Low-power rail-to-rail CMOS linear transconductor

The linearity of MOS transconductor is only moderate (around 30 to 50dB) because they rely on their square-law model, which is not very accurate (particularly in short-channel processes). In addition, only the difference in output currents is ideally linear, whereas individual currents have significant second-order harmonics. The circuit linearity is affected by the second-order effects such as the short-channel effect and the mobility degradation. In order to obtain an improved linearity of the CMOS transconductor, a crossconexion symmetrical stage is used. The wide range is achieved by using two complementary transconductors in parallel.