Ultra-low-power circuits

An ultra-low-power transconductance device is provided, (FIG. 1b, FIG. 1c), comprising a series connection of a transistor of a first channel type (A) and a transistor of a second channel type (B), the first channel type having a different polarity than the second channel type. The transistors each have a source, a drain and a gate. The source of the transistor of the first channel type (A) is coupled with the source of the transistor of the second channel type (B) and the drain of the transistor of the first channel type (A) is coupled with the gate of the transistor of the second channel type (B).