Electronic ballast for operating at least one discharge lamp (La) comprising - an input comprising a first input terminal and a second input terminal for coupling to a DC supply voltage (U Zw); - an output comprising a first output terminal and a second output terminal for coupling to the at least one discharge lamp (La); - a bridge circuit comprising at least one first electronic switch and one second electronic switch, wherein a series connection of the first electronic switch and the second electronic switch with formation of a first bridge centre point is coupled between the first input terminal and the second input terminal; - a lamp inductor coupled between the first bridge centre point and the first output terminal; - a resonance capacitor (C R) coupled in parallel with the first output terminal and the second output terminal; - a control device for driving at least the first electronic switch and the second electronic switch with a drive signal (AL, AH), wherein the drive signal (AL, AH) has an operating frequency (f) during a preheating phase (T heat) of a first filament and a second filament of at least one discharge lamp (La) connected between the first output terminal and the second output terminal, wherein the control device is designed to reduce the operating frequency (f) during an ignition phase (T Z) of the discharge lamp (La); and - a heating device (T R, La, Lb1, Lb2, S3, C 2) coupled to the control device, wherein the heating device (T R, La, Lb1, Lb2, S3, C 2) is furthermore coupled to the first bridge centre point and designed to heat the first filament and the second filament of the discharge lamp (La); characterized in that the control device furthermore has at least one trapezoidal capacitor coupled in parallel with one of the electronic switches (S1, S2) and is designed to activate the heating device (T R, La, Lb1, Lb2, S3, C 2), which has a series connection of a transformer (Tr), a capacitor and a switch, at least during a predetermined time period of the ignition phase (T Z), wherein the predetermined time period (t 3 -t 2) is dimensioned in such a way that it extends until after the point in time of the ignition of the discharge lamp (La). - an input comprising a first input terminal and a second input terminal for coupling to a DC supply voltage (U Zw); - an output comprising a first output terminal and a second output terminal for coupling to the at least one discharge lamp (La); - a bridge circuit comprising at least one first electronic switch and one second electronic switch, wherein a series connection of the first electronic switch and the second electronic switch with formation of a first bridge centre point is coupled between the first input terminal and the second input terminal; - a lamp inductor coupled between the first bridge centre point and the first output terminal; - a resonance capacitor (C R) coupled in parallel with the first output terminal and the second output terminal; - a control device for driving at least the first electronic switch and the second electronic switch with a drive signal (AL, AH), wherein the drive signal (AL, AH) has an operating frequency (f) during a preheating phase (T heat) of a first filament and a second filament of at least one discharge lamp (La) connected between the first output terminal and the second output terminal, wherein the control device is designed to reduce the operating frequency (f) during an ignition phase (T Z) of the discharge lamp (La); and - a heating device (T R, La, Lb1, Lb2, S3, C 2) coupled to the control device, wherein the heating device (T R, La, Lb1, Lb2, S3, C 2) is furthermore coupled to the first bridge centre point and designed to heat the first filament and the second filament of the discharge lamp (La);