Noise figure optimization of a noise-cancelling wide-band CMOS LNA

This paper discusses noise figure optimization techniques for a noise-cancelling single-ended-to-differential CMOS low-noise amplifier (LNA). In [1], a low noise figure was obtained through cancellation of the drain noise of the common-gate transistor. Contour plots demonstrate that drain noise cancellation does not guarantee an optimal noise figure. The optimal noise figure is achieved by minimizing the un-cancelled noise contributions as well, and utilizing LC resonance to maintain common-gate transistor drain noise cancellation. An LNA with a 0.8-1.8 GHz bandwidth is designed with this optimization. Simulations show a noise figure between 2.8dB and 1.3dB, with S₂₁ ≈ 13dB over the bandwidth.