ELECTRICS WEEK 2 NOTES Flashcards
What does the amplitude of a signal mean?
Its the measure of how far, and in what direction that variables differ from zero.
What are the 3 characteristics of an analogue signal?
Frequency
Amplitude
Phase
What does the phase of a signal mean
Its the relationship between the signals that share the same frequency
What does the frequency of a signal mean?
Its the rate at which the voltage or current changes its direction in a second
How many outputs does Op-amps have?
One
What does op-amps do?
It amplifies the difference between voltages 1 and voltages 2.
What are the 3 possible scenarios of a open-loop comparator?
If V2 > V1, Vout is positive
If V2 < V1, Vout is negative
If V2 = V1, Vout is 0.
What is impendance (Z)
also known as?
Resistance
What are the main properties of an open op-amp circuit?
A very high open-loop voltage gain of around 105 for DC and low frequency for AC
A very high input impedance, such that the current drawn from the device, or the circuit supplying it, is very small and the input voltage is passed onto the op amp with little loss
A very low output impedance, such that the output voltage is transferred efficiently to any load greater than a few kilohms
What are closed loop op-amps known as?
Inverting amplifiers
What happens in inverting amplifiers
Were feeding a portion of the output back into the inverting input.
What does virtual ground mean?
The voltage at the particular node is almost equal to ground voltage, (0V).
This only occurs in negative feedback/inverting amplifiers
What is the slew rate?
The change of voltage or current per unit of time,
What is the slew rate of an op-amp?
The maximum rate of change of output voltage following a step input voltage
What affect does the slew rate have?
It causes the output voltage to change at a slower rate than the input
