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US 7,382,181 B2Granted
Method and apparatus for tuning GMC filter
AssigneeSilicon Laboratories Inc.
InventorsGolam R. Chowdhury, Douglas R. Holberg
Life of this patent
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Abstract
A system and method for providing a tunable GMC filter is disclosed wherein a transconducted element having an attenuator in a feedback loop therewith is allowed to oscillate at a first oscillation frequency. An input to the filter enables tuning of the oscillation frequency to a pre-determined frequency.
Claims18
A tunable GMC filter, comprising:
- a transconductance element;
- an attenuator connected in a negative feedback loop with the transconductance element, wherein the transconductance element and the attenuator form an oscillation circuit having an oscillation frequency;
- an input on the oscillation circuit for receiving a tuning current for tuning the oscillation frequency of the transconductance element to a predetermined frequency;
- a comparator interfacing an output of the transconductance element and configured for driving the output of the transconductance element between a first level and a second level, and
- a multiplexer selectively interfacing an output of the comparator or an external data input and configured for transitioning the transconductance element from a first mode to allow oscillation in the negative feedback loop to a second mode wherein the negative feedback loop is broken and data is received at the attenuator in a data mode wherein the transconductance element transfers data.
2 more elements
A tunable GMC filter, comprising:
- a transconductance element;
- an attenuator connected in a negative feedback loop with the transconductance element, wherein the transconductance element and the attenuator form an oscillation circuit having an oscillation frequency;
- an input for receiving a current for tuning the oscillation frequency of the transconductance element to a predetermined frequency;
- a comparator for driving an output of the transconductance element between a first level and a second level;
- a multiplexer selecting either the output from the comparator in the negative feedback loop in a first mode or a data input in a second mode for input to said comparator and for transitioning the transconductance element from the first mode with negative feedback to a second mode for transferring data through said transconductance element;
- and
- a current generator for generating the current applied to the input, the generated current responsive to a frequency of the output of the comparator.
4 more elements
A method for tuning a GMC filter, comprising the steps of:
- providing a control signal to switch the GMC filter from a data mode wherein data is received and processed through the GMC filter to a tuning mode;
- and
- when in the tuning mode:
- operating the GMC filter at a first oscillation frequency;
- determining a difference between the first oscillation frequency and a predetermined second frequency by the steps of:
- operating the GMC filter to provide an output between a first level and a second level,
- determining the oscillation frequency of the provided output,
- selecting a tuning variable corresponding to a tuning current to provide the predetermining frequency rather than the oscillation frequency, and
- generating the tuning current responsive to the tuning variable;
- and
- providing a tuning current to the GMC filter responsive to the determined difference.
8 more elements
Dependencies are inferred from the claim text.