Low-voltage gm-enhanced CMOS differential pairs using positive feedback

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 gm 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 gm enhancement factors are easily achieved with very small additional hardware and without increasing power dissipation.