A New Adaptive Biased Voltage Differencing Transconductance Amplifier

Abstract

An adaptive biased architecture of voltage differencing transconductance amplifier (AB-VDTA) with high transconductance gain is proposed in this paper. The proposed AB-VDTA is very efficient in terms of power. The structure proposed involves of two units namely two transconductance amplifiers (TAs) and two squarer. The bias current of the TA is made to vary with a square relation of the differential input voltage. Therefore, the proposed structure provides tunable gain depending on the input differential voltage. The proposed AB-VDTA exhibits improved transconductance gain, transient characteristics, reduced standby power dissipation and linearity for large range of inputs. The mathematical formulation has been presented to establish the characteristics of the proposed AB-VDTA. The proposed structure of AB-VDTA is validated through SPICE simulations using 180[Formula: see text]nm complementary metal oxide semiconductor (CMOS) technology. The proposed scheme has an edge over the existing ones as the outlined methods enhance the transconductance gain by increasing the bias current. The [Formula: see text] values are observed to be 2.3 and 1.4[Formula: see text]mS for proposed AB-VDTA and conventional VDTA, respectively, with the corresponding 3[Formula: see text]dB frequencies 620 and 348[Formula: see text]MHz. Therefore, 64% improvement in transconductance gain is recorded for same value of bias currents. The linear input range of TA1 is observed to be [Formula: see text][Formula: see text]mV and the overall linear range of the VDTA is [Formula: see text][Formula: see text]mV for the proposed AB-VDTA. The PVT analysis is carried out to show the effect of process corners. To check the robustness of the proposed VDTA, Monte Carlo analysis is performed, and results have been included in the form of histograms. As an application example, a current mode (CM) universal single input multiple output (SIMO) biquad filter is also designed using the proposed VDTA to show its usefulness, and a 2.7 times higher pole frequency is obtained at equal bias current.