What are Low Noise Amplifiers or LNAs?
A Low noise amplifier or LNA is a type of RF amplifier that amplifies a high frequency signal while maintaining a good signal to noise ratio. These amplifiers are used at the beginning of the receive chain to amplify a signal with minimal degradation due to noise. The specification that determines the noise in a LNA is called noise figure. So the lower the noise figure of an LNA the better its performance. Other parameters like gain and P1dB also do play an important role when selecting a low noise amplifier.
The signal received by a wireless system usually has very low power. An LNA amplifies this signal with very little noise. It is usually placed at the starting of the receive chain, right after the antenna and filter. If this is placed at a later stage, other components will add noise to the signal and then when the LNA amplifies the signal, the noise along with the signal will also get amplified resulting in a signal with higher noise. RF low noise amplifiers are used in all wireless receivers.
Key specifications to look for a Low Noise Amplifier:
Frequency (MHz): The frequency range at which the lna can operate while maintaining its electrical characteristics and low level of noise figure.
Gain (dB): The gain of an amplifier is the ratio of output to input power or amplitude – It is the measure of amplification of the rf amplifier. Click here to learn about small signal gain.
Noise Figure (dB): This is the most important parameter for a low noise amplifier. The lower the noise figure, the higher the signal to noise ratio of a system.
P1dB or Power Compression (dBm or W): Power Compression (P1dB) is the point at which the input signal is amplified by an amount, which is 1 dB below the small signal gain of the device. It is the point beyond which the gain of the device no longer increases linearly as the input power is raised.
Package Type: Low noise amplifiers are available in a number of package types - Connectorized, Surface Mount, In a die or chip form.
Low Noise amplifiers from the leading manufacturers are listed on everything RF. Find products based on your requirement - you can specify the frequency, gain, noise figure, power, voltage and other parameters to identify products that meet your specific requirement. View product details, download datasheets and get quotes on LNAs.
