Patent ID: 7027589

Claim:
Analog front end circuitry for a DSL modem, comprising: transmit path circuitry for processing a serial signal stream from a codec; output amplifiers having inputs coupled to the transmit path circuitry, and having outputs for driving a subscriber loop with signals corresponding to the processed serial signal stream; receive path circuitry, for processing signals received from the subscriber loop and forwarding the processed signals to the codec; a hybrid circuit, for isolating the receive path circuitry from signals transmitted by the output amplifiers to the subscriber loop; active termination circuitry, coupled to the outputs of the output amplifiers, for synthesizing an output impedance corresponding to the subscriber loop impedance; first bypass switch circuitry, coupled to the hybrid circuit, for selectively bypassing the hybrid circuit; and second bypass switch circuitry, coupled to the active termination circuitry, for selectively disabling the active termination circuitry.