Product Details

Low Noise Amplifiers


RF and Microwave Low Noise Amplifiers:- About, Application, Selection Specification:

A low-noise amplifier (LNA) is an active RF device that will amplify a very low-power signal without degrading its signal-to-noise ratio significantly.

  • Both Power amplifiers and LNA will increase the power of both the received RF signals and the noise at their input. The power amplifier will introduce additional noise in the output signal however LNAs are designed to minimize these internal generated additional noise.

For the design of LNA, the designer needs to choose low-noise components, circuit topologies and operating points of the amplifier design by matching other design goals such as RF power gain and impedance matching.

  • LNA generally offer a power gain of 20 to 30 dB while decreasing the signal-to-noise ratio in the range of 3 dB. 

To learn more about RF communication systems, we recommend you to check the following books.

To understand the RF low noise amplifiers in a better way, we recommend you to check the details of the following components, which are used along with the LAN.

In this RF and Microwave amplifier article, we will cover,

  • What is an RF and microwave Low noise amplifier?
  • Design consideration of Low noise amplifiers.
  • Applications of RF and MicrowaveLow noise amplifiers?
  • Selection specifications for a Low noise amplifier?
  • RF and microwave LNA manufacturers.

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Design and Application

Design considerations for Low Noice Amplifiers:

LNAs are the prime component of communication systems building blocks, which primarily deal with weak signals, just above the noise floor and intermodulation distortion. In the design of LNA, attributes like Gain, RF input power, Noise figure, Linearity, and output impedance match need to consider.

Noise figure:

Low noise figure and high amplification in the first stage of LNA design is achieved by using high-electron-mobility transistors (HEMTs) or junction field-effect transistors (JFETs). They are driven by a high-current regime and reduce the relative amount of shot noise.

  • A low noise figure for the LNA results in better RF signal reception.


The amount of gain generated in an LNA is often compromised. High gain makes weak signals strong and such high-level signals may exceed the amplifier's dynamic range and cause other types of noise like nonlinear mixing or harmonic distortion etc.

  • Large-signal models consider non-linear mixing and Small-signal models use quasi-linear models in LNA design to match the gain.


The perfect march impedance between source and input will maximize the power transfer to the device.

  • The common base circuit topology is appropriate for the circuits with low impedance matches.
  • Common emitter common source topology is ideal for medium impedance at the source.
  • Common collector or common drain topology is appropriate for high source resistance.

Applications of RF Low Noise Amplifiers:

Low Noise Amplifiers are used in the front end of the receive chain right after the antenna and filter to amplify the received very low strength signal with minimal degradation and without amplifying the noise in it.

  • The noise figure, gain, P1dB play an important role in the applications of low noise amplifiers.

As LNA is used very close to the signal source like an antenna, the signal gain created by the LNA helps to avoid the effect of noise in the subsequent stages of the receiver. LNA enables optimum retrieval of the desired signal by boosting the signals' power and adding as little noise and distortion into the later stages of the receiver system.

Industrial Applicaitons:

  • RF low noise amplifiers are used in the receivers of all wireless systems.
  • An LNA help reduces unwanted noise in the receiver chain of RF front end in telecommunication systems, GPS receivers, wireless LANs and satellite communication systems.
  • LNAs is the front end module of radio communications and electronic test equipment like spectrum analyzers.
  • The LNA help to boost the received antenna signal to overcome the losses in the feed line between the antenna and the receiver.
  • LNAs are used to enhance the receiver performance of software-defined radio(SDR).

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Basics & Selection Feature

Main specifications need to consider in the selection of RF Low Noise Amplifiers: 

When selecting RF low noise Amplifiers for the system design, the designer needs to consider the following features to optimise the receiver chain.

The frequency range of Low noise amplifiers

The frequency range of the LNA is the range of frequency over which it operates by meeting all other electrical parameters. In general, low noise amplifiers will have a narrow bandwidth to optimize input and output impedance match and offer very high-level noise figures.

Noise figure (NF):

The noise figure indicates the amount of noise added to the signal during amplification. A lower noise figure indicates a higher signal to noise ratio and it leads to a quality output signal to the receiver chain.

  • A good LNA that has a low NF in the range of 1 dB, which can boost the signal in the range of 10 dB and offer optimised inter-modulation (IP3 ) and compression point ( P1dB).

P1dB or Power Compression (dBm or W): 

Power Compression (P1dB) is the point at which the input signal to the LNA is amplified by a level that is 1 dB below the small-signal gain of the amplifier. Power Compression indicates the gain point beyond which amplifier gain is no longer linearly to the input power.

Input and Output VSWR:

As the LAN may need to connect to various loads, it is better to have good input and output impedance match to avoid unwanted signal reflection and it may affect the LNA and the quality of the original signal.

LNA Design gain:

The gain of the LNA indicates the ratio of the output to the input power level expressed in decibels (dB). LNA usually will have a higher gain in the range of 30 to 40 dB.

  • Gdb = 10 * log (Po/Pi).

The gain flatness of LNA:

Gain flatness shows the variation in the level of the gain over the entire frequency range of operation. Lower variation, better the performance of the Low noise amplifiers.

LNA Package and Connectors:

Low noise amplifiers are generally available in various package options like a Connectorized module, Surface Mount, or as a die or chip form. For connectorised modules, the designer can choose various RF connector options as per the design requirements. 

Operating Temperature:

As LNA, mostly need to fix along with the antenna in a hub or outdoor space, the operating temperature range of low noise amplifiers need to consider for matching the environmental conditions around the antenna.


A low-noise amplifier (LNA) is the most important, active device present in radio and other signal receivers to amplify signals of very low strength from an antenna before passing on to the receiver chain. LNA’s are generally capable of amplifying the barely recognizable signals without adding any noise to the original signal.

Below is the list of top-rated LNA manufacturers, from which you can choose a suitable amplifier for the RF system design.

If you would like to add any further details about the low noise amplifiers to this article, please contact us over the contact or article submission page.

Thanks & Regards

RFMWC: RF & Microwave Community

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