Achieving Wideband sub-1dB Noise Figure and High Gain with MOSFETs if Input Power Matching is not Required

Abstract

A 0.18 μm CMOS Low Noise Amplifier (LNA) achieves sub-1dB Noise Figure over more than an octave of bandwidth without external noise matching components. It is designed for a future radio telescope, requiring millions of cheap LNAs mounted directly on phased array antenna elements. The short distance between antenna and LNA and low frequency below 2GHz allows for using an LNA with reflective input impedance, increasing the gain with 6dB. Without any matching network, very low noise figure is achieved over a wide bandwidth. At 90mW power, sub-1dB Noise is achieved for 50Ω source impedance over a 0.8-1.8GHz band without external coils, and S21>20dB, OIP2>25dBm and OIP3 15dBm. Preliminary results with 150Ω source impedance show noise temperatures as low as 25K around 900MHz.