There is provided a receiver equalizer comprising, a first equalizer unit having a basic equalizer stage and a negative impedance cell connected to said basic equalizer stage. Preferably the negative impedance cell comprises a pair of back to back transistors, and connected thereto a parallel resistor capacitor RC network. The basic equalizer stage comprises: a pair of current sources; a pair of transistors arranged as a differential pair, each transistor connected to a different one of the current sources; and a degeneration impedance connected in between the two current sources, and the transistors, wherein the negative impedance cell is connected across the outputs of the pair of transistors.