A power detection system for a phased array transmit link

Abstract

The present invention belongs to the field of radio frequency technology, and particularly relates to a power detection system for a phased array transmitting link. The power detection system of the present invention consists of five parts: a phased array transmitting link with amplitude and phase control functions, which realizes the adjustment of the amplitude and phase of the transmitted signals of each array element in phased array applications; a load antenna for radio frequency power transmission; an output matching network with power coupling function, which is used for impedance variation to achieve efficient power amplification and couple the radio frequency output power; a power detection module, which utilizes its own non-linear or time-varying characteristics to realize the conversion of radio frequency signals to direct current signals; and a baseband processing module, which processes the direct current signals generated by the power detection module according to actual requirements for subsequent further operations.

Description

Technical Field

[0001] The present invention belongs to the field of radio frequency technology, and particularly relates to a power detection system for a phased array transmit link. Background Art

[0002] In recent years, with the higher requirements for bandwidth and transmission rate in modern communication, the fifth-generation communication technology (5G) has emerged as the times require. Due to its rich spectrum resources and less interference, the 5G FR2 band located in the millimeter-wave frequency band has great development potential. However, in high-frequency and long-distance applications, signals often experience large path losses on the transmission path, thus affecting the signal quality at the receiving end. Therefore, beamforming technology, which controls the amplitude and phase of each element of the phased array to improve the gain of the transceiver antenna, is widely used in millimeter-wave communication.

[0003] In order to ensure the directivity of beamforming, it is necessary to monitor the transmit power of each channel of the phased array in real time and have the ability to calibrate between channels. At the same time, the mutual coupling between antennas will cause the actual load impedance of the transmit link to deviate from 50 ohms. Therefore, each phased array transmit channel needs to have the ability to monitor power and still maintain good detection consistency when the voltage standing wave ratio at the transmit end is greater than 1.

[0004] To meet the above requirements, the present invention proposes a power detection system for a phased array transmit link, which realizes power detection proportional to the actual transmit power by coupling power at the output matching network of the phased array transmit link. Summary of the Invention

[0005] The purpose of the present invention is to provide a power detection system for a phased array transmit link to meet the monitoring requirements of the actual transmit power in the beamforming application of the phased array transmit link.

[0006] The power detection system for a phased array transmit link provided by the present invention includes a phased array transmit link, an output matching network with a power coupling function, an antenna load, a power detection module, and a baseband processing module; wherein, the phased array transmit link is used to provide the amplitude-phase control function required by power amplification and beamforming technology, and its last stage is a radio frequency amplifier with a signal amplification function; the output matching network with a power coupling function can couple the actually output radio frequency power while providing output matching; the antenna load is used for radio frequency power transmission; the power detection module is used to realize the conversion of radio frequency power signals to direct current signals; and the baseband processing module performs corresponding processing operations on the direct current signals output by the power detection module according to actual needs.

[0007] Furthermore, in the phased array transmit link, there are modules capable of amplitude control and phase control. The amplitude control module can be implemented by a configurable attenuator, a variable gain amplifier, or any circuit with gain adjustment function. The phase control module can be implemented by any circuit with phase shifting function. The amplitude and phase control can be realized by digital control or analog signal control.

[0008] Furthermore, the final stage of the phased array transmit link should be a radio frequency amplifier with radio frequency power amplification capability. This amplifier can be a linear amplifier or a switching amplifier. The number of amplifier stages can be single-stage, multi-stage, or a combination of multiple amplifiers.

[0009] Furthermore, the output matching network with power coupling function includes: an output matching network with a directional coupling port, or an output matching network with current and voltage detection capabilities.

[0010] The matching network mentioned above includes: conductors and circuit elements.

[0011] Furthermore, in the output matching network with power coupling function, the output matching network can be composed of a transformer, or a transmission line or its equivalent circuit; the power coupling function can directly perform power coupling, or can couple current and voltage separately.

[0012] Furthermore, in the output matching network with power coupling function, when the power coupling branch couples current and voltage, at least one of the branches should have a phase adjustment function, which can be realized by a polyphase filter, an all-pass filter, or any other adjustable phase shifter method. At the same time, a gain adjustment function can be selectively added.

[0013] Furthermore, the power detection module uses its own time-varying characteristics or non-linear characteristics to complete the frequency conversion of radio frequency power to a direct current signal. In specific implementation, this module can be a self-mixer, a square-law detector, or any other circuit with frequency conversion function.

[0014] Furthermore, the baseband processing module can be configured according to actual processing requirements. It can be a baseband amplifier with low-pass filtering function, an analog-to-digital converter, or other baseband circuits with specific functions. The number of circuits included in the baseband processing module and the order of each stage of the circuit can be adjusted according to actual needs.

[0015] Furthermore, the phased array transmit link, the output matching network with power coupling function, the power detection module, and the baseband processing module can be fabricated in CMOS process, or in BiCMOS process, or in GeSi process, or in GaAs process, including but not limited to the processes listed, and other processes are also acceptable. Among them, the transistors can be made of bipolar transistors, or junction field effect transistors, or MOSFETs.

[0016] Furthermore, the phased array transmit link, the output matching network with power coupling function, the power detection module, and the baseband processing module can be implemented in a monolithic integration manner, or in a discrete component manner, or a combination of any circuit implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 FIG. is a structural diagram of the power detection system for the phased array transmit link of the present invention.

[0018] Figure 2 A circuit block diagram of a specific implementation of the present invention is shown. By detecting and multiplying the voltage and current at the main coil of the output transformer, a DC signal proportional to the actual output power is obtained.

[0019] Figure 3 FIG. is a circuit diagram of a radio frequency amplifier.

[0020] Figure 4 FIG. is a circuit diagram of a tunable phase shifter.

[0021] Figure 5 FIG. is a circuit diagram of a self-mixer. DETAILED DESCRIPTION OF THE INVENTION

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0023] The present invention provides a power detection system for a phased array transmit link. An output matching network with power coupling function is used to couple out a certain amount of radio frequency power, which is then converted into a DC signal by a power detection module and output after passing through a baseband processing module.

[0024] As Figure 1As shown in the figure, the power detection system for a phased array transmission link according to the present invention includes a phased array transmission link, an antenna load, a matching network with a power coupling function, a power detection module, and a baseband processing module. Among them, the phased array transmission link and the antenna load are respectively used for amplitude-phase control of radio frequency signals and transmission of radio frequency power; the matching network with a power coupling function is used for output load matching and radio frequency power coupling; the power detection module and the baseband processing module are respectively used for conversion of radio frequency power into a DC signal and subsequent processing of the DC signal. In the present invention, through the collaborative design of the output matching network and the power coupling network, the integration and non-invasiveness of power detection are improved.

[0025] As Figure 2 shown, it is a specific implementation example of the power detection system for a phased array transmission link according to the present invention. Among them, the final stage of the phased array transmission link is represented by a radio frequency amplifier. The radio frequency differential inputs RF IN+ and RF IN- are amplified by the radio frequency amplifier and then enter the output matching network with a power coupling function. The matching network consists of the following parts: a main transformer composed of inductors L1, L2, and coupling coefficient k 12 for outputting radio frequency power to the antenna; a secondary transformer composed of inductors L1, L3, and coupling coefficient k 13 for detecting the output current of the radio frequency amplifier; a voltage dividing network composed of capacitors C1, C2, C3, and C4 for detecting the output voltage of the radio frequency amplifier; and an adjustable phase shifter for adjusting the phase of the detected voltage. The power detection module is a self-mixer. The baseband processing module is a baseband amplifier, outputting differential DC voltages V OUT+ and V OUT- . It should be noted that the circuits in the drawings are all AC equivalent circuits, and the biases in this embodiment are all generated by current mirrors. For simplicity, they are not drawn in the drawings.

[0026] The circuit structure of the radio frequency amplifier in this embodiment is as Figure 2 shown. Among them, transistors M PA1 and M PA2 constitute the active amplification part, converting the input radio frequency differential voltages PA IN+ and PA IN- into radio frequency currents. The neutralization capacitors C N1 are connected across the gate of M PA1 and the drain of M PA2 , and the neutralization capacitors C N2 are connected across the gate of M PA2 and the drain of M PA1 to cancel the influence of the gate-drain parasitic capacitance C GD and improve the stability, reverse isolation, and power gain of the radio frequency amplifier. It should be noted that MPA1 has the same gate length and gate width as M PA2 and C N1 has the same as C N2 identical.

[0027] After the output current of the RF amplifier flows through the inductor L1, induced currents are generated in the inductor L2 and the inductor L3 through magnetic coupling respectively. Among them, the induced current in the inductor L2 flows through the antenna, is converted into RF energy and then transmitted. The induced current in the inductor L3 is sent into the self-mixer as the detected current for power detection.

[0028] The output differential voltage of the RF amplifier is divided by C1, C2, C3, and C4 and then sent into the self-mixer as the detected voltage for power detection. It should be noted that C1 is the same as C3, and C2 is the same as C4 to ensure the same voltage division ratio on the differential path and make the load capacitance seen by the RF amplifier at both ends of the differential output consistent, and its value is the series value of C1 and C2.

[0029] The circuit structure of the tunable phase shifter in this embodiment is as Figure 3 shown. When the input voltages PS IN+ , PS IN- are differential signals and the component parameters are all symmetric, that is, L PS1 is the same as L PS2 , C PS1 is the same as C PS3 , and C PS2 is the same as C PS4 , the middle node V PS1 is an equivalent AC ground, and the unilateral circuit can be used for analysis. By adjusting C PS1 and C PS2 , the phase difference between the output voltages PS OUT+ and PS IN- can be adjusted. It should be noted that the value of C PS3 should always be kept consistent with C PS1 , and the value of C PS4 should always be kept consistent with C PS2 .

[0030] The circuit structure of the self-mixer in this embodiment is as Figure 4 shown. This self-mixer is an active mixer based on a Gilbert cell. The detected current flowing through L3 is converted into a pair of differential voltages V SM1 , V SM4 after passing through the gate parasitic capacitances of the transistors M IS+ , V IS- , and then by the transconductance stage transistors M SM1 , M SM4is converted into radio frequency current. The detected voltages V S+ and V S- are respectively connected to the common-gate transistors M SM2 and M SM6 and M SM3 and M SM5 to modulate the radio frequency currents generated by M SM1 and M SM2 and generate the output current of self-mixing. This output current passes through the load R L1 , C L1 and R L2 , C L2 to be converted into the differential output voltage M OUT+ and M OUT- after low-pass filtering. It should be noted that M SM1 and M SM4 have the same gate length and gate width, M SM3 , M SM4 , M SM5 and M SM6 have the same gate length and gate width, R L1 and R L2 are the same, and C L1 and C L2 are the same.

[0031] It should be noted that the power detection system proposed by the present invention can still perform accurate power detection when the antenna load deviates from 50 ohms. In this embodiment, by adjusting the adjustable phase shifter, the phase difference between the current and voltage for multiplication in the self-mixer can be made consistent with the phase difference between the actually output radio frequency current and radio frequency voltage, thereby ensuring the accuracy and consistency of power detection.

[0032] In summary, the present invention provides a power detection system for a phased array transmit link. By using an output matching network with a power coupling function to couple radio frequency power and converting it into a DC signal through a power detection module, accurate power monitoring can be performed when the antenna load has an offset, meeting the requirements for accurate monitoring of the transmit power of each channel in phased array transmit applications.

[0033] Finally, it should be noted that those of ordinary skill in the art should understand that the technical solution of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solution of the present invention, and it should be covered by the scope of the claims of the present invention.

Claims

1. A power detection system for a phased array transmitting link, characterized in that It includes a phased array transmit link, an output matching network with power coupling function, an antenna load, a power detection module, and a baseband processing module; among them, the phased array transmit link is used to provide the amplitude and phase control functions required by power amplification and beamforming technologies, and its last stage is a radio frequency amplifier with signal amplification function; the output matching network with power coupling function can couple the actually output radio frequency power while providing output matching; the antenna load is used for radio frequency power transmission; the power detection module is used to realize the conversion of radio frequency power signal to direct current signal; the baseband processing module processes the direct current signal output by the power detection module according to actual needs; The RF amplifier represents the final stage of the phased array transmit link; RF differential input RF IN+ and RF IN- After being amplified by the RF amplifier, it enters the output matching network with power coupling function; this matching network consists of the following parts: a main transformer composed of inductor L1, inductor L2, and coupling coefficient k 12 for outputting RF power to the antenna; a secondary transformer composed of inductor L1, inductor L3, and coupling coefficient k 13 for detecting the output current of the RF amplifier; a voltage dividing network composed of capacitors C1, C2, C3, and C4 for detecting the output voltage of the RF amplifier; an adjustable phase shifter for adjusting the phase of the detected voltage; the power detection module is a self-mixer; the baseband processing module is a baseband amplifier, outputting differential DC voltages V OUT+ 、V OUT- ; Transistor M PA1 and M PA2 constitute the active amplification part, which converts the input radio frequency differential voltage PA IN+ 、PA IN- into a radio frequency current; the neutralization capacitor C N1 is connected across the gate of M PA1 and the drain of M PA2 ; the neutralization capacitor C N2 is connected across the gate of M PA2 and the drain of M PA1 to cancel the influence of the gate-drain parasitic capacitor C GD and improve the stability, reverse isolation and power gain of the radio frequency amplifier; M PA1 and M PA2 have the same gate length and gate width, and C N1 is the same as C N2 ; After the output current of the radio frequency amplifier flows through the inductor L1, induced currents are generated in the inductor L2 and the inductor L3 respectively through magnetic coupling; among them, the induced current in the inductor L2 flows through the antenna and is converted into radio frequency energy for transmission; the induced current in the inductor L3 is sent into the self-mixer as the detected current for power detection; The output differential voltage of the radio frequency amplifier is divided by C1, C2 and C3, C4 and then sent into the self-mixer as the detected voltage for power detection; C1 is the same as C3, and C2 is the same as C4 to ensure the same voltage division ratio on the differential path and make the load capacitance seen by the radio frequency amplifier at both ends of the differential output consistent, and its value is the series value of C1 and C2.

2. The power detection system according to claim 1, wherein In the phased array transmit link, it includes modules for amplitude control and phase control; the amplitude control module is implemented by a configurable attenuator, or by a variable gain amplifier, or any circuit with gain adjustment function; the phase control module is implemented by any circuit with phase shift function.

3. The power detection system according to claim 1, wherein The last stage of the phased array transmit link is an amplifier with radio frequency power amplification ability; this amplifier is a linear amplifier, or a switching amplifier; the number of stages of the amplifier is single-stage, or multi-stage, or a combination of the multiple amplifiers.

4. The power detection system according to claim 1, wherein The output matching network with power coupling function includes: an output matching network with a directional coupling port, or an output matching network with current and voltage detection capabilities.

5. The power detection system according to claim 4, wherein In the output matching network with power coupling function, the output matching network is composed of a transformer, or composed of a transmission line or its equivalent circuit; the power coupling function is to directly couple power, or to couple current and voltage respectively.

6. The power detection system according to claim 5, wherein In the output matching network with power coupling function, when the power coupling branch couples current and voltage, at least one of the branches has a phase adjustment function, which is realized by a polyphase filter, or by an all-pass filter, or any other adjustable phase shift method.

7. The power detection system according to claim 1, wherein The power detection module uses its own time-varying characteristics or non-linear characteristics to complete the frequency conversion of radio frequency power to direct current signal; this module is a self-mixer, or a square-law detector, or any other circuit with frequency conversion function.

8. The power detection system according to claim 1, characterized in that, The baseband processing module is configured according to actual processing requirements and is a baseband amplifier with a low-pass filtering function, or an analog-to-digital converter, or other baseband circuits with specific functions; the number of circuits included in the baseband processing module and the order of each stage of circuits can be adjusted according to actual requirements.

9. The power detection system according to any one of claims 1-8, characterized in that, The phased array transmit link, the output matching network with a power coupling function, the power detection module, and the baseband processing module are fabricated in CMOS process, or in BiCMOS process, or in GeSi process, or in GaAs process; among them, the transistors are fabricated using bipolar transistors, or using junction field effect transistors, or using MOSFETs.

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