Patent ID: 7710219
Filing Date: 2010-05-04
Classification: H01P,H03D

Abstract:
1. A multiplexer circuit comprising: a common terminal for conducting a first signal having a first frequency and a second signal having a second frequency different from the first frequency; a first terminal for conducting the first signal, the first terminal being electrically coupled to the common terminal; a second terminal for conducting the second signal, the second terminal being electrically coupled to the common terminal; a first transmission line having a first end coupled to the first terminal and a second end coupled to the second terminal, the first transmission line having an electrical length substantially equal to a quarter wavelength of the first frequency and a first characteristic impedance at the first frequency; and a first low-impedance circuit electrically directly connecting the second end of the first transmission line to a circuit ground, the first low-impedance circuit providing at the first frequency an impedance that is less than half of the first characteristic impedance, and the first transmission line and the first low-impedance circuit in series combination together providing at the first frequency a first high impedance to the circuit ground at the first end of the first transmission line.