ideal op amp 1.ppt
- 2. SIRT India Dr. M. Fatima Op Amp Applications
- 3. SIRT India Dr. M. Fatima
- 4. IC Classification SIRT India Dr. M. Fatima
- 5. Op-Amp Introduction • Op-amps (amplifiers/buffers in general) are drawn as a triangle in a circuit schematic • There are two inputs • inverting and non-inverting • And one output • Also power connections (note no explicit ground) SIRT India Dr. M. Fatima divot on pin-1 end + 2 3 4 7 6 inverting input non-inverting input V+ V output
- 6. The ideal op-amp • Infinite voltage gain • a voltage difference at the two inputs is magnified infinitely • in truth, something like 200,000 • means difference between + terminal and terminal is amplified by 200,000! • Infinite input impedance • no current flows into inputs • in truth, about 1012 for FET input op-amps • Zero output impedance • rock-solid independent of load • roughly true up to current maximum (usually 5–25 mA) • Infinitely fast (infinite bandwidth) • in truth, limited to few MHz range • slew rate limited to 0.5–20 V/s SIRT India Dr. M. Fatima + 2 3 4 7 6 inverting input non-inverting input V+ V output
- 7. Op-amp without feedback • The internal op-amp formula is: Vout = gain(V+ V) • So if V+ is greater than V, the output goes positive • If V is greater than V+, the output goes negative • A gain of 200,000 makes this device (as illustrated here) practically useless SIRT India Dr. M. Fatima + V V+ Vout
- 8. SIRT India Dr. M. Fatima