LOW-PASS FILTER, HIGH-PASS FILTER, BAND-PASS FILTER, BAND REJECTION FILTER, FILTER AND RADIO COMMUNICATION DEVICE

摘要

PROBLEM TO BE SOLVED: To provide various kinds of filters that negate the need of a large area on an integrated circuit and have excellent frequency characteristics, and further to provide a radio communication device.;SOLUTION: A low-pass filter that causes an input signal from an input terminal to pass such that an attenuation amount of a signal component with a cut-off frequency not less than that set beforehand becomes not less than a predetermined amount and outputs the input signal from an output terminal comprises: a semiconductor element connected between the input terminal and the output terminal; and a capacity connected between the output terminal and a ground terminal. The semiconductor element includes: a semiconductor substrate; an acoustic wave propagation layer formed on the semiconductor substrate in a shape that has long sides with lengths according to the cut-off frequency and short sides shorter than the long sides; acoustic wave reflection layers formed at least on both ends of the acoustic wave propagation layer in a long side direction; a first contact that is formed on the acoustic wave propagation layer and is electrically connected to the input terminal; and a second contact that is formed apart from the first contact on the acoustic wave propagation layer and is electrically connected to the output terminal.;COPYRIGHT: (C)2013,JPO&INPIT