Semiconductor integrated circuit and non-contact electronic device using the same

• US 20070249398A1
• Filed: 04/19/2007
• Published: 10/25/2007
• Est. Priority Date: 04/21/2006
• Status: Active Grant

• Current Assignee: Renesas Electronics Corporation
• Original Assignee: Renesas Technology Corporation (Renesas Electronics Corporation)
• Inventors: Watanabe, Kazuki, Tsunoda, Hisataka, Funane, Tetsuo
• Granted Patent: US 8,198,983 B2
• Time in Patent Office: Days
• US Class Current: 455/558
• CPC Class Codes: G06K 19/0707 the arrangement being capable of collecting energy from external energy sources, e.g. thermocouples, vibration, electromagnetic radiation G06K19/0702 takes precedence
• CPC Class Codes: G06K 19/0712 the arrangement being capable of triggering distinct operating modes or functions dependent on the strength of an energy or interrogation field in the proximity of the record carrier active means for hindering electromagnetic reading or writing G06K19/07336
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer

Abstract

Depending on the power supplied to the non-contact electronic device, the voltage suppression characteristic of the regulator function mounted in a power supply circuit is changed. When the power supplied to the non-contact electronic device is small, the voltage change amount of the voltage between antenna terminals for the current flowing in the antenna is increased, and when the power supplied to the non-contact electronic device is large, the voltage change amount of the voltage between the antenna terminals for the current flowing in the antenna is decreased. By this means, the current change of the entire consumption current for the current change of the load modulator (transmitting circuit) at the time of the long distance communication is increased.

Claims

1. A semiconductor integrated circuit, comprising:

first and second antenna terminals to which an antenna is connected;

a power supply circuit for performing rectification of signals between the first and second antenna terminals and voltage control; and

a load modulator for performing modulation of the signals between the first and second antenna terminals,

wherein, in a current-voltage characteristic between the first and second antenna terminals in a region where an output voltage of the power supply circuit reaches a predetermined voltage and a voltage suppression operation works, a voltage change slope in a first current region is larger than a voltage change slope in a second current region having a higher current than that of the first current region.

2. The semiconductor integrated circuit according to claim 1,

wherein the load modulator has a function to switch the current-voltage characteristic between the first and second antenna terminals in the region where the voltage suppression operation works to either of a first characteristic in which the voltage change slope in the first current region is larger than the voltage change slope in the second current region or a second characteristic in which the voltage change slope in the first current region and the voltage change slope in the current region are equal.

3. The semiconductor integrated circuit according to claim 1,

wherein the power supply circuit has a first voltage controlled circuit and a first voltage detector,

the first voltage controlled circuit is provided with a first input terminal and a first output terminal,

between the first input terminal and the first output terminal, a first MOS transistor having a first resistor and a second resistor connected in series between a gate and a drain thereof is connected,

between a connecting point of the first resistor and the second resistor and a ground terminal, a second MOS transistor whose gate is connected to the first input terminal and a third MOS transistor are connected in series,

between the gate of the first MOS transistor and the ground terminal, a fourth MOS transistor whose gate is connected to the first input terminal, a current limiter, and a fifth MOS transistor are connected in series,

the gates of the third MOS transistor and the fifth MOS transistor are connected to an output terminal of the first voltage detector,

the current limiter controls current flowing between a drain and a source of the fifth MOS transistor, thereby controlling voltage which can be generated in the second resistor,

a first input terminal of the first voltage controlled circuit is connected to the first antenna terminal,

a first output terminal of the first voltage controlled circuit is connected to a power supply terminal, and

the first voltage detector outputs a voltage corresponding to a power supply voltage generated between the power supply terminal and the ground terminal.

4. The semiconductor integrated circuit according to claim 3,

wherein the power supply circuit further comprises a second voltage controlled circuit, a first rectifier element, and a second rectifier element,

the second voltage controlled circuit is provided with a second input terminal and a second output terminal,

the second input terminal of the second voltage controlled circuit is connected to the second antenna terminal,

the second output terminal of the second voltage controlled circuit is connected to the power supply terminal,

the first rectifier element is connected between the first antenna terminal and the ground terminal, and

the second rectifier element is connected between the second antenna terminal and the ground terminal.

5. The semiconductor integrated circuit according to claim 3,

wherein the current limiter is a fifth resistor.

6. The semiconductor integrated circuit according to claim 3,

wherein the current limiter comprises a fifth resistor and a tenth MOS transistor connected in series, and

the tenth MOS transistor serves also as the load modulator.

7. The semiconductor integrated circuit according to claim 3,

wherein a resistance value of the second resistor is larger than a resistance value of the first resistor.

8. The semiconductor integrated circuit according to claim 1,

wherein the power supply circuit comprises a third voltage controlled circuit and a first voltage detector,

the third voltage controlled circuit is provided with a third input terminal and a third output terminal,

between the third input terminal and the third output terminal, a sixth MOS transistor having a third resistor connected between a gate and a drain thereof and a fourth resistor are connected in series,

between the third output terminal and the ground terminal, a seventh MOS transistor is connected,

between the gate of the sixth MOS transistor and the ground terminal, an eight MOS transistor whose gate is connected to the third input terminal, a current limiter, and a ninth MOS transistor are connected in series,

the seventh MOS transistor and the ninth MOS transistor are connected to an output terminal of the first voltage detector,

the third input terminal of the third voltage controlled circuit is connected to the first antennal terminal,

the third output terminal of the third voltage controlled circuit is connected to a power supply terminal,

the current limiter controls a current flowing between a drain and a source of the ninth MOS transistor, thereby controlling a voltage which can be generated in the third resistor, and

the first voltage detector outputs a voltage corresponding to a power supply voltage generated between the power supply terminal and the ground terminal.

9. The semiconductor integrated circuit according to claim 8,

wherein the power supply circuit further comprises a fourth voltage controlled circuit, a first rectifier element, and a second rectifier element,

the fourth voltage controlled circuit is provided with a fourth input terminal and a fourth output terminal,

the fourth input terminal of the fourth voltage controlled circuit is connected to the second antenna terminal,

the fourth output terminal of the fourth voltage controlled circuit is connected to the power supply terminal,

between the first antenna terminal and the ground terminal, the first rectifier element is connected, and

between the second antenna terminal and the ground terminal, the second rectifier element is connected.

10. The semiconductor integrated circuit according to claim 8,

wherein the current limiter is a fifth resistor.

11. The semiconductor integrated circuit according to claim 8,

wherein the current limiter comprises a fifth resistor and a tenth MOS transistor connected in series, and

the tenth MOS transistor serves also as the load modulator.

12. A non-contact electronic device, comprising:

the semiconductor integrated circuit according to claim 1; and

an antenna connected to the first and second antenna terminals.