Analysis and design of a 55–74 GHz ultra‐compact low‐noise amplifier using highly asymmetric transformers

This letter presents a low‐noise amplifier with a 3 dB‐bandwidth, from 55 to 74 GHz, excellent noise performance and low power consumption based on a three‐stage common‐source topology. For the first time to the authors' best knowledge, an analytical equation that also considers the gate–drain capacitance is derived for the employed shunt–series transformer feedback input matching network. To enable shunt–series transformer feedback matching without significant gain reduction a highly asymmetric transformer is designed. Furthermore, a compact transformer‐implemented T‐shaped output matching network is investigated to minimize the required area. To prove these concepts, the circuit has been fabricated in a 22 nm fully depleted silicon‐on‐insulator technology. Thanks to the transformer‐based matching, an ultra‐compact active footprint of 0.039 mm2 is achieved. At a power consumption of 8.4 mW from a 0.41 V supply an average noise figure of 4.8 dB and a peak gain of 14.2 dB has been measured. In‐ and output matching better than −10 dB over the 19 GHz wide 3 dB‐bandwidth are demonstrated.