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Method for ASK demodulation and ASK demodulator

A shift keying and demodulator technology, which is applied in the demodulation of amplitude modulation oscillation, demodulation, instruments, etc., can solve the problems of signal loss, level difference measurement is susceptible to interference, comparator small level range, etc. Achieve the effect of high anti-spike interference security

Inactive Publication Date: 2004-04-21
INFINEON TECH AG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But the disadvantage here is that the comparator only has a small level range to work with
At the same time, it is not possible to regulate the supply voltage, since the signal to be demodulated would be lost in this way
In addition, level difference measurements are also very susceptible to interference

Method used

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  • Method for ASK demodulation and ASK demodulator
  • Method for ASK demodulation and ASK demodulator
  • Method for ASK demodulation and ASK demodulator

Examples

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Embodiment Construction

[0017] figure 1 The illustrated circuit arrangement comprises an inductance 1 in which an RF reception voltage is induced by the electromagnetic field emitted by the card writer / reader when a card is inserted into the card writer / reader. The inductance is connected to a dual rectifier 2 (bridge rectifier). A current mirror circuit 3 consisting of two transistors T1 , T2 is connected to the output of the rectifier, and a fraction of the total current is coupled out by means of the mirror circuit and fed into the demodulator 4 . Furthermore, the output of the rectifier 2 is connected to a shunt voltage regulator 5 and a digital circuit 7 containing the actual circuit for driving the chip card. Finally, a larger chip capacitance is represented by a capacitor 6 which is also connected in parallel thereto.

[0018] exist figure 1 In the circuit shown, all voltages refer to the negative supply on the DC voltage side. The HF input voltage induced in the inductor 1 is rectified by...

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PUM

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Abstract

The invention relates to a method for demodulating a voltage which is amplitude shift keyed(ASK)between a low and a high level, especially for use in contactless data transmission from a card read / write device to a chip card. Said method is characterized in that a first average value is produced in an initialing phase from a high voltage and a partial voltage which is derived thereof and saved. In a subsequent comparison of the modulated voltage with the first average value a shift to a low voltage representing a starting value is detected. In a subsequent demodulation phase a second average value is produced on the basis of the detected low and high voltage levels in order to demodulate the modulated voltage by comparison with the second average value.

Description

technical field [0001] The invention relates to a method for demodulating (amplitude shift keying) modulated voltages by changing the amplitude between high and low levels, which is especially suitable for the contactless transmission of data from a card writer / reader to a chip card, Furthermore, the invention relates to a demodulator for carrying out the method and a circuit arrangement for a chip card having the demodulator. Background technique [0002] A chip card differs from a magnetic card in that it has an electronic chip. Due to the high performance of a chip card, it can be linked to various application possibilities and is becoming more and more significant. Since the chip card is to operate contactlessly after insertion into the card reader, not only must the voltage received on the chip card be demodulated, but also the supply voltage required by the chip must be derived therefrom. [0003] For the transmission of data from the card reader to the chip card, dif...

Claims

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Application Information

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IPC IPC(8): H03D1/00G06K7/00G06K19/07H04L25/06H04L27/04H04L27/06
CPCG06K7/0008G06K19/0723H04L27/06H04L25/062
Inventor G·尼贝尔V·贡格里希A·布鲁姆U·韦德尔D·埃希纳R·雷纳G·施劳德
Owner INFINEON TECH AG
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