Continuous-time sigma-delta modulator and offset correction method for continuous-time sigma-delta modulator

Abstract

A continuous-time sigma-delta modulator and an offset correction method for the continuous-time sigma-delta modulator. The continuous-time sigma-delta modulator comprises a continuous-time sigma-delta modulation module, a data monitoring module, and an offset correction module. In addition to the continuous-time sigma-delta modulation module, the data monitoring module and the offset correction module are added. On the basis of the hardware architecture design of the offset correction module and the data monitoring module in combination with software data processing, and on the basis of the feedback of the signal-to-noise ratio of a digital signal, offset of a quantizer in the continuous-time sigma-delta modulation module can be pre-corrected according to a preset correction algorithm, and an offset correction digital code is obtained; and finally, the offset correction digital code is input into the quantizer by means of the offset correction module, and offset of the quantizer is finally corrected by means of the offset correction digital code. On the basis of the hardware architecture design and software data processing, offset of the quantizer in the continuous-time sigma-delta modulation module can be quickly and effectively corrected.

Description

Continuous-time sigma-delta modulator and offset correction method for continuous-time sigma-delta modulator Technical Field

[0001] The present invention relates to the technical field of sigma-delta modulators, and in particular to a continuous-time sigma-delta modulator and an offset correction method for the continuous-time sigma-delta modulator. Background Art

[0002] Continuous-time low-pass sigma-delta modulators are widely used in wideband zero-IF receivers, primarily due to their high speed, low power consumption, resistive input, and inherent anti-aliasing properties. Firstly, unlike traditional analog-to-digital converters, continuous-time low-pass sigma-delta modulators lack sample-and-hold circuits within the modulator's internal circuitry, enabling higher speeds and significantly reducing the operational amplifier requirements, thus achieving lower power consumption. Secondly, for external modules, the resistive input significantly reduces the requirements for external driver circuitry, while the modulator's inherent anti-aliasing properties also reduce the need for front-end anti-aliasing filters. In summary, while achieving high speed and low power consumption, continuous-time low-pass sigma-delta modulators simplify external driver and filtering circuitry, contributing to low power consumption and high integration of the entire system.

[0003] However, the actual design of a continuous-time low-pass sigma-delta modulator involves numerous non-ideal factors that must be considered. Quantizer offset is one of the most significant non-ideal factors. Quantizer offset affects the performance and stability of the entire modulator system. Existing techniques typically optimize quantizer offset through layout optimization. However, even with rigorous layout optimization during design, significant offset is still inevitable during chip manufacturing due to variations in the actual production process.

[0004] Therefore, how to correct the offset of the quantizer in the actual chip of the continuous-time low-pass sigma-delta modulator is a technical problem that needs to be solved urgently.

[0005] Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the present invention aims to provide a technical solution for offset correction of a quantizer in a continuous-time sigma-delta modulator. Based on a conventional continuous-time sigma-delta modulator, a data monitoring module and an offset correction module are added. Combined with the offset correction module and the data monitoring module, the offset of the quantizer in the continuous-time sigma-delta modulator is pre-corrected to obtain an offset correction digital code. The offset correction digital code is then input into a quantizer via the offset correction module, and the offset of the quantizer is finally corrected using the offset correction digital code.

[0007] To achieve the above-mentioned objectives and other related objectives, the present invention provides the following technical solutions.

[0008] A continuous-time sigma-delta modulator, comprising:

[0009] A continuous-time sigma-delta modulation module receives an analog signal and samples and quantizes the analog signal to obtain a digital signal;

[0010] a data monitoring module, connected to the continuous-time sigma-delta modulation module, monitoring the digital signal and calculating the signal-to-noise ratio of the digital signal;

[0011] an offset correction module, connected to the continuous-time sigma-delta modulation module and the data monitoring module, respectively, and configured to: perform offset pre-correction on the continuous-time sigma-delta modulation module according to a preset correction algorithm based on feedback of the signal-to-noise ratio of the digital signal to obtain an offset correction digital code; and perform offset correction on the continuous-time sigma-delta modulation module using the offset correction digital code.

[0012] Optionally, the continuous-time sigma-delta modulation module includes at least a fourth-order continuous-time sigma-delta modulation module, and the fourth-order continuous-time sigma-delta modulation module includes two active RC resonators, a quantizer, and multiple current-type digital-to-analog converters. The two active RC resonators and the one quantizer are cascaded in sequence, and the digital signal output by the quantizer is fed back to the two active RC resonators and the quantizer respectively after passing through the multiple current-type digital-to-analog converters.

[0013] Optionally, the quantizer is further connected to the data monitoring module and the offset correction module respectively, and the offset correction module sends the offset pre-correction digital code or the offset correction digital code to the quantizer.

[0014] Optionally, when the offset of the quantizer is closer to zero, the signal-to-noise ratio of the digital signal output by the fourth-order continuous-time sigma-delta modulation module is higher; when the offset of the quantizer is zero, the signal-to-noise ratio of the digital signal output by the fourth-order continuous-time sigma-delta modulation module is the highest.

[0015] Optionally, when performing offset pre-correction on the continuous-time sigma-delta modulation module according to the preset correction algorithm, the offset correction module is specifically configured to:

[0016] Inputting an offset correction analog signal into the continuous-time sigma-delta modulation module, sampling and quantizing the offset correction analog signal through the continuous-time sigma-delta modulation module to obtain an offset correction digital signal;

[0017] Inputting an offset pre-correction digital code into the quantizer through the offset correction module, pre-correcting the offset correction digital signal through the offset pre-correction digital code, and calculating a signal-to-noise ratio of the offset correction digital signal after pre-correction through the data monitoring module;

[0018] The adjustable range of the offset pre-correction digital code is traversed to obtain the signal-to-noise ratios of the offset correction digital signal after pre-correction corresponding to the offset pre-correction digital codes of different sizes, and the maximum signal-to-noise ratio of the offset correction digital signal after pre-correction is found. The offset pre-correction digital code corresponding to the maximum signal-to-noise ratio of the offset correction digital signal after pre-correction is the offset correction digital code.

[0019] Optionally, when performing offset correction on the continuous-time sigma-delta modulation module using the offset correction digital code, the offset correction module is specifically configured as follows:

[0020] The offset correction digital code is input into the quantizer through the offset correction module, and the offset of the quantizer is corrected by the offset correction digital code.

[0021] A method for correcting an offset of a continuous-time sigma-delta modulator, wherein the continuous-time sigma-delta modulator receives an analog signal and samples and quantizes the analog signal to obtain a digital signal. The continuous-time sigma-delta modulator includes a quantizer. The method for correcting an offset of a continuous-time sigma-delta modulator includes:

[0022] Based on feedback of the signal-to-noise ratio of the digital signal, performing offset pre-correction on the continuous-time sigma-delta modulator according to a preset correction algorithm to obtain an offset correction digital code;

[0023] The offset correction digital code is used to correct the offset of the quantizer in the continuous-time sigma-delta modulator.

[0024] Optionally, when the offset of the quantizer is closer to zero, the signal-to-noise ratio of the digital signal is higher; when the offset of the quantizer is zero, the signal-to-noise ratio of the digital signal is the highest.

[0025] Optionally, the step of performing offset pre-correction on the continuous-time sigma-delta modulator according to a preset correction algorithm based on feedback of the signal-to-noise ratio of the digital signal to obtain an offset correction digital code includes:

[0026] Inputting an offset correction analog signal into the continuous-time sigma-delta modulator, sampling and quantizing the offset correction analog signal through the continuous-time sigma-delta modulator to obtain an offset correction digital signal;

[0027] Inputting an offset pre-correction digital code into the quantizer, pre-correcting the offset-corrected digital signal using the offset pre-correction digital code, and calculating a signal-to-noise ratio of the pre-corrected offset-corrected digital signal;

[0028] The adjustable range of the offset pre-correction digital code is traversed to obtain the signal-to-noise ratios of the offset correction digital signal after pre-correction corresponding to the offset pre-correction digital codes of different sizes, and the maximum signal-to-noise ratio of the offset correction digital signal after pre-correction is found. The offset pre-correction digital code corresponding to the maximum signal-to-noise ratio of the offset correction digital signal after pre-correction is the offset correction digital code.

[0029] Optionally, the step of correcting the offset of the quantizer in the continuous-time sigma-delta modulator by using the offset correction digital code includes:

[0030] The offset correction digital code is input into the quantizer, and the offset of the quantizer is corrected by the offset correction digital code.

[0031] As described above, the continuous-time sigma-delta modulator and the offset correction method for the continuous-time sigma-delta modulator provided by the present invention have at least the following beneficial effects:

[0032] A continuous-time sigma-delta modulator is designed by combining a continuous-time sigma-delta modulation module, a data monitoring module and an offset correction module. On the basis of the continuous-time sigma-delta modulation module, a data monitoring module and an offset correction module are added. Based on the hardware architecture design of the offset correction module and the data monitoring module, combined with software data processing, according to the feedback of the signal-to-noise ratio of the digital signal, the offset of the quantizer in the continuous-time sigma-delta modulation module can be pre-corrected according to a preset correction algorithm to obtain an offset correction digital code; then, the offset correction digital code is input into the quantizer through the offset correction module, and the offset of the quantizer is finally corrected by the offset correction digital code. Combined with the hardware architecture design and software data processing, the offset of the quantizer in the continuous-time sigma-delta modulation module can be corrected quickly and effectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG1 shows a circuit block diagram of a conventional fourth-order continuous-time low-pass sigma-delta modulator.

[0034] FIG2 shows a curve showing the relationship between the output signal-to-noise ratio of a conventional fourth-order continuous-time low-pass sigma-delta modulator and the quantizer offset.

[0035] FIG3 is a block diagram showing the structure of a continuous-time sigma-delta modulator according to the present invention.

[0036] FIG4 is a block diagram showing a structure of a continuous-time sigma-delta modulator according to an alternative embodiment of the present invention.

[0037] FIG5 is a circuit block diagram of the fourth-order continuous-time sigma-delta modulation module in FIG4 .

[0038] FIG6 shows a flow chart of offset pre-correction of a continuous-time sigma-delta modulator according to an alternative embodiment of the present invention. DETAILED DESCRIPTION

[0039] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0040] Please refer to Figures 1 to 6. It should be noted that the diagrams provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner. Therefore, the diagrams only show the components related to the present invention rather than being drawn according to the number, shape and size of the components during actual implementation. During actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated. The structure, proportion, size, etc. shown in the diagrams attached to this specification are only used to match the content disclosed in the specification for people familiar with this technology to understand and read. They are not used to limit the conditions under which the present invention can be implemented, so they have no technical significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in the present invention without affecting the efficacy and purpose that can be achieved by the present invention.

[0041] As described above in the background technology, due to its performance advantages, continuous-time low-pass sigma-delta modulators are widely used in broadband zero-IF receivers. As shown in Figure 1, a circuit principle block diagram of a fourth-order continuous-time low-pass sigma-delta modulator is shown. The fourth-order continuous-time low-pass sigma-delta modulator receives an analog signal u(t) and samples and quantizes the analog signal u(t) to obtain a digital signal v[n]. The fourth-order continuous-time low-pass sigma-delta modulator includes two active RC resonators, a 17-level quantizer, and multiple current-type digital-to-analog converters DAC1 to DAC4, DAC 5a DAC 5b , two active RC resonators and 17levels quantizer are cascaded in sequence, the active RC resonator is composed of resistors (R1~R4, R F1 ~R F2 、R ELD ), capacitors (C1~C4) and transconductance amplifiers (OTA1~OTA4). The detailed structure is shown in Figure 1. The input end of the first active RC resonator is connected to the analog signal u(t), and the output end of the 17-levels quantizer outputs the digital signal v[n]. The digital signal v[n] is fed back to the two active RC resonators and the 17-levels quantizer after passing through multiple current-type digital-to-analog converters, and operates under the control of clock signals CLK1~CLK2.

[0042] However, the actual design of a continuous-time low-pass sigma-delta modulator involves numerous non-ideal factors, one of the most significant of which is quantizer offset. A key characteristic of a sigma-delta modulator is its noise-shaping effect on the quantization error generated by the quantizer. Therefore, if the quantizer has a non-zero offset, the spectral noise floor of the digital signal output from the sigma-delta modulator will rise, thereby degrading the output signal-to-noise ratio (SNR). To better measure the impact of quantizer offset on the sigma-delta modulator's output SNR, simulations were performed to determine the SNR of the fourth-order continuous-time low-pass sigma-delta modulator shown in Figure 1 for quantizer offsets ranging from -3LSB to +3LSB. This relationship is plotted in Figure 2. Figure 2 shows that the SNR of the modulator increases as the quantizer offset approaches zero.

[0043] It can be seen that the quantizer offset affects the performance and stability of the entire modulator system. The source of quantizer offset error within the modulator may come from the incomplete symmetry of the layout design or (and) deviations in chip manufacturing. The existing technology generally optimizes the quantizer offset through layout. However, even if the quantizer offset is optimized through strict layout in the design, due to deviations in the actual production process, relatively obvious offset will inevitably appear in the chip manufacturing.

[0044] Based on this, the present invention proposes a technical solution for offset correction of a quantizer in a continuous-time sigma-delta modulator: a continuous-time sigma-delta modulator is designed by combining a continuous-time sigma-delta modulation module, a data monitoring module and an offset correction module; a data monitoring module and an offset correction module are added to the continuous-time sigma-delta modulation module; based on the hardware architecture design of the offset correction module and the data monitoring module, and in combination with software data processing, the offset of the quantizer in the continuous-time sigma-delta modulation module is pre-corrected according to a preset correction algorithm based on feedback of the signal-to-noise ratio of the digital signal to obtain an offset correction digital code; the offset correction digital code is then input into the quantizer through the offset correction module, and the offset of the quantizer is finally corrected by the offset correction digital code; the hardware architecture design and software data processing are combined to quickly and effectively correct the offset of the quantizer in the continuous-time sigma-delta modulation module.

[0045] As shown in FIG3 , the present invention proposes a continuous-time sigma-delta modulator, which includes:

[0046] The continuous-time sigma-delta modulation module receives the analog signal u(t) and samples and quantizes the analog signal u(t) to obtain the digital signal v[n];

[0047] A data monitoring module is connected to the continuous-time sigma-delta modulation module to monitor the digital signal v[n] and calculate the signal-to-noise ratio (SNR) of the digital signal v[n].

[0048] The offset correction module is connected to the continuous-time sigma-delta modulation module and the data monitoring module respectively. The offset correction module is configured to: based on the feedback of the signal-to-noise ratio (SNR) of the digital signal v[n], perform offset pre-correction on the continuous-time sigma-delta modulation module according to a preset correction algorithm to obtain an offset correction digital code; and use the offset correction digital code to perform offset correction on the continuous-time sigma-delta modulation module.

[0049] In detail, the continuous-time sigma-delta modulation module includes a quantizer, which is connected to the data monitoring module and the offset correction module respectively. The offset correction module sends an offset pre-correction digital code or an offset correction digital code to the quantizer, as shown in Figure 3, using an N+1-bit digital code cal_bits <n:0>To correct the quantizer offset, the offset correction module sends the digital code cal_bits <n:0>(It can be an offset pre-correction digital code or an offset correction digital code) to the quantizer in the continuous-time sigma-delta modulation module.

[0050] Wherein, N is an integer greater than or equal to 1. The value of N can be flexibly selected according to the offset correction accuracy and is not limited here.

[0051] In detail, the continuous-time sigma-delta modulation module includes at least a fourth-order continuous-time sigma-delta modulation module. In an optional embodiment of the present invention, as shown in FIG4-FIG5, the fourth-order continuous-time sigma-delta modulation module receives an analog signal u(t) and samples and quantizes the analog signal u(t) to obtain a digital signal v[n]. The fourth-order continuous-time sigma-delta modulation module includes two active RC resonators, a 17-levels quantizer, and a plurality of current-type digital-to-analog converters DAC1 to DAC4, DAC 5a DAC 5b , two active RC resonators and 17levels quantizer are cascaded in sequence, the active RC resonator is composed of resistors (R1~R4, R F1 ~R F2 、R ELD ), capacitors (C1 to C4) and transconductance amplifiers (OTA1 to OTA4). The input of the first active RC resonator is connected to the analog signal u(t), the output of the first active RC resonator is connected to the input of the second active RC resonator, the output of the second active RC resonator is connected to the input of a 17-levels quantizer, and the output of the 17-levels quantizer outputs a digital signal v[n]. The digital signal v[n] is then fed back to the two active RC resonators and the 17-levels quantizer after passing through multiple current-type digital-to-analog converters. The entire fourth-order continuous-time sigma-delta modulation module operates under the control of clock signals CLK1 to CLK2.

[0052] In more detail, as shown in Figures 4 and 5, the quantizer in the fourth-order continuous-time sigma-delta modulation module is also connected to the data monitoring module and the offset correction module respectively. The offset correction module sends a 4-bit digital code cal_bits<3:0> (offset pre-correction digital code or offset correction digital code) to the quantizer for offset pre-correction and offset correction.

[0053] It can be understood that the continuous-time sigma-delta modulation module in the present invention is not limited to the fourth-order continuous-time low-pass sigma-delta modulator shown in Figures 4 and 5. It can also be a continuous-time low-pass sigma-delta modulator of other digital orders (such as third-order, fifth-order, etc.). Here, only the fourth-order continuous-time low-pass sigma-delta modulator is used as an example for explanation, and the present invention is not limited to this.

[0054] In detail, as can be seen from Figure 2, when the offset of the quantizer is closer to zero, the signal-to-noise ratio (SNR) of the digital signal v[n] output by the fourth-order continuous-time sigma-delta modulation module (or any continuous-time sigma-delta modulation module) is higher; when the offset of the quantizer is zero, the signal-to-noise ratio (SNR) of the digital signal v[n] output by the fourth-order continuous-time sigma-delta modulation module (or any continuous-time sigma-delta modulation module) is the highest.

[0055] Based on the relationship curve between the modulator signal-to-noise ratio (SNR) and the quantizer offset (offset) shown in FIG2 , and according to the feedback of the signal-to-noise ratio (SNR) of the digital signal v[n], in combination with the offset correction module and the data monitoring module, the offset of the quantizer in the continuous-time sigma-delta modulation module is pre-corrected according to a preset correction algorithm. First, an offset pre-correction digital code is sent to the quantizer through the offset correction module, and the entire adjustable range of the offset pre-correction digital code is traversed to find the maximum value of the signal-to-noise ratio (SNR) of the digital signal v[n], thereby obtaining the offset correction digital code. Then, the offset correction digital code is input to the quantizer through the offset correction module, and the offset of the quantizer is finally corrected using the offset correction digital code. Combining hardware architecture design with software data processing, the offset of the quantizer in the continuous-time sigma-delta modulation module can be corrected quickly and effectively.

[0056] In detail, in an optional embodiment of the present invention, as shown in FIG6 , when performing offset pre-correction on the continuous-time sigma-delta modulation module according to a preset correction algorithm, the offset correction module is specifically configured as follows:

[0057] Stp1, input the offset correction analog signal to the continuous time sigma-delta modulation module, sample and quantize the offset correction analog signal through the continuous time sigma-delta modulation module to obtain the offset correction digital signal;

[0058] Stp2, input the offset pre-correction digital code to the quantizer through the offset correction module, pre-correct the offset correction digital signal through the offset pre-correction digital code, and calculate the signal-to-noise ratio of the offset correction digital signal after pre-correction through the data monitoring module;

[0059] Step 3: Traverse the adjustable range of the offset pre-correction digital code to obtain the signal-to-noise ratio of the offset correction digital signal after pre-correction corresponding to each offset pre-correction digital code of different sizes, and find the maximum signal-to-noise ratio of the offset correction digital signal after pre-correction. The offset pre-correction digital code corresponding to the maximum signal-to-noise ratio of the offset correction digital signal after pre-correction is the offset correction digital code.

[0060] In more detail, in step Stp1, an offset correction analog signal is first input into the continuous-time sigma-delta modulation module. The offset correction analog signal can be a coherent single-tone signal of -6dBFS, or an analog signal of other amplitudes. As long as the continuous-time sigma-delta modulation module can work normally without oscillation, the offset correction analog signal is sampled and quantized by the continuous-time sigma-delta modulation module to obtain an offset correction digital signal.

[0061] In more detail, in step Stp2, an offset pre-correction digital code is input to the quantizer through the offset correction module, the offset pre-correction digital code is used to pre-correct the offset-corrected digital signal, and the signal-to-noise ratio (SNR) of the offset-corrected digital signal after pre-correction is calculated through the data monitoring module. This completes a pre-correction process, inputs an offset pre-correction digital code, and outputs a signal-to-noise ratio (SNR) of a digital signal.

[0062] In more detail, in step Stp3, the code value of the offset pre-correction digital code is changed and step Stp2 is repeated multiple times until the adjustable range of the offset pre-correction digital code is traversed (assuming that the offset pre-correction digital code has M different values, M=2 N+1 ), obtaining the signal-to-noise ratio (SNR) of the offset-corrected digital signal after pre-correction corresponding to each offset pre-correction digital code of different sizes, completing the pre-correction process N times to obtain the signal-to-noise ratio (SNR) of N digital signals, and finding the maximum signal-to-noise ratio (SNRmax) of the offset-corrected digital signal after pre-correction. The offset pre-correction digital code corresponding to the maximum signal-to-noise ratio (SNRmax) of the offset-corrected digital signal after pre-correction is the offset correction digital code.

[0063] It should be noted that, in the embodiment shown in FIG6 , the traversal starts from the minimum value of the offset pre-correction digital code, and the initial value of the maximum signal-to-noise ratio SNRmax is set to 0 dB, and then the code value of the offset pre-correction digital code is cumulatively added by 1 to perform traversal and screening, traversing the entire adjustable range of the offset pre-correction digital code (there are M different values ​​of the offset pre-correction digital code, M=2 N+1 ), find the maximum signal-to-noise ratio SNRmax and its corresponding offset pre-correction digital code. It is understood that in other optional embodiments of the present invention, the screening can also be started from the maximum value of the offset pre-correction digital code, which is not limited here.

[0064] In detail, as shown in FIG3 to FIG5 , when the offset correction digital code is used to perform offset correction on the continuous-time sigma-delta modulation module, the offset correction module is specifically configured as follows:

[0065] Step 4: Input an offset correction digital code to the quantizer through the offset correction module, and correct the offset of the quantizer through the offset correction digital code.

[0066] In more detail, in step Stp4, after the quantizer receives the offset correction digital code, it will first perform digital-to-analog conversion on the offset correction digital code internally to obtain an offset correction analog signal, and then superimpose the offset correction analog signal on the analog signal input by the active RC resonator to obtain a corrected analog signal. Finally, the corrected analog signal is quantized to obtain a corrected digital signal v[n]. The feedback superposition of the offset correction digital code can effectively offset the error caused by the offset of the quantizer, thereby correcting the offset of the quantizer.

[0067] Based on the design concept of the above-mentioned continuous-time sigma-delta modulator, the present invention also provides a method for correcting the offset of a continuous-time sigma-delta modulator. The continuous-time sigma-delta modulator receives an analog signal and samples and quantizes the analog signal to obtain a digital signal. The continuous-time sigma-delta modulator includes a quantizer. The method for correcting the offset of the continuous-time sigma-delta modulator includes:

[0068] S1. Based on the feedback of the signal-to-noise ratio of the digital signal, the continuous-time sigma-delta modulator is pre-corrected according to a preset correction algorithm to obtain an offset correction digital code;

[0069] S2. Correct the offset of the quantizer in the continuous-time sigma-delta modulator using an offset correction digital code.

[0070] Similarly, the basis for offset pre-correction and offset correction is the relationship between the signal-to-noise ratio (SNR) of a continuous-time sigma-delta modulator and the quantizer offset (offset), as shown in Figure 2. As the quantizer offset (offset) approaches zero, the SNR of the digital signal output by the continuous-time sigma-delta modulator increases. When the quantizer offset (offset) is zero, the SNR of the digital signal output by the continuous-time sigma-delta modulator is highest.

[0071] Similarly, based on the relationship curve between the signal-to-noise ratio (SNR) of the continuous-time sigma-delta modulator and the quantizer offset shown in FIG2 , the step S1 of performing offset pre-correction on the continuous-time sigma-delta modulator according to a preset correction algorithm based on feedback of the signal-to-noise ratio of the digital signal to obtain an offset correction digital code further includes:

[0072] S11, inputting an offset correction analog signal into a continuous-time sigma-delta modulator, sampling and quantizing the offset correction analog signal through the continuous-time sigma-delta modulator to obtain an offset correction digital signal;

[0073] S12, inputting an offset pre-correction digital code into the quantizer, pre-correcting the offset correction digital signal using the offset pre-correction digital code, and calculating a signal-to-noise ratio of the offset correction digital signal after pre-correction;

[0074] S13. Traverse the adjustable range of the offset pre-correction digital code to obtain the signal-to-noise ratios of the offset correction digital signal after pre-correction corresponding to the offset pre-correction digital codes of different sizes, and find the maximum signal-to-noise ratio of the offset correction digital signal after pre-correction. The offset pre-correction digital code corresponding to the maximum signal-to-noise ratio of the offset correction digital signal after pre-correction is the offset correction digital code.

[0075] Among them, steps S11 to S13 are similar to steps Stp1 to Stp3. For details, please refer to the above description of steps Stp1 to Stp3, which will not be repeated here.

[0076] Similarly, step S2 of correcting the offset of the quantizer in the continuous-time sigma-delta modulator using an offset correction digital code includes inputting the offset correction digital code into the quantizer and correcting the offset of the quantizer using the offset correction digital code. Step S2 is similar to step Stp4. For details, refer to the aforementioned description of step Stp4 and are not further described here.

[0077] In summary, in the continuous-time sigma-delta modulator and the offset correction method for the continuous-time sigma-delta modulator provided by the present invention, the continuous-time sigma-delta modulator is designed by combining the continuous-time sigma-delta modulation module, the data monitoring module and the offset correction module. On the basis of the continuous-time sigma-delta modulation module, the data monitoring module and the offset correction module are added. Based on the hardware architecture design of the offset correction module and the data monitoring module, combined with software data processing, according to the feedback of the signal-to-noise ratio of the digital signal, the offset of the quantizer in the continuous-time sigma-delta modulation module can be pre-corrected according to the preset correction algorithm. The offset correction digital code is obtained, and finally the offset correction digital code is input to the quantizer through the offset correction module, and the offset of the quantizer is finally corrected by the offset correction digital code; combined with hardware architecture design and software data processing, the offset of the quantizer in the continuous-time sigma-delta modulation module can be corrected quickly and effectively, and different correction amounts of continuous-time sigma-delta modulator chips with different offset sizes can be achieved, so that each chip can achieve its own optimal performance; in addition, the specific number of bits of the offset pre-correction digital code during offset pre-correction is flexibly adjustable, and a more precise signal-to-noise ratio maximum approximation can be achieved by adopting an offset pre-correction digital code with more bits, thereby achieving a better quantizer offset correction effect.

[0078] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A continuous-time sigma-delta modulator, characterized in that: include: A continuous-time sigma-delta modulation module receives an analog signal and samples and quantizes the analog signal to obtain a digital signal; A data monitoring module, connected to the continuous-time sigma-delta modulation module, monitors the digital signal and calculates the signal-to-noise ratio of the digital signal; An offset correction module is connected to the continuous-time sigma-delta modulation module and the data monitoring module respectively, and the offset correction module is configured to: based on the feedback of the signal-to-noise ratio of the digital signal, perform offset pre-correction on the continuous-time sigma-delta modulation module according to a preset correction algorithm to obtain an offset correction digital code; and perform offset correction on the continuous-time sigma-delta modulation module using the offset correction digital code.

2. The continuous-time sigma-delta modulator according to claim 1, characterized in that: The continuous-time sigma-delta modulation module at least includes a fourth-order continuous-time sigma-delta modulation module, and the fourth-order continuous-time sigma-delta modulation module includes two active RC resonators, a quantizer, and multiple current-type digital-to-analog converters. The two active RC resonators and the one quantizer are cascaded in sequence, and the digital signal output by the quantizer is fed back to the two active RC resonators and the quantizer respectively after passing through the multiple current-type digital-to-analog converters.

3. The continuous-time sigma-delta modulator according to claim 2, characterized in that: The quantizer is also connected to the data monitoring module and the offset correction module respectively, and the offset correction module sends an offset pre-correction digital code or the offset correction digital code to the quantizer.

4. The continuous-time sigma-delta modulator according to claim 3, characterized in that: When the offset of the quantizer is closer to zero, the signal-to-noise ratio of the digital signal output by the fourth-order continuous-time sigma-delta modulation module is higher; when the offset of the quantizer is zero, the signal-to-noise ratio of the digital signal output by the fourth-order continuous-time sigma-delta modulation module is the highest.

5. The continuous-time sigma-delta modulator according to claim 4, characterized in that: When the continuous-time sigma-delta modulation module is pre-corrected according to the preset correction algorithm, the offset correction module is specifically configured as follows: Inputting an offset correction analog signal into the continuous-time sigma-delta modulation module, sampling and quantizing the offset correction analog signal through the continuous-time sigma-delta modulation module to obtain an offset correction digital signal; The offset pre-correction digital code is input into the quantizer through the offset correction module, and the offset pre-correction digital code is input into the quantizer through the offset correction module. The offset correction digital signal is pre-corrected by the code, and the signal-to-noise ratio of the offset correction digital signal after the pre-correction is calculated by the data monitoring module; The adjustable range of the offset pre-correction digital code is traversed to obtain the signal-to-noise ratios of the offset correction digital signal after pre-correction corresponding to the offset pre-correction digital codes of different sizes, and the maximum signal-to-noise ratio of the offset correction digital signal after pre-correction is found therefrom. The offset pre-correction digital code corresponding to the maximum signal-to-noise ratio of the offset correction digital signal after pre-correction is the offset correction digital code.

6. The continuous-time sigma-delta modulator of claim 5, characterized in that: When the offset correction digital code is used to perform offset correction on the continuous time sigma-delta modulation module, the offset correction module is specifically configured as follows: The offset correction digital code is input into the quantizer through the offset correction module, and the offset of the quantizer is corrected through the offset correction digital code.

7. A method for correcting an offset of a continuous-time sigma-delta modulator, wherein the continuous-time sigma-delta modulator receives an analog signal and samples and quantizes the analog signal to obtain a digital signal, wherein the continuous-time sigma-delta modulator includes a quantizer, characterized in that: The offset correction method of the continuous-time sigma-delta modulator comprises: Based on the feedback of the signal-to-noise ratio of the digital signal, the continuous-time sigma-delta modulator is pre-corrected according to a preset correction algorithm to obtain an offset correction digital code; The offset correction digital code is used to correct the offset of the quantizer in the continuous-time sigma-delta modulator.

8. The offset correction method of a continuous-time sigma-delta modulator according to claim 7, characterized in that: When the offset of the quantizer is closer to zero, the signal-to-noise ratio of the digital signal is higher; when the offset of the quantizer is zero, the signal-to-noise ratio of the digital signal is the highest.

9. The offset correction method of a continuous-time sigma-delta modulator according to claim 8, characterized in that: The step of performing offset pre-correction on the continuous-time sigma-delta modulator according to a preset correction algorithm based on the feedback of the signal-to-noise ratio of the digital signal to obtain an offset correction digital code comprises: Inputting an offset correction analog signal into the continuous-time sigma-delta modulator, sampling and quantizing the offset correction analog signal through the continuous-time sigma-delta modulator to obtain an offset correction digital signal; Inputting an offset pre-correction digital code into the quantizer, pre-correcting the offset correction digital signal by using the offset pre-correction digital code, and calculating a signal-to-noise ratio of the offset correction digital signal after pre-correction; The adjustable range of the offset pre-correction digital code is traversed to obtain the signal-to-noise ratios of the offset correction digital signal after pre-correction corresponding to the offset pre-correction digital codes of different sizes, and the maximum signal-to-noise ratio of the offset correction digital signal after pre-correction is found therefrom. The offset pre-correction digital code corresponding to the maximum signal-to-noise ratio of the offset correction digital signal after pre-correction is the offset correction digital code.

10. The offset correction method of a continuous-time sigma-delta modulator according to claim 9, characterized in that: The step of correcting the offset of the quantizer in the continuous-time sigma-delta modulator by using the offset correction digital code comprises: The offset correction digital code is input into the quantizer, and the offset of the quantizer is corrected by the offset correction digital code.

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