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

Abstract

A 0.18 mum CMOS low noise amplifier (LNA) achieves sub-1 dB 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 2 GHz allows for using an LNA with reflective input impedance, increasing the gain with 6 dB. Without any matching network, very low noise figure is achieved over a wide bandwidth. At 90 mW power, sub-1 dB Noise is achieved for 50 Omega source impedance over a 0.8-1.8 GHz band without external coils, and S21>20 dB, OIP2>25 dBm and OIP3>15 dBm. Preliminary results with 150 Omega source impedance show noise temperatures as low as 25 K around 900 MHz.