Communication device, non-contact type ic card mounting same, and information apparatus

Abstract

A communication device able to share one antenna and in addition able to sufficiently exhibit characteristics of a function as a reader, writer and a card function, a non-contact type IC card provided with that, and an information apparatus, wherein the device has a first transmission circuithaving first and second output terminals and outputting a carrier from the first and second output terminals in a first mode; an antenna circuitincluding a node ND, an inductorhaving one end connected to the node, and having the other end connected to the second output terminal of the first transmission circuit, and a capacitorconnected between the node and the first output terminal of the first transmission circuit; a second transmission circuitconnected to the node of the antenna circuit and outputting the transmission data in a second mode; at least one reception circuitconnected to the node of the antenna circuit and performing reception processing with respect to data received at the antenna circuit; and a circuit switch unitforming the antenna circuit as a serial resonance circuit including the inductor and the capacitor in the first mode and forming the antenna circuit as a parallel resonance circuit including the inductor and the capacitor in the second mode.