High voltage generating circuit and method of operating the same

摘要

A high voltage generating circuit includes first and second high voltage pump circuits and an oscillator. The oscillator is configured to output a first clock signal driving the first high voltage pump circuit and a second clock signal driving the second high voltage pump circuit. The oscillator includes a first delay circuit configured to output the second clock signal by delaying the first clock signal by a first delay time. The first delay circuit is configured to adjust the first delay time according to a period of the first clock signal.

主权项

1. A method of operating a high voltage generating circuit comprising:
using an adjustable oscillator to generate a first pumping clock signal by delaying a clock signal by a first delay time; performing a first charge pumping operation using a first high voltage pump circuit in response to the first pumping clock signal; using a first adjustable delay circuit to generate a second pumping clock signal by delaying the first pumping clock signal by a second delay time; performing a second charge pumping operation using a second high voltage pump circuit in response to the second pumping clock signal; generating an output voltage in response to the first and second charge pumping operations; using a level detector to detect a level of the output voltage; and activating the adjustable oscillator when the level of the output voltage is not greater than a target voltage, else inactivating the adjustable oscillator when the level of the output voltage is greater than the target voltage.