Echo cancellation device and echo cancellation method thereof applied in communication device

An echo cancellation device adapted for a communication device, comprising:

• an echo canceller configured to obtain a plurality of delayed signals from a local signal of the communication device, wherein the delayed signals are divided into a plurality of delayed signal groups, the echo canceller selectively ignores at least one of the delayed signal groups, and the echo canceller generates an echo cancellation signal with the others of the delayed signal groups;
• and
• a combine circuit coupled to the echo canceller to receive the echo cancellation signal, and coupled to an interface circuit of the communication device to receive a received signal, wherein the combine circuit cancels an echo component of the received signal with the echo cancellation signal to generate a cancelled signal,
• wherein the echo canceller comprises:
• an insertion loss detection circuit coupled to the interface circuit to receive the received signal, wherein the interface circuit transmits the local signal of the communication device through a communication channel to a far end device, and the insertion loss detection circuit examines a power loss of the received signal to determine length information of the communication channel;
• and
• an echo cancelling circuit coupled to the insertion loss detection circuit to receive the length information, wherein the echo cancelling circuit is configured to obtain the delayed signals from the local signal, the echo cancelling circuit selectively ignores the at least one delayed signal group of the delayed signal groups according to the length information, and the echo cancelling circuit generates the echo cancellation signal with the other delayed signal groups of the delayed signal groups.