Dual-band high-linearity variable-gain low-noise amplifiers for wireless applications

A typical dual-band RF receiver front-end architecture is shown. The low-noise amplifiers (LNA) should have low noise figures to increase sensitivity of the receivers, and high linearity to prevent interference from undesired adjacent-channel signals. To increase the dynamic range of the receivers and to reduce linearity required of the downconversion mixers, the LNAs are required to provide variable gain. When the RF input power is large, the gain of the LNA should be reduced.