Electromagnetic-noise protection circuit
First Claim
1. An electromagnetic-noise protection circuit for protecting an electrical device, which processes wanted signals, the electromagnetic-noise protection circuit comprising:
- a sensor which senses the presence of ambient electromagnetic noise from which the electrical device is to be protected, the sensor including a high impedance point capacitively coupled to a ground external of the electrical device;
a discriminator which monitors the sensor and discriminates time periods when the sensor senses ambient electromagnetic noise from time periods when the sensor does not sense ambient electromagnetic noise; and
a filter coupled to the sensor and removing the influence of ambient electromagnetic noise in time periods during which the sensor senses the presence of the ambient electromagnetic noise.
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Accused Products
Abstract
An electromagnetic-noise protection circuit for protecting an electrical device, which processes wanted signals, comprises a sensor which senses the presence of ambient electromagnetic noise from which the electrical device is to be protected, and a filter coupled to the sensor and intermitting the operation of the electrical device in time periods during which the sensor senses the presence of the ambient electromagnetic noise. The sensor can include a discriminator which discriminates wanted signals affected by ambient electromagnetic noise from wanted signals not affected by ambient electromagnetic noise. The discriminator can be implemented as a window comparator comprising at least three triggers and a logical gate and producing a logic output signal indicating if the input signal is either below a certain lower threshold or beyond a certain upper threshold.
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Citations
29 Claims
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1. An electromagnetic-noise protection circuit for protecting an electrical device, which processes wanted signals, the electromagnetic-noise protection circuit comprising:
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a sensor which senses the presence of ambient electromagnetic noise from which the electrical device is to be protected, the sensor including a high impedance point capacitively coupled to a ground external of the electrical device; a discriminator which monitors the sensor and discriminates time periods when the sensor senses ambient electromagnetic noise from time periods when the sensor does not sense ambient electromagnetic noise; and a filter coupled to the sensor and removing the influence of ambient electromagnetic noise in time periods during which the sensor senses the presence of the ambient electromagnetic noise. - View Dependent Claims (2, 3)
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4. An electromagnetic-noise protection circuit for protecting an electrical device, which processes wanted signals, the electromagnetic-noise protection circuit comprising:
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a sensor which senses the presence of ambient electromagnetic noise from which the electrical device is to be protected, the sensor including a discriminator which discriminates wanted signals affected by ambient electromagnetic noise from wanted signals not affected by ambient electromagnetic noise, the discriminator being a window comparator producing a logic output signal indicating if the input signal is either below a certain lower threshold Vwc,low or beyond a certain upper threshold Vwc,up; and a filter coupled to the sensor and intermitting the operation of the electrical device in time periods during which the sensor senses the presence of the ambient electromagnetic noise. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12)
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13. An electromagnetic-noise protection circuit for protecting an electrical device, which processes wanted signals, the electromagnetic-noise protection circuit comprising:
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a sensor configured to sense the presence of ambient electromagnetic noise from which the electrical device is to be protected, the sensor including at least one conductive sensing plate providing a high impedance point configured to be capacitively coupled to a ground external of the electrical device; and a filter coupled to the sensor and configured to remove the influence of ambient electromagnetic noise in time periods during which the sensor senses the presence of the ambient electromagnetic noise. - View Dependent Claims (14, 15, 16, 17)
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18. An electrical system comprising:
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an electrical device; and an electromagnetic-noise protection circuit configured to protect the electrical device, the electromagnetic-noise protection circuit including a sensor configured to sense the presence of ambient electromagnetic noise from which the electrical device is to be protected, the sensor including a plate configured to be capacitively coupled to an external ground, the electromagnetic-noise protection circuit further including a discriminator configured to monitor the sensor and discriminate time periods when the sensor senses ambient electromagnetic noise from time periods when the sensor does not sense ambient electromagnetic noise, the discriminator including a window comparator, and the electromagnetic-noise protection circuit including a filter coupled to the sensor to remove the influence of ambient electromagnetic noise in time periods during which the sensor senses the presence of the ambient electromagnetic noise. - View Dependent Claims (19, 20, 21)
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22. An electrical system comprising:
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an electrical device including an oscillator measuring capacitive changes; an electromagnetic-noise protection circuit protecting the electrical device, the electromagnetic-noise protection circuit including a sensor which senses the presence of ambient electromagnetic noise from which the electrical device is to be protected, and the electromagnetic-noise protection circuit including a filter coupled to the sensor and interrupting operation of the electrical device in time periods during which the sensor senses the presence of the ambient electromagnetic noise; and charging circuitry having an input terminal and an output terminal, and a resistor coupled to the sensor and to the output terminal of the charging circuitry, the charging circuitry charging and discharging the sensor via the resistor, the oscillator including a unity gain buffer buffering the voltage over the sensor without imposing any load on the sensor, and the unity gain buffer having an output terminal coupled to the input terminal of the charging circuitry. - View Dependent Claims (23, 24, 25)
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26. An electromagnetic-noise protection circuit for protecting an electrical device which processes wanted signals, the electromagnetic-noise protection circuit comprising:
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sensing means for sensing the presence of ambient electromagnetic noise from which the electrical device is to be protected, the sensing means including discriminating means for discriminating wanted signals affected by ambient electromagnetic noise from wanted signals not affected by ambient electromagnetic noise, the discriminating means having an input and including window comparator means for producing a logic output signal in response to at least one of a signal at the input of the discriminating means falling below a predetermined lower threshold and a signal at the input of the discriminating means rising above a predetermined upper threshold, the window comparator means including at least three triggers and a logical gate; and means, coupled to the sensing means, for interrupting the operation of the electrical device in time periods during which the sensor senses the presence of the ambient electromagnetic noise. - View Dependent Claims (27, 28, 29)
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Specification