According to a disclosed embodiment, the ideal magnitude and phase of an
ideal impedance for interfacing a modem with a telephone line is determined. This
ideal impedance can be determined in the presence of an external impedance load
and associated circuitry, such as an ADSL modem and accompanying POTS splitter.
Thereafter, a model for an interface circuit inside the modem is utilized to arrive
at an appropriate impedance for an impedance network inside the interface circuit.
As an example, the interface circuit can be a DAA circuit inside a V.90 modem.
Then, a relationship between the ideal impedance and an input impedance of the
impedance network is established. Thereafter, the impedance network is synthesized
to that the relationship between the input impedance of the impedance network and
the ideal impedance is in fact satisfied. The impedance network can be, for example,
a circuit comprising at least one capacitor.
