A novel topology for an active balun which allows a differential gain 6 dB higher than a single differential pair is proposed. A transimpedance amplifier for 10 Gbit/s receivers has been designed based on this topology, which shows a transimpedance gain of 62.5 dBΩ and an input impedance of 150 Ω. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 27: 257–259, 2000.