A digital broadcast demodulator receives a tuner signal output from a tuner and carries out demodulation processing on the tuner signal by using an internal clock signal that is synchronized with a reference signal. Such crosslinked polymers may be used to make polymer electrolyte membranes that may be used in electrolytic cells such as fuel cells. The GaN-based second material layer may be doped with a second conductive type impurity at a density that is less than a density of the first conductive type impurity in the first GaN-based material layer. Each protective boot includes an interior space for receiving a triaxial cable connector. An existing multiplier may be reconfigured into an adder tree to process the absolute difference results obtained in the first stage. More particularly, it relates to an electrical insulating material which is excellent in mechanical properties and durability, an electrical insulating cover produced from the material and a method of electrical insulation using the material.