A multiband transceiver for backscatter

Abstract

The application discloses a multi-band transceiver for backscattering, and belongs to the field of multi-band transceivers. The application comprises an up-conversion circuit, a down-conversion circuit, a radio frequency switch, a filter, a power amplifier, a low noise amplifier, a coaxial switch, a multiplexer, a digital circuit and a power supply. The application realizes band switching in a small signal part through circuit design, replaces a traditional power amplifier plus a single-pole double-throw switch switching scheme, and reduces the power amplifier output power under the condition of the same antenna transmitting power, that is, the total power consumption of the module is reduced. Since a high-power single-pole double-throw switch is omitted, the cost is not obviously increased. The application realizes a communication backup function, that is, when a transceiving link is abnormal, the application can be switched to another channel to continue communication, and the communication reliability is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of multi-band transceiver, in particular to a multi-band transceiver for backscattering, which is suitable for FDD communication system in wireless communication field. BACKGROUND

[0002] There are two ways of FDD and TDD in wireless communication, in which FDD communication capacity is large. Figure 1 As shown in the FDD wireless communication, the traditional multi-band transceiver generally uses single-pole four-throw switch, and the power amplifier is available in full frequency band. Since the frequency band is selected in advance, the power amplifier needs to be available in the full frequency band range, so the requirement for the power amplifier is higher. Moreover, in the transceiver link, as long as there is a problem, the communication will be interrupted. In addition, the selection of the wave band is placed after the power amplifier, which not only increases the insertion loss and reduces the transmission efficiency of the single power amplifier, but also makes the link connection complex and increases the hardware cost. SUMMARY

[0003] Therefore, the present application discloses a multi-band transceiver for backscattering. The present application realizes the wave band switching in the small signal part through circuit design, instead of the traditional switching scheme of single-pole double-throw switch after power amplifier, so that the power amplifier output power can be reduced under the same antenna transmission power, and the communication reliability is improved.

[0004] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0005] A multi-band transceiver for backscattering, comprising an up-conversion circuit 1, an up-conversion frequency selection path, a down-conversion circuit 27, a down-conversion frequency selection path, two coaxial switches 8, 10 and a multiplexer 9, the multiplexer 9 is integrated with four filters with frequencies f1, f2, f3 and f4, and the up-conversion frequency selection path and the down-conversion frequency selection path each include four filters with frequencies f1, f2, f3 and f4;

[0006] The up-conversion circuit 1 is connected to the four filters in the up-conversion frequency selection path through a two-level one-select-two switching switch, and the down-conversion circuit 27 is connected to the four filters in the down-conversion frequency selection path through a two-level one-select-two switching switch;

[0007] In the up-conversion frequency selection path, the filters with frequencies f1 and f2 form a group and are connected to a power amplifier through a switching switch, and the filters with frequencies f3 and f4 form a group and are connected to a power amplifier through a switching switch;

[0008] In the down-conversion frequency selection path, the filters with frequencies f1 and f2 form a group, which are selected by a switch and a low-noise amplifier; the filters with frequencies f3 and f4 form another group, which are selected by a switch and a low-noise amplifier;

[0009] The power amplifier and the low-noise amplifier corresponding to the frequencies f1 and f2 are connected to the same coaxial switch, which is selected by the coaxial switch and the filters with frequencies f1 and f2 in the multiplexer 9;

[0010] The power amplifier and the low-noise amplifier corresponding to the frequencies f3 and f4 are connected to the other coaxial switch, which is selected by the coaxial switch and the filters with frequencies f3 and f4 in the multiplexer 9.

[0011] Further, when transmitting signals, the intermediate frequency signals are transmitted by the up-conversion circuit 1 without distortion to the radio frequency band, then selected by two-stage switches according to the frequency band, then filtered by the corresponding filters to remove the out-of-band interference and harmonics, then connected to the power amplifier through the switches, and then transmitted by the antenna.

[0012] When receiving signals, the radio frequency signals received by the antenna are filtered by the low-stage filters in the multiplexer 9, then enter the corresponding low-noise amplifiers through the coaxial switch, then the received signals are amplified by the low-noise amplifiers, then enter the corresponding filters through the switches to remove the interference, out-of-band noise and mirror frequency, then enter the down-conversion circuit 27 through the switches, and then the radio frequency signals are transmitted without distortion to the intermediate frequency band and sent to the demodulator for demodulation and recovery.

[0013] Further, the power supply circuit is also included, when one power amplifier is selected, the power supply of the other power amplifier is disconnected, and when one low-noise amplifier is selected, the power supply of the other low-noise amplifier is disconnected.

[0014] Further, the switches are small power electronic switches.

[0015] Further, the up-conversion circuit 1 includes a filter circuit, a mixing circuit and an amplification circuit, which are used to transmit the intermediate frequency modulation signals without distortion to the radio frequency band, remove the combined interference frequencies generated by mixing, and amplify the small signals.

[0016] Further, the down-conversion circuit 27 includes a filter circuit, a mixing circuit and an amplification circuit, which are used to transmit the radio frequency modulation signals without distortion to the intermediate frequency band, remove the combined interference frequencies generated by mixing, and amplify the small signals.

[0017] The present application has the following advantages compared with the prior art:

[0018] 1、The switch of the wave band switching in the present application is located before the power amplifier, and a small power electronic switch can be used. In the traditional scheme, a single-pole double-throw switch is located after the power amplifier to realize mutual switching between the transmitting end, the receiving end and the high section filter and the low section filter of the duplexer. Compared with the traditional scheme, the link insertion loss after the power amplifier is reduced, so that the power amplifier output power is reduced under the condition of the same transmitting power, and the whole machine power consumption is reduced.

[0019] 2、The present application can realize full-band communication. By designing two transceiving channels and an electronic switch, the same module can be used at both ends to realize full-band operation.

[0020] 3、The transmitting and receiving of the present application have four independent channels, and have a backup function in actual use. For example, if there is an abnormality in the transmitting link or the receiving link at one end during use, the other frequency band (i.e. the other channel) can be switched through monitoring to continue normal communication, and the reliability is increased by four times.

[0021] 4、Although the present application has four channels for transmitting and receiving, the power consumption is not increased, because when the wave band is determined, the corresponding wave band path is opened, and the power supply of the backup transmitting and receiving path is controlled and cut off through the digital circuit part. The whole module only has one transmitting link and one receiving link.

[0022] 5、Although the present application increases the final power amplifier, the cost is not significantly increased because the high-power single-pole double-throw switch is omitted, but the communication reliability is improved because the backup is realized. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a schematic diagram of a multi-band transceiver in the prior art.

[0024] Figure 2 is a schematic diagram of a multi-band transceiver in the embodiment of the present application.

[0025] Figure 3 is a schematic diagram of an up-conversion circuit in the embodiment of the present application. DETAILED DESCRIPTION

[0026] The present application will be further described in detail below with reference to the drawings.

[0027] Reference is made to Figure 2A multi-band transceiver for backscatter, comprising up-conversion circuit 1, down-conversion circuit 27, digital circuit and power supply circuit 28, small signal switching switch 2, 3, 6, 14, 15, 16, 23, 24, 25, 26, filter 4, 5, 17, 18, 19, 20, 21, 22, power amplifier 7, 11, low noise amplifier 12, 13, coaxial switch 8, 9.

[0028] The multi-band transceiver can be used to transmit high segment frequency and receive low segment frequency link. The specific process is as follows:

[0029] Transmit link: the intermediate frequency signal passes through the up-conversion circuit 1, and the intermediate frequency signal is moved to the radio frequency frequency without distortion, then through the switch 2, the band is selected, then through the filter 4 / filter 5 to filter out the out-of-band spurs and harmonics, then through the switch 3 and the switch 6 for frequency band selection, then through the power power amplifier 7 to amplify the power of the radio frequency signal, then through the coaxial switch 8 selection and the multiplexer 9 into the antenna, then through the antenna to send out the radio frequency signal.

[0030] Receive link: the radio frequency signal received by the antenna passes through the low segment filter of the multiplexer 9, then through the coaxial switch 10 for frequency band selection, then through the low noise amplifier 13 to amplify the power of the received signal with low noise, then through the switch 16 into the low segment filter filter 21 / filter 22 to filter out the interference in the received signal, out-of-band noise, and mirror frequency, then through the switch 25 into the down-conversion circuit 2, the radio frequency signal is moved to the intermediate frequency frequency without distortion, and then sent to the demodulator for demodulation and recovery.

[0031] The multi-band transceiver can also be used to transmit low segment frequency and receive high segment frequency link. The specific process is as follows:

[0032] Transmit link: the intermediate frequency signal passes through the up-conversion circuit 1, and the intermediate frequency signal is moved to the radio frequency frequency without distortion, then through the switch 2, the band is selected, then through the filter 17 / filter 18 to filter out the out-of-band spurs and harmonics, then through the switch 23 and the switch 14 for frequency band selection, then through the power power amplifier 11 to amplify the power of the radio frequency signal, then through the coaxial switch 10 selection and the multiplexer 9 into the antenna, then through the antenna to send out the radio frequency signal.

[0033] Receive link: the radio frequency signal received by the antenna passes through the low segment filter of the multiplexer 9, then through the coaxial switch 8 for frequency band selection, then through the low noise amplifier 12 to amplify the power of the received signal with low noise, then through the switch 15 into the low segment filter filter 19 / filter 20 to filter out the interference in the received signal, out-of-band noise, and mirror frequency, then through the switch 24 into the down-conversion circuit 2, the radio frequency signal is moved to the intermediate frequency frequency without distortion, and then sent to the demodulator for demodulation and recovery.

[0034] Further, as Figure 3 The up-conversion circuit 1 includes a filter circuit, a mixing circuit, and an amplification circuit, for moving the intermediate frequency modulation signal to the radio frequency band without distortion, and filtering the combined interference frequency generated by mixing, and performing a certain degree of small signal amplification.

[0035] The down-conversion circuit 2 includes a mirror filter, a mixer, an intermediate frequency filter, and an intermediate frequency amplifier, for performing mirror filtering on the received radio frequency signal, moving the signal to the intermediate frequency frequency through the mixer, filtering out the combined interference frequency generated by mixing, and finally performing a certain degree of small signal amplification.

[0036] The digital circuit part of the multi-band transceiver includes an MCU and a 485 conversion chip, the MCU sends a binary bit stream to the local oscillator VCO of the up-conversion and down-conversion through the SPI bus, so that the required frequency is generated; the MCU communicates with the upper-level monitoring through the RS485 bus, for changing the frequency and power, or reporting the module status.

[0037] The low noise amplifiers 12 and 13 include a limiter and a low noise amplifier bypass function, which ensures that when a large signal enters, the limiter protects the low noise amplifier behind it, and when the signal is too large, the bypass function of the low noise amplifier is started to ensure that the link output will not be saturated due to the input signal being too large.

[0038] The working principle of the multi-band transceiver is as follows:

[0039] In the multi-band transceiver, switches 2, 3, 6, 23, 14, 15, 16, 24, 25, and 26 are used for selecting high and low working frequency bands in the FDD link; filters 4, 5, 17, 18, 19, 20, 21, and 22 are used for filtering out link out-of-band noise and spurs generated by frequency conversion; power amplifiers 7 and 11 perform power amplification on the frequency-converted radio frequency signal to meet the requirements of long-distance communication. The low noise amplifiers 12 and 13 have the same structure and contain a limiter and a low noise amplifier circuit with bypass function. The limiter is used to prevent the antenna from receiving a signal that is too large, which can cause the back-end amplification module to burn out. The low noise amplifier circuit is used to amplify the signal received by the antenna with low noise introduction. Coaxial switches 8 and 10 are used to realize the sharing of a single antenna port duplexer for the transceiver link in the same frequency band.

[0040] During communication, an RF transceiver module is placed at each end of the communication. The overall monitoring sets the transmission and reception frequencies at both ends, such as transmitting at a high frequency A and receiving at a low frequency B at the local end, and transmitting at a low frequency B and receiving at a high frequency A at the remote end. After the MCU of the digital circuit section at the local end receives the instructions from the overall monitoring through the RS485 bus, it first switches switch 2 to the high frequency selection switch 3 and switches switch 26 to the low frequency selection switch 25. Then, it controls the local oscillator of the up-conversion and down-conversion circuit through the SPI bus to generate the transmission operating frequency A and the reception operating frequency B required by the overall monitoring.

[0041] After the MCU of the digital circuit section at the other end obtains the command of the overall monitoring through the RS485 bus, it first switches switch 2 to the low-segment frequency selection switch 23, switches switch 26 to the high-segment frequency selection switch 24, and controls the local oscillator of the up-and-down conversion through the SPI bus to generate the transmit working frequency B and receive working frequency A required by the overall monitoring.

[0042] After successful setup, the MCU in the digital circuit section will report to the central monitoring system via the RS485 bus. Once the setup is complete, the local intermediate frequency (IF) input modulation signal passes through the up-conversion circuit, which shifts the IF modulation signal to the operating frequency A without distortion. It then passes through switches 2 and 3, enters the high-band filter 4, and then through switch 6 and power amplifier 7, where the power is amplified to the level required for the communication distance. After passing through a coaxial switch, it enters the multiplexer to filter harmonics generated by the power amplifier's nonlinearity and to remove combined spurious signals before being transmitted via the antenna. The transmission process at the receiving end is the same as the local process.

[0043] In the receiving link, the small radio frequency signal received by the local antenna enters the duplexer to filter out out-of-band interference, then passes through coaxial switch 10 and enters low-noise amplifier 13 to amplify the received signal. After passing through switch 16 and low-band filter 22 to filter out image frequencies, it then passes through switches 25 and 26 before entering down-converter 2. The received radio frequency signal is then down-converted and mixed, shifted to the intermediate frequency without distortion, filtered and amplified, and then sent to the demodulator for signal demodulation. The receiving process at the other end is the same as that at the local end.

[0044] This invention achieves high and low operating frequency switching through a small-signal switch, replacing a high-power double-pole double-throw switch. It also features four independent channels for both transmission and reception, with backup functionality in practical use, improving communication reliability by four times. Since the other channel is completely powered off once the channel's operating frequency is determined, power consumption remains unchanged. Furthermore, eliminating the high-power double-pole double-throw switch at the back end reduces the power amplifier's output power, thereby lowering the overall module's power consumption.

Claims

1. A multiband transceiver for backscatter, characterized by The application relates to a frequency conversion circuit, which comprises an up-conversion circuit (1), an up-conversion frequency selection channel, a down-conversion circuit (27), a down-conversion frequency selection channel, two coaxial switches (8, 10) and a multiplexer (9), four filters with frequencies f1, f2, f3 and f4 are integrated in the multiplexer (9), and four filters with frequencies f1, f2, f3 and f4 are arranged in the up-conversion frequency selection channel and the down-conversion frequency selection channel. The up-conversion circuit (1) is connected with the four filters in the up-conversion frequency selection channel through two-stage two-select switches, and the down-conversion circuit (27) is connected with the four filters in the down-conversion frequency selection channel through two-stage two-select switches. In the up-conversion frequency selection channel, the filters with frequencies f1 and f2 form a group and are connected with a power amplifier through a switch, and the filters with frequencies f3 and f4 form a group and are connected with a power amplifier through a switch. In the down-conversion frequency selection channel, the filters with frequencies f1 and f2 form a group and are connected with a low-noise amplifier through a switch, and the filters with frequencies f3 and f4 form a group and are connected with a low-noise amplifier through a switch. The power amplifier and the low-noise amplifier corresponding to the frequencies f1 and f2 are connected with the same coaxial switch and are connected with the filters with frequencies f1 and f2 in the multiplexer (9) through the coaxial switch. The power amplifier and the low-noise amplifier corresponding to the frequencies f3 and f4 are connected with the other coaxial switch and are connected with the filters with frequencies f3 and f4 in the multiplexer (9) through the coaxial switch. When transmitting a signal, the intermediate frequency signal is transmitted through the up-conversion circuit (1) and is converted into a radio frequency signal without distortion, then the frequency band is selected through two-stage switches, then the out-of-band interference and harmonics are filtered through corresponding filters, then the radio frequency signal is connected with the power amplifier through the switch, the power amplifier amplifies the radio frequency signal, then the radio frequency signal is transmitted into the corresponding filter in the multiplexer (9) through the coaxial switch (8), and finally the radio frequency signal is transmitted through an antenna. When receiving a signal, the radio frequency signal received by the antenna is filtered through the corresponding filter in the multiplexer (9), then the radio frequency signal is transmitted into the corresponding low-noise amplifier through the coaxial switch, the low-noise amplifier amplifies the received signal with low noise, then the signal is transmitted into the corresponding filter through the switch, the interference, out-of-band noise and mirror frequency in the received signal are filtered, then the signal is transmitted into the down-conversion circuit (27) through the switch, the radio frequency signal is converted into an intermediate frequency signal without distortion, and the signal is demodulated and recovered by a demodulator.

2. A multiband transceiver for backscatter communication according to claim 1, wherein, The frequency conversion circuit further comprises a power supply circuit, when one power amplifier is selected, the power supply of the other power amplifier is disconnected, and when one low-noise amplifier is selected, the power supply of the other low-noise amplifier is disconnected.

3. A multiband transceiver for backscatter according to claim 1, wherein, The switches are small-power electronic switches.

4. A multiband transceiver for backscatter communication according to claim 1, wherein, The up-conversion circuit (1) comprises a filter circuit, a mixing circuit and an amplification circuit, is used for converting an intermediate frequency modulation signal into a radio frequency band without distortion, filtering combined interference frequencies generated in mixing and performing small signal amplification.

5. A multiband transceiver for backscatter communication according to claim 1, wherein, The down-conversion circuit (27) comprises a filter circuit, a mixing circuit and an amplification circuit, which are used to move the radio frequency modulated signal to the intermediate frequency band without distortion, filter the combined interference frequency generated by mixing, and carry out small signal amplification.

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