CMOS Non-tailed differential pair

A continuous-time complementary metal–oxide–semiconductor differential pair that does not require the traditional tail current source as a way to control the direct current and common-mode current is presented. Compared with a p-channel long-tailed pair, the proposed non-tailed solution operates under a higher maximum input common-mode voltage that includes (VDD+VSS)/2 even under low supply voltages. Experimental measurements on a prototype fabricated in a 0.35-μm technology (with metal–oxide–semiconductor thresholds greater than 0.6 V) confirm this behavior for supply voltages as low as 1.2 V, whereas the long-tailed pair with the same technology offers the same capability only for supplies higher than 1.6 V.