The invention relates to Closed-Loop Digital Pre-Distortion (DPD) circuit and related methods, devices. According to the invention, examples of front-end modules, apparatuses and methods for coupling compensation in a closed-loop digital pre-distortion system are described. The closed-loop DPD circuit may include a loopback path (RF loopback path, RFLB) which has an output end which is coupled to a power amplifier so as to receive an output signal of the power amplifier and generate a loopback signal. The PA may receive a PA input signal and amplify the PA input signal to provide a PA output signal. A forward coupling and a backward coupling may exist between the PA input signal and an output of the loopback path. The loopback path may include a coupling cancellation mechanism configured to reduce or cancel couplings between the PA input signal and the loopback signal, such that the output of the loopback path may be proportional to the PA output signal of the power amplifier. According to the embodiments of the invention, the DPD circuit is provided with a coupling compensation mechanism, and by introducing a non-zero phase deviation to the DPD circuit, reduces or cancels unexpected coupling in the RFLB circuit.