CMOS LNA design at 30 GHz — A case study

Abstract

This paper presents a case study of LNA design at 30 GHz. Two single-stage LNA topologies are implemented, namely a magnetic feedback LNA and a cascode LNA. The simulation results reveal that a single-stage LNA can deliver adequate power gain along with low noise figure and high linearity even at mm-wave frequencies. The cascode LNA topology, using SNIM is analyzed and described in detail. The post layout simulations give a forward gain (S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> ) of 5.9 dB, a reverse isolation (-S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> ) of 18.1 dB, an input reflection (S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> ) of -11.8 dB and an output reflection (S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">22</sub> ) of -11.4 dB. The NF of the circuit is 3.9 dB while the corresponding IIP3 is 4.9 dBm. The power consumption is 7.2 mW and the circuit occupies 0.37 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> including the pads. The design is implemented in TSMC's LP 90 nm CMOS process.