Serial communications systems suffer from channel bandwidth limitations that result in eye closure and inter-symbol interference. Adaptive equalization at the receiver is widely implemented to alleviate this, and a number of continuous-time techniques aiming multi-gigabit operation have been proposed. The operation of adaptive equalizers is based on signal filtering carried out by loop filters whose characteristics are usually given ad-hoc after a trial and error process. This paper presents a unified analysis of the operation of continuous-time adaptive equalizers that results in a general design methodology to select the frequency characteristics of the filters implemented in the adaptation loop. Using the proposed methodology, a novel adaptation loop filter combination incorporating two low-pass filters is presented.