If a radio had a single most important active component, it would be the low-noise amplifier. Sitting right after the antenna on the receive path, the LNA decides how weak a signal the system can still hear. Get it wrong and the whole receiver is noisy no matter how good everything else is. This guide explains what an LNA does and how to think about selecting one.
Why the first stage dominates
Noise figure describes how much a device degrades the signal-to-noise ratio. The catch is that noise from later stages is divided by the gain of everything before them. So the first amplifier's noise figure, multiplied by its gain, sets the noise floor of the entire receiver. A tenth of a dB saved here is worth more than a dB saved anywhere downstream.
We stock low-noise and gain-block amplifiers such as the TQP3M9019, the SGA-6389Z, the ERA-1SM+, the GALI-21+ and the MGA-30889-TR1G.
The trade-offs
- Noise figure vs gain. The first stage wants low noise; enough gain to bury downstream noise; but not so much that strong signals compress it.
- Noise figure vs linearity (OIP3). In a crowded band, linearity can matter as much as noise, because interferers create intermodulation that lands on your signal.
- Bandwidth vs noise. A wider-band LNA is more flexible but typically noisier than a narrow-band one.
Where LNAs are used
Anywhere a weak signal must be recovered: base-station receive paths, satellite communications, GNSS receivers, test and measurement equipment, and the receive side of every cellular and IoT radio. In a handset the LNA lives inside the front-end module; in a basestation it is often a discrete, higher-performance part.
Supporting the LNA
A low-loss switch selects the band or antenna before the LNA, and a filter rejects out-of-band interferers so the LNA is not overloaded. We supply switches such as the QPC6044TR13 and filters such as the LFCN-3800+ low-pass filter for this role.
Sourcing LNAs
LNAs are often the performance-critical, hard-to-find line in a receiver bill of materials. We supply from traceable sources with date-code verification and inspection options. Browse the RF and interface chip range and the Qorvo and Mini-Circuits collections.
Frequently asked questions
What is a low-noise amplifier and why is it important?
An LNA is the first active block after the antenna on the receive path. Its job is to add gain while adding as little noise as possible, because the noise it contributes is amplified by everything downstream. A better LNA directly improves receiver sensitivity and range.
What is noise figure and why is lower better?
Noise figure is how much the device degrades the signal-to-noise ratio, in dB. The first stage dominates the total, so even a small improvement in the LNA noise figure can mean a noticeably longer range or a more robust link.
Is gain or noise figure more important?
For the first stage, noise figure usually wins, because it sets the floor for the whole receiver. After the first LNA has lifted the signal above the noise of later stages, gain and linearity take over. The right balance depends on the system.
Can you supply LNAs and gain blocks?
Yes. We stock low-noise and gain-block amplifiers such as the TQP3M9019, SGA-6389Z, ERA-1SM+, GALI-21+ and MGA-30889-TR1G, from traceable sources. Send the part number and quantity for a quote.
About us & trademarks: JTDZ Tech (Shenzhen Jingteng Electronics Technology Co., Ltd.) is an independent distributor of electronic components. We are not an authorised distributor or representative of the manufacturers named in this article. Manufacturer and part names are used for indicative purposes only, to help identify the components discussed; all trademarks remain the property of their respective owners. Always verify specifications against the manufacturer's datasheet before design-in or purchase.
