Operational amplifiers Flashcards
Define an op amp
a special integrated circuit with a complicated amplifier
-can be made with a variety of transistors
What are the inputs on an op amp?
-ve inverting input
+ve non-inverting input
What are the assumptions of an ideal op amp
-infinite input impedance
-infinite voltage gain
-zero output impedance
-infinite slew rate
What is the slew rate of an op amp?
rate of change of output voltage with time
Define input resistance
the ratio of input voltage over input current
What is the typical range of the slew rate?
0.2V/ms to 20V/ms
Describe how a differential amp works
-the output voltage of the signal is proportional to the difference between the two inputs
-a positive output is given if non-inverting voltage is greater than the inverting voltage
Describe the difference between an open loop and closed loop amp
-open loop has maximum voltage gain due to no feedback
-closed loop has a small portion of output fed-back to the input
-CL reduces voltage gain to a predictable value
IMPORTANT: what is the main difference between a BJT and op-amp
op-amps are DC coupled so they can operate with DC inputs unlikes BJTs
Give some names for popular op-amps
-301
-741
-TL072
-LF351
What is the importance of the slew rate?
The slew rate is a factor that affects how quickly an op amp responds
-which in turn affects the output response
How do op amps relate to differential amplifiers
The op-amp is a differential amplifier
-the difference between the 2 inputs is amplified
What is the output waveform from a comparator op amp if the input is a sinusoid?
Rectangular waveform
What is the input and output waveforms of an integrator?
Rectangular wave to triangular
