Pipelined recycling ADC with shared operational amplifier function

A pipelined recycling ADC, converting an analog input signal into a digital output signal, comprising:

• a first conversion stage comprising:
• a first processing unit generating a first analog value and a first digital code according to the analog input signal;
• and
• a second processing unit generating a second analog value and a second digital code according to first analog value, wherein the first and the second processing units share an operational amplifier;
• and
• a second conversion stage comprising a comparing unit,
• wherein the first processing unit generates a third analog value and a third digital code according to the second analog value,
• wherein the second processing unit generates a fourth analog value and a fourth digital code according to the third analog value,
• wherein the second conversion stage generates a fifth digital code according to the fourth analog value, and
• wherein the comparing unit determines the second analog value and resets the operational amplifier according to the determined result.