| 摘要 |
The present invention relates to a method for calibrating an analog-to-digital converter, ADC, converting an input voltage signal into a N bit output signal representing said input voltage signal. The method comprises :
- sampling the input voltage signal applied to the analog-to-digital converter,
- comparing the sampled input voltage signal with an output signal of a feedback digital-to-analogue converter, DAC, (40),
- determining in a search logic block (30) of the ADC a (N+1) bit code representation for the comparison result, the (N+1) bit code yielding the N bit output signal,
- on detection of the (N+1) bit code being equal to a predefined calibration trigger code, performing a calibration for one of the most significant bits of the (N+1) bit code by
replacing said (N+1) bit code by an alternative (N+1) bit code which yields the same N bit output signal,
performing an additional comparison cycle using said alternative (N+1) bit code, determining, using the comparison results of said additional comparison cycle and of the preceding (N+1) th cycle, the sign of a DAC capacitor mismatch error,
tuning a set of programmable binary scaled calibration capacitors (41) in parallel to a capacitor corresponding to said one of the most significant bits of said (N+1) bit code for which the calibration is performed. |
