A signal applied equally to both ungrounded inputs of a balanced amplifier stage or other differential device. Also known as inphase signal.
Related Terms 
OFFSET VOLTAGE
The differential input voltage that must be applied to an operational amplifier to return the zerofrequency output voltage to zero volts, due to device mismatching at the input stage.

NONINTEGRABLE SYSTEM
A dynamical system whose motion is governed by an equation that is not an integrable differential equation.

NAVIER'S EQUATION
A vector partial differential equation for the displacement vector of an elastic solid in equilibrium and subjected to a body force.

MINIMAL REALIZATION
In linear system theory, a set of differential equations, of the smallest possible dimension, which have an input/output transfer function matrix equal to a given matrix function G(s).

MEMBRANE ANALOGY
A formal identity between the differential equation and boundary conditions for a stress function for torsion of an elastic prismatic bar, and those for the deflection of a uniformly stretched membrane with the same boundary as the cross section of the bar, subjected to a uniform pressure.

LINEAR REGULATOR PROBLEM
A type of optimal control problem in which the system to be controlled is described by linear differential equations and the performance index to be minimized is the integral of a quadratic function of the system state and control functions. Also known as optimal regulator problem; regulator problem.

INTEGRABLE SYSTEM
A dynamical system whose motion is governed by an integrable differential equation.

BUBBLE POINT
The differential gas pressure at which the first steady stream of gas bubbles is emitted from a wetted filter element under specified test conditions.

BURST PRESSURE RATING
The maximum specified insideout differential pressure that can be applied to a filter element without outward structural or filtermedium failure.

BYPASS VALVE
A valve mechanism that assures system fluid flow when a preselected differential pressure across is exceeded; the valve allows all or part of the flow to bypass the filter element.
