BPSK encoder circuit

• US 6,424,682 B1
• Filed: 05/04/1999
• Issued: 07/23/2002
• Est. Priority Date: 05/06/1998
• Status: Active Grant

• Current Assignee: STMicroelectronics SA (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SA (STMicroelectronics NV)
• Inventors: Enguent, Jean-Pierre, Legou, Thierry
• Primary Examiner(s): CORRIELUS, JEAN B
• Application Number:
  US09/304,731
• Time in Patent Office: 1,176 Days
• Field of Search: 375/279, 375/280, 375/282, 375/295, 375/308, 375/354, 375/355, 375/347, 332/103, 332/104, 327/141, 327/144, 327/145, 340/10.34, 340/10.4, 340/10.41, 340/10.42, 370/503, 370/516, 370/517, 370/518, 370/522
• US Class Current: 375/308
• CPC Class Codes: G06K 7/10336 the antenna being of the near field type, inductive coil
• CPC Class Codes: H04L 27/2035 using a single or unspecified number of carriers

Abstract

A BPSK encoder is provided with a first circuit which processes a carrier signal and a binary signal to be encoded, and produces an output binary signal having synchronous phase shifts representing a change in the value of the signal to be encoded. Also, the first circuit is provided with a sampling signal from a second circuit. The second circuit includes a delay circuit to deliver a shifted carrier signal that is smaller than the half-period of the carrier signal, and a logic gate for the logic combination of the carrier signal and the shifted carrier signal. The logic gate also delivers a binary sampling signal having at least two leading or trailing edges at each period of the carrier signal.

Claims

1. An encoder for receiving a carrier signal and an input signal, and generating an output signal therefrom, the encoder comprising:

a first circuit for generating the output signal having synchronous phase shifts which represent changes in a value of the input signal; and

a second circuit for providing the first circuit with a sampling signal, the second circuit comprising

delaying means for providing a shifted carrier signal having a shift with respect to the carrier signal that is less than a half-period of the carrier signal, and

combining means for combining the carrier signal and the shifted carrier signal and for delivering the sampling signal having at least two leading or trailing edges at each period of the carrier signal.

2. An encoder according to claim 1, wherein the first circuit comprises first sampling means for sampling the input signal at a rate of leading or trailing edges of the carrier signal, and for providing a synchronized signal to be encoded.

3. An encoder according to claim 2 wherein the second circuit further comprises an inverter for receive the shifted carrier signal and providing an inverted shifted carrier signal to the combining means;

and wherein the first circuit further comprises;

a logic gate for providing a composite carrier signal equal to the shifted carrier signal or to the inverted shifted carrier signal depending on a logic value of the synchronized signal; and

second sampling means for sampling the composite carrier signal at a rate of the leading or trailing edges of the sampling signal, and for generating the output signal.

4. An encoder according to claim 3, wherein the logic gate comprises an XOR gate for receiving the shifted carrier signal and the synchronized signal.

5. An encoder according to claim 3, wherein the second sampling means comprises a D type flip-flop circuit for receiving the sampling signal at a clock input and the composite carrier signal at a D input.

6. An encoder according to claim 2, wherein the first sampling means comprises a D type flip-flop circuit for receiving the carrier signal at a clock input and the input signal at a D input.

7. An encoder according to claim 1, wherein the delaying means comprises at least two series-connected inverter gates.

8. An encoder according to claim 1, wherein the combining means comprises an XOR gate.

9. An encoder according to claim 1, wherein the input signal is a binary input signal and the output signal is a binary output signal so that the encoder is a BPSK encoder.

10. A BPSK encoder for receiving a carrier signal and an binary input signal and generating a binary output signal therefrom, the encoder comprising:

a first circuit for generating the binary output signal having synchronous phase shifts which represent changes in a value of the binary input signal; and

a second circuit for providing the first circuit with a sampling signal, the second circuit comprising

at least one delay element for providing a shifted carrier signal, and

at least one logic gate for receiving the carrier signal and the shifted carrier signal and for delivering the sampling signal to the first circuit.

11. A BPSK encoder according to claim 10, wherein the shifted carrier signal has a shift that is less than a half-period of the carrier signal.

12. A BPSK encoder according to claim 10, wherein the sampling signal has at least two leading or trailing edges at each period of the carrier signal.

13. A BPSK encoder according to claim 10, wherein the at least one logic gate of the second circuit comprises an XOR gate.

14. A BPSK encoder according to claim 10, wherein the at least one delay element of the second circuit comprises at least two series connected inverters.

15. A BPSK encoder according to claim 10, wherein the first circuit comprises a D type flip-flop circuit for sampling the binary input signal at a rate of leading or trailing edges of the carrier signal, and for providing a synchronized signal to be encoded, the D type flip-flop circuit receiving the carrier signal at a clock input and the input signal at a D input.

16. A BPSK encoder according to claim 15, wherein the second circuit further comprises an inverter for receiving the shifted carrier signal and providing an inverted shifted carrier signal to the at least one logic gate;

and wherein the first circuit further comprises;

an XOR gate for receiving the shifted carrier signal and the synchronized signal and for providing a composite carrier signal equal to the shifted carrier signal or to the inverted shifted carrier signal depending on a logic value of the synchronized signal; and

a second D type flip-flop circuit for sampling the composite carrier signal at the rate of the leading or trailing edges of the sampling signal, and for delivering the binary output signal, the second D type flip-flop circuit receiving the sampling signal at a clock input and the composite carrier signal at a D input.

17. An electronic device comprising:

an antenna;

a switch to modulate a load on the antenna; and

an encoder connected to the switch for receiving a binary input signal and a carrier signal, the encoder comprising a first circuit for outputting a binary output signal having synchronous phase shifts which represent a change in a value of the binary input signal, and a second circuit for providing the first circuit with a sampling signal, the second circuit comprising

at least one delay element for providing a shifted carrier signal, and

at least one logic gate for receiving the carrier signal and the shifted carrier signal and for delivering the sampling signal to the first circuit.

18. An electronic device according to claim 17, further comprising a capacitor connected to the antenna thereby forming an inductive resonant circuit.

19. An electronic device according to claim 17, further comprising a rectifier bridge for rectifying a voltage induced at the antenna.

20. An electronic device according to claim 19, further comprising a divider for dividing an oscillation frequency of the voltage and for providing the carrier signal to the encoder.

21. An electronic device according to claim 17, further comprising a data memory for providing the binary input signal to the encoder.

22. An electronic device according to claim 17, wherein the shifted carrier signal has a shift that is less than a half-period of the carrier signal.

23. An electronic device according to claim 17, wherein the sampling signal has at least two leading or trailing edges at each period of the carrier signal.

24. An electronic device according to claim 17, wherein the at least one logic gate of the second circuit is an XOR gate.

25. An electronic device according to claim 17, wherein the at least one delay element of the second circuit comprises at least two series connected inverters.

26. An electronic device according to claim 17, wherein the first circuit comprises a D type flip-flop circuit for sampling the binary input signal at a rate of leading or trailing edges of the shifted carrier signal, and for providing a synchronized signal to be encoded, the D type flip-flop circuit receiving the carrier signal at a clock input and the input signal at a D input.

27. An electronic device according to claim 26, wherein the second circuit further comprises an inverter for receiving the shifted carrier signal and providing an inverted shifted carrier signal to the at least one logic gate;

and wherein the first circuit further comprises;

an XOR gate for receiving the shifted carrier signal and the synchronized signal and for providing a composite carrier signal equal to the shifted carrier signal or to the inverted shifted carrier signal depending on a logic value of the synchronized signal; and

a second D type flip-flop circuit for sampling the composite carrier signal at the rate of the leading or trailing edges of the sampling signal, and for delivering-the binary output signal, the second D type flip-flop circuit receiving the sampling signal at a clock input and the composite carrier signal at a D input.

28. An electronic device according to claim 17, further comprising a substrate for carrying the antenna, the switch and the encoder.

29. A method of encoding a binary input signal, the method comprising the steps of:

generating a shifted carrier signal from a carrier signal;

combining the carrier signal and the shifted carrier signal to produce a sampling signal having at least two leading or trailing edges at each period of the carrier signal; and

generating a binary output signal having synchronous phase shifts which represent a change in a value of the binary input signal and is based upon the sampling signal.

30. A method according to claim 29, wherein the shifted carrier signal has a shift, with respect to the carrier signal, that is less than a half-period of the carrier signal.

31. A method according to claim 29, further comprising the steps of:

sampling the binary input signal at a rate of leading or trailing edges of the shifted carrier signal; and

providing a synchronized signal to be encoded.

32. A method according to claim 41, further comprising the steps of:

providing a composite carrier signal equal to the shifted carrier signal or to an inverted shifted carrier signal depending on a logic value of the synchronized signal; and

sampling the composite carrier signal at the rate of the leading or trailing edges of the sampling signal