Integrated imager circuit comprising a monolithic array of single photon avalanche diodes

Integrated circuit (1) comprising: an array of single photon avalanche diodes (SPADs), a plurality of read-out circuits, each SPADs being coupled to one read-out circuit, wherein at least some of the read-out circuits comprise time-to-digital converters (TDC) and/or a digital asynchronous counter, wherein a plurality of SPADs are coupled to one single read-out circuit. The read-out circuit may comprise a transformer for decoupling the SPAD from other parts of said read-out circuit.