Dual frequency HF-UHF identification integrated circuit

Abstract

A dual frequency HF-UHF RFID integrated circuit including a power supply. The power supply includes: an HF branch including an HF rectifier and a linear voltage regulator, wherein the HF rectifier is configured to be connected to a resonance circuit formed by a HF antenna-coil and a resonance capacitor and wherein the HF rectifier is connected to the linear voltage regulator; a UHF branch including a UHF rectifier and a shunt voltage regulator, wherein the UHF rectifier has a charge pump and is configured to be connected to a UHF antenna and wherein the UHF rectifier is connected to the shunt voltage regulator; and a supply line, wherein the linear voltage regulator and the shunt voltage regulator are both connected to the supply line of the power supply.

Claims

1. A dual frequency HF-UHF RFID integrated circuit comprising a power supply, the power supply comprising: an HF branch comprising an HF rectifier and a linear voltage regulator, wherein the HF rectifier is configured to be connected to a resonance circuit formed by a HF antenna-coil and a resonance capacitor and wherein the HF rectifier is connected to the linear voltage regulator; a UHF branch comprising a UHF rectifier and a shunt voltage regulator, wherein the UHF rectifier comprises a charge pump and is configured to be connected to a UHF antenna and wherein the UHF rectifier is connected to the shunt voltage regulator; and a supply line; wherein the linear voltage regulator and the shunt voltage regulator are both connected to the supply line of the power supply.

2. The RFID integrated circuit according to claim 1, wherein the linear voltage regulator is a series linear voltage regulator.

3. The RFID integrated circuit according to claim 2, wherein the series linear voltage regulator is a low-dropout series linear voltage regulator.

4. The RFID integrated circuit according to claim 1, wherein a first reference voltage is provided to the linear voltage regulator and a second reference voltage is provided to the shunt voltage regulator.

5. The RFID integrated circuit according to claim 1, wherein the linear voltage regulator and the shunt voltage regulator are provided with the same voltage reference.

6. The RFID integrated circuit according to claim 1, further comprising an output buffer capacitor arranged at the output of the linear voltage regulator.

7. The RFID integrated circuit according to claim 1, further comprising an output buffer capacitor arranged at the output of the shunt voltage regulator.

8. The RFID integrated circuit according to claim 1, wherein the HF branch further comprises an active diode arranged between the output of the linear voltage regulator and the supply line.

9. The RFID integrated circuit according to claim 1, wherein the supply line comprises an output buffer capacitor.

10. The RFID integrated circuit according to claim 1, further comprising a first output buffer capacitor arranged at the output of the linear voltage regulator.

11. The RFID integrated circuit according to claim 10, further comprising a second output buffer capacitor arranged at the output of the shunt voltage regulator.

12. The RFID integrated circuit according to claim 11, wherein the HF branch further comprises an active diode arranged between the output of the linear voltage regulator and the supply line.

13. The RFID integrated circuit according to claim 12, wherein the UHF branch further comprises an active diode arranged between the output of the shunt voltage regulator and the supply line.

14. The RFID integrated circuit according to claim 13, wherein the supply line comprises a third output buffer capacitor.

15. A dual frequency HF-UHF RFID integrated circuit comprising a power supply, the power supply comprising: an HF branch comprising an HF rectifier and a linear voltage regulator, wherein the HF rectifier is configured to be connected to a resonance circuit formed by a HF antenna-coil and a resonance capacitor and wherein the HF rectifier is connected to the linear voltage regulator; a UHF branch comprising a UHF rectifier and a shunt voltage regulator, wherein the UHF rectifier comprises a charge pump and is configured to be connected to a UHF antenna and wherein the UHF rectifier is connected to the shunt voltage regulator; and a supply line; wherein the linear voltage regulator and the shunt voltage regulator are both connected to the supply line of the power supply, and the UHF branch further comprises an active diode arranged between the output of the shunt voltage regulator and the supply line.

16. A dual frequency HF-UHF identification device comprising: a dual frequency HF-UHF RFID integrated circuit comprising a power supply, the power supply comprising: an HF branch comprising an HF rectifier and a linear voltage regulator, wherein the HF rectifier is configured to be connected to a resonance circuit formed by a HF antenna-coil and a resonance capacitor and wherein the HF rectifier is connected to the linear voltage regulator; a UHF branch comprising a UHF rectifier and a shunt voltage regulator, wherein the UHF rectifier comprises a charge pump and is configured to be connected to a UHF antenna and wherein the UHF rectifier is connected to the shunt voltage regulator; and a supply line; a resonance circuit formed by a HF antenna-coil and a resonance capacitor and connected to said HF rectifier; and a UHF antenna connected to said UHF rectifier.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) By way of example a, preferred, non-limiting embodiment of the invention will now be described in detail with reference to the accompanying drawing, in which:

(2) FIG. 1: is a schematic layout of the power supply of a dual frequency HF-UHF RFID integrated circuit according to the invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

(3) A preferred embodiment of the invention is described with reference to FIG. 1. FIG. 1 shows a power supply of a dual frequency HF-UHF identification device 10 comprising a RFID integrated circuit connected to an HF antenna coil 12 and to a UHF antenna 14. The power supply of the RFID circuit comprises a HF branch 16 and a UHF branch 18.

(4) The HF branch 16 comprises a HF rectifier 20 connected to a resonance circuit formed by the HF antenna coil 12 and the resonance capacitor 22. The resonance circuit provides an induced alternating voltage to the input terminals V.sub.1a and V.sub.1b of the HF rectifier 20. The output of the HF rectifier 20 is connected to a terminal of a smoothing capacitor 24 and provides a first DC supply voltage V.sub.HF. Alternatively or additionally, the HF rectifier 20 is associated to a voltage amplifying circuit for generating the first DC supply voltage V.sub.HF.

(5) The first DC supply voltage V.sub.HF is provided to the input terminal of a low-dropout series linear voltage regulator 25 for regulating the first DC supply voltage V.sub.HF. The low-dropout series linear voltage regulator 25 allows for regulating the voltage V.sub.HF even when the desired regulated voltage V.sub.HF,reg is very close to V.sub.HF. A first output buffer capacitor 26 is arranged at the output of the linear voltage regulator 25. The regulated voltage V.sub.HF,reg is provided to the input terminal of a first active diode 28. The first active diode 28 is configured so as to block a reverse current through the HF branch 16. It will be appreciated that the first active diode mitigates and/or suppresses voltage dropouts, when compared to passive diode such as a passive Schottky diode, and reverse current leakages (e.g. from the UHF branch 18).

(6) The UHF branch 18 comprises a UHF rectifier 30, comprising a charge pump, linked to the two wires of the UHF antenna 14. The UHF rectifier 30 receives at its two input terminals V.sub.2a and V.sub.2b an AC induced voltage. The UHF rectifier 26 provides at its output a second DC supply voltage V.sub.UHF.

(7) The second DC supply voltage V.sub.UHF is provided to the input terminal of a shunt voltage regulator 32 to absorb a shunt current so as to regulate the second DC supply voltage V.sub.UHF. The shunt voltage regulator 32 (providing the regulated voltage) is connected to the input terminal of a second active diode 34 through a second output buffer capacitor 36. The second active diode 34 is configured so as to block a reverse current through the UHF branch 18. Like in the HF branch 16, the second active diode 34 mitigates and/or suppresses voltage dropouts, when compared to passive diode such as a passive Schottky diode, and reverse current leakages (e.g. from the HF branch 16).

(8) It will further be appreciated that the use of low dropout components such as e.g. the first active diode 28, the second active diode 34 and/or the linear voltage regulator 25, allow for mitigating voltage drops across the integrated circuit, thereby efficiently managing HF and UHF the received HF and UHF electromagnetic fields. This is a significant advantage for powering the integrated circuit e.g. with ISO15693 compliant HF and/or UHF electromagnetic fields.

(9) The reference input terminals of both the low-dropout series linear voltage regulator 25 and the shunt voltage regulator 32 are connected to the same reference voltage V.sub.REF. It will be appreciated that providing the same reference voltage V.sub.REF allows for balancing the HF and UHF branches contribution for supplying power to the device. Alternatively, they may be connected to different reference voltages V.sub.REF,HF, V.sub.REF,UHF for the HF and UHF branches, respectively.

(10) Both the output terminal of the first active diode 28 and the second active diode 34 are continuously connected to a supply line 38 for supplying a supply voltage V.sub.SUP to the integrated circuit.

(11) The supply line 34 comprises a third output buffer capacitor 40.

(12) It will be appreciated that the power supply of the dual frequency HF-UHF RFID integrated circuit according to the first aspect of the invention is stable at least in the following operating conditions: V.sub.UHF>V.sub.SUP and V.sub.HF,reg<V.sub.SUP: (i.e. strong UHF field and weak or no HF field); V.sub.UHF<V.sub.SUP and V.sub.HF,reg>V.sub.SUP: (i.e. weak or no UHF field and strong HF field); and V.sub.UHF>V.sub.SUP and V.sub.HF,reg>V.sub.SUP: (i.e. strong UHF field and strong HF field).

(13) The power supply of a dual frequency HF-UHF RFID integrated circuit according to the invention, for instance the power supply of the preferred embodiment described hereinabove, can be implemented in diverse RFID integrated circuits and can be associated with other specific circuits arranged for controlling the power consumption of such circuits, in particular for minimizing their power consumption. In a case of a battery assisted HF-UHF identification device, the RFID integrated circuit can have a wake-up circuit associated with a listening mode. In a particular embodiment, the RFID integrated circuit comprises a HF field detector and/or a UHF field detector arranged for activating and/or controlling some parts the RFID integrated circuit. Further means for regulating the supply voltage V.sub.SUP and/or protecting some parts of the RFID integrated circuit as well as specific boosting means (in particular a voltage amplifier for further increasing the supply voltage) can be provided by a person skilled in the art.

(14) While specific embodiments have been described herein in detail, those skilled in the art will appreciate that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention, which is to be given the full breadth of the appended claims and any and all equivalents thereof.