Operational Amplifier

Input Offset Voltage - Operational Amplifier

Input Offset Voltage – Operational Amplifier

Input offset voltage, VIO, is defined as “the DC voltage that must be applied between the input terminals to force the quiescent DC output voltage to zero or some other level, if specified”. If the input stage was perfectly symmetrical and the transistors were perfectly matched, VIO = 0. Because of process variations, geometry and doping are never exact to […]

Input Current – Operational Amplifier

A certain amount of bias current is required at each input. The input bias current, IIB, is computed as the average of the two inputs, IIB = (IN+IP)/2 Input offset current, IIO, is defined as the difference between the bias currents at the inverting and non-inverting inputs, IIO = IN-IP Bias current is of concern when the input […]

Absolute Maximum Ratings and Recommended Operating Conditions

The following typical parameters are listed in the absolute maximum ratings and the recommended operating conditions for TI op amps. The op amp will perform more closely to the typical values for parameters if operated under the recommended conditions. Stresses beyond the maximums listed will cause unpredictable behavior and may cause permanent damage. Absolute Maximums Supply Voltage Differential input voltage […]

Op Amp Specifications

If you have experimented with op amp circuits at moderate gain and frequency, you probably have noted very good agreement between actual performance and ideal performance. As gain and/or frequency are increased, however, certain op amp limitations come into play that effect circuit performance. In theory, with proper understanding of the internal structures and processes used to fabricate an op […]

Simplified Op Amp Circuit Diagram

Simplified Op Amp Circuit Diagram

Real op amps are not ideal. They have limitations. To understand and discuss the origins of these limitations, see the simplified op amp circuit diagram shown in Figure Although simplified, this circuit contains the three basic elements normally found in op amps: Input stage Second stage Output stage The function of the input stage is to amplify the […]

Inverting Amplifier

Inverting Amplifier

Another useful basic op amp circuit, the inverting amplifier. The triangular gain block symbol is again used to represent an ideal op amp. The input terminal, + (Vp), is called the non-inverting input, whereas – (Vn) marks the inverting input. It is similar to the non-inverting circuit shown in Figure 4 except that now the signal is applied to […]

Closed Loop Concepts and Simplifications – Op Amp

Substituting a = ∞ (1) into (16) results in, [pmath]A  = 1- 1/b = R2/R1[/pmath] Recall that in equation (6) we state that Vd, the voltage difference between Vn and Vp, is equal to zero and therefore, Vn = Vp. Still they are not shorted together. Rather there is said to be a virtual short between Vn and […]

Non Inverting Amplifier

Non Inverting Amplifier

An ideal op amp by itself is not a very useful device since any finite input signal would result in infinite output. By connecting external components around the ideal op amp, we can construct useful amplifier circuits. Figure 4 shows a basic op amp circuit, the non-inverting amplifier. The triangular gain block symbol is used to represent an ideal op […]

Ideal Op Amp Model

Ideal Op Amp Model

The Thevenin amplifier model shown in Figure 1 is redrawn in Figure 2 showing standard op amp notation. An op amp is a differential to single-ended amplifier. It amplifies the voltage difference, Vd = Vp – Vn, on the input port and produces a voltage, VO, on the output port that is referenced to ground. Standard Op Amp Notation […]

Thevenin Model of Amplifier with Source and Load

Operational Amplifier Basics

Before jumping into op amps, lets take a minute to review some  amplifier fundamentals. An amplifier has an input port and an output port. In a linear amplifier, output signal = A x input signal, where A is the amplification factor or gain. Depending on the nature of input and output signals, we can have four types of amplifier gain: […]

What Is Operational Amplifier?

The term operational amplifier, abbreviated op amp, was coined in the 1940s to refer to a special kind of amplifier that, by proper selection of external components, can be configured to perform a variety of mathematical operations. Early op amps were made from vacuum tubes consuming lots of space and energy. Later op amps were […]