Performance enhancement of current differencing transconductance amplifier (CDTA) by using a new approach of gm boosting and its application

Abstract

The transconductance of current differencing transconductance amplifier (CDTA) has been enhanced by combining the two methods. The first method is reported recently in Rai and Gupta (2015) while the second method is a novel one. These methods can also be merged together to enhance the transconductance of other analog building blocks (ABBs). In the first method, MOSFETs used in the differential pair of transconductance amplifier (TA) has been replaced by the networks N1 and N2 which contains the ‘n’ symmetrical MOSFETs in parallel; where n is the number of MOSFETs. Thus, the voltage which was applied earlier to the differential pairs has now been applied to these networks (N1 and N2) which inject equal currents in all the MOSFETs used. The total current (IT) coming out of the networks (N1 and N2) will be the sum of currents drawn by all the MOSFETs used in these networks. In the second method, the total current (IT) copied by various current mirrors are added at the output node (X+ and X−) of CDTA in order to enhance the transconductance effectively. The advantage of this method is that the transconductance has been boosted while the power dissipation of CDTA remains unaffected for a particular biasing current.