CN203872135U - Active low-noise mixer at front end of X-waveband radar receiver - Google Patents
Active low-noise mixer at front end of X-waveband radar receiver Download PDFInfo
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- CN203872135U CN203872135U CN201420186313.6U CN201420186313U CN203872135U CN 203872135 U CN203872135 U CN 203872135U CN 201420186313 U CN201420186313 U CN 201420186313U CN 203872135 U CN203872135 U CN 203872135U
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- mixer
- directional coupler
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- bias
- microstrip line
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Abstract
The utility model relates to a low-noise mixer, and concretely relates to an active low-noise mixer at the front end of an X-waveband radar receiver. The active low-noise mixer comprises a directional coupler, a match circuit, a frequency mixing diode and a low-pass filter. A radio frequency signal is connected with an input end of the directional coupler. A local oscillator signal is connected with another input end of the directional coupler. Two output ends of the directional coupler are connected with the frequency mixing diode. An output end of the frequency mixing diode is connected with the match circuit. Output of the match circuit is connected with the low-pass filter. The two output ends of the directional coupler are each provided with a DC bias circuit. The mixer helps to solve problems that X-waveband signals are high in noise coefficient during frequency mixing. Compared with products of the same kind, the mixer is smaller in noise coefficient and smaller in geometrical dimension.
Description
Technical field:
The invention belongs to microwave circuit field, relate to a kind of low-noise mixer, be specially a kind of active low-noise mixer that is applied to X-band radar receiver front end
Background technology:
Radar receiver is the important component part of radar system, its major function is that the small-signal that radar antenna is received is carried out preliminary election, amplification, frequency conversion, filtering, solution mediation digitized processing, suppress outside interference, clutter and set noise simultaneously, make echo-signal keep as much as possible target information, to further carry out signal processing and data processing.
Mixer is generally used for according to local oscillator (LO) frequency, by input signal from a frequency inverted to another frequency.For frequency reducing transformation applications, frequency mixer, by high incoming frequency, is transformed to low output frequency; For up-conversion application, incoming frequency will be low-frequency signals, and output will be high-frequency signal.Local oscillator (LO) frequency or signal are also considered to reference frequency or signal, and firing frequency (RF) frequency or signal are also considered to data frequency signal.These frequency inverted are by carrying out nonlinear operation and realize being embedded in the frequency mixer kernel of mixer.Together with required mixer output signal, frequency mixer typically generates other intermodulation products and end-to-end leakage, and these have all been suppressed well.In radar receiver front end system, often need to utilize mixer that the signal in a certain radio frequency band is converted to another midband.
Summary of the invention:
For having the excessive deficiency of noise factor in existing X-band radar receiver front end mixer design, the invention provides the method for designing of the active low-noise mixer of a kind of X-band radar receiver front end, operating frequency is 9.31GHz-9.51GHz (X-band).This active mixer has solved the excessive problem of noise factor that X-band signal occurs in Frequency mixing processing, and compared with similar products, the design has less noise factor and less physical dimension.
For achieving the above object, technical scheme of the present invention is:
The active low-noise mixer of a kind of X-band radar receiver front end, comprise directional coupler, match circuit, mixer diode and low pass filter, radiofrequency signal connects an input of directional coupler, local oscillation signal connects another input of directional coupler, two output termination mixer diodes of directional coupler, mixer diode output matching connection circuit, match circuit output connects low pass filter, and two outputs of described directional coupler are respectively equipped with a DC bias circuit.
Further design of the present invention is, DC bias circuit is comprised of DC power supply, bias voltage access point, microstrip line and fan-shaped offset of microstrip line, DC power supply is connected with bias voltage access point, the another two-port of bias voltage access point is connected with fan-shaped offset of microstrip line with microstrip line respectively, the output of another termination directional coupler of microstrip line.
Described microstrip line length is 1/4 wavelength; The fan-shaped radius of fan-shaped offset of microstrip line is 1/4 wavelength, and fan-shaped central angle is 45-90 degree.1/4 wavelength is 4.75 millimeters, and 4.75 millimeters is 1/4 wavelength dimension during frequency centered by 9.41GHz.
Two-way DC bias circuit Zhong Yi road is forward bias, and another road is reverse bias.
In forward bias, DC power anode is connected with bias voltage access point, minus earth; In reverse bias, DC power cathode is connected with bias voltage access point, plus earth.
In two-way DC bias circuit be divided into+2V of DC power supply and-2V.
Compared with prior art, invention tool of the present invention has the following advantages:
(1) the present invention is by the selection to substrate and mixer diode, and added innovatively positive and negative DC bias circuit, improve the initial bias of diode, make described frequency mixer there is good performance parameter, as reduced the noise factor (NF<5dB) of frequency mixer and improving conversion loss (GonvGain<5dB).
(2) the active low-noise mixer of the present invention has less physical dimension and the strong feature of adjustable, and actual size is 30mm*31mm, can be used for, in the ship-navigation radar receiver of corresponding frequency band, being convenient to the volume production of product.
Accompanying drawing explanation:
Below in conjunction with accompanying drawing and embodiment, the present invention is further elaborated:
Fig. 1 is the circuit topology figure of existing X-band low-noise mixer.
Fig. 2 is the initial circuit schematic diagram of existing X-band low-noise mixer.
Fig. 3 is that schematic diagram (the equal forward bias of two-way DC bias circuit) is changed in the correction for the first time of the active low-noise mixer of X-band of the present invention.
Fig. 4 is circuit theory diagrams after the correction for the first time of the active low-noise mixer of X-band of the present invention.
Fig. 5 is that the active low-noise mixer of X-band of the present invention is revised change schematic diagram (two-way DC bias circuit Zhong Yi road is forward bias, and another road is reverse bias) for the second time.
Fig. 6 is the active low-noise mixer of X-band of the present invention revised circuit theory diagrams for the second time.
In figure: 1. directional coupler, 2. match circuit, 3. mixer diode, 4. low pass filter, 5. DC bias circuit, 6. 7. pad, 8. screw hole, 9. bias voltage access point, 10. main line access point of reverse bias voltage.
Embodiment:
Embodiment mono-:
As shown in Figure 1, be the circuit topology figure of X-band low-noise mixer of the present invention.This frequency mixer is comprised of directional coupler, match circuit, mixer diode and low pass filter.Radiofrequency signal adds from the input port 1 of directional coupler, and local oscillation signal adds from another input port 2 of directional coupler.Directional coupler guarantees that local oscillator port and signal port have suitable isolation, and isolation is generally got 10dB, and the degree of coupling is got 3dB.Directional coupler, to there being 1/4 wavelength impedance transformer between mixer tube, to complete impedance matching, divides signal and local oscillation power etc. and is added to mixer diode.Circuit requirement hybrid circuit can make radiofrequency signal and local oscillation signal be added on mixer diode with the power of decile and the phase difference of 90 °.
As shown in Figure 2, be the initial circuit schematic diagram of X-band frequency mixer of the present invention.1. circuit comprises directional coupler, and 2., 3., low pass filter 4. for mixer diode for match circuit.
The operation principle of this invention is, radiofrequency signal is inputted by a directional coupler input 1., local oscillation signal is inputted by directional coupler another input 1., two output terminations of directional coupler are mixer diode 3., two-way input signal becomes the intermediate-freuqncy signal of 60MHz after mixer diode, and 2. mixer diode connects match circuit, and 4. match circuit connects low pass filter, for screening the signal of 60MHz, other high-frequency signals of elimination.In conjunction with substrate calculation of parameter, 1. in 50 Ω micro belt line widths be 1.12 millimeters, 35 Ω micro belt line widths are 1.92 millimeters.Reasonable selection, what the mixer diode in was 3. chosen is HSMS8202 type diode.
As shown in the table, be conversion loss and the noise factor of the low-noise mixer of X-band shown in Fig. 2.In working frequency range, conversion loss is 6.745dB, and circuit noise coefficient is 6.911dB.
| Frequency | Conversion gain | Noise frequency | Noise factor |
| 60.00MHz | -6.745dB | 60.00MHz | 6.911dB |
Embodiment bis-:
As shown in Figure 3, the active low-noise mixer of X-band of the present invention is for Optimal performance, and noise-reduction coefficient, has adopted the method that adds DC bias circuit on embodiment mono-, and concrete form is fan-shaped offset of microstrip line DC bias circuit.5. be DC bias circuit, this circuit is by direct voltage source, bias voltage access point, the fan-shaped offset of microstrip line that the quarter-wave microstrip line of input radio frequency signal and quarter-wave are radius forms, 9. bias DC voltage source is connected with bias voltage access point, 9. bias voltage access point locates to connect quarter-wave microstrip line and quarter-wave fan-shaped offset of microstrip line, 10. the other end of quarter-wave microstrip line accesses main circuit, and the access point on main circuit is positioned at two output port positions of directional coupler.Due to fan-shaped edge open circuit, be transformed into bias voltage access point be 9. short circuit to radiofrequency signal, and therefore for main circuit, power unit is considered as open circuit, so power unit can not affect the circuit of 9. locating inner side.Due to main line access point 10. and the microstrip line of bias voltage access point between be 9. 1/4th wavelength, 10. the short circuit of 9. locating is locating to be considered as open circuit, so the not impact of the AC characteristic of biasing circuit radiofrequency signal in 10. locating for main line.In biasing circuit, bias direct current voltage is 2V, and quarter-wave is 4.75 millimeters.
As shown in Figure 4, the active low-noise mixer of X-band of the present invention adds respectively forward bias circuit at two output ports of directional coupler, to play the effect of Optimal performance.
As shown in the table, be the active low-noise mixer of X-band of the present invention revised conversion loss and noise factor for the first time.Added the frequency mixer performance of biasing circuit to obtain obvious optimization, noise factor drops to 5.3dB from 6.9dB originally as we can see from the figure.
| Frequency | Conversion gain | Noise frequency | Noise factor |
| 60.00MHz | -4.677dB | 60.00MHz | 5.322dB |
Embodiment tri-:
As shown in Figure 5, the active low-noise mixer of X-band of the present invention is revised for the second time schematic diagram on embodiment bis-bases.Correction step is, the reverse bias voltage during 6. one of them forward bias voltage in is 5. changed into, can obtain more optimal performance.
As shown in Figure 6, for the active low-noise mixer of X-band of the present invention is revised rear circuit theory diagrams for the second time, improving place is by the output port of revised biasing circuit access directional coupler below in Fig. 5, and the noise factor of whole system is further reduced.
As shown in the table, be the active low-noise mixer of X-band of the present invention revised conversion loss and noise factor for the second time.Through adopting, add after the optimization method of forward and reverse biasing circuit, by adopting ADS software emulation, can see that noise factor has dropped to below 5dB.
| Frequency | Conversion gain | Noise frequency | Noise factor |
| 60.00MHz | -4.569dB | 60.00MHz | 4.985dB |
Embodiment tetra-:
Pcb board of the present invention is double-clad board, its Outside Dimensions 31mm*30mm, and sheet material is Rogers4003C, and thickness of slab is 0.508mm, and relative dielectric constant is 3.55.Capacitance resistance ware is 0603 encapsulation preferably, guarantees that circuit structure is compact.Wherein, be 1. directional coupler part, be 2. match circuit part, be 3. mixer diode placement part, be 4. low pass filter part.Four jiaos of screw holes that are respectively drilled with metallic shield (cavity) box 8..7. pcb board leaves the pad used of welding sub-miniature A connector.Use AltiumDesigner mapping software that the final circuit of frequency mixer is depicted as to PCB domain, in input-output adapt ation network open circuit branch line leave adjusting surplus, after later stage processing in kind, can adjust according to test result.
The content not being described in detail in specification of the present invention belongs to those skilled in the art's known technology.
Claims (7)
1. the active low-noise mixer of X-band radar receiver front end, comprise directional coupler, match circuit, mixer diode and low pass filter, radiofrequency signal connects an input of directional coupler, local oscillation signal connects another input of directional coupler, two output termination mixer diodes of directional coupler, mixer diode output matching connection circuit, match circuit output connects low pass filter, it is characterized in that: two outputs of described directional coupler are respectively equipped with a DC bias circuit.
2. frequency mixer according to claim 1, it is characterized in that: described DC bias circuit is comprised of DC power supply, bias voltage access point, microstrip line and fan-shaped offset of microstrip line, DC power supply is connected with bias voltage access point, the another two-port of bias voltage access point is connected with fan-shaped offset of microstrip line with microstrip line respectively, the output of another termination directional coupler of microstrip line.
3. frequency mixer according to claim 2, is characterized in that: described microstrip line length is 1/4 wavelength; The fan-shaped radius of fan-shaped offset of microstrip line is 1/4 wavelength, and fan-shaped central angle is 45-90 degree.
4. frequency mixer according to claim 3, is characterized in that: described 1/4 wavelength is 4.75 millimeters.
5. according to the frequency mixer described in claim 2,3 or 4, it is characterized in that: two-way DC bias circuit Zhong Yi road is forward bias, another road is reverse bias.
6. frequency mixer according to claim 5, is characterized in that: in forward bias, DC power anode is connected with bias voltage access point, minus earth; In reverse bias, DC power cathode is connected with bias voltage access point, plus earth.
7. frequency mixer according to claim 5, is characterized in that: in two-way DC bias circuit be divided into+2V of DC power supply and-2V.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420186313.6U CN203872135U (en) | 2014-04-16 | 2014-04-16 | Active low-noise mixer at front end of X-waveband radar receiver |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420186313.6U CN203872135U (en) | 2014-04-16 | 2014-04-16 | Active low-noise mixer at front end of X-waveband radar receiver |
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| CN203872135U true CN203872135U (en) | 2014-10-08 |
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| CN201420186313.6U Expired - Fee Related CN203872135U (en) | 2014-04-16 | 2014-04-16 | Active low-noise mixer at front end of X-waveband radar receiver |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114341667A (en) * | 2020-07-10 | 2022-04-12 | 深圳市速腾聚创科技有限公司 | Laser receiving circuit and laser radar |
-
2014
- 2014-04-16 CN CN201420186313.6U patent/CN203872135U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114341667A (en) * | 2020-07-10 | 2022-04-12 | 深圳市速腾聚创科技有限公司 | Laser receiving circuit and laser radar |
| CN114341667B (en) * | 2020-07-10 | 2023-08-04 | 深圳市速腾聚创科技有限公司 | Laser receiving circuit and laser radar |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20141008 Termination date: 20160416 |
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| CF01 | Termination of patent right due to non-payment of annual fee |