1. An apparatus comprising: a programmable ring oscillator; a charge pump circuit coupled with the programmable ring oscillator to provide a first voltage and a second voltage, wherein the second voltage is higher than the first voltage, wherein a boosting ratio of the second voltage to the first voltage is determined by control signals from the programmable ring oscillator; and a two stage level shifter (2SLS) circuit coupled with the charge pump circuit to: provide the second voltage to a word line of a memory array responsive to an access operation of the memory array.