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Op-amp inverting amplifier. An active virtual ground circuit is sometimes called a rail splitter. Such a circuit uses an op-amp or some other circuit element that has gain. . Since an operational amplifier has very high open-loop gain, the potential difference between its inputs tends to zero when a feedback network is implement
The op-amp inverting amplifier is a typical circuit, with parallel negative feedback, based on the Miller theorem, where the op-amp differential input impedance is apparently decreased to zero Zeroed impedance uses an inverting (usually op-amp) amplifier with enormously high gain A v → ∞ {\displaystyle A_{v}\to \infty } .
Referring to the above diagram, if the op-amp is assumed to be ideal, then the voltage at the inverting (-) input is held equal to the voltage at the non-inverting (+) input as a virtual ground. The input voltage passes a current V in / R 1 {\displaystyle V_{\text{in}}/{R_{1}}} through the resistor producing a compensating current flow through ...
Basic opamp diode log amplifier. The basic opamp diode log amplifier shown in the diagram utilizes the diode's exponential current-voltage relationship for the opamp's negative feedback path, with the diode's anode virtually grounded and its cathode connected to the opamp's output , used as the circuit output.
Some sensors require external voltage or current source of excitation, These sensors are called active sensors. (E.g. a temperature sensor like a thermistor & RTD, a pressure sensor (piezo-resistive and capacitive), etc.). The stability and precision of the excitation signal directly relates to the sensor accuracy and stability.
The result is that it can operate in many applications with the negative supply pin on the op amp being connected to the signal ground, thus eliminating the need for a separate negative power supply. The LM324 (released in 1972) was one such op amp that came in a quad package (four separate op amps in one package) and became an industry standard.
Here there is no virtual ground, and the steady op-amp output voltage is applied through R 1-R 2 network to the input source. The op-amp output passes an opposite current through the input source (it injects current into the source when the input voltage is positive and it draws current from the source when it is negative).
Quadruple op-amps with an adjustable voltage reference [22] LM675 Power op-amp with a maximal current output of 3 amperes [23] LM709 Yes General-purpose op-amp [24] LM741 LM709 General-purpose op-amp. [25] Widely used. LM747: Yes General-purpose dual op-amp. [26] LM748 General-purpose op-amp with external compensation [27] LM833