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US 8,810,307 B2Granted
Apparatus and method for tuning a GM-C filter
AssigneeQUALCOMM Incorporated
InventorsFrancesco Piazza, Claudio Cantoro
Life of this patent
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Abstract
An apparatus to control a tuneable Gm-C filter, including and a filter that can be reconfigured as a free running oscillator by toggling the feedback sign of an output amplifier (304), a digital controller (42), sensitive to the output of the filter in the calibration configuration, and a DAC (44) to provide an analogue control signal (48) to the gm inputs of the transconductance amplifiers (310, 320) composing the filter.
Claims17
Apparatus for tuning a Gm-C filter, comprising:
- a Gm-C filter including one or several interconnected Gm-C cells, the Gm-C cells having a transconductance amplifier, a tuning terminal, and a transconductance gain (gm) that is dependent from an electric value present on the tuning terminal;
- the Gm-C filter including one or more switching elements, allowing to configure the Gm-C filter in a calibration configuration and in a filtering configuration;
- a digital controller, operatively arranged to measure a response of the Gm-C filter in the calibration configuration, and to generate a digital tuning value depending on the response measured;
- a digital-to-analogue converter, converting said digital tuning value into an analogue tuning signal, fed to the tuning terminals of the Gm-C cells;
- and
- an amplitude regulation unit operatively arranged to limit the forward gain when the Gm-C filter is in the calibration configuration;
- wherein the apparatus is operatively arranged to converge, in the calibration configuration, to a predefined response, and the digital-to-analogue converter is operatively arranged to maintain the resulting tuning signal in the filtering configuration.
4 more elements
Apparatus for tuning a Gm-C filter, comprising:
- means for filtering, including one or several interconnected Gm-C cells, the Gm-C cells having a transconductance amplifier, a tuning terminal, and a transconductance gain (gm) that is dependent from an electric value present on the tuning terminal;
- means for switching the means for filtering between a calibration configuration and a filtering configuration;
- means for measuring a response of the means for filtering in the calibration configuration;
- means for generating a digital tuning value depending on the response measured;
- means for converting said digital tuning value into an analogue tuning signal, fed to the tuning terminals of the Gm-C cells;
- and
- means for limiting the forward gain when the Gm-C filter is in the calibration configuration;
- wherein the apparatus is operatively arranged to converge, in the calibration configuration, to a predefined response, and the means for converting is operatively arranged to maintain the resulting tuning signal in the filtering configuration.
5 more elements
A method for tuning a Gm-C filter, comprising:
- obtaining a Gm-C filter including one or several interconnected Gm-C cells, the Gm-C cells having a transconductance amplifier, a tuning terminal, and a transconductance gain (gm) that is dependent from an electric value present on the tuning terminal;
- switching the Gm-C filter between a calibration configuration and a filtering configuration;
- measuring a response of the means for filtering in the calibration configuration;
- generating a digital tuning value depending on the response measured;
- converting said digital tuning value into an analogue tuning signal, fed to the tuning terminals of the Gm-C cells;
- and
- limiting the forward gain when the Gm-C filter is in the calibration configuration;
- wherein the Gm-C filter is operatively arranged to converge, in the calibration configuration, to a predefined response, and the converting step is operatively arranged to maintain the resulting tuning signal in the filtering configuration.
5 more elements
Dependencies are inferred from the claim text.