A low noise and highly linear 2.4-GHz RF front-end circuit for wireless sensor networks

This paper presents highly linear and low noise RF front-end circuits for 2.4-GHz low-IF receiver. The proposed RF front-end circuits consist of a low noise amplifier (LNA) using on-chip transformer and a down-conversion mixer using parasitic vertical NPN bipolar junction transistor. By adopting these devices, both linearity and noise performance are improved. The RF front-end circuits have been implemented in 0.18 μm deep n-well CMOS process. A gain of 33 dB, an IIP3 of -12 dBm, and a DSB noise figure of 4.5 dB have been achieved. The circuits consumes 5 mW from 1.8 V supply and occupies a chip area of 0.45 mm².