Basic Op-amp Characteristics
An operational amplifier(often op-amp) is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output.The amplifier's differential inputs consist of a non-inverting input (+) with voltage V+ and an inverting input (–) with voltage V−. It has high input impedance and low output impedance and has the capability to amplify the dc or ac signal.
Summary
An operational amplifier(often op-amp) is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output.The amplifier's differential inputs consist of a non-inverting input (+) with voltage V+ and an inverting input (–) with voltage V−. It has high input impedance and low output impedance and has the capability to amplify the dc or ac signal.
Things to Remember
- The Operational Amplifier, or Op-amp as it is most commonly called, can be an ideal amplifier with infinite Gain and Bandwidth when used in the Open-loop mode with typical DC gains of well over 100,000 or 100dB.
- An operational amplifier also has zero output impedance, ( Z = 0 ).
- Op-amps sense the difference between the voltage signals applied to their two input terminals and then multiply it by some pre-determined Gain, ( A ).This Gain, ( A ) is often referred to as the amplifiers “Open-loop Gain”.
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Subjective Questions
Q1:
Wrote short notes on Promethazine.
Type: Short Difficulty: Easy
<p>Promethazine histamine drugs which have little dopaminergic reaction/effects. It is sometimes combined with narcotic cough suppressants for the relief of allergy related cough and nasal congestion. It is an anti- histamine with additional sedative and anti- emetic properties, it blocks the H1 receptors.</p>
<p> </p>
<p><strong>Mechanism of action</strong></p>
<ul>
<li>It competes with histamine H1 receptors for sites on effectors cells. It does not reverse the histamine-mediated response. It also produces anti- emetic properties because of inhibiting effects on the chemoreceptors trigger zone in the medulla.</li>
</ul>
<p> </p>
<p> </p>
<p><strong>Indication</strong></p>
<ul>
<li>Allergic reaction</li>
<li>Motion sickness</li>
<li>Meniere's disease</li>
<li>Nausea ,vomiting</li>
</ul>
<p> </p>
<p><strong>Doses</strong></p>
<ul>
<li>Adult- 25mg orally at night and 10 mg at day</li>
<li>Adult(parental route)- 25-50 mg deep IM( maximum doses 100mg/day)</li>
<li>Child (5-10yrs)- IMb6.25-12.5mg</li>
<li>IV slowly in emergency- 25-50mg</li>
</ul>
<p> </p>
<p><strong>Contraindication</strong></p>
<ul>
<li>Hypersensitivity</li>
<li>Obstruction of gastro- intestinal tract</li>
<li>Paralytic ileus</li>
<li>Seizure disorder</li>
<li>Newborn and premature newborns</li>
<li>Lactating mother</li>
</ul>
<p> </p>
<p><strong>Adverse effect</strong></p>
<ul>
<li>Tremor</li>
<li>Nausea/vomiting</li>
<li>Hypertension</li>
<li>Hypotension</li>
<li>Urine retention</li>
<li>Dry mouth</li>
<li>Blurred vision</li>
<li>Photosensitivity</li>
<li>Sedation</li>
<li>Confusion</li>
<li>Dizziness</li>
</ul>
<p> </p>
<p><strong>Nursing consideration</strong></p>
<ul>
<li>Advise the patient to take the prescribed dose properly.</li>
<li>Inform the patient not to consume the alcohol while taking medicine as it causes central nervous depression</li>
<li>Instruct the patient not to drive or perform hazardous work during treatment.</li>
<li>Explain the patient about the side effect and adverse effect of medicine and advice him/ her to visit doctors if CNS depression and retention of urine occurs.</li>
<li>Advise the patient to have plenty of fluid to relieve from dry mouth.</li>
</ul>
<p> </p>
Videos
Anti-Histamine
Basic Op-amp Characteristics
Introduction:
An operational amplifier(often op-amp) is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output. In this configuration, an op-amp produces an output potential (relative to circuit ground) that is typically hundreds of thousands of times larger than the potential difference between its input terminals. It has high input impedance and low output impedance and has the capability to amplify the dc or ac signal. An op-amp can be originally designed to perform mathematical operations like summation, subtraction, multiplication, differentiation, integration etc. Nowadays , it can be used for sign changing, rectification, an oscillator circuit, scale changing , voltage regulation , active filters,rectification, wave generators etc.
Operation:
The amplifier's differential inputs consist of a non-inverting input (+) with voltageV+and an inverting input (–) with voltageV−; ideally the op-amp amplifies only the difference in voltage between the two, which is called the differential input voltage. The output voltage of the op-ampVoutis given by the equation:
whereAOLis the open-loop gain of the amplifier (the term "open-loop" refers to the absence of a feedback loop from the output to the input).
Fig:circuit symbol of op-amp
Op-amp characteristics:
An ideal op-amp is usually considered to have the following properties:
- Infinite open-loop gain G =vout/vin
- Infinite input impedance Rin, and so zero input current
- Zero input offset voltage
- Infinite output voltage range
- Infinite bandwidth with zero phase shift and infinite slew rate
- Zero output impedance Rout
- Zero noise
- Infinite common-mode rejection ratio(CMRR)
- Infinite power supply rejection ratio.
References-
1.R.F. Coughlin, F.F. Driscoll(1982)Operational Amplifiers and Linear Integrated Circuits (2nd Ed)
2.http://www.electrical4u.com/op-amp-working-principle-of-op-amp/
3.http://www.electronics-tutorials.ws/opamp/
Lesson
Electrical Signal Conditioning,Processing and Transmission
Subject
Electrical Engineering
Grade
Engineering
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