Patent ID: 7477097

Claim:
An internal voltage generating circuit, comprising: a back bias voltage detector for detecting a level difference between a back bias voltage and a reference voltage; a period controller for controlling a period of an oscillating signal based on a detecting signal of the back bias voltage detector; and a pumping unit for pumping the back bias voltage according to an activation period of the oscillating signal, wherein the period controller includes: an initial signal generator for generating an initial signal in response to the detecting signal, a power-up signal and an enable signal; an enable signal generator for generating the enable signal having a delay time controlled by the power-up signal; a shift register unit for counting the initial signal according to the detecting signal in activation condition of the enable signal and outputting plural count signals; a decoder and latch unit for decoding and latching the plural count signals and outputting plural pumping control signals; and a pumping voltage oscillator for controlling capacitance according to conditions of the plural pumping control signals and outputting the oscillating signal having different periods.