Abstract: A feedback control system configured to drive a load is disclosed. The feedback control system includes an up-sampling circuit, configured to perform an un-sampling operation on a source signal and produce an up-sampled signal with an up-sampling frequency according to the up-sampled signal and a feedback signal from the load; a delta circuit, coupled to the up-sampling circuit and configured to produce a delta signal; a sigma circuit, configured to produce a density modulation signal according to the delta signal; and a driving device, configured to drive the load according to the density modulation signal with the up-sampling frequency.

Abstract: Provided is an active light-emitting alert device including a first light alarm, a second light alarm, a control unit, a power supply, and at least one connection component. Both first and second light alarms have at least one surface provided with a light-emitting alert block including a plurality of light-emitting components arranged in a matrix. The control unit and the power supply enable the light-emitting alert blocks to emit textual or glittering alert light or alert light for indicating a direction. Two ends of each of the connection components are coupled to a selected portion of the first and second light alarms. With the connection component, the active light-emitting alert device is carried by a user or placed at a specific venue to emit alert light and indication light actively, alerting other drivers or persons to imminent danger, and ensuring the user's safety.