Four novel compact differential pair (DP) topologies with enhanced transconductance gain are introduced: direct positive feedback DP, quasi floating gate DP, floating gate DP and tunable quasi floating gate DP. All of them use positive feedback to achieve g_m enhancement and have the same supply requirements as the conventional differential pair. Results for 0.13 μm CMOS designs supplied at 1.0 V show that 5 to 10 g_m enhancement factors are easily achieved with very small additional hardware and without increasing power dissipation.