operational amplifier. uses and application
- 1. OPERATIONAL AMPLIFIER Ajay Yadav M.Sc -𝟐𝒏𝒅 Year (3-SEM) HARISHCHANDRA POST GRADUATE COLLEGE , VARANASI
- 2. AMPLIFIER It is an electronic circuit or device which increases the amplitude of a signal
- 3. OPERATIONALAMPLIFIER (OP AMP) Historically an Op Amp was designed to perform such mathematical operations as addition, subtraction, integration and differentiation. Hence the name Operational Amplifier. Background • Originally invented in early 1940s using vacuum tube technology – Initial purpose was to execute math operations in analog electronic calculating machines • Shrunk in size with invention of transistor • Most now made on integrated circuit (IC) • Huge variety of applications, low cost, and ease of mass production make them extremely popular
- 4. ICS
- 5. 741 Op-Amp –Internal Circuitry
- 6. OP AMP – A MULTISTAGE AMPLIFIER Differential Amplifier stage High gain CE amplifier stage Class B push pull emitter follower Differential Amplifier More stages of gain Class B Push pull Amplifier
- 7. Op Amp Equivalent Circuit
- 9. Ideal Op Amp Zin = ∞ Zout = 0 AV = ∞ Practical Op Amp Zin = 2MΩ Zout = 100Ω AV = 105 Voltage Transfer Characteristic
- 12. Op-Amp Summing Amplifier Op-Amp Differential Amplifier If R1 = R2 and Rf = Rg:
- 13. Op-Amp Integrator Vo = - Op-Amp Differentiator
- 14. Low-pass Filter (active) • Cutoff frequency • This works because the capacitor needs time to charge. High pass filter (active)
- 15. Applications of Op-Amps • Electrocardiogram (EKG) Amplification – Need to measure difference in voltage from lead 1 and lead 2 – 60 Hz interference from electrical equipment
- 16. • Simple EKG circuit – Uses differential amplifier to cancel common mode signal and amplify differential mode signal • Realistic EKG circuit – Uses two non-inverting amplifiers to first amplify voltage from each lead, followed by differential amplifier – Forms an “instrumentation amplifier”
- 17. Strain Gauge Use a Wheatstone bridge to determine the strain of an element by measuring the change in resistance of a strain gauge (No strain) Balanced Bridge R #1 = R #2 (Strain) Unbalanced Bridge R #1 ≠ R #2
- 18. Half-Bridge Arrangement Using KCL at the inverting and non-inverting terminals of the op amp we find that ε ~Vo = 2ΔR(Rf /R2) R + ΔR Rf + - + V0 __ +Vcc -Vcc - + Rf Vref R R - ΔR R Op amp used to amplify output from strain gauge
- 19. Op Amps Applications • Audio amplifiers – Speakers and microphone circuits in cell phones, computers, mpg players, boom boxes, etc. • Instrumentation amplifiers – Biomedical systems including heart monitors and oxygen sensors. • Power amplifiers • Analog computers – Combination of integrators, differentiators, summing amplifiers, and multipliers