BER-based Adaptation of I/O Link Equalizers

Many equalization techniques have been demonstrated for multi-Gb/s I/O transceivers in order to compensate for the limited bandwidth of the communication medium. Since the performance of links is typically defined by the bit-error-rate (BER), this paper proposes a new adaptation method using the BER as the objective function to maximize the receiver voltage margin. Measurement results compare the new algorithm with commonly used sign-sign least mean square (SS-LMS) adaptation. The results show significant improvement when applied to a transmitter FIR equalizer with peak power constraint, and modest improvement when used in a receiver DFE.