Low noise amplifier, amplifier with low noise figure. It is generally used as high-frequency or intermediate frequency preamplifier of various radio receivers and amplification circuit of high-sensitivity electronic detection equipment. When amplifying a weak signal, the noise of the amplifier itself may seriously interfere with the signal. Therefore, it is hoped to reduce this noise in order to improve the signal-to-noise ratio of the output.

1. Isolator: it is mainly used for one-way input of high-frequency signal, isolate the reverse high-frequency signal, and match the standing wave of each port at the same time.

2. Low noise tube: atf54143 uses the low noise characteristics of the tube to reduce the internal noise of the module, reduce the noise level of the low noise module and improve the receiving sensitivity of the whole machine.

3. Amplification tube: further amplify the high-frequency signal.

4. Limiting component: it includes voltage controlled attenuation circuit (ALC) composed of pin tube and numerical control attenuation circuit (ATT) composed of hmc273.

5. Detection module: detect the output power of the module. The detection circuit composed of max-4003 chip detects the output power.

6. Limiting operation circuit: the detection component calculates the output DC voltage of the detected power of the high-frequency signal and controls the limiting circuit.

Low noise amplifier, amplifier with low noise figure. It is generally used as high-frequency or intermediate frequency preamplifier of various radio receivers and amplification circuit of high-sensitivity electronic detection equipment. When amplifying a weak signal, the noise of the amplifier itself may seriously interfere with the signal. Therefore, it is hoped to reduce this noise in order to improve the signal-to-noise ratio of the output.

The deterioration degree of signal-to-noise ratio caused by amplifier is usually expressed by noise coefficient F. The noise figure of the ideal amplifier is f = 1 (0 dB), and its physical meaning is that the output signal-to-noise ratio is equal to the input signal-to-noise ratio. Modern low noise amplifiers mostly use transistors and field effect transistors; The microwave low-noise amplifier adopts varactor parametric amplifier. The noise temperature te of normal temperature parametric amplifier can be lower than tens of degrees (absolute temperature), and the refrigeration parametric amplifier can be less than 20K. The application of GaAs FET low-noise microwave amplifier has become more and more widely, and its noise coefficient can be less than 2 dB. The noise figure of the amplifier is also related to the working state of the transistor and the internal resistance of the source. When the operating frequency and the internal resistance of the source are given, the noise figure is also related to the DC operating point of the transistor. In order to meet the requirements of low noise and high gain, low noise amplifier circuits with common emitter and common base cascade are often used.

Application:

Noise amplifier (LNA) is mainly designed for mobile communication infrastructure base station applications, such as transceiver wireless communication card, tower top amplifier (TMA), combiner, repeater and remote / digital wireless broadband head end equipment, and sets a new benchmark for low noise figure (NF). At present, the wireless communication infrastructure industry is facing the challenge of providing the best signal quality and coverage in the crowded spectrum. Receiver sensitivity is one of the most key requirements in the design of base station receiving path. Appropriate LNA selection, especially the first level LNA, can greatly improve the sensitivity performance of base station receiver, and low noise index is also the key design goal.