A comparator circuitry includes an input pair circuit, a load circuit, and a compensation circuit. The input pair circuit is configured to compare a first input signal with a second input signal, in order to control a first bias current. The load circuit is coupled to the input pair circuit, and is configured to output an output signal having a first level from a first output terminal of the load circuit in response to the first bias current. The compensation circuit is coupled to the input pair circuit and the load circuit, and is configured to drain a compensation current from the first output terminal to a voltage source during the load circuit generates the output signal having a first level, in which the voltage source is configured to provide a voltage having a second level.