A series of 4.8V high linearity low noise amplifiers for cellular base station applications

This paper describes the development of a new series of highly linear low noise amplifiers for cellular base station applications using a proprietary 0.25µm enhancement-mode GaAs pHEMT technology. All LNAs has an input third order intercept point of greater than 20dBm, an output 1dB gain compression of approximately 22dBm, ideal to be used as a second stage LNA or gain block in a typical base station receiver chain. The low band common source LNA measures a noise figure of 0.44dB at 700MHz and consumes 108mA of current while the high band cascode LNA has a noise figure of 0.87dB at 2.5GHz consuming 84mA of current. Use of different LNA circuit configurations allow these LNAs to operate within a narrow 5dB gain window across various cellular frequency bands. The 4.8V operating voltage allows a current sense resistor to be connected to the Vdd pin from a 5V supply and the biasing circuits include a digital power down feature, compatible with TDD applications.