Multi-stage charge pump without threshold drop with frequency modulation between embedded mode operations

Abstract

A multimode charge pump circuit has a single charge pump that is responsive to a set of clock signals. The set of clock signals is provided in a first mode with a variable frequency according to a first function of the supply potential and temperature, and in a second mode with a variable frequency according to a second function of the supply potential and temperature. Circuitry configures all of the plurality of stages in series during the first mode in order to produce a higher voltage output, and configures a subset of the plurality of stages in series, while disabling the other stages, during the second mode in order to produce a lower voltage output. A precharge circuit is provided that operates as a supply node in the second mode, and as a precharge/clamp in the first mode.