A low voltage folded cascode LNA for ultra-wideband applications

Abstract

A low noise amplifier scheme to achieve low-voltage and wide-bandwidth operation is presented. This circuit is based on folded cascade topology combined with wideband impedance matching and shunt peaking load. One of the drawbacks of the proposed scheme is that it uses more at-ea than the conventional cascade due to the two additional inductors and capacitors to implement the capacitively coupled LC tanks. To reduce the at-ea of the circuit, we have used stacked inductors, a brief study of these kinds of inductors is presented. Two low noise amplifiers have been fabricated using a mature 0.35 mu m BiCMOS technology, one using the cascade conventional approach and the other using the proposed topology. Measurement results show that for the same transistors operating conditions, the love-voltage amplifier performance is similar than the conventional cascode. By virtue of the small area of stacked inductors, the size of both low noise amplifiers is comparable. (C) 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2495-2500, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25530