CN217824901U - Short wave broadband ultra-low noise amplifier - Google Patents

Abstract

The utility model discloses a short-wave broadband ultra-low noise amplifier, which comprises a directional coupler composed of two transformers and a low noise amplifier. One output end of the low noise amplifier is connected in series with a transformer, and one input end of the low noise amplifier is connected in parallel with a transformer. Connect the primary coil L1 of the transformer T2 in series between the output of the amplifier A1 and the load, and use two transformers to realize a short-wave broadband ultra-low noise amplifier. Unlike resistor feedback, the lossless feedback network will not reduce the noise figure and gain of the LNA . From the perspective of wide frequency band and structure, the transformer adopts the traditional lumped parameter transformer, which is formed by winding the coil on the ferrite magnetic ring, so it has the characteristics of lumped parameter components, that is, small size and relatively large bandwidth. The low noise amplifier of this design Compared with monolithic amplifiers, it has the following characteristics: low operating frequency, small noise figure, wide frequency band, and good return loss.

Description

Shortwave Broadband Ultra Low Noise Amplifier

technical field

The utility model relates to the technical field of communication, in particular to a short-wave broadband ultra-low noise amplifier.

Background technique

The low noise amplifier is an essential and important part in communication, radar, electronic countermeasures and remote control telemetry systems. It is located at the front end of the radio frequency receiving system. Noise interference, improve the sensitivity of the system. Especially with the development of communication, electronic countermeasures, and microwave measurement in the direction of broadband, low noise, and miniaturization, the low noise and wideband design of amplifiers has received more and more attention.

The main obstacle in the design of broadband amplifiers is the restriction of the gain-bandwidth product of active devices, that is, the gain of active devices decreases at a rate of 6dB/octave at the high end of the frequency as the frequency increases. Commonly used design methods for broadband amplifiers are: balanced structure amplifiers, negative feedback amplifiers, active matching circuits, reactance network matching, broadband resistance matching, distributed amplifiers, etc. Among them, the negative feedback amplifier has the following obvious advantages: reduce the sensitivity of the whole circuit to the performance change of the transistor itself; obtain better input impedance matching and lower noise figure; increase the stability of the amplifier in the working frequency band; linearity etc. Therefore, negative feedback technology is widely used in the design of broadband amplifiers.

In the traditional broadband amplifier stage, the resistance feedback method is often used (as shown in Figure 1). In the low frequency band with high gain, the gain can be reduced through the negative feedback of the transmitter resistance and the collector resistance; At the frequency end, the collector feedback will decrease, thereby increasing the gain of the amplifier, but the resistance feedback has a great impact on the dynamic range of the amplifier; on the one hand, due to the harmonic interference caused by the resistance's own noise, the system noise figure will vary The number of system feedback increases and increases, making the noise figure of this broadband amplifier very poor, even worse than that of a broadband RF amplifier without feedback.

For this reason, a short-wave broadband ultra-low noise amplifier is proposed.

Contents of the invention

The purpose of this utility model is to provide a short-wave broadband ultra-low noise amplifier. Two transformers are used to realize the short-wave broadband ultra-low noise amplifier. Unlike the resistance feedback, the lossless feedback network will not reduce the noise coefficient and gain of the low noise amplifier. From the perspective of broadband and structure, the transformer adopts the traditional lumped parameter transformer, which is formed by winding the coil on the ferrite magnetic ring, so it has the characteristics of lumped parameter elements, that is, small size and large relative bandwidth, to solve the above-mentioned background technology. proposed question.

In order to achieve the above object, the utility model provides the following technical solutions: a short-wave broadband ultra-low noise amplifier, including a directional coupler composed of two transformers, and a low noise amplifier, an output terminal of the low noise amplifier is connected in series with a transformer, and the low noise amplifier One input end of the noise amplifier is connected in parallel with a transformer, and the primary coil L1 of the transformer T2 is connected in series between the output of the amplifier A1 and the load. The secondary coil L2 is cascaded with the primary coil L1 of T1, and the secondary coil L2 of T1 is connected in parallel at the input end.

Preferably, the low noise amplifier adopts AST54S.

Compared with the prior art, the beneficial effects of the utility model are:

Two transformers are used to realize the short-wave broadband ultra-low noise amplifier. Unlike resistive feedback, the lossless feedback network will not reduce the noise figure and gain of the low-noise amplifier. From the perspective of wide frequency band and structure, the transformer adopts the traditional lumped parameter transformer, which is formed by winding the coil on the ferrite magnetic ring, so it has the characteristics of lumped parameter components, that is, small size and relatively large bandwidth. The low noise amplifier of this design Compared with monolithic amplifiers, it has the following characteristics: low operating frequency, small noise figure, wide frequency band, and good return loss, which fills the gap in the market for short-wave low-noise amplifiers.

Description of drawings

In order to more clearly illustrate the specific implementation of the utility model or the technical solutions in the prior art, the accompanying drawings that need to be used in the description of the specific implementation or the prior art will be briefly introduced below. Obviously, the following descriptions The accompanying drawings are some implementations of the utility model, and those skilled in the art can also obtain other drawings according to these drawings without any creative work.

Figure 1 is a simplified model of a traditional parallel negative feedback circuit;

Fig. 2 is the block diagram of the feedback amplifier without loss and low noise of the present utility model;

Fig. 3 is the AWR emulation schematic diagram of the present utility model;

Fig. 4 is the simulation result figure of the present utility model;

Fig. 5 is a block diagram of the noise figure test of the utility model.

Fig. 6 is the noise figure test result of the present utility model.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. example. Based on the embodiments of the present utility model, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

Please refer to Figure 1 to Figure 6, the utility model provides a technical solution:

A short-wave broadband ultra-low noise amplifier, including a directional coupler composed of two transformers, and a low noise amplifier, one output terminal of the low noise amplifier is connected in series with the transformer, one input terminal of the low noise amplifier is connected in parallel with the transformer, and the primary of the transformer T2 Coil L1 is connected in series between the output of amplifier A1 and the load. The secondary coil L2 is cascaded with the primary coil L1 of T1, and the secondary coil L2 of T1 is connected in parallel at the input end.

Specifically, the low noise amplifier adopts AST54S.

A low-noise monolithic amplifier AST54S with a relatively high frequency is used, and lossless feedback technology is adopted. First, the simulation is carried out through the AWR RF microwave simulation software according to the schematic diagram of the AST54S low-noise amplifier in Figure 3. The simulation results are shown in Figure 4. It can be seen that in The gain flatness in the range of 8~20MHz is less than 0.1dB, and the input return loss is less than -22.35dB (equivalent to VSWR 1.17)

Carry out circuit design according to the simulation parameters. After the assembly is completed, test according to the block diagram in Figure 5 to get better results. NF: 0.8-1.0dB@10MHz, 0.5-0.6dB@20MHz, G: 19-20dB@1M-28M, input Wave loss: >20dB@(8-28MHz).

Working principle: The output signal is coupled to the secondary coil through the primary coil of T2, and the secondary coil L2 is connected in series with the primary coil L1 of T2. Then, the negative feedback signal is coupled in parallel to the input terminal of the amplifier A1 through T2 to form negative feedback, thereby optimizing the S parameter of the transistor.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present utility model, and are not intended to limit it; although the present utility model has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand : It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements to some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions depart from the various embodiments of the present invention Scope of technical solutions.

Claims (2)

1. A short-wave broadband ultra-low noise amplifier, comprising a directional coupler formed by two transformers, and a low noise amplifier, characterized in that: an output terminal of the low noise amplifier is connected in series with a transformer, and an input terminal of the low noise amplifier is connected in parallel with the transformer , the primary coil L1 of the transformer T2 is connected in series between the output of the amplifier A1 and the load, the secondary coil L2 is cascaded with the primary coil L1 of T1, and the secondary coil L2 of T1 is connected in parallel at the input end. 2. The shortwave broadband ultra-low noise amplifier according to claim 1, characterized in that: said low noise amplifier adopts AST54S.

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