Ultra-wideband step-frequency radio-frequency front end with high-order harmonic suppression

Abstract

The invention discloses an ultra-wideband step-frequency radio-frequency front end with high-order harmonic suppression, which comprises a transmitter and a receiver, a high-frequency local oscillator enters a power divider after passing through a driving amplifier and a band-pass filter, one path of output signal is used as an intermediate-frequency signal of a down-conversion mixer and is mixed with a step-frequency signal, and the step-frequency signal is output to the receiver; taking a sideband signal through a low-pass filter, and transmitting the sideband signal to a transmitting antenna through a power amplifier; in a receiver, a signal of a receiving antenna sequentially passes through a low-noise amplifier and a band-pass filter, enters a frequency mixer and is mixed with a coupled stepping frequency signal, an upper sideband signal in an output signal is taken, passes through a driving amplifier and the band-pass filter and then is subjected to IQ frequency mixing with the other path of signal output by a power divider, and a signal output by a power divider is obtained. And respectively carrying out AD sampling on the I channel and the Q channel. According to the invention, the high-order harmonic of the transmitted signal can be effectively suppressed without switching a filter bank, and the cost is effectively reduced while the complexity of the system is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of radar application, and in particular to an ultra-wideband stepped frequency radio frequency front end with high-order harmonic suppression. Background Art

[0002] With the development of information technology, RF front-end systems are constantly developing. The main function of RF front-ends is to transmit and receive RF signals. The stepped frequency RF front-end occupies an important position in modern radar research and applications due to its unique advantages. The significance of studying the stepped frequency RF front-end is that it can provide high sensitivity and dynamic range, which is essential for accurate detection and identification of targets. The research on the stepped frequency RF front-end can not only promote the development of radar technology, but also provide more powerful and reliable detection tools for various military, industrial and civilian fields. However, the existing stepped frequency RF front-end will generate a series of high-order harmonics due to the nonlinear characteristics of the RF synthesis source and mixer, which will affect the working performance of the system. Summary of the invention

[0003] In view of the shortcomings existing in the prior art, the purpose of the present invention is to provide an ultra-wideband stepped frequency RF front end with high-order harmonic suppression, which obtains an ultra-wideband signal of a difference frequency by mixing a stepped frequency local oscillator with a high-frequency frequency. There are no harmonic components within the step frequency range of the local oscillator, and the out-of-band harmonics and spurious can be effectively filtered out by a bandpass filter, that is, the high-order harmonics of the transmitted signal can be effectively suppressed without switching the filter group, which reduces the complexity of the system and effectively reduces the cost. In order to achieve the above-mentioned purpose and other advantages of the present invention, an ultra-wideband stepped frequency RF front end with high-order harmonic suppression is provided, comprising:

[0004] A transmitter, the transmitter comprising a high-frequency local oscillator, a first driving amplifier connected to the high-frequency local oscillator signal, a first band-pass filter connected to the first driving amplifier signal, a first power divider connected to the first band-pass filter signal, a down-conversion mixer connected to the first power divider signal, a first low-pass filter connected to the down-conversion mixer signal, a power amplifier connected to the first low-pass filter signal, and a transmitting antenna connected to the power amplifier signal;

[0005] A receiver, the receiver comprising a receiving antenna, a low noise amplifier connected to the receiving antenna signal, a second low pass filter connected to the low noise amplifier signal, an up-conversion mixer connected to the second low pass filter signal, a second power divider and a second driving amplifier connected to the up-conversion mixer signal, a step frequency local oscillator connected to the second power divider signal, a second band pass filter connected to the second driving amplifier signal, an IQ mixer connected to the second band pass filter signal, and an AD sampling connected to the IQ mixer signal; the first power divider is connected to the IQ mixer signal; the second power divider is connected to the down-conversion mixer signal. In the transmitter, the high-frequency local oscillator passes through the driving amplifier and the bandpass filter and enters the power divider. One of the output signals is used as the intermediate frequency signal of the down-conversion mixer, mixed with the step frequency signal, and the lower sideband signal is removed through the low-pass filter, and then passes through the power amplifier to the transmitting antenna; in the receiver, the signal from the receiving antenna passes through the low-noise amplifier and the bandpass filter in turn, enters the up-conversion mixer, mixed with the coupled step frequency signal, and the upper sideband signal in the output signal is taken. After passing through the driving amplifier and the bandpass filter, it is IQ mixed with another signal output from the power divider, and AD sampling is performed on the I channel and the Q channel respectively. The sampled digital signal enters the digital signal processing module.

[0006] Compared with the prior art, the present invention has the following beneficial effects: an ultra-wideband signal of a difference frequency is obtained by mixing a stepped frequency local oscillator with a high intermediate frequency, no harmonic components exist within the stepped frequency range of the local oscillator, and out-of-band harmonics and spurious signals can be effectively filtered out by a bandpass filter, that is, effective suppression of high-order harmonics of the transmission signal can be achieved without switching the filter group, thereby reducing system complexity and effectively reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a schematic diagram of the architecture of an ultra-wideband stepped-frequency RF front end with high-order harmonic suppression according to the present invention;

[0008] Figure 2 FIG. 4 is a frequency conversion diagram of an example of an ultra-wideband stepped-frequency RF front end with high-order harmonic suppression according to the present invention.

[0009] 100——transmitter, 200——receiver, 1001——high frequency local oscillator, 1002-first driver amplifier, 1003——first bandpass filter, 1004——first power divider, 1005——coupled signal, 1006——through signal, 1007——down-conversion mixer, 1008——first low-pass filter, 1009——power amplifier, 1010——transmitting antenna, 2001——receiving antenna, 2002——low noise amplifier, 2003——second low-pass filter, 2004——second power divider, 2005——up-conversion mixer, 2006——second driver amplifier, 2007——stepped frequency local oscillator, 2008——second bandpass filter, 2009——IQ mixer, 2010——I channel, 2011——Q channel, 2012——AD sampling. DETAILED DESCRIPTION

[0010] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0011] Reference Figure 1 , an ultra-wideband stepped frequency RF front end with high-order harmonic suppression, comprising:

[0012] The transmitter 100 includes a high-frequency local oscillator 1001, a first driving amplifier 1002 connected to the high-frequency local oscillator 1001 signal, a first bandpass filter 1003 connected to the first driving amplifier 1002 signal, a first power divider 1004 connected to the first bandpass filter 1003 signal, a down-conversion mixer 1007 connected to the first power divider 1004 signal, a first low-pass filter 1008 connected to the down-conversion mixer 1007 signal, a power amplifier 1009 connected to the first low-pass filter 1008 signal, and a transmitting antenna 1010 connected to the power amplifier 1009 signal; a suitable high-frequency local oscillator 1001 is selected according to the operating frequency of the RF front end; the first driving amplifier 1002 is used to Amplify the signal of the high-frequency local oscillator 1001; the first bandpass filter 1003 is used to filter out the undesired frequency components in the output signal of the first driving amplifier 1002; the first power divider 1004 is used to divide the signal output by the first bandpass filter 1003 into a coupling signal 1005 and a direct-pass signal 1006; the down-conversion mixer 1007 is used to mix the coupling signal 1005 with the step frequency signal; the first low-pass filter 1008 is used to filter out the undesired frequency components in the output signal of the down-conversion mixer 1007 and take out the lower sideband signal; the power amplifier 1009 is used to amplify the lower sideband signal output by the down-conversion mixer 1007; the transmitting antenna 1010 is used to transmit the signal amplified by the power amplifier 1009.

[0013] A receiver 200, the receiver 200 comprising a receiving antenna 2001, a low noise amplifier 2002 connected to the receiving antenna 2001, a second low pass filter 2003 connected to the low noise amplifier 2002, an up-conversion mixer 2005 connected to the second low pass filter 2003, a second power divider 2004 and a second driver amplifier 2006 connected to the up-conversion mixer 2005, a stepped frequency local oscillator 2007 connected to the second power divider 2004, a second band pass filter 2008 connected to the second driver amplifier 2006, an IQ mixer 2009 connected to the second band pass filter 2008, and an AD sampling 2012 connected to the IQ mixer 2009; a receiving antenna 2001 is used to receive the signal reflected by the target; the low noise amplifier 2002 is used to filter out the undesired frequency components in the output signal of the low noise amplifier 2002; the up-conversion mixer 2005 is used to mix the second low-pass filter 2003 with the step-frequency local oscillator 2007; the second driving amplifier 2006 is used to amplify the signal output by the up-conversion mixer 2005; the second band-pass filter 2008 is used to filter out the undesired frequency components in the output signal of the up-conversion mixer 2005 and obtain the upper sideband signal; the IQ mixer 2009 is used to perform IQ mixing on the signal output by the second band-pass filter 2008 and the direct signal 1006; the AD sampling 2012 is used to digitally collect the I channel 2010 and the Q channel 2011 respectively. The sampled digital signal enters the digital signal processing module.

[0014] The first power divider 1004 is signal-connected to the IQ mixer 2009;

[0015] The second power divider 2004 is signal-connected to the down-conversion mixer 1007 .

[0016] Furthermore, the frequency of the high-frequency local oscillator 1001 is lower than that of the step-frequency local oscillator 2007. There is a frequency difference between the high-order harmonics generated by mixing the high-frequency local oscillator 1001 and the step-frequency local oscillator 2007 and the target signal, which can be suppressed by a filter.

[0017] Furthermore, the passbands of the first low-pass filter 1008 and the second low-pass filter 2003 are below the high-order harmonic frequency.

[0018] Furthermore, the IQ mixer 2009 performs AD sampling on the I channel 2010 and the Q channel 2011 respectively.

[0019] Example 1

[0020] See also Figure 2 As shown, Figure 2The frequency conversion diagram of a specific example of the present invention is shown in FIG. 1 . In this example, the transmitting and receiving operating frequency bands are 300 MHz to 3 GHz, and a stepped frequency method is used to achieve transmission covering the entire ultra-wideband. The following is a detailed description of a specific embodiment of the present invention:

[0021] In this specific embodiment, the high-frequency local oscillator frequency in the architecture is selected as 7.5 GHz, and a coupler is used as a power distribution device, and the coupled signal enters the up-conversion mixer; at the same time, 7.8-10.5 GHz is an ultra-wideband stepped frequency signal with an agile characteristic of a hopping time of less than 1 ms, and a power divider is used as a power distribution device to generate two local oscillator signals for the mixer local oscillators of the transmitter and the receiver respectively; the local oscillator signal of 7.8-10.5 GHz is mixed with the 7.5 GHz intermediate frequency signal, and the sideband signal, that is, 0.3-3 GHz, is taken as the transmission signal, and the target signal has a low frequency characteristic of a frequency lower than 3 GHz and an agile characteristic of a hopping time of less than 1 ms; the receiver inputs a 0.3-3 GHz signal, mixes it with another 7.8-10.5 GHz local oscillator signal, takes the sideband signal, that is, 7.5 GHz as the intermediate frequency signal, and then performs IQ mixing with the 7.5 GHz direct signal output by the coupler to obtain a zero intermediate frequency baseband signal.

[0022] The number of devices and processing scales described here are used to simplify the description of the present invention, and the application, modification and variation of the present invention will be obvious to those skilled in the art.

[0023] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. An ultra-wideband stepped frequency RF front end with high-order harmonic suppression, characterized in that: include: A transmitter (100), the transmitter (100) comprising a high-frequency local oscillator (1001), a first driving amplifier (1002) connected to the high-frequency local oscillator (1001) signal, a first band-pass filter (1003) connected to the first driving amplifier (1002) signal, a first power distributor (1004) connected to the first band-pass filter (1003) signal, a down-conversion mixer (1007) connected to the first power distributor (1004) signal, a first low-pass filter (1008) connected to the down-conversion mixer (1007) signal, a power amplifier (1009) connected to the first low-pass filter (1008) signal, and a transmitting antenna (1010) connected to the power amplifier (1009) signal; A receiver (200), the receiver (200) comprising a receiving antenna (2001), a low noise amplifier (2002) signal-connected to the receiving antenna (2001), a second low pass filter (2003) signal-connected to the low noise amplifier (2002), an up-conversion mixer (2005) signal-connected to the second low pass filter (2003), a second power distributor (2004) signal-connected to the up-conversion mixer (2005) and a second driver amplifier (2006), a step-frequency local oscillator (2007) signal-connected to the second power distributor (2004), a second band pass filter (2008) signal-connected to the second driver amplifier (2006), an IQ mixer (2009) signal-connected to the second band pass filter (2008), and an AD sampling (2012) signal-connected to the IQ mixer (2009); The first power distributor (1004) is signal-connected to the IQ mixer (2009); The second power divider (2004) is signally connected to the down-conversion mixer (1007).

2. An ultra-wideband stepped frequency RF front end with high-order harmonic suppression as claimed in claim 1, characterized in that: The first power divider (1004) is used to divide the signal output by the first bandpass filter (1003) into a coupled signal (1005) and a direct signal (1006).

3. An ultra-wideband stepped frequency RF front end with high-order harmonic suppression as claimed in claim 2, characterized in that: The down-conversion mixer (1007) is used to mix the coupled signal (1005) with the stepped frequency signal.

4. The ultra-wideband stepped frequency RF front end with high-order harmonic suppression as claimed in claim 2, characterized in that: The IQ mixer (2009) is used to perform IQ mixing on the pass-through signal (1006) and the signal output by the second bandpass filter (2008).

5. The ultra-wideband stepped frequency RF front end with high-order harmonic suppression as claimed in claim 1, characterized in that: The up-conversion mixer (2005) is used to mix the second low-pass filter (2003) with the stepped frequency local oscillator (2007).

6. The ultra-wideband stepped frequency RF front end with high-order harmonic suppression according to claim 1, characterized in that: The local oscillators of the up-conversion mixer (2005) and the down-conversion mixer (1007) are generated by the stepped frequency local oscillator (2007) via the second power divider (2004).

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