Patent ID: 6845252

Claim:
A programmable echo cancellation filter for echo signal cancellation for a transceiver, said filter comprising: a signal output; a signal input for receiving a transmission signal emitted by the transceiver; an input resistor connected to the signal input; an operational amplifier, having a signal input connected to the input resistor and having a signal output connected to an output resistor; a first programmable resistor circuit provided between the signal output of the operational amplifier and the signal input of the operational amplifier; a second programmable resistor circuit provided between the output resistor and the signal output; a third programmable resistor circuit provided between the first programmable resistor circuit and the signal output; the first, second, and third programmable resistor circuits each having a plurality of switching elements connected in parallel each switching element having a resistor and an associated controllable switch, each controllable switch having a first terminal connected to the resistor and a second terminal connected to a virtual reference voltage terminal.