Application of the back gate in MOS weak inversion translinear circuits

Though the MOS transistor is a four-terminal device, it is most often used as a three-terminal device. Therefore, a large number of possible MOS circuits are overlooked. In this brief, the four-terminal point of view is elaborated with respect to MOS weak inversion translinear circuits, a class of circuits naturally very suitable for low-voltage and low-power applications. Some new circuits are described which sometimes are more suitable for low-voltage applications than bipolar translinear networks performing the same function. It is also shown that, using the back gate, translinear networks can be derived which cannot be realized with bipolar transistors. These network topologies increase the possibilities offered by translinear technology. As an example, measurement results of a low input-voltage current mirror and a sin(x)-circuit are shown.