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US 2010/0060348 A9Published application
Bandwidth-adjustable filter
AssigneeRealtek Semiconductor Corp.
InventorsChao-Cheng Lee, Ying-Yao Lin
Life of this patent
Estimating the term…
Abstract
A bandwidth-adjustable filter includes an operational amplifier, a first resistor, a first capacitor and a first resistor ladder circuit. The operational amplifier has a negative input terminal and a positive input terminal The first resistor is coupled to one of the input terminals of the operational amplifier. The first capacitor is coupled to the first resistor. The first resistor ladder circuit is coupled in parallel to the first resistor for changing the resistance of the first resistor so as to adjust the bandwidth of the filter.
Claims17
A filtering device, comprising:
- an operational amplifier, having a first input, a second input and an output;
- a first resistor device, coupled to the first input of the operational amplifier;
- and
- a first capacitor, coupled to the first resistor device and the output of the operational amplifier;
- wherein the first resistor device has an equivalent resistance and includes a resistor ladder circuit, and the equivalent resistance corresponds to the resistor ladder circuit;
- wherein the bandwidth of the filtering device corresponds to the equivalent resistance of the first resistor device and capacitance of the first capacitor.
3 more elements
A filtering device, comprising:
- a differential amplifier, having a first input, a second input, a first output and a second output;
- a first resistor device, coupled to the first input of the differential amplifier;
- a first resistor device, coupled to the second input of the differential amplifier;
- a first capacitor, coupled to the first resistor device;
- a second capacitor, coupled to the second resistor device;
- and
- wherein the first resistor device has an equivalent resistance and includes a first resistor ladder circuit, and the equivalent resistance corresponds to the first resistor ladder circuit;
- wherein by adjusting the first resistor ladder circuit, the multiplication of the equivalent resistance of the first resistor device and the capacitance of the first capacitor is substantially the same as the multiplication of the resistance of the second resistor device and the capacitance of the second capacitor.
5 more elements
Dependencies are inferred from the claim text.