Voltage regulation of near field communication communicators

• US 9,182,771 B2
• Filed: 11/26/2009
• Issued: 11/10/2015
• Est. Priority Date: 11/26/2008
• Status: Expired due to Fees

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Broadcom Europe Ltd (Broadcom, Inc.)
• Inventors: Butler, Paul, Miles, David, Wilson, Robin
• Primary Examiner(s): Tsvey, Gennadiy
• Application Number:
  US13/130,365
• Publication Number:
  US 20110306295A1
• Time in Patent Office: 2,175 Days
• Field of Search: 455/41.1, 363/125, 323/222, 323/223, 323/312, 323/316
• US Class Current: 1/1
• CPC Class Codes: G05F 1/613 using semiconductor devices in parallel with the load as final control devices G05F1/461 takes precedence
• CPC Class Codes: H02J 50/001 Energy harvesting or scavenging
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 7/00308 Overvoltage protection
• CPC Class Codes: H04B 5/26 using coils
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

A NFC enabled device to couple inductively to the H field of an RF signal and a regulator to regulate a voltage derived from an RF signal inductively coupled to the inductive coupler. The regulator has at least one voltage controlled impedance having a switch on voltage. A regulator controller provides a control voltage to each voltage controlled impedance such as that the control voltage is not less than the switch on voltage of the voltage controlled impedance.

Claims

1. A near field communications (NFC) enabled device, comprising:

a rectifier configured to rectify an output of an antenna circuit to provide a rectified output; and

a regulator configured to regulate an output of the antenna circuit based upon the rectified output, the regulator comprising;

an amplifier configured to determine a difference between the rectified output and a reference voltage to provide a control signal, the amplifier comprising;

a differential transistor pair, wherein each transistor of the differential transistor pair configured to be a respective amplifier input,

a first transistor and a second transistor configured to draw a bleed current,

a first current mirror configured to couple the differential transistor pair to a voltage source;

a second current mirror and a third current mirror respectively coupled to the first transistor and the second transistor; and

a voltage setter configured to combine the bleed current with the control signal; and

a plurality of voltage controlled impedances configured to regulate the output of the antenna circuit based upon an output of the voltage setter, wherein;

the bleed current causes the plurality of voltage controlled impedances to be active; and

each of the plurality of voltage controlled impedances couples a respective output of an antenna circuit to ground.

2. The NFC enabled device of claim 1, wherein each of the plurality of voltage controlled impedances comprises:

a metal oxide semiconductor field-effect transistor (MOSFET);

or

a bipolar junction transistor (BJT).

3. The NFC enabled device of claim 1, wherein the voltage setter comprises:

a third transistor and a fourth transistor configured as a current mirror, the fourth transistor being configured to mirror a reference current that flows through the third transistor to provide the bleed current.

4. The NFC enabled device of claim 3, wherein the voltage setter further comprises:

a fifth transistor configured to cause the reference current to flow through the first transistor.

5. The NFC enabled device of claim 4, wherein the output of the voltage setter is greater than a threshold voltage of the fifth transistor.

6. The NFC enabled device of claim 5, wherein thresholds of the plurality of voltage controlled impedances are substantially equal to the threshold voltage of the fifth transistor.

7. The NFC enabled device of claim 4, wherein the voltage setter is further configured to ensure that a voltage difference between the control signal and an electrode of one of the plurality of voltage controlled impedances is not less than a threshold voltage of the fifth transistor.

8. The NFC enabled device of claim 1, wherein the amplifier comprises:

a differential amplifier configured to determine the difference between the rectified output and the reference voltage.

9. The NFC enabled device of claim 1, wherein the antenna circuit is configured to receive an inductively coupled communication to provide a recovered communications signal.

10. The NFC enabled device of claim 9, wherein the regulator is further configured to regulate a power level of the recovered communications signal.

11. The NFC enabled device of claim 10, further comprising:

a demodulator configured to demodulate the recovered communication signal to provide recovered information.

12. The NFC enabled device of claim 1, wherein the amplifier further comprises:

a current source configured to set the bleed current and a tail current in the amplifier;

a fourth current mirror configured to draw a current from the second and third current mirrors; and

a third transistor coupled between the third current mirror and the fourth current mirror.

13. A near field communications (NFC) enabled device, comprising:

a receiver configured to receive a communications signal;

a rectifier configured to rectify an output of the receiver to provide a rectified output; and

a regulator configured to regulate an output of the receiver based upon the rectified output, the regulator comprising;

an amplifier configured to a difference between the rectified output and a reference voltage to provide a control signal, the amplifier comprising;

a differential transistor pair, wherein each transistor of the differential transistor pair is configured to be a respective amplifier input,

a first transistor and a second transistor configured to draw a bleed current,

a first current mirror configured to couple the differential transistor pair to a voltage source;

a second current mirror and a third current mirror respectively coupled to the first transistor and the second transistor; and

a voltage setter configured to combine a bleed current with the control signal; and

a plurality of voltage controlled impedances configured to regulate the output of the receiver based upon an output of the voltage setter, wherein;

the bleed current causes the plurality of voltage controlled impedances to be active; and

each of the plurality of voltage controlled impedances couples a respective output of an antenna circuit to ground.

14. The NFC enabled device of claim 13, wherein each of the plurality of voltage controlled impedances comprises:

a metal oxide semiconductor field-effect transistor (MOSFET);

or

a bipolar junction transistor (BIT).

15. The NFC enabled device of claim 13, wherein the receiver is configured to receive an inductively coupled communication to provide a recovered communications signal.

16. The NFC enabled device of claim 15, wherein the regulator is configured to regulate a power level of the recovered communications signal.

17. The NFC enabled device of claim 16, further comprising:

a demodulator configured to demodulate the recovered communication signal to provide recovered information.

18. The NFC enabled device of claim 13, wherein the amplifier further comprises:

a current source configured to set the bleed current and a tail current in the amplifier;

a fourth current mirror configured to draw a current from the second and third current mirrors; and

a third transistor coupled between the third current mirror and the fourth current mirror.

19. A near field communications (NFC) enabled device, comprising:

a host device; and

a NFC device coupled to the host device, the NFC device comprising;

a rectifier configured to rectify an output of an antenna circuit to provide a rectified output; and

a regulator configured to regulate an output of the antenna circuit based upon the rectified output, the regulator comprising;

an amplifier configured to determine a difference between the rectified output and a reference voltage to provide a control signal, the amplifier comprising;

a differential transistor pair, wherein each transistor of the differential transistor pair is configured to be a respective amplifier input,

a first transistor and a second transistor configured to draw a bleed current,

a first current mirror configured to couple the differential transistor pair to a voltage source;

a second current mirror and a third current mirror respectively coupled to the first transistor and the second transistor; and

a voltage setter configured to combine a bleed current with the control signal; and

a plurality of voltage controlled impedances configured to regulate the output of the antenna circuit based upon an output of the voltage setter, wherein;

the bleed current causes the plurality of voltage controlled impedances to be active; and

each of the plurality of voltage controlled impedances couples a respective output of an antenna circuit to ground.

20. The NFC enabled device of claim 19, wherein the host device comprises a mobile telephone.

21. The NFC enabled device of claim 19, wherein the host device comprises a portable computer.

22. The NFC enabled device of claim 19, wherein the host device comprises:

a long range communicator configured to transmit or receive a communications signal outside a maximum operable range of NFC.

23. The NFC enabled device of claim 19, wherein the amplifier further comprises:

a current source configured to set the bleed current and a tail current in the amplifier;

a fourth current mirror configured to draw a current from the second and the third current mirrors; and

a third transistor coupled between the third current mirror and the fourth current mirror.