A digital envelop tracker, comprising: a supply filter configured to filter a supply voltage; a level selection circuitry configured to determine a level of supply voltage based on an instantaneous power of an input data stream, schedule a series of switching events based on the determined level of supply voltage, and generate a level select signal based on the scheduled series of switching events; a switch configured to connect one of a plurality of supply voltages in different levels to the supply filter based on the level select signa wherein the level selection circuitry comprises; a primary switching circuitry configured to schedule a primary switching event of the switch based on the determined level of supply voltage; a secondary switching circuitry configured to schedule secondary switching events of the switch at time instances delayed from the primary switching event based on the determined level of supply voltage; a combiner configured to combine the primary switching event and previously scheduled secondary switching events to generate the level select signal, wherein the secondary switching includes a first secondary switching at a first delay time from the primary switching in an opposite direction from the primary switching and a second secondary switching at a second delay time from the first secondary switching in a same direction as the primary switching, wherein the first delay time and the second delay time are determined based on a step response of the supply filter; and the digital envelop tracker comprising: a peak detector configured to provide a peak measurement signal representing an amount of peaking of a step response of the supply filter; a calibration circuitry configured to tune the first delay time and/or the second delay time based on the peak measurement signal in a direction which reduces the peaking of the step response of the supply filter. a supply filter configured to filter a supply voltage; a level selection circuitry configured to determine a level of supply voltage based on an instantaneous power of an input data stream, schedule a series of switching events based on the determined level of supply voltage, and generate a level select signal based on the scheduled series of switching events; a switch configured to connect one of a plurality of supply voltages in different levels to the supply filter based on the level select signa wherein the level selection circuitry comprises; a primary switching circuitry configured to schedule a primary switching event of the switch based on the determined level of supply voltage; a secondary switching circuitry configured to schedule secondary switching events of the switch at time instances delayed from the primary switching event based on the determined level of supply voltage; a combiner configured to combine the primary switching event and previously scheduled secondary switching events to generate the level select signal, wherein the secondary switching includes a first secondary switching at a first delay time from the primary switching in an opposite direction from the primary switching and a second secondary switching at a second delay time from the first secondary switching in a same direction as the primary switching, wherein the first delay time and the second delay time are determined based on a step response of the supply filter; and the digital envelop tracker comprising: a peak detector configured to provide a peak measurement signal representing an amount of peaking of a step response of the supply filter; a calibration circuitry configured to tune the first delay time and/or the second delay time based on the peak measurement signal in a direction which reduces the peaking of the step response of the supply filter. a peak detector configured to provide a peak measurement signal representing an amount of peaking of a step response of the supply filter; a calibration circuitry configured to tune the first delay time and/or the second delay time based on the peak measurement signal in a direction which reduces the peaking of the step response of the supply filter.