Transceiver, modulation integrated circuit, and RFID reader/writer

• US 7,822,388 B2
• Filed: 10/17/2006
• Issued: 10/26/2010
• Est. Priority Date: 10/31/2005
• Status: Active Grant

• Current Assignee: Omron Corporation
• Original Assignee: Omron Corporation
• Inventors: Yamasaki, Kazushi
• Primary Examiner(s): Anderson; Matthew D
• Assistant Examiner(s): Tsvey; Gennadiy
• Application Number:
  US11/581,484
• Publication Number:
  US 20070096878A1
• Time in Patent Office: 1,470 Days
• Field of Search: 375/239
• US Class Current: 455/73
• CPC Class Codes: H04B 1/40 Circuits

Abstract

In a transceiver that selectively transmits a modulated wave and a non-modulated wave to the outside, and receives a response signal from the outside, an S/N ratio during reception is improved. A transceiver, which selectively transmits a modulated wave and a non-modulated wave to the outside, and receives a response signal from the outside, includes an oscillator generating a predetermined carrier wave; a modulator modulating the carrier wave generated by the oscillator with a transmitted baseband signal to generate the modulated wave; a power amplifier amplifying the modulated wave being modulated by the modulator, or the non-modulated wave being not modulated by the modulator; and a circulator for sending output of the power amplifier to an antenna. When the non-modulated wave is transmitted from the antenna, switches are switched to a bypass circuit side such that the oscillator is directly connected to the power amplifier.

Claims

1. A transceiver, which selectively transmits a modulated wave to a tag when transmitting a transmitted signal to the tag and a non-modulated wave to the tag when receiving a response signal from the tag, comprising:

an oscillator generating a predetermined carrier wave,

a modulator modulating the carrier wave generated by the oscillator to generate the modulated wave,

a transmission unit transmitting the modulated wave being modulated by the modulator or the non-modulated wave being not modulated,

a control unit for causing the transmission unit to transmit the modulated wave to the tag through the modulator when the transmitted signal is transmitted to the tag, and for directly connecting the oscillator to the transmission unit while bypassing the modulator and causing the transmission unit to transmit the non-modulated wave to the tag when the response signal from the tag is received, and

a bypass circuit for bypassing the modulator by directly connecting the oscillator to the transmission unit, wherein when the transmission unit transmits the non-modulated wave, the control unit transmits the non-modulated wave to the transmission unit via the bypass circuit,

wherein a switch for routing through one of the bypass circuit or the modulator is provided between the oscillator and the transmission unit, and the control unit performs selection of whether the oscillator is connected to the modulator, or directly connected to the transmission unit, by controlling the switch, so that one of the modulated wave or the non-modulated wave is transmitted from the transmission unit.

2. A modulation integrated circuit, which selectively transmits a modulated wave to a tag when transmitting a transmitted signal to the tag and a non-modulated wave to the tag when receiving a response signal from the tag, comprising:

a carrier wave input terminal for inputting the carrier wave from the outside,

a modulator for modulating the carrier wave inputted from the carrier wave input terminal,

an output terminal for outputting the modulated wave modulated by the modulator, or the non-modulated wave,

a connection unit connecting the carrier wave inputted from the carrier wave input terminal to the output terminal while passing through the modulator when the modulated wave for transmitting the transmitted signal to the tag is outputted to the tag, and directly connecting the carrier wave to the output terminal without passing through the modulator when the non-modulated wave is outputted to the tag upon receipt of the response signal from the tag, according to a switching signal from the outside, and

a bypass circuit for bypassing the modulator by directly connecting the oscillator to the transmission unit, wherein when the transmission unit transmits the non-modulated wave, the control unit transmits the non-modulated wave to the transmission unit via the bypass circuit,

wherein a switch for routing through one of the bypass circuit or the modulator is provided between the oscillator and the transmission unit, and the control unit performs selection of whether the oscillator is connected to the modulator, or directly connected to the transmission unit, by controlling the switch, so that one of the modulated wave or the non-modulated wave is transmitted from the transmission unit.

3. An RFID reader/writer, comprising:

the integrated circuit according to claim 2.