A Reconfigurable 3-4 GHz Low-Noise Amplifier With Transformer-Based integrated Filter

A reconfigurable low-noise amplifier (LNA) with integrated filter response covering 3 to 4 GHz is proposed in this paper. The proposed LNA consists of three cascaded transistors, and a transformer-based filter is integrated into the inter-stage matching network of the amplifier. Resonating with the switched capacitors, the matching circuits provide good matching and filtering performance. The proposed LNA is designed to achieve high gain and low noise figure simultaneously. The LNA has a maximum gain of 33 dB and 1.3-1.8dB noise figure in the range of 3 to 4 GHz. The maximum out of band suppression of the proposed LNA is 39dB. The LNA area is 2 mm × 1.6mm including pads.