Special case of the phase corrector
Synthesis method for LC filters

LC ladder networks can be used for all kinds of attenuation filters, provided that the polynomial P (p ), the numerator of the transfer function, is even or odd. Phase-correcting all-pass circuits do not meet this constraint, and therefore cannot be realized in ladder form.

What's more, to correct the phase behavior of an LC filter by cascading corrector cells, they must not alter the load impedance R ₂ of the initial filter.

Symmetrical lattice cells meet the dual requirement of being realizable as LC quadrupoles and of being constant impedance, i.e. not changing the filter's load impedance.