CN114370814A - Angle extraction circuit, method and chip - Google Patents

Abstract

The invention belongs to the technical field of sensing signal processing, and particularly discloses an angle extraction circuit, method and chip. The angle extraction circuit includes: the analog-to-digital converter is used for receiving the voltage signal and performing analog-to-digital conversion on the voltage signal, wherein the voltage signal comprises angle information output by the angle sensor; a signal generator for generating a modulation signal and a reference signal, wherein the modulation signal is used for modulating a voltage signal to obtain a modulated signal; a filter to which the first modulated signal and the second modulated signal are added and inputted to extract angle information; and the phase comparison unit is used for receiving the reference signal output by the signal generator and the output signal of the filter and comparing the reference signal with the output signal so as to acquire the phase difference of the output signal relative to the reference signal. The invention has simple calculation process and greatly reduces the hardware resources required by the calculation process.

Description

Angle extraction circuit, method and chip

technical field

The invention belongs to the technical field of sensor signal processing, and in particular relates to an angle extraction circuit, method and chip.

technical background

In the Hall angle sensor manufactured using the Hall principle, the Hall element starts to rotate from the reference position under the action of the electric field force, and the rotated angle θ is what the Hall angle sensor needs to output. In the existing mature technology, CORDIC (Coordinate Rotation Digital Computer, coordinate rotation digital computer) algorithm is usually used to calculate the value of the angle. This method is based on the presupposition that the tangent (tan) value of the angle θ is equal to the nth power of 1/2 within a certain interval (that is, the formula tanα ⁱ =2 ^-i ), using a series of fixed angle values, by accumulating step by step method to get the value of the angle θ rotated by the Hall angle sensor. Finally, in order to remove part of the noise, the CORDIC algorithm also performs a filtering.

However, the calculation process of this method is relatively complicated, a large amount of memory needs to be used to record the table data used for the table look-up instruction, and the corresponding digital system is also complicated and consumes a lot of resources. For chip manufacturing, the more resources are consumed, the more difficult it is to miniaturize the chip. In order to reduce the difficulty of angle calculation, an angle calculation method that saves more resources and maintains the current level of calculation accuracy is urgently needed.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned defects, the present invention proposes an angle extraction circuit for extracting the angle value output by the angle sensor, including:

a first analog-to-digital converter, configured to receive a first voltage signal and perform analog-to-digital conversion on the first voltage signal, where the first voltage signal includes the angle information output by the angle sensor;

a second analog-to-digital converter, configured to receive a second voltage signal and perform analog-to-digital conversion on the second voltage signal, where the second voltage signal includes the angle information output by the angle sensor;

a signal generator for generating a modulation signal and a reference signal, wherein the first modulation signal is used to modulate the first voltage signal to obtain a first modulated signal, and the second modulation signal is used to modulate the second voltage signal , to obtain the second modulated signal;

a filter, the first modulated signal and the second modulated signal are added and input into the filter to extract the angle information;

a phase comparison unit, receiving the reference signal output by the signal generator and the output signal of the filter, and comparing the reference signal and the output signal to obtain the phase of the output signal relative to the reference signal Difference.

In the above circuit, the filter includes at least two low-pass filters.

In the above circuit, the filter is a four-stage IIR (Infinite Impulse Response, infinite impulse response) filter.

In the above circuit, the characteristic function of the filter is:

_REGn =k×REGn _-1 +(1-k)×new,

Wherein, REG _n is the current output value of the filter, REG _n-1 is the last output value of the filter, new is the input value of the filter, and k is a control coefficient.

In the above circuit, the modulation signal is a square wave.

In the above circuit, the phase comparison unit is a phase shift counter, and the phase shift counter starts counting from the rising/falling edge of the reference signal and ends with the rising/falling edge of the output signal of the filter. count.

The present invention also provides an angle extraction method for extracting the angle value output by the angle sensor, including the following steps:

The analog-to-digital conversion step converts the first voltage signal and the second voltage signal from the angle sensor into digital signals, wherein the first voltage signal and the second voltage signal include the output of the angle sensor angle information;

a modulating step of modulating the first voltage signal and the second voltage signal with a first modulation signal and a second modulation signal, respectively, to obtain a first modulated signal and a second modulated signal;

a filtering step, wherein the first modulated signal and the second modulated signal are added and filtered to extract the angle information;

In the phase comparison step, a reference signal is received, and the reference signal is compared with the output signal obtained by the filtering step to obtain a phase difference of the output signal relative to the reference signal.

In the above method, in the filtering step, multi-stage IIR filters are used for filtering.

In the above-mentioned method, the characteristic function of each stage filter of described multistage recursive filter is:

_REGn =k×REGn _-1 +(1-k)×new,

Wherein, REG _n is the current output value of the filter, REG _n-1 is the last output value of the filter, new is the input value of the filter, and k is a control coefficient.

In the above method, the first modulation signal and the second modulation signal are square waves.

Correspondingly, the present invention also provides a chip, the chip includes an angle sensing unit, and also includes a signal processing unit, the signal processing unit receives the angle information output by the angle sensing unit and analyzes the angle from the angle according to the above method. The angle value is extracted from the information.

Compared with the prior art, the present invention provides a modulation signal and a reference signal of the same frequency through a signal generator, wherein the modulation signal adopts a square wave, and the reference signal adopts a sine wave or a cosine wave. The modulation signal is used to modulate the angle information output by the angle sensing unit, so as to output a signal waveform including the angle information, and the waveform is generally a staircase wave. The standard sin(t+θ) waveform is obtained after multi-stage IIR filtering to remove the high-frequency components carried in the square wave. The reference signal sin t (or cos t) is used to compare with the filtered sin(t+ Compared with θ) waveforms, the delay of sin(t+θ) relative to sin t (ie, the phase difference θ) is obtained by counting, so as to obtain the angle information output by the angle sensing unit. The above algorithm is relatively simple, only shift and addition operations are needed in the filter part, and only a simple counter is needed in the comparison waveform part. Moreover, by simplifying the modulated signals sin t and cos t into square waves of the same frequency, the modulation part omits the multiplication process and only needs an adder. Therefore, the calculation process of the present invention is simple, and the hardware resources required for the calculation process are greatly reduced.

In addition, the present invention uses a multi-stage filter in the process of calculating the angle, which has already played the role of noise filtering. It is not necessary to use another filter to filter the noise after the calculation, which saves one step compared with the prior art.

Description of drawings

1 is a hardware block diagram of some embodiments of the present invention;

Fig. 2 is the principle schematic diagram of the induction unit in Fig. 1;

3a is a schematic block diagram of an angle extraction circuit according to some embodiments of the present invention;

Figure 3b is a schematic block diagram of replacing the sine/cosine signal in the circuit shown in Figure 3a with a square wave of the same frequency;

FIG. 4 is a comparison diagram of waveforms at five positions A, B, C, D, and E shown in FIG. 3 b;

Fig. 5 is the comparison chart of square wave and standard sine wave;

Figure 6-10 is a comparison diagram of the output waveform of the four-stage filter shown in Figure 3b and the reference waveform Ref filtered by the four-stage filter;

FIG. 11 is a schematic diagram of a circuit for obtaining the angle θ by counting in the present invention.

specific embodiment

In order to make the objects and features of the present invention more clearly understood, the specific embodiments of the present invention will be further described below with reference to the accompanying drawings. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Although the description of the invention will be presented in conjunction with the preferred embodiment, this does not mean that the features of the invention are limited to this embodiment. On the contrary, the purpose of introducing the invention in conjunction with the embodiments is to cover other options or modifications that may be extended based on the claims of the invention. The following description will contain numerous specific details in order to provide a thorough understanding of the present invention. The invention may also be practiced without these details. Furthermore, some specific details will be omitted from the description in order to avoid obscuring or obscuring the gist of the present invention. Moreover, the embodiments of the present invention and the features of the embodiments are allowed to be combined or substituted with each other without conflict.

It should be noted that, the accompanying drawings are all in a very simplified form and in inaccurate scales, and are only used to facilitate and clearly assist the purpose of explaining the embodiments of the present invention. Also, in this specification, like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it need not be further defined in subsequent figures and explanation.

It should also be stated that the purpose of numbering the steps in the present invention is to facilitate reference, rather than limiting the sequence. For individual steps that need to be emphasized in order, the text will be specially explained in special words.

When describing the various embodiments of the present invention in conjunction with the accompanying drawings, the orientation or positional relationship indicated by the terms "upper", "lower", "inside", "bottom", etc. is based on the orientation or positional relationship shown in the accompanying drawings, Or the orientation or positional relationship that the product of the invention is usually placed in use is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operation, and therefore should not be construed as a limitation of the present invention.

In order to make the objectives, technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

FIG. 1 shows a hardware block diagram of some embodiments of the present invention. The angle extraction circuit provided by the present invention includes: an induction unit 101 , an analog-to-digital conversion unit 102 , a signal processing unit 103 and a digital-to-analog conversion unit 104 .

The sensing unit 101 includes an angle sensor for sensing the direction of the magnetic field, and outputs a voltage or current containing the information of the direction of the magnetic field. This embodiment takes the output voltage as an example for description. In some embodiments, the angle sensor may be a Hall element, an Anisotropic Magneto resistance (AMR) element, a Giant Magneto resistance (GMR) element, and a Tunnel Magneto Resistance (Tunnel MagnetoResistance, TMR). For details, please refer to FIG. 2 . FIG. 2 is a schematic diagram of the principle of the sensing unit 101 in FIG. 1 . In the figure, the Hall elements HD1 to HD2 are respectively arranged on the X axis and the Y axis of the plane coordinate system. A current is applied to each of the Hall elements HD1 to HD2, and if there is a magnetic field B as shown in the figure parallel to the XY axis plane, induced voltages of different magnitudes will be generated on each of the Hall elements HD1 to HD2. The magnitude of the induced voltage is related to the components of the magnetic field B in the X-axis and Y-axis directions, respectively, so the direction of the magnetic field B can be estimated according to the difference in the induced voltages on the Hall elements HD1-HD2. Taking the direction of the X-axis as an angle of 0°, the included angle θ between the direction of the applied magnetic field B and the X-axis can be determined by analyzing the voltage values on each of the Hall elements HD1 to HD2.

Returning to FIG. 1 , the sensing unit 1 outputs the Hall voltage including the information of the angle θ generated on the Hall elements HD1 to HD2 .

In order to facilitate subsequent digital filtering, the analog-to-digital conversion unit 102 is configured to perform analog-to-digital conversion on the induced voltage. The analog-to-digital conversion unit 102 may include, for example, an 8-bit or 16-bit ADC (Analog Digital Converter, analog-to-digital converter). The larger the number of bits of the ADC, the higher the accuracy of the subsequently calculated value of the included angle θ.

After the signal processing unit 103 receives the digital Hall voltage output by the analog-to-digital conversion unit 102, it modulates and digitally filters it. After multi-stage low-pass filtering, the filtering effect is stable, and the output sin(t+θ) curve The phase shift (including the phase shift) relative to the standard sin t curve (that is, the curve with a phase shift of 0) becomes stable, and the phase shift is the angle θ between the direction of the applied magnetic field B and the X axis. Specifically, the signal processing unit 103 may include a signal generator 26 , a modulation and filtering unit 1032 and a phase comparison unit 211 . In one embodiment, the sensing unit 101 outputs a set of voltage signals, eg, sin θ and cos θ. The signal generator 26 can correspondingly output standard (not including phase shift) cos t and sin t signals as modulation signals, which are used to modulate the signal sinθ and the signal cosθ respectively, and then add the two modulated signals to obtain the modulated signal. The signal sin t×cosθ+cos t×sinθ (that is, the signal at the position of point E in Fig. 3a). The phase comparison unit 211 can compare the modulated signal sin(t+θ) with the standard signal cos t or sin t output by the signal generator 26 to obtain the actual value of the included angle θ (generally a digital signal). If the standard signal cos t or sin t is further replaced with a square wave of the same frequency, the multiplier can also be omitted in the process of designing the filter to save the use of on-chip resources. Wherein, the square wave of the same frequency means that the frequency of the square wave is the same as that of the standard signal, and the position of the zero-crossing point also coincides with the zero-crossing point of the standard signal. For example, referring to the comparison diagram of square wave and standard sine wave shown in Figure 5, the three zero-crossing points of the square wave that replaces the standard sine wave are the same as the sine wave, and the positive and negative amplitudes of the square wave are also the same as the sine wave. Similar to a square wave is the envelope of a sine wave. If the standard signal is a standard cosine wave, the square wave is adjusted accordingly. Specifically, an amplifier whose gain can be regarded as infinite can be added to the output end of the signal generator 26, and the amplitudes of the standard signals cos t and sin t are clamped to a fixed value, thereby forming a square wave. For example, the standard signal sin t shown by the dotted line in Fig. 5 is amplified to obtain the square wave shown by the solid line.

Returning to FIG. 1, the digital-to-analog conversion unit 104 is an optional unit. When the analog value of the included angle θ needs to be output, the digital value about the included angle θ output by the phase comparison unit 211 is converted into an analog value by the digital-to-analog conversion unit 104 .

The following description is made with reference to Fig. 3a and Fig. 3b. 3a is a schematic block diagram of an angle extraction circuit according to some embodiments of the present invention. FIG. 3b is a schematic block diagram of replacing the sine/cosine signals in the circuit shown in FIG. 3a with square waves of the same frequency.

也就是说，本来需要使用乘法器的部分，现在只需要进行加减法(即只使用加法器)即可代替。也就是说，图3b中，将cosθ与方波1相乘、将sinθ与方波2相乘的部分在实际实施的时候，并不是以一个乘法器的硬件单元出现的，而是需要若干个判断器和加法器硬件即可。因此，本实施例在硬件层面上减少了很多逻辑门的使用，降低了系统资源的使用率。但是，本领域普通技术人员可知，简化后的已调信号

相对已调信号sint×cosθ+cos t×sinθ来说，简化后的已调信号中引入了高频分量。因此，为了使已调信号不变形，本实施例还设置了多级滤波器，用来将附加的高频分量滤除。具体的，本实施例中使用了四级IIR滤波器：一级滤波器27、二级滤波器28、三级滤波器29、四级滤波器30。其中，每个滤波器占用一个寄存器，即第一寄存器、第二寄存器、第三寄存器和第四寄存器。前一级滤波器的寄存器在前一次的值和本级滤波器的寄存器在前一次的值取加权和后存入本级滤波器的寄存器中。结合图3a和图3b来说，一级滤波器27的特征函数为：In Figs. 3a and 3b, the first analog-to-digital converter 21 receives a voltage signal (the first voltage signal), and outputs a digital signal cosθ after digital-to-analog conversion, and the second analog-to-digital converter 22 receives another voltage signal (the first voltage signal). Two voltage signals), after digital-to-analog conversion, the digital signal sinθ is output. Specifically, the number of bits of the first analog-to-digital converter 21 and the second analog-to-digital converter 22 can be 8bit, 10bit, 12bit, etc. The more the number of bits, the more accurate the value of the subsequently outputted angle θ. In the embodiment shown in FIG. 3a, the signal generator 26 may be a digital signal generator, which directly outputs the modulated signals sint and cos t in digital form for modulating the signals cosθ and sinθ. However, for the chip manufacturing industry, using hardware to implement a multiplier requires a lot of hardware resources, and is prone to waste of resources. In order to save hardware resources and facilitate the implementation of the modulation process (ie, the multiplication process) inside the chip, the embodiment shown in FIG. 3b uses a square wave of the same frequency (refer to the foregoing description about the square wave and FIG. 5 ) instead of modulated signal sin t and cos t, after adding, the modulated signal obtained at point E in Figure 3b is simplified by (sin t×cosθ+cos t×sinθ) as

That is to say, the part that originally needed to use multipliers now only needs to be added and subtracted (that is, only adders are used). That is to say, in Fig. 3b, the part of multiplying cosθ by square wave 1 and sinθ by square wave 2 does not appear as a hardware unit of a multiplier when actually implemented, but requires several The judger and adder hardware are sufficient. Therefore, the present embodiment reduces the use of many logic gates at the hardware level, and reduces the utilization rate of system resources. However, those of ordinary skill in the art know that the simplified modulated signal

Compared with the modulated signal sint×cosθ+cos t×sinθ, the simplified modulated signal introduces high frequency components. Therefore, in order to keep the modulated signal from being deformed, a multi-stage filter is also provided in this embodiment to filter out additional high-frequency components. Specifically, four stages of IIR filters are used in this embodiment: a first stage filter 27 , a second stage filter 28 , a third stage filter 29 , and a fourth stage filter 30 . Among them, each filter occupies one register, namely the first register, the second register, the third register and the fourth register. The previous value of the register of the previous stage filter and the previous value of the register of the current stage filter are stored in the register of the current stage filter after taking the weighted sum. Referring to Fig. 3a and Fig. 3b, the characteristic function of the first-stage filter 27 is:

REG1 _n =k×REG1 _n-1 +(1-k)×new,

Among them, REG1 _n is the current value of the first register of the first-stage filter 27, REG1 _n-1 is the previous value of the first register of the first-stage filter 27 (that is, the result of the previous recursion), and new is a The input value of the stage filter 27 (ie the signal value at point E in Figure 3a and Figure 3b), k is the control coefficient, according to the control coefficient, the weights of REG1 _n-1 and new are respectively k and (1-k) .

The characteristic function of the secondary filter 28 is:

REG2 _n =k×REG2 _n-1 +(1-k)×REG1 _n-1 ,

Among them, REG2 _n is the current value of the second register of the secondary filter 28, REG2 _n-1 is the value of the second register of the secondary filter 28 at the previous moment (that is, the result of the previous recursion), REG1 _{n -1} is the input value of the secondary filter 28 (ie, the signal value at point A in Fig. 3a and Fig. 3b), k is the control coefficient, according to the control coefficient, the weights of REG2 _n-1 and REG1 _n-1 are respectively k and (1-k).

The characteristic function of the three-stage filter 29 is:

REG3 _n =k×REG3 _n-1 +(1-k)×REG2 _n-1 ,

Among them, REG3 _n is the current value of the third register of the three-stage filter 29, REG3 _n-1 is the value of the third register at the previous moment (that is, the result of the previous recursion), and REG2 _n-1 is the third-stage filter. The input value of the device 29 (that is, the signal value at point B in Fig. 3a and Fig. 3b), k is the control coefficient, according to the control coefficient, the weights of REG3 _n-1 and REG2 _n-1 are k and (1-k respectively) ).

The characteristic function of the four-stage filter 210 is:

REG4 _n =k×REG4 _n-1 +(1-k)×REG3 _n-1 ,

Among them, REG4 _n is the current value of the fourth register of the four-stage filter 210, REG4 _n-1 is the value of the fourth register at the previous moment (that is, the result of the previous recursion), and REG3 _n-1 is the fourth-stage filter. The input value of the controller 210 (that is, the signal value at point C in Fig. 3a and Fig. 3b), k is the control coefficient, according to the control coefficient, the weights of REG4 _n-1 and REG3 _n-1 are k and (1-k respectively) ).

After experiments, the signal curve after the fourth-stage filtering can basically filter out the additional high-frequency components due to the use of square waves instead of sine waves (cosine waves), so the signal output by the fourth-stage filter 210 is relatively complete. The modulated signal sin(t+θ) of , and then compare the signal with the standard signal sin t (or cos t) to obtain the value of the included angle θ. Of course, if the precision of the included angle θ is relatively high, several stages of filters can be added according to the above-mentioned characteristic function, in order to filter out more high-frequency signals.

其中，x为小于256的正整数，则上述的滤波器也可以仅使用加法器和移位寄存器即可实现，这将大大减少硬件资源的使用，对于芯片制造行业来说，可以实现芯片小型化或者将资源用来实现其他电路。Further, in the above filter, the value of the control coefficient k is set as

Among them, x is a positive integer less than 256, and the above filter can also be realized by using only adders and shift registers, which will greatly reduce the use of hardware resources. For the chip manufacturing industry, it can achieve chip miniaturization. Or use the resources to implement other circuits.

The phase comparison unit 211 receives the standard signal sin t (or cos t) output by the signal generator 26 and the modulated signal sin(t+θ) output by the fourth-stage filter 210 . Among them, sin t (or cos t) can also be simplified as a square wave of the same frequency as a reference signal. In conjunction with FIG. 11 , this will be explained more clearly.

FIG. 11 is a schematic diagram of a circuit for obtaining the value of the angle θ by counting in the present invention. The modulated signal sin(t+θ) is input to the zero-crossing detection 110, the rising edge (or falling edge) of which is extracted, and input to the counter 111, and the counter 111 is at the rising edge ( or falling edge) count, so that the phase offset (that is, the value of the included angle θ) of the modulated signal sin(t+θ) can be calculated. Alternatively, in other embodiments, a phase detector may also be used to implement phase detection.

It can be said that in the above-mentioned embodiments, the functions of the multiplier and the adder are realized only by the adder and the shift register, which greatly simplifies the process (calculation process) of angle extraction. The hardware resources to be used are also greatly reduced, which simplifies the complexity of the circuit.

In addition, since the multi-stage filter is used in the calculation process, it also plays the role of filtering out noise while filtering out additional high-frequency signals. Compared with the solution in the prior art, which usually requires noise filtering after the value of the included angle θ is obtained, the present invention also saves an independent noise filtering process.

E点处的信号数字形式的已调信号如图4中的阶梯波所示，也就是一级滤波器27的输入信号。A点处的信号为图4中的近似三角波的波形，其是经过一级滤波器27滤波后的信号。B点处的信号为图4中近似正弦波，但是有明显变形的波形，其是经过二级滤波器28滤波后的信号。C点处和D点处的信号已经非常接近正弦波，其依次是经过三级滤波器29和四级滤波器210滤波后的信号。Fig. 4 is a comparison diagram of the waveforms at five points A, B, C, D, and E shown in Fig. 3b. The figure is obtained by simulating the calculation process of the above-mentioned four-stage IIR filter in the mathematical calculation software matlab. Among them, the control coefficient k in the characteristic function takes the value of

The modulated signal in digital form of the signal at point E is shown as the staircase wave in FIG. The signal at point A is the approximate triangle wave waveform in FIG. 4 , which is the signal filtered by the first-stage filter 27 . The signal at point B is an approximate sine wave in FIG. 4 , but has a significantly deformed waveform, which is a signal filtered by the secondary filter 28 . The signals at points C and D are very close to sine waves, which are the signals filtered by the third-stage filter 29 and the fourth-stage filter 210 in sequence.

In order to more clearly show the filtering effect of the four-stage filter, Figure 6-10 shows a comparison diagram of the filtering effect of the single-cycle reference signal Ref and the modulated signal.

其波形为阶梯波。In FIG. 6, the reference signal Ref is a square wave with a fixed frequency (corresponding to the reference signal Ref input to the phase comparison unit 211 in FIG. 3b), and the modulated signal is replaced by the above-mentioned square wave of the same frequency instead of the modulated signals sin t and cost t method to simplify (simplified modulated signal)

Its waveform is a staircase wave.

FIG. 7 shows that the reference signal Ref in the form of a square wave is deformed into an approximate triangular wave after being filtered by the first-stage filter 27, and the modulated signal sin(t+θ) in the shape of a staircase wave becomes an irregular zigzag waveform.

FIG. 8 shows that after being filtered by the secondary filter 28, the reference signal Ref is deformed into an approximate sine wave, and the modulated signal sin(t+θ) is also shaped into an approximate sine wave. However, both waveforms are significantly deformed relative to the standard sine wave.

FIG. 9 shows that after being filtered by the three-stage filter 29, the reference signal Ref is deformed into an approximate sine wave, and the modulated signal sin(t+θ) is also shaped into an approximate sine wave. Both waveforms have no obvious deformation relative to the standard sine wave.

FIG. 10 shows that after being filtered by the four-stage filter 210, the reference signal Ref is deformed into an approximate cosine wave, and the modulated signal sin(t+θ) is also shaped into an approximate cosine wave. Both waveforms have no obvious deformation relative to the standard sine wave.

After laboratory simulation, even after the fifth and sixth filters, the waveforms of the reference signal Ref and the modulated signal sin(t+θ) are no longer significantly changed, that is, the recursion can end, and the waveform shown in Figure 10 The phase comparison is performed on the basis of , to obtain the value of the included angle θ.

Although the present invention has been illustrated and described above with reference to some embodiments of the present invention, those of ordinary skill in the art should understand that the above content is a further detailed description of the present invention combined with specific The specific implementation of the invention is limited only by these descriptions. Those skilled in the art can make various changes and modifications in form and details, including making some simple deductions or substitutions, without departing from the spirit and scope of the present invention. Therefore, if these changes and modifications of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these changes and modifications.

Claims (11)

1. An angle extraction circuit for extracting an angle value output from an angle sensor, comprising:

the first analog-to-digital converter is used for receiving a first voltage signal and performing analog-to-digital conversion on the first voltage signal, wherein the first voltage signal comprises angle information output by the angle sensor;

the second analog-to-digital converter is used for receiving a second voltage signal and performing analog-to-digital conversion on the second voltage signal, wherein the second voltage signal comprises angle information output by the angle sensor;

a signal generator for generating a modulation signal and a reference signal, wherein the first modulation signal is used for modulating the first voltage signal to obtain a first modulated signal, and the second modulation signal is used for modulating the second voltage signal to obtain a second modulated signal;

a filter to which the first modulated signal and the second modulated signal are added and inputted to extract the angle information;

and the phase comparison unit is used for receiving the reference signal output by the signal generator and the output signal of the filter, and comparing the reference signal with the output signal to acquire the phase difference of the output signal relative to the reference signal.

2. The circuit of claim 1, wherein the filter comprises at least a 2-stage low pass filter.

3. The circuit of claim 1 or 2, wherein the filter is a four-stage IIR (Infinite Impulse Response) filter.

4. The circuit of claim 3, wherein the filter characteristic function is:

REG_n＝k×REG_n-1+(1-k)×new，

wherein, REG_nIs the value of the current output of the filter, REG_n-1Is the last output value of said filter, new isThe input value of the filter, k, is a control coefficient.

5. The circuit of claim 1, wherein the modulated signal is a square wave.

6. The circuit of claim 5, wherein the phase comparison unit is a phase shift counter that counts from a rising/falling edge of the reference signal to an end of a rising/falling edge of the output signal of the filter.

7. An angle extraction method is used for extracting an angle value output by an angle sensor, and is characterized by comprising the following steps:

an analog-to-digital conversion step of converting a first voltage signal and a second voltage signal from the angle sensor into digital signals, wherein the first voltage signal and the second voltage signal contain angle information output by the angle sensor;

a modulation step of modulating the first voltage signal and the second voltage signal with a first modulation signal and a second modulation signal, respectively, to obtain a first modulated signal and a second modulated signal;

a filtering step of adding the first modulated signal and the second modulated signal and then filtering the added signals to extract the angle information;

and a phase comparison step of receiving a reference signal and comparing the reference signal with the output signal obtained in the filtering step to obtain the phase difference of the output signal relative to the reference signal.

8. The method of claim 7, wherein in the filtering step, the filtering is performed using a multi-stage IIR filter.

9. The method of claim 8, wherein each stage of the multi-stage recursive filter has a characteristic function of:

REG_n＝k×REG_n-1+(1-k)×new，

wherein, REG_nIs the value of the current output of the filter, REG_n-1Is the output value of the filter in the last time, new is the input value of the filter, and k is the control coefficient.

10. The method of claim 7, wherein the first modulation signal and the second modulation signal are square waves.

11. A chip comprising an angle sensing unit, characterized by further comprising a signal processing unit, wherein the signal processing unit receives the angle information output by the angle sensing unit and extracts an angle value from the angle information according to the method of any one of claims 7 to 10.

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