CMOS Transconductors With Continuous Tuning Using FGMOS Balanced Output Current Scaling

A technique to achieve highly linear scaling of differential currents in CMOS technology is presented. It is based on operation in weak or moderate inversion, and features performance improvements over previous proposals aimed to the same goal, like reduced supply voltage requirements, increased power efficiency, and avoidance of bulk effect. As an example, this technique is applied to attain continuous tuning for two novel voltage-to-current converters, achieving highly linear programmable transconductance over a rail-to-rail input range. Both implementations fabricated in a 0.5- $\mu{\hbox {m}}$ CMOS technology using a dual supply of $\pm$1.5 V achieve a THD of $-$60 dB with differential input swings of 6 ${\rm V}_{\rm pp}$ (i.e., twice the supply voltage). The area and power consumption are 0.12 ${\hbox {mm}}^{2}$ and 2.6 mW for the first implementation and 0.11 ${\hbox {mm}}^{2}$ and 2.2 mW for the second one, respectively.