A Simple Ultra-Low Power Opamp in 22 nm FDSOI

An ultra-low power opamp is described. The amplifier has been designed and prototyped in 22nm CMOS FDSOI technology. Very low current consumption (1.1 μA at V
_DD
=0.8v) and very low area (0.0277 mm
²
) make it suitable for multichannel bio signal recording arrays. Noise efficiency factor of 3.3 has been achieved. A unique feature of this opamp architecture is a negative feedback loop from the output to the body of an input transistor, which serves as a second gate. This circuit technique, possible only in FDSOI technology, allows to achieve perfectly linear voltage transfer curve while leaving both signal inputs of the amplifier free.