Method and apparatus for pulse signal automatically gain control

An apparatus for a pulse automatically gain control comprises a step attenuator, a directional detector, a compare module and a processing unit. The step attenuator receives an input pulse signal and attenuates the input pulse signal according a N bits control signal, wherein, the N is a positive integer. Than, the output of the step attenuator is transmitted to the directional detector. The directional detector generates an output pulse signal and a detecting voltage, when it receives the output of the step attenuator. The compare module receives the detecting voltage, and compares it with a first reference voltage and a second reference voltage respectively to output a comparing result. The processing generates the N bits control signal to the step attenuator to control an attenuation amount of the input pulse signal according to the comparing result.