A 2.4 GHz fast switchable LNA with transformer matching for wireless wake-up receivers

In this paper the design of a fully integrated fast switchable cascode low noise amplifier (LNA) for application in wireless wake-up receivers is presented. The circuit contains an integrated balun and a transformer for 50Ω-input-matching. The LNA exhibits a voltage gain of 20dB while only consuming an overall current of 750μA in its on-mode from a 2.5V supply. The measured input return loss is -18dB at 2.4 GHz with a corresponding noise figure of 3.3 dB. This amplifier exhibits a third order intermodulation input intercept point of -8 dBm. To enable the operation within an on-time of 200 ns the LNA is able to settle in less than 32 ns until the output obtains -1 dB of its steady state amplitude. The chip size is 0.21 mm² excluding the pads. All parameters are verified with measurements of the proposed LNA fabricated in IHP 130 nm-SiGe-BiCMOS process.