Patent ID: 7298199

Claim:
A substrate bias voltage generating circuit, comprising: a charge pump for generating a substrate bias voltage in response to a clock signal; a first inverter type detector for detecting whether the substrate bias voltage reaches a target voltage; a second differential amplifier type detector for detecting whether the substrate bias voltage reaches the target voltage; a driver for generating the clock signal in response to an output of one of the first and second detectors; and a selector for generating a selection signal in response to a flag signal indicating whether an operating mode of a memory device is set up, wherein before the operating mode is set up, the first detector detects the substrate bias voltage in response to the selection signal, wherein the first detector comprises: an inverter type detection section; and a switch connected to the inverter type detection section, the switch for receiving an output of the inverter type detection section and the selection signal and outputting a first detection signal in response to the selection signal.