Method and associated apparatus of data extraction, including: sampling a signal and obtaining a plurality of sampled values, providing a reference sample quantity when the sampled values transit, providing a unit bit sample quantity according to the reference sample quantity, and corresponding each of the sampled values to each data bit of the signal according to the unit bit sample quantity. The metal gate transistor includes a substrate, a metal gate on the substrate, and a sourcedrain region in the substrate. By applying a supply voltage to the test mode enable bond pads through the NC pin, a test mode is initiated in the dice. As a result, when connection management by the private branch exchange develops a failure, the back-up device secures connection management in the network to which the back-up device is connected.