On the design and performance of a balanced-cascade LNA for FDD-WCDMA direct-conversion node-B RF receiver

In this paper, the design requirements, design procedure, and performance of a low noise amplifier (LNA) used in wideband code division multiple access (WCDMA) base station receiver, is illustrated. The amplifier design is aimed for a direct-conversion architecture. It simultaneously achieves good input-match, ultra-low noise figure and high linearity in terms of low third order intermodulation (IMD3). The LNA achieves an overall gain of 55 dB, noise figure (NF) better than 0.7 dB, and IMD3 less than -67 dBc. Devices used are E-pHEMT type with gate widths of 800 /spl mu/m and 6400 /spl mu/m. A distributed type quadrature-hybrid is used for balanced configuration with good amplitude and phase balance.