Self-Adaptation of Line Driver Pre-Emphasis Parameters via Embedded Line Loss Sensing

The paper proposes a method for automated optimization of line driver pre-emphasis parameters by utilizing the measured transfer function (TF) of the channel. Pulseecho measurements are performed in which pulses with a given frequency and duration are transmitted into the channel and the amplitude of the resulting echo detected to evaluate frequency-dependent line loss. The echo amplitude is indirectly detected using transmit pulses with different amplitudes and a simple comparator-based circuit that detects when the echo amplitude exceeds a user-defined threshold. The result is used to estimate the cable loss, and the process repeated for different input frequencies to estimate the channel TF. The proposed estimation procedure is validated using a transistor-level implementation in 65 nm CMOS for data rates up to 1 Gb/s, channel losses up to 15 dB, and a receiver reflection coefficient of −20dB.