Apparatus and methods for continuous-time equalization are provided. In one aspect, an apparatus includes an integrator configured to track and process an asynchronous input signal according to actual or approximated frequency-dependent subtraction. The apparatus further includes a comparator or subtractor configured to compare a threshold, output by the integrator, with the asynchronous input signal. In various embodiments, the integrator can include a leaky integrator configured to apply a transform in the form 1/(1+s/γ), wherein s can be adjusted based on the complex angular frequency of the asynchronous input signal. In various embodiments, the integrator can include a programmable network having a resistance R and a capacitance C, and γ can include 1/(RC). In various embodiments, the integrator can include one or more programmable current sources configured to adjust a level of boost in said frequency-dependent subtraction.