Reference generator circuit and method for nonvolatile memory devices

Abstract

Reference generator circuitry for providing a reference to sense amplifiers in a flash memory device. The circuitry includes a reference current generator for generating a reference current for use by the sense amplifier circuits. A current buffer circuit in the flash memory device mirrors the reference current and applies a plurality of mirrored reference currents to the reference inputs of the sense amplifiers. A startup circuit is utilized in order to provide a fast settling time of the reference node appearing at the input of the sense amplifiers. The startup circuit includes first and second discharge current stages, with the first discharge current stage discharging the charge appearing at the reference node input of the sense amplifiers based upon a bandgap reference current. The second discharge current stage discharging the charge appearing at the reference node input of the sense amplifiers based upon the reference current. Each discharge current stage utilizes feedback to gradually decrease the rate of discharge by the discharge current stage so that the discharge current stages are disabled by the time the voltage appearing at the reference node input of the sense amplifiers reaches the desired voltage level.