Active load with cross-coupled bulk for high-gain high-CMRR nanometer CMOS differential stages

Nanometer CMOS technologies are characterized by low intrinsic gain and limited rejection to common-mode disturbances, issues that analog designers must counteract through nonconventional circuit solutions able to operate under sub-1-V supply voltages. In this letter, an approach originally proposed as a common-mode control loop for body-driven amplifiers is exploited by cross-connecting the bulk terminals of the active-load transistors of a source-coupled pair to sensibly improve its small-signal performance. A design example in 65-nm process supplied from 750 mV shows that the presented solution offers both a nominal 20-dB increase in differential gain and 29-dB increase in CMRR, as compared with the standard counterpart.