Lumped Circuits#
Definition: Lumped Circuit
A physical electronic circuit is lumped if the greatest distance between two of its points is small enough that electromagnetic interactions propagate nearly instantaneously from one end to the other.
In practice, this means that the greatest distance \(d\) is much smaller than the wavelength \(\lambda\) of the signals which are travelling across the circuit:
\[ d \ll \lambda \]
"Much smaller" should be interpreted as smaller by at least a factor of \(10\).
When this condition is met, currents flowing into and out of each terminal as well as the voltages between all pairs of terminals are well-defined and the distances within the circuit become irrelevant.