A New Low Voltage Low Power Fully Differential Current Buffer and Its Application as a Voltage Amplifier

Abstract

In this paper a novel low voltage low power fully differential current buffer with high CMRR is introduced. The proposed current buffer is designed and simulated with HSPICE in TSMC 0.18µm CMOS process and supply voltage of ±0.75V. The simulation results show 39.5Ω and 5.64KΩ differential mode and common mode input resistances respectively. The differential mode input impedance is 142.7 times smaller than the common mode one which is a unique feature. This result is quite significant when it is considered that in the conventional current buffers differential mode input resistance is equal to common mode one. The proposed current buffer exhibits a CMRR of 72.2dB and consumes only 83.9µW. PSRR+ and PSRR- are 160dB and 120dB respectively which make the proposed current buffer very suitable for mixed mode designs. Application of the proposed current buffer as a voltage amplifier is also presented which benefits from the outstanding property of independency of gain from related -3dB bandwidth.