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Non-contact type IC card preventing data from error restoring while AM wave-carrier demodulation

A non-contact, demodulation circuit technology, applied to record carriers used in machines, near-field transmission systems using transceivers, instruments, etc., can solve erroneous phase inversion, data 1 data 0 misjudgment, voltage data 0 data 1 Misjudgment, etc.

Inactive Publication Date: 2009-08-05
コラボイノベーションズインコーポレイテッド
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Here, since the non-contact IC card 10 obtains power from radio waves, its source impedance is high. In this case, instantaneous power consumption causes the power supply voltage to drop sharply, which in turn affects the waveform of the power supply voltage, and causes such as Figure 4 Clutter indicated by middle arrow A or C
On the other hand, this supply voltage waveform also carries data and accompanying information that needs to be recovered by demodulation, so if a disturbance in the supply voltage waveform induces a spur large enough to exceed any threshold of comparator 908, even the data value There is virtually no change between 0 and 1, and the output of comparator 908 will also falsely invert
When this happens, the original data cannot be restored correctly
[0020] For example, the clutter caused by the voltage drop at point A will cause data 1 to be misjudged as data 0 (from point A to point B), or the voltage rise caused by the rebound at point C will cause data 0 to be judged as data 1 Misjudgment (from point C to point D)

Method used

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  • Non-contact type IC card preventing data from error restoring while AM wave-carrier demodulation
  • Non-contact type IC card preventing data from error restoring while AM wave-carrier demodulation
  • Non-contact type IC card preventing data from error restoring while AM wave-carrier demodulation

Examples

Experimental program
Comparison scheme
Effect test

no. 1 example

[0061] Figure 5 is a circuit diagram of an example configuration of a demodulation circuit incorporated in the modulation / demodulation section 41 of the non-contact IC card 10 of the first embodiment of the present invention. This demodulation circuit and image 3 The one shown in is different in that a transistor 107 is provided for shorting the two inputs (nodes B and C) of the comparator 108 at predetermined times to prevent the output of the comparator 108 from inverting. Structural elements other than transistor 107, that is, resistors 101 and 102, capacitors 103 and 104, resistors 105 and 106, and comparator 108 are all and image 3 are the same as those shown in , and therefore will not be described in detail here.

[0062] More specifically, the nodes B and C are connected to the source and drain of the transistor 107 respectively, and the demodulation delay signal is input to the gate of the transistor 107 . In the case of this structure, the nodes B and C are sho...

no. 2 example

[0069] In the first embodiment, the demodulation suspend signal is applied to the gate of transistor 107 to short-circuit node B and node C, thereby avoiding erroneous data recovery due to noise in the power supply voltage waveform. On the other hand, in the second embodiment, when the demodulation delay signal is turned on, the time constant of the differential circuit constituted by the capacitor 104 and the resistor 105 is increased, and the voltage of the node B is prevented from exceeding even if a noise appears in the power supply voltage waveform. Comparator 108 threshold.

[0070] Figure 7 is a circuit diagram of an example of a demodulation circuit provided in the modulation / demodulation section 41 of the non-contact IC card 10 of the second embodiment of the present invention. As shown in the figure, capacitor 103 is connected in parallel with a new capacitor 109, transistor 107 is connected to capacitor 109, and the demodulation delay signal is input to the gate o...

no. 3 example

[0073] In the third embodiment, when the demodulation delay signal is turned on, the hysteresis width of the comparator 108 is increased (that is, the upper and lower thresholds of the comparator 108 are increased and decreased by a certain value) so as to avoid data loss due to clutter in the power supply voltage waveform. Error recovery.

[0074] Figure 8 is a circuit diagram of an example structure of the comparator 108 in the demodulation circuit of this embodiment. The comparator 108 includes P-channel MOS transistors (hereinafter referred to as "PchMOS transistors") 301 to 305 and N-channel MOS transistors (hereinafter referred to as "NchMOS transistors") 306 to 315, and the power supply voltage (V dd ) are input to the sources of the PchMOS transistors 301, 304 and 305.

[0075] In addition, a bias voltage for current control is applied to the gate of the PchMOS transistor 301 . The level of this bias voltage is not particularly limited, but depends on V dd and V ...

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PUM

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Abstract

A non-contact IC card whose function is to detect the envelope of the ASK-modulated carrier and demodulate the carrier to recover the data carried on the carrier. In such a non-contact IC card, the demodulation operation is suspended while the data value of the digital data carried on the carrier wave is unlikely to change (from data 0 to data 1, or from data 1 to data 0). By doing so, data error recovery can be avoided even when noise appears in the power supply voltage waveform due to power consumption of the internal memory, etc.

Description

[0001] This application is based on application No. H11-268632 filed in Japan, the contents of which are incorporated herein by reference. technical field [0002] The present invention relates to a kind of contactless IC (integrated circuit) card, is used for receiving the carrier wave that the modulation factor is less than 100% amplitude modulation, and demodulates the carrier wave after amplitude modulation to recover the data carried on the carrier wave, specifically the present invention relates to A technique that prevents data from being erroneously recovered during demodulation. Background technique [0003] In recent years, a non-contact IC card system consisting of an IC card and a reader / writer (hereinafter referred to as "R / W") has been increasingly considered in systems such as train ticket collection systems, security systems, and electronic cash systems, in which R / W conducts non-contact data communication with the IC card through a fixed-frequency carrier. ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04B5/00G06K19/07H04B5/02
CPCG06K19/0723
Inventor 中根让治角辰己
Owner コラボイノベーションズインコーポレイテッド