The LinComp technology is derived from techniques developed for adaptive antenna array processing used to null interfering signals and enhance the desired signal. Linearity errors are treated as interference and their harmonic distortion profile can be used to effectively null the errors in the digital output. The approach requires less computational processing and hardware than competing compensation approaches while providing greater reduction in harmonic and intermodulation distortion. A linearity error profile can be measured and used in the LinComp digital signal processing algorithm to correct the distortion in real time. To calibrate the LinComp compensator, known analog test signals are injected to characterize the harmonic distortion of the device for a wide range of input frequencies and amplitudes.
Calibration is computationally efficient, only requiring a few clock cycles.
Once calibrated, the LinComp compensator digitally processes the outputs of the device being compensated to correct the distortion products and outputs the compensated data. Limited Performance Improvement One technique for ADC compensation is simply a static look-up table to correct the digitized output. This method is effective for errors caused by resistor component variance in the comparator ladder and sometimes provides up to 10 dB reduction in harmonic distortion. However, most current high-performance ADCs use laser trimmed resistors, so this type of error is minimal. In addition, researchers have realized that this type of correction improves the dynamic range of the converter only near the calibration frequency.