Amplifier and filter having cutoff frequency controlled according to digital code
AssigneeSamsung Electronics Co., Ltd.
InventorJong-Woo LEE
Life of this patent
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Abstract
An amplifier circuit is provided. The amplifier circuit includes an operational amplifier, a feedback resistor for changing gain and cutoff frequency characteristics of the operational amplifier, and a feedback variable capacitor for changing the cutoff frequency characteristics of the operational amplifier, wherein a capacitance of the feedback variable capacitor increases exponentially according to a digital control code, and the cutoff frequency of the operational amplifier is inversely proportional to the capacitance of the feedback variable capacitor and varies linearly on a logarithmic scale.
Claims20
An amplifier circuit comprising:
- an operational amplifier;
- a feedback resistor for changing gain and cutoff frequency characteristics of the operational amplifier;
- and
- a feedback variable capacitor for changing the cutoff frequency characteristics of the operational amplifier,
- wherein a capacitance of the feedback variable capacitor increases exponentially according to a digital control code, and the cutoff frequency of the operational amplifier is inversely proportional to the capacitance of the feedback variable capacitor and varies linearly on a logarithmic scale.
An amplifier circuit comprising:
- a logic circuit for performing logic operations on a digital control code;
- a feedback capacitor having a capacitance varying according to a digital output signal of the logic circuit;
- and
- an operational amplifier having cutoff frequency characteristics inversely proportional to the capacitance of the feedback capacitor,
- wherein a cutoff frequency of the operational amplifier is inversely proportional to the capacitance of the feedback variable capacitor and varies linearly on a logarithmic scale.
Dependencies are inferred from the claim text.