Why choose low-noise coaxial amplifiers



Found in radio communications systems, low-noise amplifiers are also used in electronic equipment and medical instruments

Baffled by the ever-evolving coaxial cable industry? You’ve come to the right place! In this article, we aim to tell you all about one product, in particular – the low noise coaxial amplifier. So, why should you choose it – and what benefits will it bring to your project? In short, the low-noise amplifier (also known as the LNA) is an electronic amplifier that amplifies a very low-power signal. It does this without degrading its signal-to-noise ratio; increasing the power of both the signal and the noise present at its output, the

LNA is designed to minimise any additional noise. But how does it work? Designers in the industry work hard to minimise additional noise by considering trade-offs, including impedance matching. They might also choose the right amplifier technology and select low-noise biasing conditions too.

Found in radio communications systems, low-noise amplifiers are also used in electronic equipment and medical instruments. To give you an idea of how a typical low-noise amplifier might work, it would generally supply a power gain of 100 (20 decibels) while decreasing the signal-to-nose ratio by a factor of two.

Of course, low-noise amplifiers like the ones you’ll find on component sites online, are primarily concerned with weak signals just above the noise floor. However, they might also consider the presence of much larger signals which cause intermodulation distortion.

Dealing with noise
Helping reduce unwanted noise, an LNA is simply the key component found at the front end of a radio receiver. The Friis’ formulas for noise helps those who need to calculate noise to ensure they have the right LNA for the job. Used in ISM radios, cellular phones, GPS receivers, cordless phones and automotive keyless systems, as you can tell, the LNA is key to ensure a variety of people can do their jobs properly.

By using an LNA close to the signal source, for example, the effect of noise from other stages of the receive chain can be reduced. The absolute building blocks of any communications system, LNAs undergo a strict design process to ensure they can perform effectively.

In a satellite system specifically, the ground station receiving antenna will connect to the LNA as the signal received is generally weak. Another thing to consider about these satellites is that they’re distant and suffer path loss – low earth orbit satellites, for example, might be some 200lm away – so the LNA offers an easy and cost-effective problem to combat any issues.

Boosting the antenna signal to compensate for the feed-line losses between the (outdoor) antenna and the (indoor) receiver, the LNA includes a frequency block down-converter which also shifts the satellite downlink frequency. The design is simply based on the S-parameters of a transistor and there are three key stages of design.

There are a few requirements for the low noise coaxial amplifier, and they include:
Operating Supply Voltage – Typically, LNAs require operating voltages in the range 2V to 10VOperating Supply Current – Low noise amplifies require supply current in the mA range. The current is generally dependent on its design and what it’s used for.
Operating Frequency – The frequency range of the LNA operation is typically very large; operating between 500 kHz and 50 GHz, it’s relatively versatile.
Operating Temperature Range – A low noise amplifier, much like any other semiconductor of its type, is required for operation in a specific temperature range – usually from 30°C to 50 °C (-22°F to 122 °F).

Of course, all these factors should be taken into consideration when you are choosing a low noise amplifier online. And should you need a custom product manufacturing, you will also find that you can get the job done via components sites relatively easily and quickly.

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