An adjustable equalizer that includes a first branch including a low pass filter (LPF) and having a variable gain (β), and a second branch including a high pass filter (HPF) and having another variable gain (α). The equalizer can be implemented using CMOS technology so that the gain parameters β and α are independently adjustable and the equalizer is capable of equalizing an input indicative of data having a maximum data rate of at least 1 Gb/s. In some embodiments, the equalizer includes two differential pairs of MOS transistors and a controllable current source determines the tail current for each differential pair. When the equalizer includes purely resistive impedances Z0 and Z1, the equalizer's transfer function is Z1/Z0·(β+α·(1+s·C0·Z0)), where β is a gain parameter determined by the tail current of one differential pair and α is a gain parameter determined by the tail current of the other differential pair.