POWER MANAGEMENT IN AN ELECTROMAGNETIC TRANSPONDER

• US 20150137953A1
• Filed: 06/11/2013
• Published: 05/21/2015
• Est. Priority Date: 06/13/2012
• Status: Active Grant

• Current Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SAS (STMicroelectronics NV)
• Inventors: Tramoni, Alexandre
• Granted Patent: US 9,367,784 B2
• Time in Patent Office: Days
• US Class Current: 340/10.5
• CPC Class Codes: G06K 19/0701 at least one of the integrated circuit chips comprising an arrangement for power management
• CPC Class Codes: G06K 19/0702 the arrangement including a battery
• CPC Class Codes: G06K 19/0705 the battery being connected to a power saving arrangement
• CPC Class Codes: G06K 19/0709 the source being an interrogation field
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card

Abstract

An electromagnetic transponder includes an oscillatory circuit, a battery and a first rectifier bridge. Alternating current input terminals of the rectifier bridge are connected to the terminals of the oscillatory circuit, and at least two rectifier elements of the rectifier bridge are controllable on the basis of the voltage supplied by the battery.

Claims

1. An electromagnetic transponder comprising:

an oscillating circuit;

a first rectifying bridge having first and second alternating current (AC) input terminals connected across the oscillating circuit and having at least two controllable rectifying elements; and

a battery configured to provide an output voltage that controls the at least two controllable rectifying elements.

2. The transponder of claim 1, further comprising

a second rectifying bridge having first and second inputs and an output, the inputs being coupled across the oscillating circuit;

and

an amplitude demodulator having an input coupled to the output of the second rectifying bridge.

3. The transponder of claim 1, wherein said at least two controllable rectifying elements include first and second MOS transistors.

4. The transponder of claim 3, wherein each of the first and second MOS transistors has a gate, the transponder further comprising:

a first series association of a first resistive element and a third MOS transistor coupled between the first AC input terminal of the first rectifying bridge and a reference potential terminal; and

a second series association of a second resistive element and a fourth MOS transistor coupled between the second AC input terminal of the first rectifying bridge and the reference potential terminal.

5. The transponder of claim 4, wherein each of the third and fourth MOS transistors has a gate, that is configured to receive a voltage representative of a charge level of the battery.

6. The transponder of claim 5, wherein said battery is configured to supply the output voltage to the gates of the third and fourth transistors as the voltage representative of the charge level of the battery.

7. The transponder of claim 1, further comprising a comparator configured to compare a level of the output voltage of the battery with a threshold and provide an output that controls the first rectifying bridge.