Apparatus and methods for multi-mode low noise amplifiers

摘要

Apparatus and methods for multi-mode low noise amplifiers (LNAs) are provided herein. In certain configurations, a radio frequency (RF) system includes a multi-mode LNA including at least a first amplification stage and a second amplification stage electrically connected in a cascade. The RF system further includes a mode control circuit, which receives a mode selection signal and controls the biasing of the first and second amplification stages based on the mode selection signal. The mode control circuit operates the multi-mode LNA in one of a plurality of modes including both a first mode in which the LNA operates with higher gain and better noise figure and a second mode in which the LNA operates with lower gain and higher linearity. Controlling the mode of the multi-mode LNA using the mode selection signal allows the multi-mode LNA to advantageously achieve both the benefits of low noise figure and high linearity.

主权项

1. A low noise amplification system comprising:
a multi-mode low noise amplifier (LNA) comprising two or more amplification stages comprising a first amplification stage and a second amplification stage electrically connected in a cascade, wherein the two or more amplification stages are configured to provide amplification to an input signal with a total gain that is based on a first bias current of the first amplification stage and a second bias current of the second amplification stage; and a mode control circuit configured to control the multi-mode LNA to a selected mode chosen from a plurality of modes based on a state of a mode selection signal, wherein the plurality of modes includes a first mode and a second mode, wherein the mode control circuit is configured to control the first bias current to be greater than the second bias current in the first mode such that the input signal is amplified with lower noise figure and greater total gain in the first mode relative to the second mode, wherein the mode control circuit is configured to control the second bias current to be greater than the first bias current in the second mode such that the input signal is amplified with higher linearity and lower total gain in the second mode relative to the first mode.