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 (V-DD+V-SS)/2 even under low supply voltages. Experimental measurements on a prototype fabricated in a 0.35-mu m technology (with metal-oxide-semiconductor thresholds greater than 0.6V) confirm this behavior for supply voltages as low as 1.2V, whereas the long-tailed pair with the same technology offers the same capability only for supplies higher than 1.6V.