X-waveband radar receiver front end active low noise mixer

A receiver front-end and mixer technology, applied in instruments, radio wave measurement systems, diode modulation conversion, etc., to achieve good performance parameters, improve initial bias, and facilitate mass production

Inactive Publication Date: 2014-10-15
NANJING UNIV OF INFORMATION SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This active mixer solves the problem of excessive noise figure in the mixing process of X-band signals. Compared with similar products, this design has a smaller noise figure and smaller geometric size

Method used

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  • X-waveband radar receiver front end active low noise mixer
  • X-waveband radar receiver front end active low noise mixer
  • X-waveband radar receiver front end active low noise mixer

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033] Such as figure 1 Shown is the circuit topology diagram of the X-band low noise mixer of the present invention. The mixer is composed of a directional coupler, a matching circuit, a mixing diode and a low-pass filter. The RF signal is added from the input port 1 of the directional coupler, and the local oscillator signal is added from the other input port 2 of the directional coupler. The directional coupler ensures proper isolation between the local oscillator port and the signal port. Generally, the isolation is 10dB and the coupling is 3dB. There is a 1 / 4 wavelength impedance converter between the directional coupler and the mixer tube to complete impedance matching, so that the signal and local oscillator power are equally divided into the mixer diode. The circuit requires the hybrid circuit to enable both the RF signal and the local oscillator signal to be applied to the mixing diode with equal power and a 90° phase difference.

[0034] Such as figure 2 Shown ...

Embodiment 2

[0038] Such as Figure 4 As shown, in order to optimize the performance and reduce the noise figure, the X-band active low-noise mixer of the present invention adopts the method of adding a DC bias circuit in the first embodiment, and the specific form is a fan-shaped microstrip line DC bias circuit. ⑤ is a DC bias circuit, which is composed of a DC voltage source, a bias voltage access point, a quarter-wavelength microstrip line for inputting radio frequency signals, and a fan-shaped microstrip line with a quarter-wavelength radius. The voltage source is connected to the bias voltage access point ⑨, the bias voltage access point ⑨ is connected to the quarter-wavelength microstrip line and the quarter-wavelength fan-shaped microstrip line, and the other end of the quarter-wavelength microstrip line ⑩ Access to the main circuit, the access point on the main circuit is located at the two output ports of the directional coupler. Since the fan-shaped edge is open, the RF signal c...

Embodiment 3

[0042] Such as Figure 7 As shown, the X-band active low-noise mixer of the present invention is modified for the second time on the basis of the second embodiment. The correction step is to change one of the forward bias voltages in ⑤ to the reverse bias voltage in ⑥ to get more optimized performance.

[0043] Such as Figure 8 As shown, it is the circuit schematic diagram after the second revision of the X-band active low-noise mixer of the present invention, and the improvements are as follows: Figure 7 The corrected bias circuit is connected to the output port below the directional coupler, which further reduces the noise figure of the whole system.

[0044] Such as Figure 9Shown is the frequency conversion loss and noise figure after the second correction of the X-band active low-noise mixer of the present invention. After adopting the optimization method of adding forward and reverse bias circuits, and by using ADS software simulation, it can be seen that the noise...

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Abstract

The invention relates to a low noise mixer and especially relates to an X-waveband radar receiver front end active low noise mixer. The mixer comprises a directional coupler, a match circuit, a mixing diode and a low-pass filter. Radio-frequency signals are connected to one input end of the directional coupler; local oscillator signals are connected to the other input end of the directional coupler; the two output ends of the directional coupler are connected with the mixing diode; the output end of the mixing diode is connected with the match circuit; the output end of the match circuit is connected with the low-pass filter; and the two output ends of the directional coupler are respectively provided with a DC bias circuit. The mixer helps to solve the problem that the noise coefficient is over large when X-waveband signals are in mixer processing; and compared with the similar product, the mixer has smaller noise coefficients and smaller geometric dimensions.

Description

Technical field: [0001] The invention belongs to the field of microwave circuits and relates to a low-noise mixer, in particular to an active low-noise mixer applied to the front end of an X-band radar receiver Background technique: [0002] The radar receiver is an important part of the radar system. Its main function is to perform preselection, amplification, frequency conversion, filtering, demodulation and digital processing of the weak signals received by the radar antenna, while suppressing external interference, clutter and internal noise. Noise, so that the echo signal retains as much target information as possible for further signal processing and data processing. [0003] Mixer circuits are typically used to convert an input signal from one frequency to another based on the local oscillator (LO) frequency. For down-conversion applications, the mixer converts a high input frequency to a low output frequency; for up-conversion applications, the input frequency wil...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03D7/02G01S7/32
Inventor 葛俊祥徐硕孟季春王晨昊潘安
Owner NANJING UNIV OF INFORMATION SCI & TECH
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