Transponder, especially for a contactless chip card

US7093765B2 · kind B2 · utility

Assignee

• GIESECKE & DEVRIENT GMBH · DE

Inventors

• Michael Baldischweiler · Munich, DE
• Klaus Finkenzeller · Unterföhring, DE

Key dates

• Filing date: Feb 1, 2001
• Grant date: Aug 22, 2006
• Expiry date: Dec 17, 2021

Classification

• Technology area (CPC G): Physics
• CPC primary: G06K19/0723
• WIPO field: Computer technology
• WIPO sector: Electrical engineering

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.