Most analog electronic appliances are constructed from combinations of a few types of basic circuits. Analog circuits use a continuous range of voltage as opposed to discrete levels as in digital circuits. Sometimes it may be difficult to differentiate between analog and digital circuits as they have elements of both linear and non-linear operation. What are Digital circuits? Digital circuits are electric circuits based on a number of discrete voltage levels. Building-blocks: • Logic gates • Adders • Binary • Multipliers • Flip-Flops • Counter • Registers • Multiplexers • Schmitt triggers Highly integrated devices: • Microprocessors • Microcontrollers • Application-specific integrated circuit(ASIC) • Digital signal processor (DSP) • Field-programmable gate array (FPGA)