A circuit arrangement (1) for a photodiode (2) has a microprocessor (3) with an output (4) which emits a pulse-width-modulated voltage signal via a low-pass filter (5) to the cathode of the photodiode (2). The voltage which is applied to the cathode of the photodiode (2) is detected by an input (12) of the microprocessor (3) and is regulated at a nominal value by adjusting the voltage signal at the output (4) of the microprocessor (3). The circuit arrangement (1) has a particular wide dynamic measurement range.