Basic Concepts
current flows in only one direction and can be constant or time varying
What is direct current
a voltage source connected between two nonreference nodes and any elements connected in parallel with it.
V=IR
What is Ohm's Law
Source transformation allows you to swap a voltage source in series with a resistor for this equivalent circuit.
What is a current source in parallel with the same resistor?
This type of op amp circuit connects the input signal to the inverting (−) terminal through a resistor, and the output is always flipped — meaning a positive input produces a negative output.
What is an inverting amplifier?
The unit for current
What is an ampere
The application of Kirchhoff's voltage law around meshes in a planar circuit.
What is mesh analysis?
A circuit element with resistance approaching infinity
What is an open circuit?
This is the relationship between Vth, IN, and Rth that allows you to convert between Thévenin and Norton equivalents using a single formula.
hat is Vth = IN × Rth (or equivalently IN = Vth / Rth)?
This type of op amp circuit has the input signal connected directly to the non-inverting (+) terminal, and the output is fed back to the inverting (−) terminal through a resistor divider. The output signal is in phase with the input.
What is a non-inverting amplifier?
P = dw/dt
What is power
This is the name of the reference node in nodal analysis, the node to which all other node voltages are measured.
What is the ground node?
Elements that exclusively share a single node and consequently carry the same current
What are elements in series?
When using superposition, this type of source is NOT deactivated — it remains in the circuit every time because it depends on a circuit variable and cannot be independently turned off.
What is a dependent source?
This op amp circuit takes two or more input voltages, each connected through their own resistor to the inverting terminal, and produces a single output that represents the combined total of all inputs — usually with a sign flip.
What is a summing amplifier (also called an inverting summing amplifier)
is satisfied when the current enters through the positive terminal of an element and p = +vi
What is passive sign convention?
In nodal analysis, this law is applied at each node to write the system of equations.
What is Kirchhoff's Current Law (KCL)?
The algebraic sum of currents entering a node is zero.
What is Kirchhoff's Current Law (KVL)?
To convert a 12 V voltage source in series with a 4 Ω resistor into a current source, this is the value of the equivalent current source.
What is 3 A (I = V/R = 12/4)?
This op amp circuit takes two separate input voltages — one at each terminal — and produces an output equal to the voltage at the non-inverting terminal minus the voltage at the inverting terminal. It is used to detect the difference between two signals
What is a difference amplifier
What is 110V?
Before writing mesh equations, you must confirm that the circuit meets this requirement — meaning it can be drawn on a flat surface with no branches crossing over each other.
What is a planar circuit?
An electric heater draws 10 A from a 120V line. What is the resistance of the heater?
What is 12 ohms?
To find R_th in a circuit with both independent and dependent sources, you must first do this to all independent sources before applying a test signal."
What is deactivate (turn off) all independent sources: short voltage sources and open current sources while leaving dependent sources active?
This is the name of the two golden rules analysts use to simplify ideal op amp circuit analysis — one about current into the terminals, and one about the voltage between them.
What are no current enters the input terminals (i₊ = i₋ = 0) and the two input terminals are at the same voltage (V₊ = V₋, virtual short)?