A low noise amplifier (LNA) is an electronic device that amplifies weak signals at its input without adding significant noise. These amplifiers are typically used in receivers. For LNAs the most important specifications are:
- Noise Figure
The LNA’s gain refers to its ability to increase the value of the input signal. It is most often specified in dB. Typical gain values for an LNA are between 10 and 30 dB.
Noise figure provides a measure of the noise contribution due to the LNA itself. In the picture below, the LNA amplifies both the signal and noise present at its input equally. In addition, the output includes noise due to the LNA. This in turn reduces the signal-to-noise ratio. A good LNA contributes very little noise to the overall picture.
The linearity of an LNA is a measure of its ability to amplify the signal without distortion. When an LNA is operating linearly, the output power in dB is the sum of the input signal and the gain. However, as the input signal level increases beyond a certain point, the output starts to level off and the LNA is no longer linear.
In the picture below, the LNA is operating linearly when the signal present at its input has an amplitude of -60 dBm. However, as the input signal is increased to 0 dBm, the device is no longer linear, the output signal is distorted, the gain is no longer 20 dB and the output signal amplitude is only +5 dBm.
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Jon has some spectrum scanning projects in which he uses our LNA and FM notch filters. It’s interesting how he puts them into die-cast boxes. This is something we get asked about all the time. You can read about the projects here and here. Jon’s wireless projects are definitely worth reading about.
David Goldstein sent in a few pictures that show FM reception without and with the 40 dB LNA. A significant gain in performance with the LNA. Thanks David!
Some of our LNAs provide in excess of 40 dB of gain and operate over a wide frequency range. The primary application of these products is to amplify weak signals by increasing the signal-to-noise ratio at the receiver.
One important consideration when using these LNAs is that they amplify everything across their frequency range of operation. If your receiver does not have any front-end filtering, you might find yourself having to deal with a large assortment of strong unwanted signals. Most software-defined radios are wideband and therefore susceptible to these strong signals. A strong signal present at the input of a receiver can cause it to saturate and produce garbage at the output.
When using these high gain LNAs we recommend using a bandpass filter for your frequency range of interest. We have a number of such filters for GPS, 426, 433 MHz, 915 MHz and 2450 MHz bands: http://stores.ebay.com/gpiolabs/Bandpass-Filters-/_i.html?_fsub=28020158018
and we are looking to add new filters. If you would like to see us develop a filter for your application, get in touch.
Our LNA products use a micro-USB connector for powering the device. The choice of this connector was based on the popularity of USB and the reasoning that it’s easy to find cell phone chargers. The only negative with this connector is that it is easy to rip them off the board if handled improperly. Once the connector detaches from the board, in most situations, the hardware cannot be repaired.
There are a few precautions that users can take to prevent damage to the board.
- When setting up to use the LNA, we recommend connecting the SMA connectors to cables prior to connecting the USB power cable. This is to prevent potentially torquing the board.
- Similarly when you’re done using the LNA and if it’s not part of a permanent fixture, detach the USB power cable first and then take the SMA connectors off.
- Finally, avoid dangling the LNA with the USB cable while it’s connected.
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This is a wideband low noise amplifier that provides excellent gain (35-40 dB between 100 MHz and 2 GHz) and noise figure (3 dB at 2 GHz). The LNA is very general purpose and can be used in a number of different applications such as Ham Radio, Software radio, TV reception, etc. The product is ideally suited for software radio products such as RTL-SDR, HackRF, USRP, etc. where the USB power supply means you can power it off your laptop. Our design is unique as it provides broadband performance from 10 MHz to 8 GHz at a fraction of the cost of similar LNAs. As well, all our products are made with genuine ICs sourced directly from the manufacturer and reliable distributors.
• Wideband LNA operates from 10 MHz to 8 GHz
• USB-powered; includes pads for external DC power
• Suitable for use with software radio receivers such as HackRF, RTL-SDR, USRP, etc.
• 2.9 dB Noise Figure at 2 GHz
• PCB edge-mount connectors are SMA-F
• Micro USB cable not included
10 MHz 30 dB
100 MHz 40 dB
1 GHz 39 dB
2 GHz 35 dB
3 GHz 31 dB
4 GHz 28 dB
5 GHz 26 dB
6 GHz 23 dB
7 GHz 20 dB
8 GHz 14 dB
9 GHz 10 dB
Maximum RF Input Power
1.5″ x 1.7″
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This is a low noise RF amplifier that provides excellent gain and noise figure. The gain at 100 MHz is 30 dB while the noise figure is 2.2 dB. The LNA can be used in a number of different receiver applications such as Ham Radio, Software radio, TV reception, etc. The product is ideally suited as a pre-amplifier for software radio products such as RTL-SDR, HackRF, USRP, etc., where the USB power supply means you can power it off your laptop.
- Wideband LNA with 30 dB Maximum Gain between 100 kHz and 2 GHz;
- Operational from 100 kHz to 5 GHz
- Suitable for use with software radio receivers such as HackRF, BladeRF, RTL-SDR, USRP, etc.
- LED power indicator
- SMA-F connectors
- USB powered (cable not included)
- Pads for two-pin power header
100 kHz 18 dB
1 MHz 25 dB
10 MHz 27 dB
100 MHz 31 dB
1 GHz 24 dB
2 GHz 19 dB
3 GHz 14 dB
4 GHz 12 dB
5 GHz 10 dB
6 GHz 6 dB
Maximum RF Input Power
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