Patent ID: 7705660

Claim:
A substrate bias voltage generator comprising: a substrate bias voltage detection unit configured to compare a level of a substrate bias voltage with a reference voltage in response to a self-refresh signal, an idle signal, and a refresh count signal so as to output an oscillating driving signal, to enable the oscillating driving signal when the substrate bias voltage is equal to or higher than a first level in a normal mode, to disable the oscillating driving signal when the substrate bias voltage is at a second level in a self-refresh mode, and to disable the oscillating driving signal when the substrate bias voltage is at a third level in the self-refresh mode; an oscillation unit having an input to receive the oscillating driving signal and an output to output an oscillating signal according to the oscillating driving signal; and a voltage pumping unit configured to control pumping of the substrate bias voltage according to the oscillating signal and to output a pumped substrate bias voltage, wherein the pumped substrate bias voltage in the normal and self-refresh modes are different levels and wherein the substrate bias voltage detection unit includes: a pulse generation unit configured to receive the idle signal and to output a pulse having a predetermined width in response to the idle signal; a latch unit configured to receive the pulse of the pulse generation unit and the refresh count signal and to output a substrate bias voltage rising signal in response thereto, the substrate bias voltage rising signal being enabled when the refresh count signal is enabled; a regulator coupled between a reference voltage input terminal and a substrate bias voltage input terminal and configured to detect the level of the substrate bias voltage in response to the self-refresh signal and the substrate bias voltage rising signal and to output an output signal from an output terminal; and a level shifter configured to received the output signal of the regulator and to output the oscillating driving signal in response thereto.