Patent ID: 7196553

Claim:
A signal detection device, comprising: an internal power supply voltage generation circuit for generating an internal power supply voltage from a power supply voltage; an input circuit for receiving at an input terminal thereof pulse signals; a first pull-up element for pulling up the input terminal of the input circuit to the internal power supply voltage; a first pull-down element for pulling down the input terminal of the input circuit to a ground potential; a first pair of switches for electrically connecting the first pull-up element or first pull-down element to the input terminal of the input circuit; an amplifier for receiving at an input terminal thereof output signals of the input circuit; a second pull-up element for pulling up the input terminal of the amplifier to the internal power supply voltage; a second pull-down element for pulling down the input terminal of the amplifier to the ground potential; a second pair of switches for electrically connecting the second pull-up element or second pull-down element to the input terminal of the amplifier; and a failure inspection circuit for controlling the connection of said first and second pair of switches in a predetermined sequence and measuring the internal power supply voltage when power supply is started up, so as to inspect said input circuit and said amplifier.