Patent ID: 6067336
Filing Date: 2000-05-23
Classification: H03L

Abstract:
A charge pump comprising:an output terminal for generating an output voltage;a constant current source for providing a first constant current and a second constant current;a charging transistor, responsive to the first constant current, for providing a charging current, the charging transistor having a drain node;a discharging transistor, responsive to the second constant current, for providing a discharging current, the discharging transistor having a drain node;a first pair of switching transistors, respectively connected to the charging transistor at the drain node thereof and responsive to a first pair of complementary control signals, for selectively conducting the charging current;a first pair of transistors, each of the first pair of the transistors being coupled to respective one of the first pair of switching transistors for conducting the charging current to the output terminal, each of the first pair of transistors being controlled by the output voltage and being set to operate in saturation region such that a voltage of the drain node of the charging transistor keeps a substantially constant value during transition of the first pair of complementary control signals;a second pair of switching transistors, respectively connected to the discharging transistor and responsive to a second pair of complementary control signals, for selectively conducting the discharging current; anda second pair of transistors, each of the second pair of the transistors being coupled to respective one of the second pair of switching transistors for conducting the discharging current to a reference ground, each of the second pair of transistors being controlled by the output voltage and being set to operate in saturation region such that a voltage of the drain node of the discharging transistor keeps a substantially constant value during transition of the second pair of complementary control signals.