Modulation method for data transmission from a transponder to a read-write device

• US 6,480,099 B1
• Filed: 10/14/1998
• Issued: 11/12/2002
• Est. Priority Date: 10/14/1997
• Status: Expired due to Term

• Current Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Original Assignee: Temic Semiconductor GmbH (Microchip Technology Incorporated)
• Inventors: Ziegler, Werner
• Primary Examiner(s): ZIMMERMAN, BRIAN A
• Application Number:
  US09/172,080
• Time in Patent Office: 1,490 Days
• Field of Search: 340/572.5, 340/10.1, 340/10.4, 340/10.34
• US Class Current: 340/10.1
• 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

Abstract

A modulation method for transponders where data transmission from the transponder to the read-write device is ensured even if the transponder circuits are supplied only with the minimum requisite operating voltage in that the amplitude of modulation voltage provided by a modulator is caused by reducing the supply current flowing in the transponder.

Claims

1. Modulation method for data transmission from a transponder to a read-write device, including creating an amplitude of modulation voltage with a modulator contained in the transponder, causing the amplitude of modulation voltage by a reduction of the supply current flowing in the transponder, and wherein an additional capacitor stores surplus energy during data transmission from the transponder to the read-write device, which energy can then be supplied to the transponder circuits as required.

2. Modulation method according to claim 1, wherein the modulator is formed by a circuit which creates a voltage drop, thus reducing the supply current flowing in the transponder.

3. Configuration for implementing a modulation, comprising a transponder that contains a modulator, an antenna circuit, a rectifier, a clamping and protective circuit, an additional capacitor, and transponder circuits, where the antenna circuit, the clamping and protective circuit, the additional capacitor, and the transponder circuits are connected in parallel and where the modulator is arranged in series between the antenna circuit and the clamping and protective circuit and where the rectifier is arranged in series before or after the modulator.

4. Configuration according to claim 3, wherein the antenna circuit is formed by a transponder coil and a capacitor connected in parallel.

5. Configuration according to claim 3, wherein the modulator is formed by a modulator resistor with a controllable switch connected in parallel.

6. Configuration according to claim 3, wherein the clamping and protective circuit is formed by a Zener diode.

7. Configuration according to claim 3, wherein the transponder circuits comprise a demodulator, a data storage device and a control unit, and are connected in parallel to one another and in parallel to the antenna circuit.