Direct current offset calibration method and radio frequency receiving device

Abstract

The application discloses a direct current offset calibration method and a radio frequency receiving device. The method comprises the following steps: obtaining a calibration mode; initializing a gain index to obtain an initial gain index when the calibration mode is offline calibration; determining a plurality of to-be-compensated gain indexes according to the initial gain index, a preset gain step and a preset maximum gain index; performing adaptive iteration on the plurality of to-be-compensated gain indexes respectively to obtain a plurality of pre-compensation coefficients corresponding to the plurality of to-be-compensated gain indexes respectively; determining a target pre-compensation coefficient corresponding to a current gain index according to the plurality of pre-compensation coefficients corresponding to the plurality of to-be-compensated gain indexes respectively and the current gain index; determining the target pre-compensation coefficient corresponding to the current gain index according to the current gain index of the radio frequency receiving device when the calibration mode is online calibration; and performing analog domain direct current offset calibration on the radio frequency receiving device according to the target pre-compensation coefficient, so that saturation of an analog channel and an analog-to-digital converter caused by direct current offset can be avoided.

Description

Technical Field

[0001] This invention relates to the field of radio frequency communication technology, and in particular to a DC offset calibration method and a radio frequency receiving device. Background Technology

[0002] Radio frequency (RF) transceiver chips play a crucial role in the field of communications, used for signal reception and transmission in wireless communication systems. DC offset is a common problem in RF receiving devices, especially under high gain conditions. DC offset not only degrades communication quality but can even completely block communication.

[0003] To improve the performance of RF receivers and ensure high-quality operation of the receiving channel under different gain conditions, existing technologies typically perform compensation in the digital domain at the back end of the signal chain to calibrate DC offset. However, calibration in the digital domain has limitations: 1) DC offset has already occurred in the analog channel. If the DC offset is too large, it will cause saturation in the analog channel, and digital domain compensation cannot solve the saturation problem that has already occurred in the analog channel. 2) The input dynamic range of the analog-to-digital converter (ADC) is limited. DC offset will occupy the effective input range of the ADC, which may lead to ADC saturation, thereby compressing the dynamic range of the RF receiver.

[0004] Therefore, there is an urgent need in the existing technology for a calibration method that can solve the DC offset problem from the source of the analog domain, so as to avoid the analog channel and ADC from saturating due to DC offset and ensure that the RF receiving device can maintain good working performance under different gains. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention aims to provide a DC offset calibration method and an RF receiving device, which performs DC offset calibration on the RF receiving device in the analog domain to avoid saturation of the analog channel and analog-to-digital converter due to DC offset, and ensure that the RF receiving device can maintain good working performance under different gains.

[0006] This invention is implemented according to the following scheme: A DC offset calibration method is provided, comprising: Get calibration mode; When the calibration mode is offline calibration, the gain index is initialized to obtain the initial gain index; Based on the initial gain index, the preset gain step, and the preset maximum gain index, multiple gain indices to be compensated are determined, and adaptive iteration is performed on each of the multiple gain indices to be compensated to obtain the pre-compensation coefficients corresponding to each of the multiple gain indices to be compensated. Based on the pre-compensation coefficients corresponding to the multiple gain indices to be compensated, and the current gain index when the RF receiving device is working, the target pre-compensation coefficient corresponding to the current gain index is determined. When the calibration mode is online calibration, the target pre-compensation coefficient corresponding to the current gain index is determined according to the current gain index of the radio frequency receiving device; Based on the target pre-compensation coefficient, the radio frequency receiving device is calibrated for DC offset in the analog domain.

[0007] Optionally, an adaptive iteration is performed for each gain index to be compensated to obtain the pre-compensation coefficients corresponding to each gain index to be compensated, including: Collect the digital signal and compensation coefficient of the current iteration cycle; and determine the compensation coefficient of the next iteration cycle based on the digital signal and compensation coefficient of the current iteration cycle. The above process is repeated for the next iteration cycle to obtain the compensation coefficient for each iteration cycle until the iteration cycle reaches the preset iteration cycle. The compensation coefficient of the last iteration cycle is then determined as the pre-compensation coefficient corresponding to the gain index to be compensated, and the adaptive iteration ends.

[0008] Optionally, based on the target pre-compensation coefficient, the radio frequency receiving device is calibrated for DC offset in the analog domain, including: The pre-compensation current is obtained based on the target pre-compensation coefficient; Based on the pre-compensation current, the intermediate frequency analog signal of the radio frequency receiving device is calibrated for DC offset to obtain the calibrated analog signal to be converted. The analog signal to be converted is subjected to analog-to-digital conversion to obtain the digital signal output by the radio frequency receiving device.

[0009] A radio frequency receiving device is also provided, which applies the above-mentioned DC offset calibration method for calibration, including: a front-end module, a back-end module and a calibration module, wherein the back-end module is connected to the front-end module and the calibration module; When the calibration mode is offline calibration, the front-end module enters the calibration stage, sequentially configuring the front-end module as multiple gain indices to be compensated, and receiving radio frequency signals under each of the multiple gain indices to be compensated, downconverting the radio frequency signals into intermediate frequency analog signals and outputting them to the back-end module; the calibration module performs adaptive iteration based on the digital signals output by the back-end module to obtain the pre-compensation coefficients corresponding to the multiple gain indices to be compensated respectively; After the front-end module enters the working stage, the calibration module determines the target pre-compensation coefficient corresponding to the current gain index based on the pre-compensation coefficients corresponding to the multiple gain indices to be compensated and the current gain index when the front-end module is working, and performs DC offset compensation on the intermediate frequency analog signal input to the back-end module based on the target pre-compensation coefficient. When the calibration mode is online calibration, after the front-end module enters the working stage, the front-end module receives the radio frequency signal under the current gain index, downconverts the radio frequency signal into an intermediate frequency analog signal and outputs it to the back-end module; the calibration module obtains the target pre-compensation coefficient corresponding to the current gain index according to the digital signal output by the back-end module, and performs DC offset compensation on the intermediate frequency analog signal input to the back-end module according to the target pre-compensation coefficient.

[0010] Optionally, the calibration module includes an adaptive unit and a current-rudder digital-to-analog converter. The adaptive unit is connected to the current-rudder digital-to-analog converter and the back-end module, and the current-rudder digital-to-analog converter is connected to the back-end module.

[0011] Optionally, the front-end module includes a low-noise amplifier, a mixer, and a local oscillator unit; the mixer is connected to the low-noise amplifier, the local oscillator unit, and the back-end module.

[0012] Optionally, the back-end module includes an intermediate frequency unit and an analog-to-digital converter. The intermediate frequency unit is connected to the analog-to-digital converter, the front-end module, and the calibration module. The analog-to-digital converter is connected to the calibration module.

[0013] Optionally, the intermediate frequency unit includes a first filtering unit and a second filtering unit, wherein the first filtering unit is connected to the second filtering unit, the front-end module, and the calibration module, and the second filtering unit is connected to the analog-to-digital converter.

[0014] Optionally, the first filtering unit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a first capacitor, and a first operational amplifier; The first resistor is connected to the front-end module and the calibration module, and the second filter unit is connected to the third resistor and the fourth resistor; The positive input terminal of the first operational amplifier is connected to the first resistor, the second resistor, the fourth resistor, and the first capacitor, and the negative input terminal of the first operational amplifier is connected to the first resistor, the second resistor, the fourth resistor, and the first capacitor. The positive output terminal of the first operational amplifier is connected to the second resistor, the third resistor, and the first capacitor, and the negative output terminal of the first operational amplifier is connected to the second resistor, the third resistor, and the first capacitor.

[0015] Optionally, the second filtering unit includes a second operational amplifier and a second capacitor; The positive input terminal of the second operational amplifier is connected to the negative output terminal of the second operational amplifier through the second capacitor, and the negative input terminal of the second operational amplifier is connected to the positive output terminal of the second operational amplifier through the second capacitor. The second capacitor is connected to the first filter unit and the analog-to-digital converter.

[0016] Compared with the prior art, the beneficial effects of the DC offset calibration method of the present invention are as follows: By traversing multiple gain indices to be compensated and performing adaptive iterations in offline calibration mode, the corresponding pre-compensation coefficients are obtained, ensuring that DC offset compensation can be achieved under different gain conditions. In online calibration mode, the target pre-compensation coefficients can also be obtained in real time, thus achieving DC offset compensation in different calibration modes. At the same time, by performing DC offset calibration on the RF receiver in the analog domain, the influence of DC offset on the analog channel can be fundamentally eliminated, avoiding the problem of saturation of the analog channel or analog-to-digital converter in the RF receiver due to excessive DC offset in the analog channel, ensuring that the RF receiver can maintain good working performance under different gains. Attached Figure Description

[0017] Figure 1 This is a circuit diagram of the radio frequency receiving device of the present invention; Figure 2 This is a circuit diagram of the intermediate frequency unit of the present invention; The attached diagram shows the following labels: 1. Front-end module; 101. Low-noise amplifier; 102. Mixer; 103. Local oscillator unit; 2. Back-end module; 201. Intermediate frequency unit; 2011. First filter unit; 2012. Second filter unit; 202. Analog-to-digital converter; 3. Calibration module; 301. Adaptive unit; 302. Current-controlled digital-to-analog converter. Detailed Implementation

[0018] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0019] In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims. In the description of this application, it should be understood that the terms "first," "second," "third," etc., are used only to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0020] A DC offset calibration method of the present invention includes: S1: Obtain calibration mode; wherein, the calibration mode includes offline calibration and online calibration. Offline calibration is used to instruct the RF receiver to first determine the pre-compensation coefficients for calibration at different gains during non-working periods, so that the RF receiver can directly perform DC offset calibration based on the pre-determined pre-compensation coefficients during working periods. Online calibration is used to instruct the RF receiver to perform DC offset calibration while working during working periods.

[0021] S2: When the calibration mode is offline calibration, initialize the gain index to obtain the initial gain index. The gain index is used to indicate the gain of different channels of the RF receiver. S3: Based on the initial gain index, the preset gain step, and the preset maximum gain index, determine multiple gain indices to be compensated, perform adaptive iteration on each of the multiple gain indices to be compensated, and obtain the pre-compensation coefficients corresponding to each of the multiple gain indices to be compensated. In practical applications, the DC offset changes caused by different channel gains are also different. This invention determines multiple gain indices to be compensated based on the initial gain index, preset gain step, and preset maximum gain index. This ensures that during the non-operating phase of the RF receiver, the pre-compensation coefficients corresponding to multiple channel gains within the gain operating range covered by the RF receiver are applied. This ensures that the DC offset under each channel gain can be calibrated when the RF receiver is operating, effectively avoiding the problem of DC offset calibration failure caused by gain switching.

[0022] In one embodiment of the present invention, the preset gain step can be set according to actual needs. For the same preset maximum gain index, the larger the preset gain step value, the fewer the number of gain indexes to be compensated, which can reduce the total time for multiple gain indexes to be compensated to perform adaptive iteration, thereby speeding up the calibration speed. The smaller the preset gain step value, the more the number of gain indexes to be compensated, which can perform adaptive iteration on multiple channel gains, thereby obtaining higher calibration accuracy.

[0023] In one embodiment of the present invention, adaptive iteration is performed on each gain index to be compensated to obtain the pre-compensation coefficients corresponding to each gain index to be compensated, including: Collect the digital signal and compensation coefficient of the current iteration cycle; and determine the compensation coefficient of the next iteration cycle based on the digital signal and compensation coefficient of the current iteration cycle. Repeat the above process for the next iteration cycle to obtain the compensation coefficient for each iteration cycle until the iteration cycle reaches the preset iteration cycle. Then, determine the compensation coefficient of the last iteration cycle as the pre-compensation coefficient corresponding to the gain index to be compensated, and end the adaptive iteration.

[0024] In one embodiment of the present invention, determining the compensation coefficient for the next iteration cycle based on the digital signal of the current iteration cycle and the compensation coefficient of the current iteration cycle includes: obtaining an adaptive coefficient, which is a step size factor in the adaptive iteration process, and its value is 2. -k The value of k ranges from 4 to 12, and the adaptive coefficient can be selected according to actual needs in practical applications. The compensation coefficient for the next iteration cycle is determined based on the digital signal of the current iteration cycle, the compensation coefficient of the current iteration cycle, and the adaptive coefficient. During the adaptive iteration process, the LMS adaptive algorithm is used to update the pre-compensation coefficient for each iteration cycle using gradient descent. This allows the adjustment step size of the pre-compensation coefficient to become more refined as the iteration cycle increases, thus making the final pre-compensation coefficient closer to the optimal value, i.e., higher accuracy. A smaller adaptive coefficient value results in a more refined adjustment step size, leading to a pre-compensation coefficient that is closer to the optimal value and higher accuracy. Conversely, a larger adaptive coefficient value can cause an excessively large adjustment step size, resulting in the pre-compensation coefficient oscillating or even diverging near the optimal value, leading to poor accuracy or even non-convergence.

[0025] This invention performs adaptive iteration on the RF receiving device under each gain index to be compensated. After obtaining the pre-compensation coefficients corresponding to each gain index to be compensated, the gain index to be compensated and the corresponding pre-compensation coefficients are stored. This allows the RF receiving device to call the corresponding pre-compensation coefficients for DC offset calibration according to its current gain index during subsequent operation.

[0026] S4: Based on the pre-compensation coefficients corresponding to multiple gain indices to be compensated, and the current gain index when the RF receiver is working, determine the target pre-compensation coefficient corresponding to the current gain index; by pre-storing the pre-compensation coefficients corresponding to multiple gain indices to be compensated, when the RF receiver is working normally, it is only necessary to directly match the corresponding target pre-compensation coefficient according to the current gain index, without performing complex adaptive iterative calculations in real time when the RF receiver is working normally, thus avoiding calibration delay and computational overhead during operation. It can also ensure that the corresponding pre-compensation parameters are obtained quickly and accurately when switching between different gain indices, and perform DC offset calibration on the analog domain of the RF receiver.

[0027] S5: When the calibration mode is online calibration, the target pre-compensation coefficient corresponding to the current gain index is determined based on the current gain index of the RF receiver. In this mode, the RF receiver performs adaptive iteration synchronously based on its current gain index during operation. The difference between this and offline calibration is that it does not require adaptive iteration of multiple gain indices to be compensated in advance to pre-store the pre-compensation coefficients corresponding to multiple gain indices to be compensated. This avoids the time consumed by traversing all gain indices to be compensated in advance. The target pre-compensation coefficient that matches the current gain index can be quickly determined based on the current gain index, thereby realizing real-time calibration of DC offset and ensuring that the pre-compensation coefficients under different gain indices are always synchronized with the current operating state, effectively improving the efficiency and real-time performance of online calibration.

[0028] S6: Based on the target pre-compensation coefficient, perform DC offset calibration of the RF receiver in the analog domain, including: obtaining the pre-compensation current based on the target pre-compensation coefficient; performing DC offset calibration on the intermediate frequency analog signal of the RF receiver based on the pre-compensation current to obtain the calibrated analog signal to be converted; and performing analog-to-digital conversion on the analog signal to be converted to obtain the digital signal output by the RF receiver.

[0029] In this invention, regardless of whether the calibration mode is offline or online calibration, step S6 is a calibration step performed when the radio frequency receiving device is working normally. According to the determined target pre-compensation coefficient, a corresponding pre-compensation current is generated. The pre-compensation current is injected into the intermediate frequency analog signal path of the radio frequency receiving device to cancel the DC offset component, thereby obtaining the calibrated analog signal to be converted. Finally, the digital signal is output through the analog-to-digital converter 202.

[0030] See Figure 1 As shown, an RF receiving device is calibrated using the aforementioned DC offset calibration method, comprising: a front-end module 1, a back-end module 2, and a calibration module 3, wherein the back-end module 2 is connected to the front-end module 1 and the calibration module 3. When the calibration mode is offline calibration, the front-end module 1 enters the calibration stage, and the front-end module 1 is configured as multiple gain indices to be compensated in sequence. The front-end module 1 receives radio frequency signals under multiple gain indices to be compensated, and downconverts the radio frequency signals into intermediate frequency analog signals and outputs them to the back-end module 2. The calibration module 3 performs adaptive iteration based on the digital signals output by the back-end module 2 to obtain the pre-compensation coefficients corresponding to the multiple gain indices to be compensated. After the front-end module 1 enters the working stage, the calibration module 3 determines the target pre-compensation coefficient corresponding to the current gain index based on the pre-compensation coefficients corresponding to the multiple gain indices to be compensated and the current gain index when the front-end module 1 is working, and performs DC offset compensation on the intermediate frequency analog signal input to the back-end module 2 based on the target pre-compensation coefficient. When the calibration mode is online calibration, after the front-end module 1 enters the working stage, the front-end module 1 receives the radio frequency signal under the current gain index, downconverts the radio frequency signal into an intermediate frequency analog signal and outputs it to the back-end module 2; the calibration module 3 obtains the target pre-compensation coefficient corresponding to the current gain index according to the digital signal output by the back-end module 2, and performs DC offset compensation on the intermediate frequency analog signal input to the back-end module 2 according to the target pre-compensation coefficient.

[0031] In one embodiment of the present invention, the calibration module 3 includes an adaptive unit 301 and a current rudder digital-to-analog converter 302. The adaptive unit 301 is connected to the current rudder digital-to-analog converter 302 and the back-end module 2. The current rudder digital-to-analog converter 302 is connected to the back-end module 2. When the calibration mode is offline calibration, the adaptive unit 301 performs adaptive iteration based on the digital signal output by the back-end module 2 during the calibration phase to obtain the pre-compensation coefficients corresponding to multiple gain indices to be compensated. After entering the working phase, the adaptive unit 301 matches the corresponding target pre-compensation coefficient among the pre-compensation coefficients corresponding to the multiple gain indices to be compensated based on the current gain index. Then, the current-rudder digital-to-analog converter 302 obtains the pre-compensation current based on the target pre-compensation coefficient, so that the back-end module 2 performs DC offset calibration on the intermediate frequency analog signal based on the pre-compensation current. When the calibration mode is online calibration, the adaptive unit 301 performs adaptive iteration based on the digital signal output by the back-end module 2 under the current gain index to obtain the target pre-compensation coefficient corresponding to the current gain index. Then, the current-rudder digital-to-analog converter 302 obtains the pre-compensation current based on the target pre-compensation coefficient, so that the back-end module 2 performs DC offset calibration on the intermediate frequency analog signal based on the pre-compensation current.

[0032] This invention uses calibration module 3 to perform DC offset calibration on the radio frequency receiving device in the analog domain to avoid saturation of the analog channel and analog-to-digital converter 202 due to DC offset, and to ensure that the radio frequency receiving device can maintain good working performance under different gains.

[0033] In one embodiment of the present invention, the front-end module 1 includes a low-noise amplifier 101, a mixer 102, and a local oscillator unit 103; the mixer 102 is connected to the low-noise amplifier 101, the local oscillator unit 103, and the back-end module 2; the radio frequency signal is amplified by the low-noise amplifier 101, and then the mixer 102 mixes the amplified radio frequency signal and the local oscillator signal provided by the local oscillator unit 103 to obtain an intermediate frequency analog signal output to the back-end module 2.

[0034] In one embodiment of the present invention, the back-end module 2 includes an intermediate frequency unit 201 and an analog-to-digital converter 202. The intermediate frequency unit 201 is connected to the analog-to-digital converter 202, the front-end module 1, and the calibration module 3. The analog-to-digital converter 202 is connected to the calibration module 3. After the intermediate frequency analog signal is processed by the intermediate frequency unit 201 and the analog-to-digital converter 202 in sequence, a digital signal is output. In the prior art, the digital signal output by the analog-to-digital converter 202 is usually calibrated for DC offset in the digital domain. This will cause the analog channel and the analog-to-digital converter 202 to saturate due to DC offset.

[0035] See Figure 2 As shown, in one embodiment of the present invention, the intermediate frequency unit 201 includes a first filter unit 2011 and a second filter unit 2012. The first filter unit 2011 is connected to the second filter unit 2012, the front-end module 1, and the calibration module 3. The second filter unit 2012 is connected to the analog-to-digital converter 202.

[0036] The first filter unit 2011 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first capacitor C1, and a first operational amplifier OTA1. The first resistor R1 is connected to the front-end module 1 and the calibration module 3. The second filter unit 2012 is connected to the third resistor R3 and the fourth resistor R4. The positive input terminal of the first operational amplifier OTA1 is connected to the first resistor R1, the second resistor R2, the fourth resistor R4, and the first capacitor C1. The negative input terminal of the first operational amplifier OTA1 is connected to the first resistor R1, the second resistor R2, the fourth resistor R4, and the first capacitor C1. The positive output terminal of the first operational amplifier OTA1 is connected to the second resistor R2, the third resistor R3, and the first capacitor C1. The negative output terminal of the first operational amplifier OTA1 is connected to the second resistor R2, the third resistor R3, and the first capacitor C1.

[0037] The second filter unit 2012 includes a second operational amplifier OTA2 and a second capacitor C2; the positive input terminal of the second operational amplifier OTA2 is connected to the negative output terminal of the second operational amplifier OTA2 through the second capacitor C2, and the negative input terminal of the second operational amplifier OTA2 is connected to the positive output terminal of the second operational amplifier OTA2 through the second capacitor C2. The second capacitor is connected to the first filter unit 2011 and the analog-to-digital converter 202.

[0038] Next, combine Figure 1 The illustrated radio frequency receiving device provides a detailed explanation of the DC offset calibration process: When the calibration mode is offline calibration, front-end module 1 enters the calibration phase, sequentially configuring front-end module 1 as multiple gain indices to be compensated, and receiving RF signals RFIN under each of the multiple gain indices to be compensated. The RF signals RFIN are processed sequentially by low-noise amplifier 101, mixer 102, intermediate frequency unit 201, and analog-to-digital converter 202 to output digital signal y. n_I y n_Q The formula for calculating the pre-compensation coefficient for each iteration cycle by the adaptive unit 301 is as follows: w n_I (n+1)=w n_I (n) u*y n_I (n) w n_Q (n+1)=w n_Q (n) u*y n_Q (n) Among them, w n_I (n+1), w n_Q (n+1) is the pre-compensation coefficient for the (n+1)th iteration period, w n_I (n), w n_Q (n) represents the pre-compensation coefficient for the nth iteration period, y n_I (n), y n_Q (n) is the digital signal of the nth iteration cycle, and u is the adaptive coefficient. The digital signal of each iteration cycle is obtained by calibrating the intermediate frequency analog signal with DC offset using the pre-compensation coefficient obtained in the previous iteration cycle. That is, it will be processed by the current rudder digital-to-analog converter 302, the intermediate frequency unit 201 and the analog-to-digital converter 202 in sequence before being output.

[0039] In the adaptive unit 301, the pre-compensation coefficients w corresponding to the multiple gain indices to be compensated are obtained respectively. n_I <m-1:0> 、w n_Q <m-1:0>The pre-compensation coefficient is then stored in decimal form. Upon entering the working phase, based on the current gain index, the target pre-compensation coefficient corresponding to the current gain index is matched among the pre-compensation coefficients corresponding to multiple pre-stored gain indices to be compensated, causing the current-steering digital-to-analog converter 302 to generate the pre-compensation current I. DCC_I I DCC_Q This enables the intermediate frequency unit 201 to perform DC offset calibration on the intermediate frequency analog signal output by the mixer 102 in the analog domain based on the pre-compensation current.

[0040] When the calibration mode is online calibration, the front-end module 1 receives the RF signal RFIN under the current gain index. The RF signal RFIN is processed sequentially by the low-noise amplifier 101, mixer 102, intermediate frequency unit 201 and analog-to-digital converter 202 to output the digital signal y. n_I y n_Q The adaptive unit 301 calculates the pre-compensation coefficients based on the output digital signal at this time to obtain the target pre-compensation coefficients under the current gain index. The current-controlled digital-to-analog converter 302 generates the pre-compensation current I based on the target pre-compensation coefficients. DCC_I I DCC_Q This enables the intermediate frequency unit 201 to perform DC offset calibration on the intermediate frequency analog signal output by the mixer 102 in the analog domain based on the pre-compensation current.

[0041] This invention performs DC offset calibration in the analog domain, enabling the analog-to-digital converter 202 to directly convert the calibrated intermediate frequency analog signal into an analog-to-digital signal. This avoids saturation of the analog channel and the analog-to-digital converter 202 due to DC offset, ensuring that the RF receiver maintains good operating performance at different gains.

[0042] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application. < / m-1:0>

Claims

1. A DC offset calibration method, characterized in that, include: Get calibration mode; When the calibration mode is offline calibration, the gain index is initialized to obtain the initial gain index; Based on the initial gain index, the preset gain step, and the preset maximum gain index, multiple gain indices to be compensated are determined, and adaptive iteration is performed on each of the multiple gain indices to be compensated to obtain the pre-compensation coefficients corresponding to each of the multiple gain indices to be compensated. Based on the pre-compensation coefficients corresponding to the multiple gain indices to be compensated, and the current gain index when the RF receiving device is working, the target pre-compensation coefficient corresponding to the current gain index is determined. When the calibration mode is online calibration, the target pre-compensation coefficient corresponding to the current gain index is determined according to the current gain index of the radio frequency receiving device; Based on the target pre-compensation coefficient, the radio frequency receiving device is calibrated for DC offset in the analog domain.

2. The DC offset calibration method according to claim 1, characterized in that, Perform adaptive iteration on each gain index to be compensated to obtain the pre-compensation coefficients corresponding to each gain index, including: Collect the digital signal and compensation coefficient of the current iteration cycle; and determine the compensation coefficient of the next iteration cycle based on the digital signal and compensation coefficient of the current iteration cycle. The process of determining the compensation coefficient is repeated for the next iteration cycle to obtain the compensation coefficient for each iteration cycle until the iteration cycle reaches the preset iteration cycle. The compensation coefficient of the last iteration cycle is then determined as the pre-compensation coefficient corresponding to the gain index to be compensated, and the adaptive iteration ends.

3. The DC offset calibration method according to claim 1, characterized in that, Based on the target pre-compensation coefficient, the radio frequency receiving device is calibrated for DC offset in the analog domain, including: The pre-compensation current is obtained based on the target pre-compensation coefficient; Based on the pre-compensation current, the intermediate frequency analog signal of the radio frequency receiving device is calibrated for DC offset to obtain the calibrated analog signal to be converted. The analog signal to be converted is subjected to analog-to-digital conversion to obtain the digital signal output by the radio frequency receiving device.

4. A radio frequency receiving device, calibrated using a DC offset calibration method according to any one of claims 1-3, characterized in that, include: The system includes a front-end module, a back-end module, and a calibration module, wherein the back-end module is connected to the front-end module and the calibration module. When the calibration mode is offline calibration, the front-end module enters the calibration stage, sequentially configuring the front-end module as multiple gain indices to be compensated, and receiving radio frequency signals under each of the multiple gain indices to be compensated, downconverting the radio frequency signals into intermediate frequency analog signals and outputting them to the back-end module; the calibration module performs adaptive iteration based on the digital signals output by the back-end module to obtain the pre-compensation coefficients corresponding to the multiple gain indices to be compensated respectively; After the front-end module enters the working stage, the calibration module determines the target pre-compensation coefficient corresponding to the current gain index based on the pre-compensation coefficients corresponding to the multiple gain indices to be compensated and the current gain index when the front-end module is working, and performs DC offset compensation on the intermediate frequency analog signal input to the back-end module based on the target pre-compensation coefficient. When the calibration mode is online calibration, after the front-end module enters the working stage, the front-end module receives the radio frequency signal under the current gain index, downconverts the radio frequency signal into an intermediate frequency analog signal and outputs it to the back-end module; the calibration module obtains the target pre-compensation coefficient corresponding to the current gain index according to the digital signal output by the back-end module, and performs DC offset compensation on the intermediate frequency analog signal input to the back-end module according to the target pre-compensation coefficient.

5. The radio frequency receiving device according to claim 4, characterized in that, The calibration module includes an adaptive unit and a current-rudder digital-to-analog converter. The adaptive unit is connected to the current-rudder digital-to-analog converter and the back-end module. The current-rudder digital-to-analog converter is connected to the back-end module.

6. The radio frequency receiving device according to claim 4, characterized in that, The front-end module includes a low-noise amplifier, a mixer, and a local oscillator unit; the mixer is connected to the low-noise amplifier, the local oscillator unit, and the back-end module.

7. The radio frequency receiving device according to claim 4, characterized in that, The back-end module includes an intermediate frequency unit and an analog-to-digital converter. The intermediate frequency unit is connected to the analog-to-digital converter, the front-end module, and the calibration module. The analog-to-digital converter is connected to the calibration module.

8. The radio frequency receiving device according to claim 7, characterized in that, The intermediate frequency unit includes a first filtering unit and a second filtering unit. The first filtering unit is connected to the second filtering unit, the front-end module, and the calibration module. The second filtering unit is connected to the analog-to-digital converter.

9. A radio frequency receiving device according to claim 8, characterized in that, The first filter unit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a first capacitor, and a first operational amplifier; The first resistor is connected to the front-end module and the calibration module, and the second filter unit is connected to the third resistor and the fourth resistor; The positive input terminal of the first operational amplifier is connected to the first resistor, the second resistor, the fourth resistor, and the first capacitor, and the negative input terminal of the first operational amplifier is connected to the first resistor, the second resistor, the fourth resistor, and the first capacitor. The positive output terminal of the first operational amplifier is connected to the second resistor, the third resistor, and the first capacitor, and the negative output terminal of the first operational amplifier is connected to the second resistor, the third resistor, and the first capacitor.

10. A radio frequency receiving device according to claim 8, characterized in that, The second filtering unit includes a second operational amplifier and a second capacitor; The positive input terminal of the second operational amplifier is connected to the negative output terminal of the second operational amplifier through the second capacitor, and the negative input terminal of the second operational amplifier is connected to the positive output terminal of the second operational amplifier through the second capacitor. The second capacitor is connected to the first filter unit and the analog-to-digital converter.

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