Radio power converter and radio communication apparatus

• US 8,862,054 B2
• Filed: 09/02/2010
• Issued: 10/14/2014
• Est. Priority Date: 09/08/2009
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Ishizaki, Haruya
• Primary Examiner(s): Hsien, Ping
• Assistant Examiner(s): Jia, Xin
• Application Number:
  US13/394,751
• Publication Number:
  US 20120183097A1
• Time in Patent Office: 1,503 Days
• Field of Search: 455/41.1, 455/41.2
• US Class Current: 455/41.1
• CPC Class Codes: H02J 50/001 Energy harvesting or scavenging
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/20 using microwaves or radio frequency waves
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices

Abstract

The present invention provides a radio power converter and a radio communication apparatus in which an environmental electromagnetic wave is efficiently converted into an operation power of a semiconductor integrated circuit by using a coil antenna configured within the semiconductor integrated circuit. The radio communication apparatus converts the received environmental electromagnetic wave into a direct-current voltage and charges a decoupling capacitor with an electric power so as to increase the direct-current voltage. A resonance frequencies of an antenna are changed depending upon a value of the increased direct-current voltages. The antenna sequentially receives environmental electromagnetic waves having different resonance frequencies for thereby increasing the direct-current voltage to a desired direct-current voltage.

Claims

1. A radio power converter operable to convert an inputted environmental electromagnetic wave into a direct-current voltage, comprising:

an antenna including a coil, a fixed capacitor, and a variable capacitor;

a rectifier which outputs a rectified signal from an alternate-current signal outputted from the antenna;

a decoupling capacitor which is charged with the rectified signal so that the rectified signal is held as a direct-current voltage; and

a VDD level determination circuit which divides the direct-current voltage being held and outputs N control signals (where N is a positive integer) to control a value of the variable capacitor,

wherein the antenna receives an environmental electromagnetic wave having the same frequency as an antenna resonance frequency to convert the environmental electromagnetic wave into an electric power that is to charge the decoupling capacitor and to thereby increase the direct-current voltage,

wherein the antenna resonance frequency is changed by varying the variable capacitor depending upon a value of the direct-current voltage increased,

wherein the antenna receives the environmental electromagnetic wave in a frequency band that corresponds to the direct-current voltage being increased and to thereby increase the direct-current voltage to a desired direct-current voltage, and

wherein an interval of assigning a voltage range of the direct-current voltage being increased specifies a single antenna resonance frequency to be set to the antenna and has a narrow voltage range as a value of the increased direct-current voltage becomes close to the desired direct-current voltage.

2. The radio power converter as recited in claim 1, wherein, the operation of increasing the voltage is stopped when the direct-current voltage has been increased to the desired direct-current voltage, and the operation of increasing the voltage is restarted when the increased direct-current voltage is lowered from the desired direct-current voltage.

3. A radio communication apparatus comprising:

the radio power converter as recited in claim 1;

a digital modulation signal generator; and

a modulator,

wherein the digital modulation signal generator outputs, to the modulator, a data sequence which is included therein and which is transmitted from the antenna coupled to the modulator.

4. The radio communication apparatus as recited in claim 3, wherein, the radio power converter starts the conversion to the direct-current voltage when it receives the environmental electromagnetic wave, and transmits the data sequence after the direct-current voltage has been increased to the desired direct-current voltage.

5. The radio communication apparatus as recited in claim 3, wherein, data are transmitted by reflecting the received environmental electromagnetic wave when data of the data sequence have a high level and by acquiring an operational power from the received environmental electromagnetic wave when the data of the data sequence have a low level.

6. The radio communication apparatus as recited in claim 3, wherein, the radio power converter is formed within a semiconductor integrated circuit.

7. The radio communication apparatus as recited in claim 6, wherein, the radio power converter is formed in the semiconductor integrated circuit with use of a standard CMOS logic.

10. The radio power converter as recited in claim 1, wherein, the radio power converter is formed within a semiconductor integrated circuit.

11. The radio power converter as recited in claim 1, wherein, the radio power converter is formed in the semiconductor integrated circuit with use of a standard CMOS logic.

8. A voltage increase operation method of a radio power converter that acquires an electric power from an environmental electromagnetic wave, comprising:

an antenna including a coil, a fixed capacitor, and a variable capacitor;

a rectifier which outputs a rectified signal from an alternate-current signal outputted from the antenna;

a decoupling capacitor which is charged with the rectified signal so that the rectified signal is held as a direct-current voltage; and

a VDD level determination circuit which divided the direct-current voltage being held and outputs N control signals (where N is a positive integer) to control a value of the variable capacitor,

wherein the direct-current voltage is a ground potential, and, when an antenna resonance frequency is a first antenna resonance frequency, the antenna performs a first step of receiving an environmental electromagnetic wave having the same frequency as the first antenna resonance frequency so as to increase the direct-current voltage to a first voltage and changing the antenna resonance frequency from the first antenna resonance frequency to a second antenna resonance frequency depending upon the value of the direct-current voltage increased to the first voltage,

wherein the antenna performs a second step of receiving an environmental electromagnetic wave having the same frequency as the second antenna resonance frequency so as to increase the direct-current voltage to a second voltage and changing the antenna resonance frequency from the second antenna resonance frequency to a third antenna resonance frequency depending upon the value of the direct-current voltage increased to the second voltage,

wherein the second step is repeated to increase the direct-current voltage to a desired voltage, and

wherein an interval of assigning a voltage range of the direct-current voltage being increased specifies a single antenna resonance frequency to be set to the antenna and has a narrow voltage range as a value of the increased direct-current voltage becomes close to the desired direct-current voltage.

9. The voltage increase operation method of a radio power converter as recited in claim 8, wherein, the radio power converter is formed within a semiconductor integrated circuit.

12. The voltage increase operation method of a radio power converter as recited in claim 8, wherein, the radio power converter is formed in the semiconductor integrated circuit with use of a standard CMOS logic.