Filter
AssigneeMotorola, Inc.
InventorsMark J. Callicotte, John K. Grosspietsch
Life of this patent
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Abstract
A transconductance filter (200) comprises multiple stages of a transconductor (110,120,130) having an input and an output, and a switch (260,265,270) coupled between the output and the voltage source. The switch is operatively responsive to the control signal for coupling and decoupling the voltage source directly to the output of the transconductor at least prior to the time the filter is required to filter the input voltage signal. The voltage source is within a predetermined input voltage range of the transconductor defined by a region in which a transconductance of the transconductor is substantially constant and positive.
Claims11
A filter, wherein an input voltage signal and a control signal is provided, the filter comprising:
- a first transconductor having an input and an output, wherein the input voltage signal is applied to the input;
- a first capacitor coupled to the output of the first transconductor;
- a voltage source coupled to the capacitor wherein the voltage source is within a predetermined input voltage range of the transconductor defined by a region in which a transconductance of the transconductor is substantially constant and positive;
- and
- a first switch coupled in parallel to the first capacitor, operatively responsive to the control signal, for bypassing the first capacitor at least prior to the time the filter is required to filter the input voltage signal.
A filter, wherein an input voltage signal and a control signal is provided, the filter comprising:
- a transconductor having an input and an output, for converting the input voltage signal applied to the input to a current signal at the output;
- a capacitor coupled to the output of the transconductor, for converting the current signal to an output voltage signal;
- a voltage source coupled to the transconductor, wherein the voltage source is within a predetermined input voltage range of the transconductor defined by a region in which a transconductance of the transconductor is substantially constant and positive:
- and
- a switch coupled between the output and the voltage source, operatively responsive to the control signal, for coupling the voltage source directly to the output of the transconductor at least prior to the time the filter is required to filter the input voltage signal.
A filter, wherein an input voltage signal and a control signal is provided, the filter comprising:
- a transconductor having an input and an output, for converting the input voltage signal applied, to the input to a current signal at the output;
- a capacitor coupled to the output of the transconductor, for converting the current signal to an output voltage signal;
- a voltage source coupled to the capacitor, wherein the voltage source is within a predetermined input voltage range of the transconductor defined by a region in which a transconductance of the transconductor is substantially constant and positive;
- and
- a switch coupled between the output and the voltage source and in parallel to the capacitor, operatively responsive to the control signal for bypassing the capacitor and coupling the voltage source directly to the output of the transconductor when the filter is not required to filter the input voltage signal.
A multi-stage filter, each stage of the filter comprising:
- a transconductor having an output;
- a voltage source within a predetermined input voltage range of the transconductor defined by a region in which a transconductance of the transconductor is substantially constant and positive:
- and
- a switch coupled between the output and the voltage source, for coupling the voltage source directly to the output of the transconductor.
Dependencies are inferred from the claim text.