This paper documents the fundamental and practical limits on the performance of the demultiplexing class of photonic analog-to-digital converters (ADCs). First, we review the classes of photonic ADCs that have been investigated to date. Then the reported performance of several demultiplexing photonic ADCs is compared to performance recently obtained with high rate, high resolution electronic ADCs. Next, the paper derives the fundamental limits on ADC performance that are determined by amplitude noise, timing jitter and the finite width of the optical sampling pulse. Finally, we review practical limits for the demultiplexing ADC. These practical limits are generally determined by the performance of the electronic-to-optical and optical-to-electronic interfaces, the optical modulator and the photodetector, and by the requirements on component/path matching.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.