A circuit for generating a PWM signal includes a shift register having a plurality of clock-controlled register units. Each clock-controlled register unit has an input and an output. The circuit also includes a write unit configured to set the outputs of the register units each to a designated logical value. The circuit further includes a clock generator configured to drive the register units with a common clock signal. The register units are connected in series. The shift register is configured to output the PWM signal at an output contact. The PWM signal is a chronological sequence of the logical values set in the register units, the PWM signal assumes each of the logical values with the duration of one clock of the clock signal, the clock signal is cyclic, during one cycle the duration of successive clocks changes, and the clock signal is identical per cycle.