Continuous-time noise-shaping sar adc without excess loop delay

A method of operating an analog-to-digital converter, the method comprising:

• performing a quantization operation on an input signal in a successive approximation scheme;
• integrating a residue signal generated while the quantization operation is performed;
• and
• outputting a digital value corresponding to the input signal based on an input signal quantized through the quantization operation and the integrated residue signal,
• wherein
• the residue signal corresponds to a difference between the input signal and a previous digital value output during a previous analog-to-digital conversion cycle.

A successive approximation analog-to-digital converter comprising:

• a first capacitively-coupled input unit configured to receive an input signal being a continuously changed analog signal and to quantize the input signal in a binary search scheme based on a control signal to generate a quantized input signal;
• a second capacitively-coupled input unit configured to receive the input signal and to generate a residue signal corresponding to a difference between the input signal and a previous digital value when the previous digital value is received;
• a loop filter configured to integrate the residue signal to generate an integrated residue signal;
• a comparator configured to output a digital value corresponding to the input signal in units of bits based on the quantized input signal and the integrated residue signal;
• and
• a successive approximation register logic configured to apply the control signal to the first capacitively-coupled input unit based on an output of the comparator,
• wherein
• the successive approximation register logic applies the previous digital value, output from the comparator, to the second capacitively-coupled input unit during a previous analog-to-digital conversion cycle.