Local oscillator leakage calibration circuit and electronic equipment

Abstract

The embodiment of the invention provides a local oscillator leakage calibration circuit and electronic equipment, and the circuit comprises a signal generation module which is used for generating a multi-stage calibration signal; the pre-compensation module performs pre-compensation on each stage of calibration signal by using a local oscillator leakage compensation value obtained from the previous stage of calibration signal to obtain a pre-compensation signal; the signal modulation module modulates the pre-compensation signal by using the local oscillator signal to obtain a modulation calibration signal; the detector detects the power of each stage of modulation calibration signal; the data processing module iteratively calculates a local oscillator leakage intensity estimation value step by step according to the power of the multi-stage calibration signal and the multi-stage modulation calibration signal; wherein for each level of calibration signal, the corresponding local oscillator leakage compensation value is generated according to the local oscillator leakage intensity estimation value corresponding to the level of calibration signal, and the influence caused by local oscillator leakage can be effectively eliminated.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of semiconductor technology, and in particular to a local oscillator leakage calibration circuit and electronic equipment. Background Art

[0002] With the continuous development of wireless communication technology application requirements, communication systems have put forward higher requirements for their speed, frequency and bandwidth. Due to the unique advantages of zero-IF transmitters in terms of size, power consumption and integration, they have been widely used in wireless signal transmitters such as oscilloscopes, spectrum analyzers, radar transmitters and base stations.

[0003] However, the local oscillator leakage of the zero-IF transmitter falls into the signal band and is difficult to filter out through a filter, resulting in deterioration of signal quality and system performance. Summary of the invention

[0004] Embodiments of the present application provide a local oscillator leakage calibration circuit and an electronic device.

[0005] In a first aspect, an embodiment of the present application provides a local oscillator leakage calibration circuit, a transmission link and a feedback loop; wherein the transmission link includes a signal generation module, a pre-compensation module, and a signal modulation module; the feedback loop includes a detector and a data processing module; the signal modulation module is connected to the detector, and the data processing module is connected to the pre-compensation module; wherein the signal generation module is used to generate a multi-level calibration signal; the pre-compensation module is used to receive the multi-level calibration signal, and for each level of calibration signal, pre-compensate the calibration signal of that level, output the pre-compensation signal corresponding to the calibration signal of that level, and send the pre-compensation signal to the signal modulation module; wherein the local oscillator leakage compensation value for pre-compensating the calibration signal of the next level is the local oscillator leakage compensation value obtained according to the calibration signal of the previous level and sent by the data processing module, and the local oscillator leakage compensation value corresponding to the first level calibration signal is the local oscillator leakage compensation value obtained according to the calibration signal of the previous level and sent by the data processing module The local oscillator leakage compensation value is a preset value; the signal modulation module is used to modulate each level of pre-compensation signal with the local oscillator signal to obtain a modulation calibration signal corresponding to the pre-compensation signal of this level; and send the modulation calibration signal of this level to the detector; the detector is used to detect the power of each level of modulation calibration signal, and send the power of each level of modulation calibration signal to the data processing module; the data processing module is used to iteratively calculate the local oscillator leakage intensity estimation value of each level according to the multi-level calibration signal and the power of the multi-level modulation calibration signal; for each level of calibration signal, a local oscillator leakage compensation value corresponding to the calibration signal of this level is generated according to the local oscillator leakage intensity estimation value corresponding to the calibration signal of this level; the local oscillator leakage compensation value corresponding to the calibration signal of this level is sent to the pre-compensation module to pre-compensate the calibration signal of the next level.

[0006] According to the above scheme, the detector and the data processing module are used as the feedback loop. The detector detects the power of the modulated calibration signal obtained after the calibration signal passes through the transmission link. The data processing module estimates the local oscillator leakage signal according to the above powers corresponding to multiple calibration signals and multiple modulated calibration signals, and generates a local oscillator leakage compensation value according to the estimation result to pre-compensate the local oscillator leakage of the subsequent business transmission signal. This scheme does not require the integration of a down-conversion receiver at the signal generation end, can solve the resource overhead of the feedback link of the high-frequency and broadband transmission system, and reduce the space of the transmission system. In addition, the above data processing module solves the local oscillator leakage and compensates through multiple calibration signals and corresponding modulated signals, without the need for searching, and can achieve fast local oscillator leakage calculation and compensation.

[0007] In combination with the first aspect, in some implementations of the first aspect, each level of calibration signal in the multi-level calibration signal includes a plurality of first signals, and each of the first signals corresponds to a power of a modulated calibration signal;

[0008] When the data processing module is used to iteratively calculate the local oscillator leakage strength estimation value of each level, it is specifically used to iteratively calculate the local oscillator leakage strength estimation value of each level according to the multiple first signals corresponding to each level and the power of the modulated calibration signal corresponding to the multiple first signals of each level.

[0009] According to the above scheme, multiple first signals are set for each level of calibration signal, and the multiple first signals of each level correspond to the power of the modulated calibration signal respectively. The local oscillator leakage intensity of each level can be estimated by the multiple first signals of each level and the power of the modulated calibration signal corresponding to the multiple first signals of each level, so that a more accurate local oscillator leakage intensity estimation result can be obtained.

[0010] In combination with the first aspect, in certain embodiments of the first aspect, the local oscillator leakage intensity estimation value satisfies a predefined functional relationship with the magnitude of the first signal and the power value of a modulated calibration signal corresponding to the first signal.

[0011] According to the above scheme, a preset functional relationship is set between the local oscillator leakage strength estimate value and the size of the first signal and the power of the modulated calibration signal corresponding to the first signal, thereby providing convenience for solving the local oscillator leakage strength estimate value based on multiple first signals of each level and the power of the modulated calibration signal corresponding to the first signal.

[0012] In combination with the first aspect, in certain embodiments of the first aspect, the kth level calibration signal includes a kth level I-channel calibration signal and a kth level Q-channel calibration signal; the kth level I-channel calibration signal includes more than three I-channel first signals, and the kth level Q-channel calibration signal includes more than three Q-channel first signals; the data processing module is used to iteratively calculate the local oscillator leakage strength estimation value of each level step by step according to the powers of the modulated calibration signals corresponding to the multiple first signals at each level and the multiple first signals at each level, and is specifically used to: solve the kth level I-channel local oscillator leakage strength estimation value according to the powers of the modulated calibration signals corresponding to the kth level multiple I-channel first signals and the kth level multiple I-channel first signals; solve the kth level Q-channel local oscillator leakage strength estimation value according to the powers of the modulated calibration signals corresponding to the kth level multiple Q-channel first signals and the kth level multiple Q-channel first signals.

[0013] According to the above scheme, the I-way local oscillator leakage strength estimation value and the Q-way local oscillator leakage strength estimation value are calculated through the transmitting branch, the signal modulation module and the feedback loop, and the I-way local oscillator leakage compensation value and the Q-way local oscillator leakage compensation value are generated respectively according to the I-way local oscillator leakage strength estimation value and the Q-way local oscillator leakage strength estimation value. Therefore, the distortion pre-compensation of the I-way signal and the Q-way signal can be realized respectively.

[0014] In combination with the first aspect, in some implementations of the first aspect, the data processing module is used to generate, for each level of calibration signal, a local oscillator leakage compensation value corresponding to the level of calibration signal according to the one or more local oscillator leakage intensity estimation values ​​corresponding to the level of calibration signal, specifically for:

[0015] Generate a k-th level I local oscillator leakage compensation value according to the k-th level I local oscillator leakage strength estimation value;

[0016] A k-th level Q-channel local oscillator leakage compensation value is generated according to the k-th level Q-channel local oscillator leakage strength estimation value.

[0017] According to the above solution, respective local oscillator leakage compensation values ​​are generated for the I-path and Q-path signals, thereby achieving pre-compensation for the I-path transmit signal and the Q-path transmit signal.

[0018] In combination with the first aspect, in certain embodiments of the first aspect, the multi-level calibration signal includes a multi-level I-channel digital calibration signal and a multi-level Q-channel digital calibration signal; the pre-compensation module includes a first pre-compensation module and a second pre-compensation module; the first pre-compensation module, when the pre-compensation module performs pre-compensation on each level of the calibration signal, is used to pre-compensate the I-channel digital calibration signal of each level using the I-channel local oscillator leakage compensation value corresponding to the level to obtain the I-channel digital pre-compensation signal of the level, and convert the I-channel digital pre-compensation signal of the level into the I-channel analog pre-compensation signal of the level; the second pre-compensation module, when the pre-compensation module performs pre-compensation on the calibration signal of the level, is used to pre-compensate the I-channel digital calibration signal of the level using the I-channel local oscillator leakage compensation value corresponding to the level to obtain the I-channel digital pre-compensation signal of the level, and convert the I-channel digital pre-compensation signal of the level into the I-channel analog pre-compensation signal of the level; The block is used to pre-compensate the Q-channel digital calibration signal of each level when pre-compensating the calibration signal of that level, and use the Q-channel local oscillator leakage compensation value corresponding to that level to pre-compensate the Q-channel digital calibration signal of that level to obtain the Q-channel digital pre-compensation signal of that level, and convert the Q-channel digital pre-compensation signal of that level into a Q-channel analog pre-compensation signal; the signal modulation module, when used to modulate the pre-compensation signal of each level using the local oscillator signal for the pre-compensation signal of that level, is specifically used to: modulate the I-channel analog pre-compensation signal of that level and the Q-channel analog pre-compensation signal of that level, and output a first analog modulation signal for I-channel calibration and a second analog modulation signal for Q-channel calibration.

[0019] According to the above solution, the first pre-compensation module and the second pre-compensation module perform pre-compensation on the I-path signal and the Q-path signal respectively, thereby realizing fast pre-compensation on the I-path signal and the Q-path signal.

[0020] In combination with the first aspect, in certain embodiments of the first aspect, the detector, when used to detect the power of each level of modulation calibration signal, is specifically used to: detect the power of the first analog modulation signal for I-channel calibration at each level and the power of the second analog modulation signal for Q-channel calibration at each level; the data processing module specifically includes an analog-to-digital converter and a data processor, in which the data processing module is used to iteratively calculate one or more local oscillator leakage strength estimation values ​​of each level according to the multi-level calibration signal and the power of the multi-level modulation calibration signal; for each level of calibration signal, when generating a local oscillator leakage compensation value corresponding to the calibration signal of that level according to the one or more local oscillator leakage strength estimation values ​​corresponding to the calibration signal of that level, the analog-to-digital converter is used For each stage, the analog power of the first analog modulation signal of the stage is converted into the first digital power, and the analog power of the second analog modulation signal of the stage is converted into the second digital power; the data processor is used to, for each stage, calculate the estimated value of the I-channel local oscillator leakage strength of the stage according to the first digital powers respectively corresponding to the multiple I-channel calibration signals and the multiple I-channel modulation calibration signals in the calibration signal of the stage; and calculate the estimated value of the Q-channel local oscillator leakage strength according to the second digital powers respectively corresponding to the multiple Q-channel calibration signals and the multiple Q-channel modulation calibration signals in the calibration signal of the stage; and determine the I-channel local oscillator leakage compensation value according to the I-channel local oscillator leakage strength estimate value, and determine the Q-channel local oscillator leakage compensation value according to the Q-channel local oscillator leakage strength estimate value.

[0021] According to the above scheme, the detector detects the power of the analog modulated signal used for I-channel calibration and the power of the analog modulated signal used for Q-channel calibration respectively. The detector here can reuse the detector for detecting the power value of the service signal to be transmitted in the transmission link, thereby simplifying the structure of the local oscillator leakage calibration circuit. The data processing module is provided with an analog-to-digital converter and a data processor, so that the power of the analog modulated signal can be converted into digital power, which provides convenience for solving the local oscillator leakage compensation value.

[0022] In combination with the first aspect, in certain embodiments of the first aspect, the data processing module is also used to iterate using a multi-level calibration signal, and use the local oscillator leakage intensity estimate corresponding to when the iteration stops as the target local oscillator leakage intensity estimate, and generate a target local oscillator leakage compensation value based on the target local oscillator leakage intensity estimate.

[0023] According to the above solution, a relatively accurate target local oscillator leakage compensation value can be obtained through the above iterations.

[0024] In a second aspect, an embodiment of the present application provides an electronic device, comprising the local oscillator leakage calibration circuit of the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1A schematic diagram of the structure of a zero intermediate frequency signal transmission module provided in one embodiment of the present application;

[0026] Figure 2 The structure diagram of the local oscillator leakage calibration circuit is provided for this application Figure 1 ;

[0027] Figure 3 The structure of the local oscillator leakage calibration circuit provided in this application is shown as follows: Figure 2 .

[0028] Description of reference numerals:

[0029] 101-digital-to-analog converter, 102-low-pass filter, 103-mixer, 104-adder; 105-filter;

[0030] 21-transmitting link, 22-feedback loop;

[0031] 211 - signal generation module, 212 - pre-compensation module, 213 - signal modulation module, 215 - first digital-to-analog converter, 221 - detector, 222 - data processing module;

[0032] 2121 - second digital-to-analog converter, 2122 - adder, 2123 - first pre-compensation module, 2124 - second pre-compensation module, 2221 - analog-to-digital converter, 2222 - data processor. DETAILED DESCRIPTION

[0033] The following will describe the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0034] The local oscillator leakage calibration circuit provided in the present application can be used in signal transmitters of wireless communication systems, signal measurement equipment, spectrum analyzers, base stations, etc. The role of the above-mentioned signal transmitter is crucial. It is mainly responsible for converting the information signal into a form suitable for transmission through the channel and sending it out. The functions of the signal transmitter include but are not limited to the following aspects: Signal modulation: Loading the information to be transmitted (audio, video, data, etc.) onto the carrier in a certain modulation method to facilitate the remote transmission of information. Frequency conversion: Converting the modulated signal to a radio frequency band suitable for wireless propagation. Power amplification: Amplifying the signal so that it can cover a predetermined distance and overcome attenuation and noise in the channel. Frequency stability: Ensure the stability of the carrier frequency so that the receiving end can accurately demodulate the signal.

[0035] Traditional transmitters usually up-convert the baseband signal to an intermediate frequency (IF) first, filter and amplify it at this frequency, and then up-convert it to the final radio frequency (RF). Because traditional transmitters need to convert the baseband signal to an IF first, filter and amplify it at the IF, traditional transmitters take up a large space and consume a lot of power.

[0036] In order to reduce the power consumption of the transmitter and save space, a zero intermediate frequency signal transmission module can be used in the transmitter. The zero intermediate frequency signal transmission module can directly convert the baseband signal to be transmitted into a high-frequency signal that can be propagated in space through a single up-conversion. Please refer to Figure 1 , Figure 1 FIG. 2 shows a schematic diagram of the structure of a zero intermediate frequency signal transmission module provided by an embodiment. Figure 1 In the zero intermediate frequency signal transmission module shown, the I-channel signal (in-phase component) and Q-channel signal (quadrature component) generated by the baseband signal to be transmitted are converted into analog signals through the digital to analog converter (DAC) 101. Then they are filtered through the low-pass filter 102 to filter out unnecessary signals, and then the frequency is converted through the mixer 103. Taking the I-channel signal as an example, the local oscillator signal (Lo) and the I-channel signal are input into the mixer 103. In the mixer 103, the local oscillator signal and the I-channel signal are mixed (which can be regarded as a multiplication calculation between the two) to obtain the I-channel frequency conversion signal.

[0037] The I-channel signal after frequency conversion and the Q-channel signal after frequency conversion are orthogonal signals. The I-channel signal after frequency conversion and the Q-channel signal after frequency conversion can be combined into one channel after passing through the adder 104, and then transmitted through the antenna after passing through the bandpass filter 105. In the mixing process, due to the introduction of the DC signal, local oscillator leakage will appear at the carrier frequency after mixing. Since the frequency of the local oscillator leakage signal is within the wideband signal range, it is difficult to filter it out through the filter 105. The local oscillator leakage signal will affect the dynamic range and error vector magnitude (EVM) index of the modulated signal, and deteriorate the signal quality and system performance.

[0038] In order to eliminate the influence of local oscillator leakage, one solution is to adopt an open-loop circuit solution, which requires an external local oscillator leakage acquisition device. By sending the modulated signal to be transmitted to the external local oscillator leakage acquisition device, the estimated value of the local oscillator leakage component is obtained according to the established algorithm model, and then the influence of local oscillator leakage is eliminated by pre-compensation of the baseband signal. The disadvantage of this solution is that an external local oscillator leakage acquisition device must be connected to estimate and compensate for local oscillator leakage, and it cannot be calibrated in real time. It is greatly affected by the environment and has poor robustness.

[0039] One solution is a closed-loop circuit solution, which requires the integration of a down-conversion receiver inside the system. The down-conversion receiver and the analysis module form a feedback link to estimate the value of the local oscillator leakage. The modulated signal is obtained in real time through the feedback link, thereby realizing the estimation and compensation of the local oscillator leakage. The disadvantage of this solution is that it requires the internal integration of a down-conversion receiver. The hardware architecture to achieve this approach has become increasingly difficult to design and has high costs under the requirements of large bandwidth and high carrier frequency.

[0040] In addition, the method for LO leakage calibration is mainly based on the search method. By setting the DC bias compensation range in the I and Q channels, the optimization is performed with a certain step until the LO leakage suppression index is reached, and the DC bias obtained by the optimization is used to compensate the baseband signal. The problem is that the search-based method cannot determine the accurate search space and search step in advance, and can only traverse in a large range and fine steps. The compensation value determination of the two-dimensional I and Q channels with multiple frequency points is inefficient. It is not conducive to real-time and rapid calibration. In addition, the search interval, dimension, and components will further affect the efficiency and accuracy of the calibration.

[0041] In order to efficiently implement local oscillator leakage calibration without adding components to the signal transmission module, the present application uses a local oscillator leakage calibration circuit, constructs a feedback loop based on a detector, and uses the detector in combination with a data processing module to solve the local oscillator leakage, thereby performing local oscillator leakage compensation on the signal in the zero intermediate frequency signal transmission module.

[0042] Please refer to Figure 2 , Figure 2 The structure of the local oscillator leakage calibration circuit provided in this application is shown as follows: Figure 1 .like Figure 2 As shown, the local oscillator leakage calibration circuit is used for a zero intermediate frequency signal transmission module, and the circuit includes: a transmission link 21 and a feedback loop 22. The transmission link 21 includes a signal generation module 211, a pre-compensation module 212, and a signal modulation module 213; the feedback loop 22 includes a detector 221 and a data processing module 222; the signal modulation module 213 is connected to the detector 221; the data processing module 222 is connected to the pre-compensation module 212;

[0043] The signal generating module 211 is used to generate a multi-level calibration signal. The signal generating module 211 is implemented based on a digital circuit, and can be implemented by a digital circuit chip, such as a field programmable gate array (FPGA) and a digital signal processor (DSP). Alternatively, the signal generating module 211 is implemented by discrete devices.

[0044] In the present application, the calculation of the local oscillator leakage strength is to calculate the local oscillator leakage strength estimation value of each level through each level calibration signal and the power of the modulated calibration signal corresponding to each level calibration signal. And use the multi-level calibration signal to iteratively approximate the real local oscillator leakage strength. The local oscillator leakage compensation value is determined by the above local oscillator leakage strength, and the signal is pre-compensated by the above local oscillator leakage compensation value.

[0045] The multi-level calibration signal here may refer to multiple groups of calibration signals, each group of calibration signals may include multiple calibration signals, and schematically, each group of calibration signals includes 6 calibration signals. Multiple groups of calibration signals are different from each other. After the previous group of calibration signals is input into the local oscillator leakage calibration circuit to obtain the local oscillator leakage compensation value corresponding to the group of calibration signals, the next group of calibration signals can be input into the local oscillator leakage calibration circuit to estimate the local oscillator leakage compensation value. Schematically, each group of calibration signals may include multiple pre-specified calibration signals, and each group of calibration signals may be sent to the data processing module in advance. Schematically, each group of calibration signals may include multiple randomly generated calibration signals. The above-mentioned signal generation module sends each group of randomly generated calibration signals to the data processing module.

[0046] In practice, the digital calibration signal output by the signal generation module 211 can be converted into an analog calibration signal by the first digital-to-analog converter 215 . The analog calibration signal is input into the pre-compensation module 212 .

[0047] The pre-compensation module 212 is used to receive multi-level calibration signals, pre-compensate the calibration signal of each level, output the pre-compensated signal corresponding to the calibration signal of that level, and send the pre-compensated signal to the signal modulation module; wherein the local oscillator leakage compensation value for pre-compensating the calibration signal of the next level is the local oscillator leakage compensation value obtained according to the calibration signal of the previous level and sent by the data processing module, and the local oscillator leakage compensation value corresponding to the first level calibration signal is a preset value.

[0048] The above-mentioned pre-compensation module can be implemented by an analog circuit, and specifically can be implemented in the form of a discrete device or an integrated circuit.

[0049] Specifically, the pre-compensation module may include a second digital-to-analog converter 2121 and an adder 2122. The local oscillator leakage compensation value output by the data processing module 222 is a digital signal, which is converted into an analog signal after passing through the second digital-to-analog converter. The adder adds the analog calibration signal and the analog local oscillator leakage compensation signal to achieve pre-compensation of the calibration signal.

[0050] The signal modulation module 213 is used to modulate each level of pre-compensation signal using a local oscillator signal to obtain a modulation calibration signal corresponding to the level of pre-compensation signal; and send the level of modulation calibration signal to the detector.

[0051] The signal modulation module 213 may be implemented by an analog circuit, specifically, in the form of a discrete device or an integrated circuit.

[0052] The detector 221 is used to detect the power of each level of modulation calibration signal and send the power of each level of modulation calibration signal to the data processing module 222 .

[0053] The detector 221 may be implemented by an analog circuit, specifically, in the form of a discrete device or an integrated circuit.

[0054] The data processing module 222 is used to iteratively calculate the local oscillator leakage intensity estimation value of each level according to the power of the multi-level calibration signal and the multi-level modulation calibration signal; for each level of calibration signal, generate a local oscillator leakage compensation value corresponding to the calibration signal of this level according to the local oscillator leakage intensity estimation value corresponding to the calibration signal of this level; and send the local oscillator leakage compensation value corresponding to the calibration signal of this level to the pre-compensation module to pre-compensate the calibration signal of the next level.

[0055] The data processing module 222 may be implemented based on a digital circuit, for example, by a field programmable gate array and a digital signal processor, etc. It is understandable that the calculated local oscillator leakage strength estimation value of each level may be a value.

[0056] In the calibration phase, the signal generation module 211 may generate a digital calibration signal. Specifically, a multi-level digital calibration signal may be generated, and the local oscillator leakage compensation value may be determined by each of the modules in the transmission link 21 and the feedback loop 22 .

[0057] In the service signal transmission stage, the signal generation module 211 generates a baseband signal to be transmitted. After passing through the pre-compensation module 212 and the signal modulation module 213 in the transmission link 21, the baseband signal is coupled to the antenna module for transmission.

[0058] In an example, the multi-level calibration signal may be a preset signal, and the data processing module 222 may pre-acquire the calibration signals of each level from the signal generating module 211 .

[0059] In an example, each level of calibration signal may be a signal randomly generated by the signal generating module 211 , and the signal generating module 211 may send the randomly generated signal to the data processing module.

[0060] The detector 221 can send the detected power of each level of modulated calibration signal to the data processing module. Since the calibration signal size and the power value of the modulated calibration signal corresponding to the calibration signal are known, the strength of the local oscillator leakage can be estimated through multiple calibration signals and the power values ​​of the modulated calibration signals corresponding to the multiple calibration signals. In order to obtain a more accurate local oscillator leakage strength value, a multi-level iteration method is used for estimation.

[0061] After the local oscillator leakage strength estimation value is obtained, the local oscillator leakage compensation value may be generated according to the local oscillator leakage strength estimation value. Specifically, the negative value of the local oscillator leakage strength estimation value may be used as the local oscillator leakage compensation value.

[0062] In this embodiment, the detector and the data processing module are used as a feedback loop. The detector detects the power of the modulated calibration signal obtained after the calibration signal passes through the transmission link. The data processing module estimates the local oscillator leakage according to the power corresponding to the multi-level calibration signal and the multi-level modulation calibration signal, and generates a local oscillator leakage compensation value according to the estimation result to pre-compensate the distortion of the subsequent service transmission signal. Therefore, there is no need to integrate a down-conversion receiver at the signal generation end, which can reduce the resource overhead caused by integrating the down-conversion receiver at the signal generation end; since there is no need to set up a down-conversion receiver, the space occupied by the transmission system can also be reduced. In addition, the above-mentioned data processing module solves the local oscillator leakage and compensates it through the multi-level calibration signal and the corresponding modulation signal, without the need for large-scale and fine step search, and can achieve fast local oscillator leakage calculation and compensation.

[0063] In some implementations, each level of the multi-level calibration signal includes multiple first signals, and each first signal corresponds to the power of a modulated calibration signal; when the data processing module 222 is used to iteratively calculate the local oscillator leakage intensity estimation value of each level, it is specifically used to iteratively calculate the local oscillator leakage intensity estimation value of each level according to the multiple first signals corresponding to each level and the powers of the modulated calibration signals corresponding to the multiple first signals of each level.

[0064] The number of the multi-level here can be more than 2. Specifically, each level of calibration signal can be pre-compensated in turn by the above-mentioned pre-compensation module using the local oscillator leakage compensation value generated based on the calibration signal of the previous level to obtain a pre-compensated signal, and the signal modulation module 213 modulates the pre-compensated signal of this level to obtain the modulated calibration signal of this level, and the detector 221 detects the power of the modulated calibration signal of this level; the data processing module solves the local oscillator leakage intensity estimation value of this level according to the size of the calibration signal of this level and the power of the modulated calibration signal of this level.

[0065] By setting multiple first signals for each level of calibration signal, the multiple first signals of each level correspond to the power of the modulated calibration signal respectively. The local oscillator leakage intensity of each level can be estimated by the multiple first signals of each level and the power of the modulated calibration signal corresponding to the multiple first signals of each level, so that a more accurate local oscillator leakage intensity estimation result can be obtained.

[0066] Furthermore, the local oscillator leakage strength estimation value, the magnitude of the first signal, and the power value of the modulated calibration signal corresponding to the first signal satisfy a predefined functional relationship.

[0067] As an implementation method, the above predefined functional relationship is represented by the following formula (1):

[0068]

[0069] Wherein, Dc(k) is the estimated value of the k-th level local oscillator leakage signal strength; S1, S2, S3 are the three calibration signals of the k-th level calibration signal. P1, P2, P3 are the power values ​​of the modulated calibration signals corresponding to the three calibration signals respectively. c(k-1) is the local oscillator leakage compensation value obtained by the k-1-th level calibration signal. When k=1, c(k-1)=0.

[0070] Through the above functional relationship, an estimated value of the k-th level local oscillator leakage signal strength can be obtained.

[0071] In practice, in order to improve the robustness of the calibration algorithm to power measurement errors, the result of solving the local oscillator leakage strength estimate can be used as the initial value, and a small range traversal is performed near it to find the optimal and accurate leakage estimate.

[0072] According to the above scheme, a preset functional relationship is set between the local oscillator leakage strength estimate value and the size of the first signal and the power of the modulated calibration signal corresponding to the first signal, thereby providing convenience for solving the local oscillator leakage strength estimate value based on multiple first signals of each level and the power of the modulated calibration signal corresponding to the first signal.

[0073] After a local oscillator leakage intensity estimate is calculated using multiple calibration signals of each level, a local oscillator leakage compensation value can be generated based on the local oscillator leakage intensity estimate, and the local oscillator leakage compensation value can be written into the pre-compensation module. For the calibration signal of the next level, when the calibration signal of the next level passes through the above-mentioned pre-compensation module, the calibration signal of the next level can be pre-compensated by the local oscillator leakage compensation value obtained from the calibration signal of the previous level to obtain a pre-compensated signal. The pre-compensated signal enters the signal modulation module, and the signal modulation module generates a modulated calibration signal corresponding to the calibration signal of the next level. Then the detector detects the power corresponding to the modulated calibration signal of the next level, and then the data processing module solves the local oscillator leakage intensity estimate corresponding to the next level based on these powers. After multiple levels of iteration, the actual local oscillator leakage intensity can be approximated.

[0074] In some implementations, the data processing module 222 is further configured to perform iterations using a multi-level calibration signal, use a local oscillator leakage strength estimate corresponding to when the iteration stops as a target local oscillator leakage strength estimate, and generate a target local oscillator leakage compensation value based on the target local oscillator leakage strength estimate.

[0075] The target local oscillator leakage strength estimation value obtained after multiple iterations has high accuracy. The target local oscillator leakage compensation value is determined according to the target local oscillator leakage strength estimation value, so that the local oscillator leakage can be pre-compensated more accurately.

[0076] In some implementations, when the transmission link 21 transmits a service signal, the detector 221 is used to detect the power value of the service signal to be transmitted after passing through the signal modulation module 213 .

[0077] In these embodiments, the detector 221 can be shared by the transmission link 21 and the feedback loop 22. In the calibration stage, the detector is used to detect the power of the modulated calibration signal; in the service signal transmission stage, the detector is used to detect the power value of the service signal to be transmitted after the signal modulation module. The transmission link and the feedback loop share the detector, which can further reduce the space occupation. In addition, the existing detector in the transmission link is used in the feedback loop, which can effectively suppress the local oscillator leakage of the system while reducing the hardware cost.

[0078] In some implementations, the detector 221 may be a root mean square (RMS) detector. The root mean square value is a square, average and square root operation performed on the input signal in sequence. The operations are performed within one or an integer number of cycles of the signal. The output result of the RMS detector is equal to the effective value of the measured signal.

[0079] Please refer to Figure 3 , Figure 3 The structure of the local oscillator leakage calibration circuit provided in this application is shown as follows: Figure 2. The local oscillator leakage calibration circuit can be used in the zero intermediate frequency signal transmission module of electronic equipment such as oscilloscopes and spectrum analyzers. The circuit includes: a transmission link 21 and a feedback loop 22. The transmission link 21 includes an I-channel transmission link and a Q-channel transmission link. The I-channel transmission link and the Q-channel transmission link need to pre-compensate the local oscillator leakage respectively. Therefore, each level of calibration signal generated by the signal generation module 211 in the transmission link 21 includes an I-channel calibration signal and a Q-channel calibration signal respectively.

[0080] The k-th level calibration signal includes the k-th level I-channel calibration signal and the k-th level Q-channel calibration signal; the k-th level I-channel calibration signal includes more than three I-channel first signals, and the k-th level Q-channel calibration signal includes more than three Q-channel first signals;

[0081] The data processing module 222 is used to iteratively calculate the local oscillator leakage intensity estimation value of each level according to the multiple first signals corresponding to each level and the power of the modulated calibration signal corresponding to the multiple first signals at each level, specifically for:

[0082] Calculate the k-th level I-channel local oscillator leakage strength estimation value according to the k-th level multiple I-channel first signals and the powers of the modulated calibration signals respectively corresponding to the k-th level multiple I-channel first signals;

[0083] The k-th level Q-path local oscillator leakage strength estimation value is calculated according to the k-th level multiple Q-path first signals and the powers of the modulation calibration signals respectively corresponding to the k-th level multiple Q-path first signals.

[0084] Each level of calibration signals may include multiple calibration signals. The multiple calibration signals of each level may include multiple I-path calibration signals and multiple Q-path calibration signals.

[0085] In these implementations, at the beginning of the calibration phase, the I-channel local oscillator leakage compensation value in the first pre-compensation module can be set to 0, which is expressed as And the Q-path local oscillator leakage compensation value in the second pre-compensation module is set to 0, which is recorded as .

[0086] Specifically, for a k-th level calibration signal, the local oscillator leakage strength estimation value corresponding to the k-th level calibration signal may be calculated through the following steps.

[0087] Assume that the k-th level I calibration signal is expressed as follows after pre-compensation: , which can be specifically expressed as:

[0088] I n is the nth calibration signal of channel I, and the calibration signal is a preset value.

[0089] The power of all modulated signals passing through the transmission link is measured using an RMS detector, and the result is: .

[0090] According to the measured power, the leakage compensation value of the kth level local oscillator of channel I can be obtained. The following formula (2) expresses:

[0091]

[0092] in, For the current iteration I dc An estimated value of is the power of the first k-th level modulation calibration signal of channel I, is the power of the second modulation calibration signal of the kth level in channel I, is the power of the third modulation calibration signal of the kth level in channel I.

[0093] Similarly, the k-th level Q-path calibration signal can be used to estimate the level Q-path local oscillator leakage strength through the following steps. The Q-path calibration signal generated by the signal generation module, after passing through the second pre-compensation module, is expressed as Q n is the nth calibration signal, and the calibration signal is a preset value;

[0094] The power of all modulated signals passing through the transmission link is measured using the RMS detector 221, and the result is: , the k-th level local oscillator leakage compensation value of Q path can be obtained by solving the measured power The road bias is shown in formula (3):

[0095]

[0096] in, Q in the current iteration dc The estimated value of is the power of the first modulation calibration signal of the kth level in the Q path, is the power of the second modulation calibration signal of the kth level of the Q path, is the power of the third modulation calibration signal of the kth level in the Q path.

[0097] After estimating the I-channel local oscillator leakage strength and the Q-channel local oscillator leakage strength for each level of calibration signal, it can be determined whether the current iteration meets the preset requirements, such as whether the current number of iterations meets the iteration number requirement. Specifically, it can be determined whether the number of iterations meets the preset number of iterations according to the k value. If so, the iteration is stopped.

[0098] If the number of iterations does not meet the preset number of iterations, the corresponding I-way local oscillator leakage compensation value of the group is generated according to the I-way local oscillator leakage strength estimation value of the level, and the I-way local oscillator leakage compensation value is sent to the first pre-compensation module, so that the first pre-compensation module updates the I-way local oscillator leakage compensation value stored therein. The Q-way local oscillator leakage strength estimation value of the level generates the corresponding Q-way local oscillator leakage compensation value of the group, and the Q-way local oscillator leakage compensation value is sent to the second pre-compensation module, so that the second pre-compensation module updates the Q-way local oscillator leakage compensation signal stored therein. Continue to obtain the next level of calibration signal, and continue to solve the I-way local oscillator leakage strength estimation value and the Q-way local oscillator leakage strength estimation value through the above steps.

[0099] Furthermore, the data processing module 222 is used to generate a local oscillator leakage compensation value corresponding to each level of the calibration signal according to one or more local oscillator leakage strength estimation values ​​corresponding to the level of the calibration signal, specifically for:

[0100] Generate a k-th level I local oscillator leakage compensation value according to the k-th level I local oscillator leakage strength estimation value;

[0101] A k-th level Q-channel local oscillator leakage compensation value is generated according to the k-th level Q-channel local oscillator leakage strength estimation value.

[0102] That is, for each level I-channel calibration signal, when the local oscillator leakage strength estimation value corresponding to the level calibration signal is determined, the data processing module 222 can generate the level I-channel local oscillator leakage compensation value. Specifically, the level I-channel local oscillator leakage compensation value can be negatively calculated to obtain the level I-channel local oscillator leakage compensation value. The same is true for the Q channel.

[0103] After the iteration is stopped, a target local oscillator leakage strength estimation value can be obtained, and the target local oscillator leakage compensation value is set to a negative value of the target local oscillator leakage strength estimation value, thereby achieving the purpose of local oscillator leakage calibration.

[0104] By calculating the estimated value of the I-channel local oscillator leakage strength and the estimated value of the Q-channel local oscillator leakage strength, and generating the I-channel local oscillator leakage compensation value and the Q-channel local oscillator leakage compensation value according to the estimated value of the I-channel local oscillator leakage strength and the estimated value of the Q-channel local oscillator leakage strength, distortion pre-compensation of the I-channel signal and the Q-channel signal can be achieved respectively.

[0105] In some implementations, the pre-compensation module 212 includes a first pre-compensation module 2123 and a second pre-compensation module 2124. The first pre-compensation module 2123 is located in the I-path transmission link, and the second pre-compensation module 2124 is located in the Q-path transmission link.

[0106] The first pre-compensation module 2123 is used to pre-compensate the I-channel digital calibration signal of each level using the I-channel local oscillator leakage compensation value corresponding to the level when the pre-compensation module pre-compensates the calibration signal of the level, so as to obtain the I-channel digital pre-compensated signal of the level, and convert the I-channel digital pre-compensated signal of the level into the I-channel analog pre-compensated signal of the level.

[0107] The second pre-compensation module 2124 is used to pre-compensate the Q-channel digital calibration signal of each level by using the Q-channel local oscillator leakage compensation value corresponding to the level when the pre-compensation module pre-compensates the calibration signal of the level, so as to obtain the Q-channel digital pre-compensation signal of the level, and convert the Q-channel digital pre-compensation signal of the level into a Q-channel analog pre-compensation signal.

[0108] It is understandable that the first pre-compensation module 2123 and the second pre-compensation module 2124 may each include a second analog-to-digital converter and an adder, which are not shown here.

[0109] In addition, the signal modulation module 213, when used for modulating each level of pre-compensation signal using the local oscillator signal for the level of pre-compensation signal, is specifically used to: modulate the level I analog pre-compensation signal and the level Q analog pre-compensation signal, and output a first analog modulation signal for I-channel calibration and a second analog modulation signal for Q-channel calibration.

[0110] By using the first pre-compensation module and the second pre-compensation module to pre-compensate the I-channel calibration signal and the Q-channel signal respectively, the time used for pre-compensating the two-channel signals can be reduced and the pre-compensation efficiency can be improved.

[0111] In some implementations, the data processing module 222 specifically includes an analog-to-digital converter 2221 and a data processor 2222 .

[0112] The detector 221 is used to detect the power of each level of modulation calibration signal, specifically to detect the power of the first analog modulation signal for I-channel calibration at each level and the power of the second analog modulation signal for Q-channel calibration at each level;

[0113] When the data processing module 222 is used to iteratively calculate one or more local oscillator leakage strength estimation values ​​of each level according to the power of the multi-level calibration signal and the multi-level modulated calibration signal; for each level of the calibration signal, a local oscillator leakage compensation value corresponding to the calibration signal of the level is generated according to the one or more local oscillator leakage strength estimation values ​​corresponding to the calibration signal of the level,

[0114] The analog-to-digital converter 2221 is used for, for each stage, converting the analog power of the first analog modulation signal of the stage into the first digital power, and converting the analog power of the second analog modulation signal of the stage into the second digital power;

[0115] The data processor 2222 is used to calculate, for each stage, an estimated value of the I-channel local oscillator leakage strength of the stage based on the first digital powers respectively corresponding to the multiple I-channel calibration signals and the multiple I-channel modulation calibration signals in the calibration signal of the stage; and to calculate an estimated value of the Q-channel local oscillator leakage strength based on the second digital powers respectively corresponding to the multiple Q-channel calibration signals and the multiple Q-channel modulation calibration signals in the calibration signal of the stage; and to determine an I-channel local oscillator leakage compensation value based on the I-channel local oscillator leakage strength estimate value, and to determine a Q-channel local oscillator leakage compensation value based on the Q-channel local oscillator leakage strength estimate value.

[0116] In order to facilitate the determination of the local oscillator leakage strength estimation value, it is necessary to convert the power of the first analog modulation signal and the power of the second analog modulation signal output by the detector into digital power respectively. Here, the analog-to-digital converter 2221 in the data processing module can realize the conversion of the power of the first analog modulation signal and the power of the second analog modulation signal into digital power respectively. The above-mentioned data processor 2222 can be various processors capable of storing and calculating data, such as FPGA, DSP, etc.

[0117] The data processor 2222 may be pre-set with data processing logic instructions. After receiving the power of the first signal of channel I and the modulated calibration signal corresponding to the first signal of channel I, the data processor completes the solution of the above formulas (2) and (3) according to the above data processing logic instructions, thereby obtaining the estimated value of the leakage strength of the local oscillator of channel I. Similarly, the estimated value of the leakage of the local oscillator of channel Q can be obtained. In addition, the above data processor 2222 can also generate the leakage compensation value of channel I based on the estimated value of the leakage strength of the local oscillator of channel I; and generate the leakage compensation value of channel Q based on the estimated value of the leakage strength of the local oscillator of channel Q. Through the above data processor, the local oscillator leakage compensation value can be quickly solved, thereby improving the efficiency of compensating for the local oscillator leakage.

[0118] The present application also provides an electronic device, wherein the electronic device is integrated Figure 2 or Figure 3 The local oscillator leakage calibration circuit provided in the illustrated embodiment. The electronic device may be an oscilloscope, a spectrum analyzer, a radar transmitting station, etc.

[0119] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of disclosure involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above disclosed concept. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other to form a technical solution.

[0120] Although several specific implementation details are included in the above discussion, these should not be interpreted as limiting the scope of the present application. Certain features described in the context of a separate embodiment can also be implemented in a single embodiment in combination. On the contrary, the various features described in the context of a single embodiment can also be implemented in multiple embodiments individually or in any suitable sub-combination.

[0121] Although the subject matter has been described in language specific to structural features and methodological logical actions, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. Instead, the specific features and actions described above are merely example forms of implementing the claims.

Claims

1. A local oscillator leakage calibration circuit, characterized in that: include: Transmission link and feedback loop; wherein the transmission link includes a signal generation module, a pre-compensation module, and a signal modulation module; the feedback loop includes a detector and a data processing module; the signal modulation module is connected to the detector, and the data processing module is connected to the pre-compensation module; wherein, The signal generating module is used to generate a multi-level calibration signal; The pre-compensation module is used to receive the multi-level calibration signal, pre-compensate the calibration signal of each level, output the pre-compensated signal corresponding to the calibration signal of the level, and send the pre-compensated signal to the signal modulation module; wherein the local oscillator leakage compensation value pre-compensated for the calibration signal of the next level is the local oscillator leakage compensation value obtained according to the calibration signal of the previous level and sent by the data processing module, and the local oscillator leakage compensation value corresponding to the first level calibration signal is a preset value; The signal modulation module is used to modulate each level of pre-compensation signal using a local oscillator signal to obtain a modulation calibration signal corresponding to the level of pre-compensation signal; and send the level of modulation calibration signal to the detector; The detector is used to detect the power of each level of modulation calibration signal and send the power of each level of modulation calibration signal to the data processing module; The data processing module is used to iteratively calculate the local oscillator leakage intensity estimation value of each level according to the power of the multi-level calibration signal and the multi-level modulated calibration signal; for each level of calibration signal, generate a local oscillator leakage compensation value corresponding to the calibration signal of this level according to the local oscillator leakage intensity estimation value corresponding to the calibration signal of this level; and send the local oscillator leakage compensation value corresponding to the calibration signal of this level to the pre-compensation module to pre-compensate the calibration signal of the next level.

2. The local oscillator leakage calibration circuit according to claim 1, characterized in that: Each level of calibration signal in the multi-level calibration signal includes a plurality of first signals, each of the first signals corresponds to the power of a modulated calibration signal; When the data processing module is used to iteratively calculate the local oscillator leakage strength estimation value of each level, it is specifically used to iteratively calculate the local oscillator leakage strength estimation value of each level according to the multiple first signals corresponding to each level and the power of the modulated calibration signal corresponding to the multiple first signals of each level.

3. The local oscillator leakage calibration circuit according to claim 2, characterized in that: The local oscillator leakage intensity estimation value satisfies a predefined functional relationship with the magnitude of the first signal and the power value of a modulated calibration signal corresponding to the first signal.

4. The local oscillator leakage calibration circuit according to claim 2, characterized in that: The k-th level calibration signal includes the k-th level I-channel calibration signal and the k-th level Q-channel calibration signal; the k-th level I-channel calibration signal includes more than three I-channel first signals, and the k-th level Q-channel calibration signal includes more than three Q-channel first signals; The data processing module is used to iteratively calculate the local oscillator leakage intensity estimation value of each level according to the multiple first signals corresponding to each level and the power of the modulated calibration signal corresponding to the multiple first signals at each level, specifically for: Calculate the k-th level I local oscillator leakage strength estimation value according to the k-th level multiple I-channel first signals and the powers of the modulated calibration signals respectively corresponding to the k-th level multiple I-channel first signals; The k-th level Q-path local oscillator leakage strength estimation value is calculated according to the k-th level multiple Q-path first signals and the powers of the modulated calibration signals respectively corresponding to the k-th level multiple Q-path first signals.

5. The local oscillator leakage calibration circuit according to claim 4, characterized in that: The data processing module is used to generate, for each level of calibration signal, a local oscillator leakage compensation value corresponding to the level of calibration signal according to the local oscillator leakage intensity estimation value corresponding to the level of calibration signal, specifically to: Generate a k-th level I local oscillator leakage compensation value according to the k-th level I local oscillator leakage strength estimation value; A k-th level Q-channel local oscillator leakage compensation value is generated according to the k-th level Q-channel local oscillator leakage strength estimation value.

6. The local oscillator leakage calibration circuit according to claim 1, characterized in that: The multi-level calibration signal includes a multi-level I-channel digital calibration signal and a multi-level Q-channel digital calibration signal; the pre-compensation module includes a first pre-compensation module and a second pre-compensation module; The first pre-compensation module, when the pre-compensation module performs pre-compensation on each level of calibration signal, is used to pre-compensate the I-channel digital calibration signal of each level using the I-channel local oscillator leakage compensation value corresponding to the level to obtain the I-channel digital pre-compensation signal of the level, and convert the I-channel digital pre-compensation signal of the level into the I-channel analog pre-compensation signal of the level; The second pre-compensation module, when the pre-compensation module pre-compensates the calibration signal of each level, is used to pre-compensate the Q-channel digital calibration signal of each level using the Q-channel local oscillator leakage compensation value corresponding to the level to obtain the Q-channel digital pre-compensation signal of the level, and convert the Q-channel digital pre-compensation signal of the level into a Q-channel analog pre-compensation signal; The signal modulation module, when used for modulating each level of pre-compensation signal using the local oscillator signal for the level of pre-compensation signal, is specifically used to: modulate the level I analog pre-compensation signal and the level Q analog pre-compensation signal, and output a first analog modulation signal for I-channel calibration and a second analog modulation signal for Q-channel calibration.

7. The local oscillator leakage calibration circuit according to claim 6, characterized in that: The detector is used to detect the power of each level of modulation calibration signal, specifically used to: detect the power of the first analog modulation signal for I-channel calibration at each level and the power of the second analog modulation signal for Q-channel calibration at each level; The data processing module specifically includes an analog-to-digital converter and a data processor, wherein the data processing module is used to iteratively calculate one or more local oscillator leakage strength estimation values ​​of each level according to the power of the multi-level calibration signal and the multi-level modulated calibration signal; for each level of calibration signal, when generating a local oscillator leakage compensation value corresponding to the calibration signal of this level according to the one or more local oscillator leakage strength estimation values ​​corresponding to the calibration signal of this level, The analog-to-digital converter is used for, for each stage, converting the analog power of the first analog modulation signal of the stage into the first digital power, and converting the analog power of the second analog modulation signal of the stage into the second digital power; The data processor is used to calculate, for each stage, an estimated value of leakage strength of the I-channel local oscillator of the stage according to first digital powers respectively corresponding to a plurality of I-channel calibration signals and a plurality of I-channel modulated calibration signals in the calibration signal of the stage; and to calculate an estimated value of leakage strength of the Q-channel local oscillator according to second digital powers respectively corresponding to a plurality of Q-channel calibration signals and a plurality of Q-channel modulated calibration signals in the calibration signal of the stage; And the I-channel local oscillator leakage compensation value is determined according to the I-channel local oscillator leakage strength estimation value, and the Q-channel local oscillator leakage compensation value is determined according to the Q-channel local oscillator leakage strength estimation value.

8. The local oscillator leakage calibration circuit according to any one of claims 1 to 7, characterized in that: The data processing module is also used to iterate using the multi-level calibration signal, use the local oscillator leakage strength estimation value corresponding to when the iteration stops as the target local oscillator leakage strength estimation value, and generate the target local oscillator leakage compensation value according to the target local oscillator leakage strength estimation value.

9. The local oscillator leakage calibration circuit according to any one of claims 1 to 7, characterized in that: The detector is a root mean square detector.

10. An electronic device comprising the local oscillator leakage calibration circuit according to any one of claims 1 to 9.

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