The paper presents a high-speed (500 f/s) large-format 1K x 1K 8 bit 3.3V CMOS active pixel sensor (APS) with 1024 ADCs integrated on chip. The sensor achieves an extremely high output data rate of over 500 Mbytes per second and a low power dissipation of 350 mW at the 66 MHz master clock rate. Principal architecture and circuit solutions allowing such a high throughput are discussed along with preliminary results of the chip characterization