Abstract: A nonlinearity calibration system and method for a frequency modulation (FM) transmitter. A nonlinearity calibration system for a FM transmitter includes a digitally controlled oscillator (DCO) with a variable capacitor array. The DCO receives a calibrated fine code for tuning the variable capacitor array to modulate a digitally encoded audio signal transmitted by the FM transmitter to a modulation frequency. The nonlinearity calibration system also includes a nonlinearity estimator for generating an approximation of an integral nonlinearity associated with processing of a fine code to tune the variable capacitor array. The nonlinearity calibration system further includes a subtractor for subtracting the approximation of the integral nonlinearity from the fine code to generate the calibrated fine code.

Abstract: A receiver 100 is provided. The receiver 100 comprises an in-phase analog-to-digital converter 112 operable to detect a saturation condition of the in-phase analog-to-digital converter 112 and to adjust the amplitude of a in-phase signal processed by the in-phase analog-to-digital converter 112 to remove the in-phase analog-to-digital converter 112 from the saturation condition and a in-phase digital filter 114 operable to adjust a gain applied to a digital input to the in-phase digital filter 114 from the in-phase analog-to-digital converter 112, the adjustment of the gain substantially inversely proportional to the adjustment of the amplitude of the in-phase signal processed by the in-phase analog-to-digital converter 112. In an embodiment, the receiver 100 also comprises a quadrature path that is substantially similar to the in-phase path, and the in-phase path and the quadrature path comprise a direct conversion receiver.