Disclosed is a frequency error detector and combiner at a receiving end of a mobile communication system. The semiconductor device includes an internal voltage generator circuit configured to receive operation speed information to generate an internal voltage having a different level depending on the operation speed; and an internal circuit operated using the internal voltage. The locking member may include one or more locking elements that are compressed about the wire through engagement with a wedge-shaped locking section of the body, with the biasing member urging the locking member against the locking section. The oil clearance is provided on an optical path from the light emitting element to the color light receiving element.