Semiconductor device, analog-to-digital converter and analog-to-digital converting method

A successive-approximation analog-to-digital converter configured to perform a process of sampling an analog input signal and a successive-approximation process, execute an analog-to-digital conversion process, and output a digital output signal,

• wherein the analog-to-digital converter comprises:
• an upper DAC configured to perform a digital-to-analog conversion corresponding to an upper bit of the digital output signal;
• a redundant DAC configured to perform a digital-to-analog conversion corresponding to a redundant bit added to a bit of the upper DAC;
• a lower DAC configured to perform a digital-to-analog conversion corresponding to a lower bit of the digital output signal;
• a comparator configured to compare a comparative reference voltage and output voltages of the upper DAC, the redundant DAC and the lower DAC;
• a control circuit configured to control successive approximations by the upper DAC, the redundant DAC and the lower DAC based on a comparison result of the comparator, and generate the digital output signal;
• and
• a correction circuit configured to correct the digital output signal, and
• wherein the correction circuit comprises:
• an error correction circuit configured to correct an error of the upper bit with the redundant bit;
• and
• an averaging circuit configured to calculate an average value of conversion values of a plurality of the lower bits supplied multiple times.

An analog-to-digital converting method of an analog-to-digital converter comprising:

• an upper DAC configured to perform a digital-to-analog conversion corresponding to an upper bit of a digital output signal;
• a redundant DAC configured to perform a digital-to-analog conversion corresponding to a redundant bit added to a bit of the upper DAC;
• and a lower DAC configured to perform a digital-to-analog conversion corresponding to a lower bit of the digital output signal, the analog-to-digital converting method including:
• a primary successive approximation step in which an analog input signal is converted into a digital output signal by successive approximation by the upper DAC;
• a redundant successive approximation step in which the analog input signal is converted into a digital output signal by successive approximation by the redundant DAC;
• an error correction step in which an error in the primary successive approximation step is corrected based on results obtained in the redundant successive approximation step performed multiple times;
• a secondary successive approximation step in which the analog input signal is converted into a digital output signal by successive approximation by the lower DAC;
• and
• an averaging step in which results obtained in the secondary successive approximation step performed multiple times are averaged.