OP-AMP’s OP-AMP’s (OPerational AMPlifiers) are a fundamental building block for handling analog electrical signals. An op-amp op-amp is a “differential to singlesingle-ended” amplifier, i.e. it amplifies the voltage difference voltage difference Vp – Vp – Vn Vn = Vi at the input port and produces a voltage Vo at the output port that is referenced to the ground node of the circuit in which the op-amp is used. Typically an OP AMP has two inputs called “+” and “-,” ( or VIN+ and VIN-) and a single output. The output depends only on the difference of the voltage on the two inputs. If the difference of the two input voltages is ∆VIN, then the output voltage is VOut = ∆VIN* Avi. Ideal characteristics:ġ) Infinite voltage gain A.
2) Infinite input impedance so that almost any signal can drive it and there is no loading of the preceding stage. 3) Zero output impedance so that output can drive an infinite number of other devices. 4) Zero output voltage when input voltage is zero. 5) Infinite bandwidth so that any frequency signals from 0 to ∞ can be amplified without attenuation. 6) Infinite common-mode rejection ratio so that the output common -mode noise voltage is zero. 7) Infinite slew rate so that output voltage changes o ccur simultaneously with input voltage changes. Comparison of the LM741 against the ideal OP-AMP: Sr. Input Resistance Output Resistance Voltage Gainīandwidth Offset voltage Input Current Voltage difference of inputsġ MHz, changes at 0.7 V/μsec 1 MV 30 nano Volts ( 3 X 10-8 volts ) ?įIG. 2: PIN CONFIGURATION OF IC741 AND IC741 Pin 1: EQUIVALENT CIRCUIT OF PRACTICAL OP-AMP and IDEAL OP-AMP. Purpose Since the op-amp is differential type, input offset voltage must be controlled so as to minimize offset.
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