An analog-to-digital converter for an image sensor comprises a counter circuit to generate a respective counter bit in response to a counter state of the counter circuit, and a storage circuit for storing a respective storage state in response the respective counter bit. The converter further comprises a comparator circuit for generating a level of a comparison signal, and a synchronization circuit to generate a write control signal for controlling the storing of the respective storage state in the respective storage cell. The counter circuit is configured to change the counter state, when a first edge of a cycle of the clock signal is applied to the counter circuit, and to generate the write control signal, when a second edge of the cycle of the clock signal being subsequent to the first edge of the cycle of the clock signal is applied to the synchronization circuit.