Method for calibrating frequency of g_m-C filter and devices using the method

摘要

A method of calibrating the frequency of a gm-C filter is provided. The method includes generating, by a frequency calibration circuit, a calibration code capable of tuning a cut-off frequency of the gm-C filter according to a frequency of an oscillation signal that is output from a gm-C oscillator and indicates a process distribution and a reference code, determining, by the frequency calibration circuit, whether the calibration code exists within a range of a reference code, and outputting, by the frequency calibration circuit, the calibration code to the gm-C filter or generating a variable current to simultaneously tune transconductance of the gm-C oscillator and transconductance of the gm-C filter, according to a result of the determination.

主权项

1. A method of calibrating a frequency of a gm-C filter, the method comprising:
generating, by a frequency calibration circuit, a calibration code for tuning a cut-off frequency of the gm-C filter according to a received reference code and a frequency of an oscillation signal that is output from a gm-C oscillator; determining, by the frequency calibration circuit, whether the calibration code exists within a range of the received reference code; and outputting, by the frequency calibration circuit, the calibration code to the gm-C filter when the calibration code is within the range of the reference code, and outputting a current control code when the calibration code is outside the range of the reference code to generate a variable current to tune a transconductance of the gm-C oscillator and a transconductance of the gm-C filter, wherein tuning the transconductance of the gm-C oscillator changes the frequency of the oscillation signal and tuning the transconductance of the gm-C filter adjusts a cut-off frequency of the gm-C filter.