Abstract: A charge pump circuit comprises an input terminal for receiving an input voltage, an output terminal for providing an output voltage, and a plurality of pump stages connected in series between the input and output terminals and alternately coupled to first and second clock signals having complementary states. Each of the pump stages includes a transistor having a gate terminal, a source terminal, a drain terminal, and a bulk terminal, and a capacitor connected between the gate terminal of the transistor and a corresponding one of the clock signals. Each bulk terminal is biased by the voltage of a previous pump stage driven by the same clock signal, so that each of the corresponding threshold voltages of the transistors is suppressed to a voltage sufficient for generating a higher voltage on a low power supply voltage regardless of body effect.

Abstract: Methods of programming multi-state memory devices include the steps of programming a nonvolatile multi-state memory cell (e.g., EEPROM) from a reference state (e.g., erased state) towards a first program state, by applying a first program voltage (V.sub.pgm) thereto. The first program voltage is preferably applied for a first predetermined time interval so that sufficient Fowler-Nordheim tunneling of electrons can occur into the cell's floating gate to cause a shift in the cell's threshold voltage from the reference state (e.g., Vth=-2 V) to a first program state (e.g., -1 V.ltoreq.Vth.ltoreq.-0.5). To verify the step of programming the memory cell into the first program state, a operation is performed by a sense amplifier to sense a first state of the memory cell, upon application of a first reference voltage thereto.