* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download What is an Operational Amplifier?
Scattering parameters wikipedia , lookup
Electrical ballast wikipedia , lookup
Ground (electricity) wikipedia , lookup
Power engineering wikipedia , lookup
Electrical substation wikipedia , lookup
Flip-flop (electronics) wikipedia , lookup
Control system wikipedia , lookup
Immunity-aware programming wikipedia , lookup
Audio power wikipedia , lookup
Pulse-width modulation wikipedia , lookup
History of electric power transmission wikipedia , lookup
Current source wikipedia , lookup
Power inverter wikipedia , lookup
Three-phase electric power wikipedia , lookup
Variable-frequency drive wikipedia , lookup
Regenerative circuit wikipedia , lookup
Analog-to-digital converter wikipedia , lookup
Wien bridge oscillator wikipedia , lookup
Surge protector wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Stray voltage wikipedia , lookup
Integrating ADC wikipedia , lookup
Alternating current wikipedia , lookup
Negative feedback wikipedia , lookup
Voltage regulator wikipedia , lookup
Power electronics wikipedia , lookup
Buck converter wikipedia , lookup
Voltage optimisation wikipedia , lookup
Mains electricity wikipedia , lookup
Schmitt trigger wikipedia , lookup
Operational Amplifier What is an Operational Amplifier? 1) Differential amplifier - amplifies difference between two signals. 2) Can amplify very small voltage signals to a useful level. 3) Typically an 8 lead IC. 4) Op Amps can require one power supply (single supply) or a positive and a negative power supply (dual supply) Basic Op Amp Function 1) If (inverting input) > (non-inverting input) output saturates towards -Vss 2) If (inverting input) < (non-inverting input) output saturates towards +Vss 3) Without feedback maximum saturation occurs with the slightest difference between inputs. 4) Ideal op-amp has infinite impedance on the inputs, infinite gain, and zero resistance on output. Contnd…. 5) In real life gain is limited to voltage present at +Vss/-Vss 6) For practical purposes there is no current flow from the inputs to the outputs. The input voltage serves only as a reference to control the output. Feedback 1) Degree of amplification can be controlled using feedback. 2) Feedback can be applied to the inverting or non-inverting input. 3) Feedback applied to the inverting input is more common and is called negative feedback. 4) Gain (A) = 1 + (Rf/Rin) Feed back Voltage follower 1) Rf = 0, therefore no amplification. Gain = 1 + (Rf/Rin) 2) Output voltage is equal to input voltage. 3) Use to buffer/isolate circuit. Voltage is the same, but current is supplied by Vss rather than Vin Comparator 1) Amplifies small difference between two signals. 2) Output voltage will "switch" whenever the input voltage (at the inverting input) reaches the reference voltage Vref (at the non-inverting input) 3) Very useful for comparing signals and working with sensors 4) Note that R2 and R1 form a voltage divider. Use a potentiometer in place of R2 for an adjustable reference voltage. 5) Comparator cicuits can be built with opamps, but there are also comparator ICs with large slew rates and short propagation delays - good for high speed switching. Non-Inverting Amplifier 1) Inverting input is connected to ground + feedback. 2) Noninverting input serves as signal. 3) Output is in phase with input. Negative power supply 1) Some opamps need a dual power supply. 2) If we're only interested in getting positive output from opamp, -Vss can be connected to ground. 3) Dual power supply options include building a dual power supply, using two batteries, or purchasing a dual polarity power supply. Slew Rate 1) Slew rate defines how fast the opamp can react to changes at the inputs. Different opamps have different slew rates. 2) If voltage chages faster than opamp's slew rate, signal will be attentuated. 3) The higher the gain, the more deliterious effect from slow slew rate. 4) This is only an issue with high frequencey signals. Construction tips 1) Don't reverse the power leads. This will kill the opamp. A diode can be placed in series with -Vss to avoid this. 2) +Vss and -Vss must be greater than the noninverting and inverting inputs. 3) Couple signals and output to ground with caps (1.0uf - 0.1uf) if needed to filter noise and prevent oscillation. 4) Keep leads from power supply to +/- Vss short and direct. Thanking You!