analogue

analogue (sometimes US), analog

1. 

a. a physical object or quantity, such as a pointer on a dial or a voltage, used to measure or represent another quantity

b. (as modifier): analogue watch

2. Biology an analogous part or organ

3. Chem

a. an organic chemical compound related to another by substitution of hydrogen atoms with alkyl groups

b. an organic compound that is similar in structure to another organic compound

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(electronics)

analogue - (US: "analog") A description of a continuously variable signal or a circuit or device designed to handle such signals. The opposite is "discrete" or "digital". Analogue circuits are much harder to design and analyse than digital ones because the designer must take into account effects such as the gain, linearity and power handling of components, the resistance, capacitance and inductance of PCB tracks, wires and connectors, interference between signals, power supply stability and more. A digital circuit design, especially for high switching speeds, must also take these factors into account if it is to work reliably, but they are usually less critical because most digital components will function correctly within a range of parameters whereas such variations will corrupt the outputs of an analogue circuit. See also analogue computer.