Transponder, especially for a contactless chip card

Details Transponder, especially for a contactless chip card Transponder, especially for a contactless chip card

2006-08-22

2006-08-22

Le, Thien M. (Department: 2876)

Registers

Records

Conductive

C235S451000, C235S487000, C340S572100, C340S572200, C340S572500, C340S286080, C340S870030, C340S573400

Reexamination Certificate

active

07093765

ABSTRACT:
A transponder located for example in a contactless smart card receives energy via an antenna (L2) from a high-frequency alternating field. A voltage (Udd) formed with a rectifier (12) is fed as a control quantity to a clock generator (14) with a clock frequency adjusting device. At high field strength on the antenna, the voltage (Udd) is adjusted downwards by increasing the clock frequency for a digital circuit (10). If no further increase of clock frequency of the clock signal (CLK) is possible, a charge pump (16) is connected for an EPROM (18) in order to increase the writing speed thereof. Optionally, a conventional shunt regulator can be connected as well. An interface circuit (20) is not affected by the adjusted clock frequency, but works at fixed frequency during communication with a reader.

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