Lecture 11 - Signal Amplification and Op-Amps Flashcards
What is signal amplification?
Increasing the amplitude of an electrical signal (voltage or current) by a scalar factor
What are the four examples of the applications for amplification?
1) Analog to digital conversion
2) Radio transmission (transmitted power)
3) Audio amplification
4) Video amplifiers
What is a transfer function H(w)?
A ratio of output (response) to the input (source) of a circuit
What effect does indcuctive reactance have on an alternating current?
Delays current changes (not in sync with the coltage change)
What effect does capacitive reactance have on an alternating current?
Leads current change; current changes before the voltage changes
Define ‘impedence’
The impedence of a component indicated how the component can change the current in a circuit
What are the 6 steps for a nodal analysis?
1) Identify all nodes and select a reference node
2) Identify all known voltages
3) At each node with a unknown voltage, write a KCL equation
4) Replace currents in terms of node voltages
5) Solve for unknown voltages as needed
6) Use voltages to solve for any desired values
What were operational amplifiers originally designed to do?
They were originially designed to perform mathematical operations such as addition, substraction, differentiation, and integration
Other than mathematical operations, what can op-amps be implemented to perform?
Voltage amplification, current to voltage conversion and etc.
What is op-amp short for?
Operational Amplifiers
What are operational amplifiers?
Voltage amplifying devices which can be used to perform various mathematical operations
What are the connectors on the side of the op-amps utilized for?
They are used to connect the op-amp to supply/source
What are the three points which make the ideal op-amp?
1) Infinite open-loop gain
2) Infinite input resistance
3) Zero output resistance
What are the two ‘golden rules’ that the ideal op-amp will obery?
1) No currents enter or leave the op-amp inputs
2) The op-amp output will do whatever it can (within its limitations) to make the voltage difference between the two inputs zero
What is a formula to represent the first golden rule?
i(+) = i(-) = 0
What is a formula to represent the second golden rule?
V(+) = V(-)
What should be the sign of the voltage gain for an inverting amplifier?
It should be negative; so that it will invert the voltage (amplitude will stay the same but invert the sign)
In an op-amp, what is the non-inverting input?
The non inverting input is the same thing as the positive input terminal of the op-amp.
In an op-amp, what is the inverting input?
The non inverting input is the same thing as the negative input terminal of the op-amp.
What is the gain of an op-amp?
Represents how much larger the output voltage will be compared to the input voltage difference; Gain = V3 / (V2 - V1)
What is the employment of open-loop op-amps?
Employed to create comparators
What is the employment of closed-loop op-amps?
Employed to do signal amplification and mathematical operations.
What are the three types of op-amps?
1) Unit gain buffer (no resistors)
2) Non-inverting op-amp
3) Inverting op-amp (grounded input(s) or switched polarity)
What is V(s) equal to in the context of op-amps?
V(s) equals to either V(+) or V(-) (depending on which value we have since they are the same) as it’s the input voltage
