A 0.6V multi-Vt current mirror differential OTA

A low power fully differential transconductance amplifier with rail-to-rail outputs, operating from a single 0.6V supply and simulated in a 90nm CMOS standard process is presented. Since the scaling of the threshold voltage does not proportionally follow the supply voltage scaling, transistors are driven in moderate inversion and their minimum drain source voltage becomes a significant fraction of the power supply. Through a straightforward analysis of a low voltage current mirror, the obtainable improvements due to the use of the multi-V_t option of the process are highlighted. The amplifier, whose transistors operate in moderate inversion, presents a unity gain bandwidth of 100MHz with a power consumption of 90μW.