Wideband LNA Using Active Inductor With Multiple Feed-Forward Noise Reduction Paths

In this paper, an area-efficient LNA with on-chip input matching circuit utilizing an active inductor is presented. The active inductor is implemented based on the gyrator structure and its noise is improved by employing a feed-forward path (FFP). The overall low-noise performance of the LNA is achieved by cancelling the inductor noise through an additional FFP. It is shown that the proposed LNA circuit is capable of achieving low-noise performance with wideband tuning at the input in a small die area. A 0.32- to 1-GHz LNA has been designed and fabricated in a standard 0.18-μm CMOS technology. The LNA occupies a die area of less than 0.1 mm
²
. The measured results show noise figure of 2.2-2.7 dB (2.2-2.4 dB for the UHF band), return loss of better than 10 dB (13 dB for the UHF band), and voltage gain of higher than 18 dB over the entire frequency band. The LNA draws 8.5 mA from a 1.8-V supply.