Echo cancelling system and echo cancelling method

An echo cancelling system, comprising:

• a digital-to-analog converter circuit configured to generate an analog transmitted signal according to a digital transmitted signal;
• a first echo canceller circuit configured to generate a first echo cancelling signal according to the digital transmitted signal;
• a processor circuit configured to generate an analog processed signal according to the analog transmitted signal, the first echo cancelling signal, and a received signal;
• an analog-to-digital converter circuit configured to generate a digital value according to the analog processed signal and two slicer levels of a plurality of slicer levels;
• and
• a storage circuit configured to store a look-up table, wherein the look-up table records an offset value corresponding to the digital value, wherein the storage circuit is further configured to output a first output signal according to the digital value and the offset value,
• wherein the offset value is updated according to an error value associated with the first output signal, the two slicer levels correspond to two shift values respectively, the offset value corresponding to the digital value is updated according to the two shift values corresponding to the two slicer levels to generate an updated offset value, and a sum of the digital value and the updated offset value forms the first output signal.