Modulation and demodulation circuit

• US 8,115,538 B2
• Filed: 07/10/2009
• Issued: 02/14/2012
• Est. Priority Date: 07/10/2009
• Status: Expired due to Fees

• Current Assignee: Onespan North America Incorporated (OneSpan, Inc.)
• Original Assignee: Vasco Data Security Incorporated (OneSpan, Inc.)
• Inventors: Marien, Dirk
• Primary Examiner(s): Johnson, Ryan
• Application Number:
  US12/501,213
• Publication Number:
  US 20110007846A1
• Time in Patent Office: 949 Days
• Field of Search: 329/347, 329/370, 327/58, 327/61, 327/62, 340/10.1, 340/10.3, 340/10.4, 340/10.5
• US Class Current: 329/347
• 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: H03D 1/08 by means of non-linear two-pole elements H03D1/22, H03D1/26, H03D1/28 take precedence
• CPC Class Codes: H03D 1/10 of diodes
• CPC Class Codes: H03D 2200/0011 Diodes
• CPC Class Codes: H04L 27/06 Demodulator circuits; Receiver circuits

Abstract

The invention relates to the field of modulation and demodulation circuits, such as envelope detectors used to demodulate amplitude-modulated (AM) signals. By coupling an analog circuit to a port of a digital component, an envelope detector can be obtained, which achieves demodulation of AM signals for direct coupling into a digital input port. Accordingly, an envelope detector may be used in the data receiving part of a sealed device requiring post-manufacturing data transfer, in combination with additional components that provide electromagnetic coupling, such as inductive coupling, capacitive coupling, or radiative coupling. An example of such a device is a credit card sized authentication token.

Claims

1. An apparatus for processing an electrical signal, comprising a circuit for demodulating said signal and one or more digital components, wherein said circuit is coupled to a first port of one of said one or more digital components for providing a demodulated signal from said circuit to said one or more digital components, and wherein said circuit is further coupled to a second port of one of said one or more digital components, coupling said circuit to said second port providing to the circuit an electrical equivalent of a diode connected to a reference voltage, wherein said circuit lacks a diode associated with said demodulating.

2. The apparatus of claim 1, wherein said first port and said second port are ports of the same digital component.

3. The apparatus of claim 2, wherein said digital component is a microprocessor.

4. The apparatus of claim 1, wherein said electrical signal is modulated in amplitude modulation.

5. The apparatus of claim 4, wherein said electrical signal is modulated in amplitude shift keying.

6. The apparatus of claim 5, wherein said electrical signal is modulated in binary amplitude shift keying.

7. The apparatus of claim 1, wherein said reference voltage is the system ground voltage.

8. The apparatus of claim 1, wherein said reference voltage is the system power supply voltage.

9. The apparatus of claim 1, wherein said circuit is a reduced envelope detector.

10. The apparatus of claim 1, wherein said electrical signal has a carrier frequency of approximately 16 MHz.

11. The apparatus of claim 1, wherein said electrical signal is modulated at a baud rate of 1 kHz.

12. The apparatus of claim 1, wherein said electrical signal is received through inductive coupling.

13. The apparatus of claim 12, wherein the coupling distance is approximately 0.005 meter.

14. The apparatus of claim 12, further comprising a tuned circuit for effectuating said inductive coupling.

15. The apparatus of claim 14, further comprising a switching assembly for modulating the reactance of said tuned circuit.

16. The apparatus of claim 15, wherein said switching assembly is integrated in said second port.