oscillation frequency of a pulse signal in accordance with the control voltage outputted from the voltage level sensing unit; anda charge pump for performing a pumping operation in accordance with the pulse signal from the oscillator circuit, and for outputting the boosting voltage, wherein the oscillator circuit comprises,a current source for generating a reference current in accordance with the control voltage from the voltage level sensing unit,a plurality of current mirrors including first to fifth current mirrors each connected to the current source to output first to fifth source currents,a ring oscillator including a first to the fifth inverters each connected between a corresponding one of the current mirrors and a ground to vary the oscillation frequency in accordance with a corresponding one of the first to fifth source currents, andan output buffer for buffering an output from the ring oscillator, and for outputting the pulse signal.