Patent ID: 6038431
Filing Date: 2000-03-14
Classification: H03J

Abstract:
A card-type electronic device for optional use without hardware modification of an apparatus by insertion into said apparatus, said device comprising:(a) a receiving system for selecting a desired channel from a digitally modulated signal, including:a signal input terminal supplied with a high-frequency signal;a mixer having an input port supplied with a signal from the signal input terminal and another input port for receiving an output of a local oscillator;an output terminal supplied with an output signal of the mixer;a PLL circuit having an input port for receiving the output of the local oscillator and a PLL signal output port for connection to an input of the local oscillator;a DC-DC converter connected to a power input terminal, an output of said DC-DC converter being connected to said PLL circuit so as to reduce a load on said apparatus in obtaining a tuning voltage;a data input terminal for supplying a data signal to said PLL circuit; anda digital signal processing means including at least one of an extraction means for performing a frequency conversion to extract a signal containing information of an absolute value from a carrier wave in a digitally-modulated output signal from said mixer and for use in digital signal processing of the extracted signal and an A/D converter connected between the mixer and the output terminal;wherein said mixer and said local oscillator are arranged in a vicinity of said signal input terminal so as to minimize input level attenuation;(b) a transmitting system for digitally modulated signal including:a transmission signal input terminal;digital modulation processing means connected to said transmission signal input terminal; anda transmission signal output terminal coupled to said digital modulation processing means; and(c) a card-type case having a protrusion to meet an increased circuit requirement, said receiving system and said transmitting system being packed in said card-type case;wherein said output terminal, said data input terminal, said power input terminal and said transmission signal input terminal are arranged on a lateral side of said case, and wherein said signal input terminal and said transmission signal output terminal are coupled to a duplexer connected to a single signal input/output terminal so as to prevent an output signal from said digital modulation processing means from circumventing into the receiving system.