Analog design considerations for independently driven double gate MOSfets and their application in a low-voltage OTA

This paper explores new capabilities brought on by Independently Driven Double Gate CMOS transistors (IDGMOS) for analog baseband design. Since the gates are disconnected, the corresponding channels are coupled resulting in a dynamic threshold voltage tuning. This operation mode is exploited to create new analog functions and low-voltage circuits. A current mirror is redesigned using IDGMOS and it is shown that this structure performs an efficient differential function relating to the potentials applied to the back gates. Being adapted to low-voltage operation and self compensated from input common-mode variations, the differential current mirror is employed for the active loading of a low-voltage fully-balanced OTA. It then improves the limited common-mode rejection of the original OTA structure by providing output feed-back and input feed-forward compensation.