Compact SC frequency tuning circuit for continuous-time Gm–C filters
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A novel automatic frequency tuning circuit for continuous-time filters is presented. Based on the switched-capacitor technique, the circuit offers an advantage in terms of simplicity resulting from the use of only two matched current sources, an operational amplifier with relaxed specifications and a transconductor that is a replica of the filter transconductors. Despite the simplicity of the scheme, the accuracy of the system is less than 1 % of frequency error. The circuit has been designed in a 0.5 μm CMOS technology with a 3.3 V power supply and simulation results confirm the suitability of the proposed approach.
KeywordsAutomatic frequency tuning Switched-capacitor technique Transconductor Gm–C filters Low power
This work was supported in part by the Spanish Ministerio de Ciencia e Innovación, and FEDER funds under Grants FPA2010-22131-C02-02 and TEC2010-21563-C02-02, and by the Andalusian Consejería de Economía, Innovación y Ciencia, under Grants TIC-6311 and TIC-6583.
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