CN113691264B - On-chip integrated real-time calibration network for QAM modulation - Google Patents

Abstract

The invention discloses an on-chip integrated real-time calibration network for QAM modulation, comprising: an amplitude detection path, used for detecting the amplitude of a transmitter xQAM modulation mode and calibrating according to the feedback DC voltage; a phase detection path, used for The phase of the transmitter xQAM modulation mode is detected and calibrated according to the feedback DC voltage; the feedback loop is used to feedback the DC voltage. As an on-chip integrated real-time calibration network for QAM modulation, the present invention can be widely used in the field of transmitter calibration networks.

Description

An On-Chip Integrated Real-Time Calibration Network for QAM Modulation

technical field

The invention relates to the field of transmitter calibration networks, in particular to an on-chip integrated real-time calibration network for QAM modulation.

Background technique

The traditional analog transmitter architecture is composed of modules such as DAC, filter, mixer and power amplifier. To support gigabit data rates, traditional analog transmitters require high sampling rate DACs to convert the digital I/Q baseband to analog signals, but these DACs are usually very power hungry. This extremely power-hungry high-speed baseband processing block is the main limiting factor in achieving efficient performance in conventional transmitter systems. The linearity performance of the traditional linear power amplifier is good, but the energy efficiency ratio is low. Also, the power amplifiers of this class drop off sharply when backing off, making these transmitters less efficient when transmitting signals with non-constant envelopes. Moreover, each module of a traditional analog transmitter has strict linearity, noise, and specification requirements, which increases the design difficulty of the entire transmitter system, and a large number of analog circuit modules occupy a large amount of silicon chip area, resulting in high cost. Compared with the traditional transmitter structure, the RF-DAC transmitter structure overcomes the problem of linearity and output power drop caused by the low-voltage power supply of the traditional power amplifier. Using the high-speed switch mode, the RF-DAC transmitter can work in saturation Under the output power, it has good efficiency. At present, the development of RF-DAC transmitter architecture is facing some problems. Among them, the biggest problem that limits the use of RF-DAC transmitter architecture is that RF-DAC transmitter will produce nonlinear distortion in the modulation process. . In the modulation process, the output power of the RF-DAC transmitter can be controlled by digital codes, and the digital transmitter can obtain different output powers according to different digital codes. However, when a digital transmitter outputs signals of different powers, the output impedance of the transmitter will change, thereby generating amplitude modulation distortion. Moreover, under different output powers, the parasitic capacitance of the power unit is also different, so that the output phase will also change, thereby generating phase modulation distortion.

Contents of the invention

In order to solve the above-mentioned technical problems, the object of the present invention is to provide an on-chip integrated real-time calibration network for QAM modulation, which detects the signal of the transmitter in real time and calibrates the state of the transmitter through a feedback loop in real time.

The technical scheme adopted in the present invention is: a conveyor belt type crop phenotype acquisition method, comprising the following steps:

The amplitude detection path is used to detect the amplitude of the transmitter xQAM, x=4n ⁺¹ , n>=1 modulation mode and perform calibration according to the feedback DC voltage, and the amplitude detection path includes a power detector, a first comparison device, the first D flip-flop, the first accumulator-accumulator and the first digital-to-analog converter, the power detector, the first comparator, the first D flip-flop, the first accumulator-subtractor and the first The converters are connected sequentially;

The phase detection path is used to detect the phase of the transmitter xQAM modulation mode and calibrate it according to the feedback DC voltage, and the phase detection path includes a phase detector, a second comparator, a second D flip-flop, a second accumulator A subtractor and a second digital-to-analog converter, the phase detector, the second comparator, the second D flip-flop, the second accumulator-subtractor and the second digital-to-analog converter are connected in sequence;

The feedback loop is used to feed back the DC voltage.

Further, the power detector specifically includes:

The first passive network voltage divider module divides the amplitude detection channel into a saturated output power signal amplitude detection channel and a power fallback signal amplitude detection channel, and obtains the same swing amplitude by using different voltage division ratios for input signals of different powers;

An amplitude detection module, used to convert the amplitude information into a DC voltage;

The first sampling switch module is used to perform capacitance integration, so as to obtain DC voltage information corresponding to the amplitude information.

Further, the phase detector specifically includes:

The second passive network voltage divider module divides the phase detection path into a saturated output power signal phase detection path and a power back-off signal phase detection path, and obtains the same swing amplitude through different voltage division ratios for input signals of different powers;

The phase detection module compares the phase information of the radio frequency signal and the local oscillator signal, and converts the phase information into a DC voltage;

The second sampling switch module integrates and holds the DC voltage;

The differential conversion single module converts two differential DC voltages into a single-ended DC voltage through the differential conversion single module and outputs it.

Further, through the power detector with the first sampling switch module, the continuous radio frequency signals with different amplitudes are dynamically detected, and the different amplitude information of the continuous signals are converted into DC voltages.

Further, through the phase detector with the second sampling switch module, dynamic phase detection is performed on the continuous radio frequency signals with different phases, and the different phase information of the continuous signals is converted into a DC voltage.

Further, both the first sampling switch module and the second sampling switch module include a ground switch and a series switch, the ground switch is controlled by a data square wave signal, and the series switch is controlled by a pulse signal.

The beneficial effects of the method, system and device of the present invention are: the present invention supports real-time detection of the modulation modules of the I and Q circuits of the QAM modulated RF-DAC transmitter, and the modulation modules of the I and Q circuits are fed back through the loop Real-time calibration of the performance of the transmitter and selection of the most appropriate feedback voltage can effectively reduce the problems of amplitude distortion and phase distortion in the modulation process of the transmitter, thereby reducing the error vector magnitude of the transmitter constellation diagram.

Description of drawings

Fig. 1 is a kind of frame schematic diagram of the integrated real-time calibration network on the chip of the present invention for QAM modulation;

Fig. 2 is a schematic diagram of the framework of a power detector according to a specific embodiment of the present invention;

Fig. 3 is the frame schematic diagram of the phase detector of the specific embodiment of the present invention;

Fig. 4 is a schematic diagram of a framework of a specific embodiment of the present invention applied to an RF-DAC transmitter;

Fig. 5 is the schematic diagram of sampling switch of the specific embodiment of the present invention;

Fig. 6 is a schematic diagram of a phase detector according to an embodiment of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. For the step numbers in the following embodiments, it is only set for the convenience of illustration and description, and the order between the steps is not limited in any way. The execution order of each step in the embodiments can be adapted according to the understanding of those skilled in the art sexual adjustment.

With reference to Fig. 1, the present invention provides a kind of on-chip integrated real-time calibration network for QAM modulation, and the method comprises the following steps:

The amplitude detection path is used to detect the amplitude of the transmitter xQAM, x=4 ⁽ⁿ⁺¹⁾ , n>=1, m=2 ⁿ -1 modulation mode and perform calibration according to the feedback DC voltage, the amplitude detection The path includes a power detector, a first comparator, a first D flip-flop, a first accumulation accumulator and a first digital-to-analog converter, the power detector, the first comparator, a first D flip-flop, a first The accumulation accumulator and the first digital-to-analog converter are sequentially connected;

The amplitude detection path detects the radio frequency signals of m+1 powers of the transmitter through the power detector, converts them into (m+1) DC voltages, and obtains m amplitude adjustment voltages VMAG[1:m] through the feedback loop.

The phase detection path is used to detect the phase of the transmitter xQAM modulation mode and calibrate it according to the feedback DC voltage, and the phase detection path includes a phase detector, a second comparator, a second D flip-flop, a second accumulator A subtractor and a second digital-to-analog converter, the phase detector, the second comparator, the second D flip-flop, the second accumulator-subtractor and the second digital-to-analog converter are connected in sequence;

The phase detection channel detects the phase of the radio frequency signal of m+1 powers of the transmitter through the phase detector, converts it into m+1 DC voltages, and obtains m amplitude adjustment voltages VPHASE[1:m] through the feedback loop.

The feedback loop is used to feed back the DC voltage.

When applied to xQAM modulation x=4 ⁽ⁿ⁺¹⁾ , n>=1, m=2 ⁿ -1, the power detector will obtain the VMAGL1-VMAGLm corresponding to the signal amplitudes of m different power backoffs, and will obtain DC voltage VMAGH corresponding to a saturated output power signal amplitude. There are m feedback loops, and VMAGL1-VMAGLm will be respectively connected with VMAGH through m comparators, and then the comparators will be latched through D flip-flops. The VMAG1-VMAGm are respectively obtained by accumulating the accumulator and the DAC, and the amplitudes of signals of different power backoffs of the RFDAC transmitter are adjusted.

When applied to xQAM modulation x=4 ⁿ⁺¹ , n>=1, m=2 ⁿ -1, the phase detector will obtain m VPHASEL1-VPHASELm corresponding to signal phases with different power backoffs, and will obtain one The DC voltage VPHASEH corresponding to the phase of the saturated output power signal. There are m feedback loops, and VPHASEL1-VPHASELm will be respectively connected with VPHASEH through m comparators, and then the comparators will be latched by D flip-flops. The VPHASE1-VPHASEm are respectively obtained by accumulating the accumulator and the DAC, and the phases of signals of different power backoffs of the RFDAC transmitter are adjusted.

Further as a preferred embodiment of the method, referring to FIG. 2, the power detector specifically includes:

The first passive network voltage divider module divides the amplitude detection channel into a saturated output power signal amplitude detection channel and a power fallback signal amplitude detection channel, and obtains the same swing amplitude by using different voltage division ratios for input signals of different powers;

则饱和输出功率信号幅度检测通路和功率回退信号幅度检测通路1的无源网络分压比例为1:3。相较于电阻分压网络，由电容构成的无源网络分压模块可以对射频信号进行更精确地分压。根据xQAM调制的不同，在m+1个信号幅度检测通路中，无源网络分压模块的分压比例依次为1:3:5:…：(2m-1):(2m+1)。例如，当调制方式为64QAM的时候，此时的n＝2，m＝3。此时3个功率回退信号幅度检测通路和一个饱和输出功率信号幅度检测通路的分压比例的比值为1:3:5:7。The passive network voltage divider module is mainly composed of a series capacitor and a parallel capacitor. The series capacitor Cs generally remains unchanged, and the voltage division ratio is changed by changing the values of the parallel capacitors C1, C2...C(m+1). For example, when the modulation mode is 16QAM, Cs is assumed to be 5fF, C1 is 5fF, then C2 is 25fF, and the voltage division ratio formula of the capacitor is

Then the passive network voltage division ratio of the saturated output power signal amplitude detection path and the power backoff signal amplitude detection path 1 is 1:3. Compared with the resistor divider network, the passive network divider module composed of capacitors can more accurately divide the voltage of the radio frequency signal. According to the difference of xQAM modulation, in the m+1 signal amplitude detection channels, the voltage division ratio of the passive network voltage division module is 1:3:5:...:(2m-1):(2m+1). For example, when the modulation mode is 64QAM, n=2 and m=3 at this time. At this time, the ratio of the voltage division ratios of the three power backoff signal amplitude detection channels and one saturated output power signal amplitude detection channel is 1:3:5:7.

An amplitude detection module, used to convert the amplitude information into a DC voltage;

The first sampling switch module is used to perform capacitance integration, so as to obtain DC voltage information corresponding to the amplitude information.

In addition, both the power signal amplitude detection path and the power backoff signal amplitude detection path include corresponding passive network voltage dividing units, amplitude detection units and sampling switch units. The difference between the two detection paths is distinguished by the difference of the passive network voltage dividing unit.

Further as a preferred embodiment of the method, referring to Fig. 3, the phase detector (i.e. phase detector) specifically includes:

The second passive network voltage divider module divides the phase detection path into a saturated output power signal phase detection path and a power back-off signal phase detection path, and obtains the same swing amplitude through different voltage division ratios for input signals of different powers;

则饱和输出功率信号幅度检测通路和功率回退信号幅度检测通路1的无源网络分压比例为1:3。根据xQAM调制的不同，在m+1个信号相位检测通路中，无源网络分压模块的分压比例依次为1:3:5:…：(2m-1):(2m+1)。The passive network voltage divider module is mainly composed of a series capacitor and a parallel capacitor. The series capacitor Cs generally remains unchanged, and the voltage division ratio is changed by changing the values of the parallel capacitors C1, C2...C(m+1). For example, when the modulation mode is 16QAM, Cs is assumed to be 5fF, C1 is 5fF, then C2 is 25fF, and the voltage division ratio formula of the capacitor is

Then the passive network voltage division ratio of the saturated output power signal amplitude detection path and the power backoff signal amplitude detection path 1 is 1:3. According to the difference of xQAM modulation, in the m+1 signal phase detection channels, the voltage division ratio of the passive network voltage division module is 1:3:5:...:(2m-1):(2m+1).

The phase detection module compares the phase information of the radio frequency signal and the local oscillator signal, and converts the phase information into a DC voltage;

The second sampling switch module integrates and holds the DC voltage;

The differential conversion single module converts two differential DC voltages into a single-ended DC voltage through the differential conversion single module and outputs it.

Further as a preferred embodiment of the method, the power detector with the first sampling switch module dynamically detects continuous radio frequency signals with different amplitudes, and converts the different amplitude information of the continuous signals into DC voltages.

Further as a preferred embodiment of the method, the phase detector with the second sampling switch module dynamically performs phase detection on continuous radio frequency signals with different phases, and converts different phase information of the continuous signals into DC voltages.

Specifically, referring to FIG. 6 , the phase detector performs phase detection, performs phase detection on the input radio frequency signal through a single balanced mixer, and passes through the sampling switch module. The ground switch of the sampling switch is controlled by a data square wave signal, while the series switch is controlled by a pulse switch. After the DC voltage passes through the sampling switch, two DC voltages are obtained through capacitance integration, and finally the differential signal is converted into a single-ended signal through the differential converter module, and a DC voltage is obtained by capacitance integration.

Further as a preferred embodiment of the method, the first sampling switch module and the second sampling switch module both include a grounding switch and a series switch, the grounding switch is controlled by a data square wave signal, and the series switch is controlled by a pulse signal .

Specifically, referring to FIG. 5 , the sampling switch is mainly composed of two parts, a ground switch composed of transistor M1 and a series switch composed of transistors M2-M5. The ground switch is controlled with a data square wave signal, while the series switch is controlled with a pulse signal. The ground switch can eliminate the signal interference of the irrelevant part of the VIN input signal, and the series switch is controlled by a pulse signal, which can avoid the edge alignment problem of the VIN input signal and the conduction signal using the switch, and can improve the sampling voltage. Accuracy.

With reference to Fig. 4, the RF-DAC quadrature transmitter x=4 ⁽ⁿ⁺¹⁾ that the present invention is mainly applied to xQAM modulation mode, n>=1, the self-detection network of I road and Q road passes through to I road and Q road respectively The RF-DAC transmitter of the circuit performs amplitude detection and phase detection, and feeds back 2n amplitude-adjusted DC voltage values and 2n phase-adjusted DC voltage values. VMAGI[1:n] and VMAGQ[1:n] perform amplitude calibration on the RF-DAC transmitter, VPHASEI[1:n] and VPHASEQ[1:n] perform phase calibration on the RF-DAC transmitter, so that the RF-DAC The transmitter reduces nonlinear distortion and effectively improves the quality of the modulated signal of the transmitter.

The content in the above-mentioned method embodiment is applicable to this device embodiment, and the specific functions realized by this device embodiment are the same as those of the above-mentioned method embodiment, and the beneficial effects achieved are also the same as those achieved by the above-mentioned method embodiment.

The above is a specific description of the preferred implementation of the present invention, but the invention is not limited to the described embodiments, and those skilled in the art can also make various equivalent deformations or replacements without violating the spirit of the present invention. , these equivalent modifications or replacements are all within the scope defined by the claims of the present application.

Claims (5)

1. a kind of on-chip integrated real-time calibration network for QAM modulation, it is characterized in that, comprising: The amplitude detection path is used to detect the amplitude of the transmitter xQAM, x=4n ⁺¹ , n>=1 modulation mode and perform calibration according to the feedback DC voltage, and the amplitude detection path includes a power detector, a first comparison device, the first D flip-flop, the first accumulator-accumulator and the first digital-to-analog converter, the power detector, the first comparator, the first D flip-flop, the first accumulator-subtractor and the first The converters are connected sequentially; The phase detection path is used to detect the phase of the transmitter xQAM modulation mode and calibrate it according to the feedback DC voltage, and the phase detection path includes a phase detector, a second comparator, a second D flip-flop, a second accumulator A subtractor and a second digital-to-analog converter, the phase detector, the second comparator, the second D flip-flop, the second accumulator-subtractor and the second digital-to-analog converter are connected in sequence; a feedback loop for feeding back a DC voltage; The power detector includes a first passive network voltage divider module, an amplitude detection module and a first sampling switch module; The first passive network voltage divider module divides the amplitude detection channel into a saturated output power signal amplitude detection channel and a power fallback signal amplitude detection channel, and obtains the same swing amplitude by using different voltage division ratios for input signals of different powers; An amplitude detection module, used to convert the amplitude information into a DC voltage; The first sampling switch module is used to perform capacitance integration, so as to obtain DC voltage information corresponding to the amplitude information. 2. a kind of on-chip integrated real-time calibration network for QAM modulation according to claim 1, is characterized in that, described phase detector specifically comprises: The second passive network voltage divider module divides the phase detection path into a saturated output power signal phase detection path and a power back-off signal phase detection path, and obtains the same swing amplitude through different voltage division ratios for input signals of different powers; The phase detection module compares the phase information of the radio frequency signal and the local oscillator signal, and converts the phase information into a DC voltage; The second sampling switch module integrates and holds the DC voltage; The differential conversion single module converts two differential DC voltages into a single-ended DC voltage through the differential conversion single module and outputs it. 3. according to claim 2 a kind of on-chip integrated real-time calibration network for QAM modulation, it is characterized in that, by the power detector with the first sampling switch module, the continuous radio frequency signal with different amplitudes is dynamically detected, and Convert the different amplitude information of a continuous signal into a DC voltage. 4. according to claim 3 a kind of on-chip integrated real-time calibration network for QAM modulation, it is characterized in that, by the phase detector with the second sampling switch module, the continuous radio frequency signal with different phases is dynamically phase-discriminated , and convert the different phase information of the continuous signal into a DC voltage. 5. a kind of on-chip integrated real-time calibration network for QAM modulation according to claim 4, is characterized in that, described first sampling switch module and the second sampling switch module all comprise grounding switch and series switch, and described grounding switch adopts The data square wave signal is used for control, and the series switch is controlled by a pulse signal.

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