Noise is a typical problem confronting many isolation applications. Isolation products such as analog isolation amplifiers, optocouplers, transformers and digital couplers, are used in applications to transmit signals across a high voltage barrier while providing galvanic separation between two grounds. Burr-Brown’s isolated analog amplifiers and digital couplers use one of three coupling technologies in their isolation products, each having its own set of advantages and disadvantages in noisy environments. These technologies are inductive coupling, capacitive coupling and optical coupling. Isolation amplifiers and digital couplers are used for a variety of applications including breaking of ground loops, motor control, power monitoring and protecting equipment from possible damage. An understanding of the design techniques used to transmit signals across the isolation barrier, as well as an understanding of the sources of noise, allows the users to quickly identify design and layout problems and make appropriate changes to reduce noise to tolerable levels.