Driver circuit, running time detector and corresponding method

Some aspects of the present disclosure provide a system and a method for operating a driver circuit for a light emitting element in a runtime (TOF) camera ready. A DC-DC converter is configured to output a constant current, and coupled in parallel with a first modulation switch which is configured to connect the drive circuit to ground. The first modulation switch is further configured to alternate connections between the power source and ground to a frequency in a desired operating range, to generate an alternating current. In some embodiments, an RC circuit element is coupled to an output electrode of the light-emitting element and configured to apply a reverse voltage, to reduce the Abschaltezeit the light emitting element. In some embodiments, a second modulating switch coupled to the output electrode and configured to apply the reverse voltage to the light emitting element. Other systems and methods are also disclosed.