Logantilog

Logantilog is a term used in electronics to describe a class of circuits or devices that implement logarithmic and antilogarithmic transfer characteristics. In practice, a logantilog circuit may provide a logarithmic response for one portion of its input range and an exponential (antilogarithmic) response for another, or may be designed to realize both operations in a configurable manner.

Implementation commonly relies on the exponential current–voltage relationships of diodes or transistors, often within an operational amplifier feedback network. By selecting component values and reference temperatures, the circuit can approximate y = log_b(x) or y = b^x, with base b chosen for the application (for example base 10 or base e). Temperature effects and calibration are important due to the sensitivity of exponential devices.

Applications include automatic gain control, sensor signal conditioning, analog computation, and measurement systems that require wide dynamic range or linearization of nonlinear sensors. In audio and instrumentation, logantilog devices can convert between linear and logarithmic domains, enabling logarithmic sound level meters or exponential control signals.

Historically, the concept appears in mid-20th-century analog computing and early integrated circuits as log and antilog amplifiers; the exact terminology logantilog is not universally standardized and may be used variably by manufacturers to denote a device performing both transfer functions or a pair of interacting log and antilog stages.

See also: logarithmic amplifier, exponential amplifier, antilogarithm, log-domain processing.