A 15–28 GHz Low-Noise Amplifier With 0.75-dB Gain Ripple Across the Full K-Band

The design of a 15–28 GHz broadband low-noise amplifier (LNA) is presented, employing a magnetically coupled resonator (MCR) to achieve simultaneous bandwidth extension and output matching. To address the increased in-band ripple that occurs when enhancing bandwidth with limited on-chip inductor values, an emitter-collector feedback transformer is introduced to mitigate the MCR ripple by generating an additional pole. This approach enables bandwidth expansion while maintaining minimal gain ripple. The LNA is implemented in 90-nm SiGe BiCMOS technology, occupying a core area of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.11~\text {mm}^{2}$</tex-math> </inline-formula>. It achieves a peak gain of 19.3 dB across a 3-dB bandwidth of 15–28 GHz, with a gain ripple of 0.75 dB within the 16–26.7 GHz range. The measured noise figure (NF) ranges from 2.9 to 3.9 dB. Additionally, the input 1-dB gain compression point (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text {IP}_{\text {1 dB}}$</tex-math> </inline-formula>) remains stable between −27 and −24.5 dBm throughout the entire 3-dB gain bandwidth. The LNA consumes 9.7 mW of power from a 1.2 V supply.