METHOD AND INTEGRATED CIRCUIT FOR TUNING AN LC RESONATOR AND ELECTRICAL APPARATUS COMPRISING AN LC RESONATOR

摘要

For tuning an LC resonator (2) which particularly comprises a miniaturised antenna coil (LA), a variable capacitance (CT) is connected in parallel to the LC resonator (2). At manufacturing time, a maximum resonance frequency of the LC resonator (2) is measured when the variable capacitance (CT) is set to its minimum value, a minimum resonance frequency of the LC resonator (2) is measured when the variable capacitance (CT) is set to its maximum value, and coded values of the measured maximum and minimum resonance frequencies are stored in non-volatile memories (Fmin, Fmax). At operations time, a binary tuning code (B) is computed as a linear interpolation between the stored values of the minimum and maximum resonance frequencies for a target resonance frequency (ft). The LC resonator (2) is tuned to the target resonance frequency (ft) by selectively connecting separate binary weighted capacitors (Cn-1, ..., C2, C1, C0) of the variable capacitance(CT)in parallel to the LC resonator (2) in accordance with the value of the computed binary tuning code (B).