Apparatus and Method for Tuning a GM-C Filter

Apparatus for tuning a Gm-C filter, comprising:

• a Gm-C filter including one or several interconnected Gm-C cells (310,311;
• 320,312), the Gm-C cells having a transconductance amplifier (310, 320), 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 (510a, 510b, 510c, 510d), allowing to configure the Gm-C filter in a calibration configuration and in a filtering configuration;
• a digital controller (42), operatively arranged to measure the response of the Gm-C filter in the calibration configuration, and to generate a digital tuning value (42) depending on the response measured;
• a digital-to-analogue converter (44), converting said digital tuning value into an analogue tuning signal (48), fed to the tuning terminals of the Gm-C cells;
• whereby the apparatus is operatively arranged to converge, in the calibration configuration, to a predefined response, and the digital-to-analogue converter (44) is operatively arranged to maintain the resulting tuning signal in the filtering configuration.