Correctly implemented impedance matching guarantees maximum or optimum
signal power transfer from a signal source to a load. Clearly, it is essential for the
correct operation of any modern electronic signal processing circuit (consumer
electronics, industrial process control electronics, medical electronics, and most
importantly telecommunication related electronics). Without correctly implemented
impedance matching, a significant fraction of the incident signal (on the load) energy
and power would be reflected back to the source.
Of the two types of impedance matching, broad and narrow band, the former is
more important, as a significant fraction of electronic signal processing circuits
operate over a frequency band or range, rather than a single frequency (narrow
band). However, design calculations for both broad and narrow band impedance
matching sub-circuits are complicated, multi-step, and therefore time-consuming
and very error-prone. This is especially true for traditional broad band impedance
matching schemes, which are governed by both conjugate matching (as in narrow
band impedance matching) and the Bode-Fano inequalities that impose strict upper
limits on the gain and bandwidth of the impedance matching sub-circuit. Similarly,
traditional narrow band impedance matching techniques make extensive use of the
Smith chart. Using a Smith chart to extract meaningful results requires a high level of
proficiency – a result of years of use. All the complexities of impedance matching
sub-circuit design calculations arise from the frequency dependency of the reactance
(“resistance”) of both the capacitor and inductor. To complicate matters, the most
load impedances are complex, that is, consist of a parallel or series capacitor or
inductor with a resistor. Although some extremely powerful and effective design
schemes (Zobel sub-network, active impedance matching) are used to neutralize or
nullify the frequency dependency of capacitor and inductor reactances, design
calculation complexity is reduced only a little.