Most modern computers are digital. But they function in a world of continuously varying analog input such as sound, light, and heat.
Every “digital” consumer product, from appliances and cell phones to music players, has analog ICs feeding its digital heart.
Digital IC design is to produce components such as microprocessors, FPGAs, memories (RAM, ROM, and flash) and digital ASICs. Digital design focuses on logical correctness, maximizing circuit density, and placing circuits so that clock and timing signals are routed efficiently