An operational amplifier (Op-Amp) is an integrated circuit that amplifies the difference between two input voltages and produces a single output. From signal point of view, the Op-Amp has two input terminals and one output terminal as shown in figure below.
The ideal Op-Amp senses the difference between two input signals and amplifies this difference to produce an output signal. The output terminal voltage is the voltage at the output terminal measured with respect to ground.
The ideal Op Amp equivalent is shown in figure below:
Here,
AOL = open loop gain
Transfer characteristics equation of Op-Amp:
Transfer characteristics of Op Amp
Note: Multivibrator works in open or closed loop of positive feedback.
Slew rate is defined as the maximum rate at which amplifier output can change. It is expressed in Volts per microsecond (V/μs) i.e.
Here, ∆V0 = Small change in output voltage in a small interval ∆t.
In terms of input voltage, slew rate can be expressed as:
Here, ACL = closed loop gain,
∆Vi = Small change in input voltage in a small interval ∆t
Since, any signal applied to an Op-Amp is generally have both in phase and out of phase components, the resulting output can be expressed as:
V0 = AdVd + AcVc
Here,
Ad = differential voltage
Vc = Common voltage
Ad = Differential gain of the amplifier
Ac = common mode gain of the amplifier
Common Mode Rejection Ratio: (CMRR)
CMRR is defined as the ratio of differential voltage gain to the common mode gain.
i.e. CMRR = Ad/Ac
In decibels, we may express
Non-Inverting Amplifier
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1. What is an operational amplifier (op-amp)? |
2. How does an op-amp work? |
3. What are the characteristics of an ideal op-amp? |
4. Can op-amps be used for mathematical operations? |
5. What are the different types of op-amp configurations? |
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