Filter circuit permitting adjustment of cutoff frequency
First Claim
1. A filter circuit, having a plurality of selectable impedance elements, that has a cutoff frequency dependent on a selected impedance element, comprising:
- a filter processing circuit that transmits a signal with a frequency range based on the cutoff frequency;
a pulse generation circuit that supplies a variable frequency pulse with a successively increasing or decreasing frequency to an input of the filter processing circuit; and
an impedance element selection unit that checks an attenuation of an output pulse of the filter processing circuit corresponding with the input of the variable frequency pulse and selects the plurality of impedance elements on the basis of the position of a pulse that is attenuated to or below a reference value.
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Accused Products
Abstract
A filter circuit, having a plurality of selectable impedance elements, that has a cutoff frequency dependent on a selected impedance element, comprises a pulse generation circuit that supplies a variable frequency pulse with a successively increasing or decreasing frequency to an input of the filter circuit; and an impedance element selection unit that checks the attenuation of the output pulse of the filter circuit corresponding with the input of the variable frequency pulse and selects the plurality of impedance elements on the basis of the position of a pulse that is attenuated to or below a reference value.
12 Citations
12 Claims
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1. A filter circuit, having a plurality of selectable impedance elements, that has a cutoff frequency dependent on a selected impedance element, comprising:
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a filter processing circuit that transmits a signal with a frequency range based on the cutoff frequency; a pulse generation circuit that supplies a variable frequency pulse with a successively increasing or decreasing frequency to an input of the filter processing circuit; and an impedance element selection unit that checks an attenuation of an output pulse of the filter processing circuit corresponding with the input of the variable frequency pulse and selects the plurality of impedance elements on the basis of the position of a pulse that is attenuated to or below a reference value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of measuring a cutoff frequency of a filter circuit, the cutoff frequency being dependent on an internal impedance element, the method comprising the steps of:
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supplying a variable frequency pulse with a successively increasing or decreasing frequency to an input of the filter circuit; and checking an attenuation of an output pulse of the filter circuit that corresponds with the input of the variable frequency pulse and detecting the cutoff frequency on the basis of the position of a pulse that is attenuated to or below a reference value. - View Dependent Claims (10)
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11. A filter circuit, having a plurality of selectable impedance elements, that has a cutoff frequency dependent on a selected impedance element, comprising:
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a filter circuit that transmits a signal with a frequency range based on the cutoff frequency; a pulse generation circuit that supplies a variable frequency signal with a successively increasing or decreasing frequency to an input of the filter circuit; and an impedance element selection unit that checks an attenuation of an output signal of the filter circuit corresponding with the input of the variable frequency signal and selects the plurality of impedance elements on the basis of a position of the output signal that is attenuated to or below a reference value. - View Dependent Claims (12)
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Specification