Cascade A/D converter

A cascade A/D converter comprising:

• first comparator means for comparing an analog input signal with a first analog signal for all upper bits and for outputting a first digital signal;
• latch means for holding said first digital signal outputted from said first comparator means;
• D/A converter means for converting said first digital signal outputted from said first comparator means to a second analog signal;
• waveform composition means for composing code changing waveforms from said first digital signal outputted from said D/A converter means;
• window comparator means for detecting each vicinity of code changing points of said code changing waveforms;
• and
• error correction means for rejecting noise generated at code changing points based on output signals from said first digital signal, said waveform composition means and said window comparing means.

A cascade A/D converter configured by connecting in cascade a plurality of stages, each stage comprising:

• a first comparator means for converting an analog input signal into a first digital signal;
• latch means for holding said first digital signal;
• D/A converter means for converting said first digital signal from said first comparator into a first analog signal;
• subtractor means for subtracting said first analog signal from said analog input signal and for outputting a subtracted output signal;
• window comparator means for detecting each vicinity of code changing points to detect code changes of said analog input signal during a particular time duration in two or more stages;
• and
• error correction means for rejecting noise generated at code changing points based on output signals from said first digital signal, said subtractor means and said window comparator means.