Patent ID: 8222951
Filing Date: 2012-07-17
Classification: G05F,H01L

Abstract:
1. A semiconductor device having a first operation section operable at a first power supply voltage, a second operation section operable at a second power supply voltage differing from the first power supply voltage and a bias generation circuit, the bias generation circuit comprising: a first power supply voltage input section that inputs the first power supply voltage; a second power supply voltage input section that inputs the second power supply voltage; a regulator circuit that generates a back bias voltage on the basis of the second power supply voltage, the back bias voltage being varied in accordance with a combination of bit values inputted to the regulator circuit; a selector that selects either the first power supply voltage or the back bias voltage generated by the regulator circuit as an output voltage; an output section that outputs the output voltage; and a short circuit that short-circuits the back bias voltage to the first power supply voltage to equalize potentials of the back bias voltage and the first power supply voltage, wherein the regulator circuit is turned off and the short circuit is turned on when power is applied to the semiconductor integrated circuit apparatus or when a source of the second power supply voltage is tuned off while the regulator circuit operates, and when the second voltage source is turned on before the first voltage source is turned on in response to the semiconductor device being switched on, the second power supply voltage is turned off, the short circuit is turned on, and the regulator circuit is turned off in response to the semiconductor device being switched off while the first power supply voltage is maintained on, and thereafter the first power supply voltage is turned off.