System and method for error amplification and processing. For example, the system includes: a signal processing unit configured to receive a reference signal and a feedback signal and generate a digital pulse signal, a frequency of the digital pulse signal being associated with a difference between the reference signal and the feedback signal; a counter configured to receive the digital pulse signal and generate a counter output signal based on at least information associated with the digital pulse signal; and a digital-to-analog converter configured to receive the counter output signal and generate an output signal based on at least information associated with the counter output signal.