Filter

Abstract

The invention discloses a filter. The filter comprises an original filter assembly and a potential translation branch. The original filter assembly comprises a target capacitor. And the potential translation branch is configured to increase or decrease the output voltage of the original filter component within a preset range so as to control the target capacitor to always work in a linear region. According to the filter provided by the embodiment of the invention, the output voltage of the output end of the filter can be increased or reduced by arranging the potential translation branch circuit on the basis of a universal filter circuit structure adopting the CMOS capacitor, so that the voltage drop at the two ends of the CMOS capacitor is always kept positive in the whole signal period; therefore, the CMOS capacitor is controlled to always work in a voltage region with good capacitance linearity in the whole signal period, the distortion characteristic of the filter is reduced, and the condition that the distortion of the filter exceeds an allowable range due to the fact that the CMOS capacitor works in a nonlinear region is avoided.

Description

Technical Field

[0001] The present application relates to the technical field of electronic circuits, and in particular to a filter. Background Art

[0002] In the current related technology, the capacitance value of a CMOS capacitor is related to the voltage drop across the capacitor. When the voltage polarity across the capacitor is positive and the voltage difference is high, its capacitance value remains stable; when the voltage difference drops to near or below the threshold voltage, or when the voltage polarity is reversed, its capacitance value will drop rapidly. Although most semiconductor processes usually adjust the threshold voltage of CMOS capacitors to 0V or slightly less than 0V to improve the capacitance characteristics at low voltage, the capacitance value of CMOS capacitors has begun to drop significantly near 0V or when the voltage drop is negative. This characteristic of CMOS capacitors prevents them from being used in some filters that are sensitive to distortion. Summary of the invention

[0003] The present application provides a filter.

[0004] The filter in the embodiment of the present application includes an original filter component and a potential translation branch, wherein the original filter component includes a target capacitor;

[0005] The potential shifting branch is configured to increase or decrease the output voltage of the original filter component within a preset range to control the target capacitor to always operate in a linear region.

[0006] In some embodiments, the original filter component includes an operational amplifier, the potential shift branch is connected between the output port of the operational amplifier and the second pole of the target capacitor, and the first pole of the target capacitor is connected to the inverting input port of the operational amplifier.

[0007] In some embodiments, the potential shifting branch includes a level shifter, a first electrode of the level shifter is connected to a second electrode of the target capacitor, and a second electrode of the level shifter is connected to an output port of the operational amplifier.

[0008] In some implementations, the polarity direction of the target capacitor and the polarity direction of the level shifter satisfy a preset condition, so as to reduce or increase the output voltage of the output port of the operational amplifier within a preset range.

[0009] In some embodiments, the original filter component further includes a feedback resistor connected between an inverting input port of the operational amplifier and an output port of the operational amplifier.

[0010] In some embodiments, the original filter component includes an operational amplifier, a first potential shift branch connected between a first output port of the operational amplifier and a second pole of a first target capacitor, and a second potential shift branch connected between a second output port of the operational amplifier and a first pole of a second target capacitor;

[0011] A first electrode of the first target capacitor is connected to a non-inverting input port of the operational amplifier, and a second electrode of the second target capacitor is connected to an inverting input port of the operational amplifier.

[0012] In some embodiments, the first potential shifting branch includes a first level shifter, a first electrode of the first level shifter is connected to a second electrode of the first target capacitor, and a second electrode of the first level shifter is connected to a first output port of the operational amplifier;

[0013] The second potential shifting branch includes a second level shifter, a second electrode of the second level shifter is connected to a second electrode of the second target capacitor, and a first electrode of the second level shifter is connected to a second output port of the operational amplifier.

[0014] In some embodiments, the polarity direction of the first target capacitor and the polarity direction of the first level shifter satisfy a first preset condition to reduce or increase the output voltage of the first output port of the operational amplifier within a preset range;

[0015] The polarity direction of the second target capacitor and the polarity direction of the second level shifter satisfy a second preset condition, so as to increase or decrease the output voltage of the second output port of the operational amplifier within a preset range.

[0016] In some embodiments, the original filter component also includes a first feedback resistor and a second feedback resistor, the first feedback resistor is connected between the non-inverting input port of the operational amplifier and the first output port of the operational amplifier, and the second feedback resistor is connected between the inverting input port of the operational amplifier and the second output port of the operational amplifier.

[0017] In certain embodiments, the target capacitor, the first target capacitor and / or the second target capacitor are CMOS capacitors.

[0018] In this way, the filter in the implementation mode of the present application can increase or decrease the output voltage of the output end of the filter by setting a potential shift branch on the basis of a general filter circuit structure that uses CMOS capacitors, so that the voltage drop across the CMOS capacitor remains positive throughout the entire signal cycle, thereby controlling the CMOS capacitor to always operate in a voltage region with good capacitance linearity throughout the signal cycle, reducing the distortion characteristics of the filter, and avoiding the situation where the filter distortion exceeds the allowable range due to the CMOS capacitor operating in a nonlinear region.

[0019] Additional aspects and advantages of the embodiments of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0021] Figure 1 It is a schematic diagram of the circuit structure of a filter using CMOS capacitors in the current related technology;

[0022] Figure 2 A schematic diagram of the operating voltage waveform of a filter using CMOS capacitors in the current related technology;

[0023] Figure 3 Schematic diagram of the circuit structure of a first-order low-pass filter in an embodiment of the present application;

[0024] Figure 4 A schematic diagram of the operating voltage waveform of the filter of the CMOS capacitor in the embodiment of the present application;

[0025] Figure 5 Another schematic diagram of the circuit structure of a first-order low-pass filter in an embodiment of the present application;

[0026] Figure 6 Another schematic diagram of operating voltage waveform of the filter of the CMOS capacitor in the embodiment of the present application;

[0027] Figure 7 Schematic diagram of the circuit structure of a first-order differential low-pass filter in an embodiment of the present application;

[0028] Figure 8 Schematic diagram of another circuit structure of a first-order differential low-pass filter in an embodiment of the present application.

[0029] Wherein: C, CMOS capacitor; U, reference operational amplifier; r1, reference feedback resistor; R1, input resistor; R2, feedback resistor; C1, target capacitor; L, level shifter; Ua, first operational amplifier; Ub, second operational amplifier; R1+, first input resistor; R1-, second input resistor; R2+, first feedback resistor; R2-, second feedback resistor; C1+, first target capacitor; C1-, second target capacitor; L1, first level shifter; L2, second level shifter. DETAILED DESCRIPTION

[0030] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions from beginning to end. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the embodiments of the present application, and cannot be understood as limiting the embodiments of the present application.

[0031] The filter in the implementation manner of the present application includes an original filter component and a potential translation branch, wherein the original filter component includes a target capacitor;

[0032] The potential shifting branch is configured to increase or decrease the output voltage of the original filter component within a preset range to control the target capacitor to always work in the linear region.

[0033] Specifically, CMOS capacitors are the most commonly used capacitor types in CMOS, BiCMOS or BCD semiconductor processes. Their structure is almost completely consistent with normal NMOS or PMOS tubes, and they have a higher capacitance per unit area. At the same time, they are compatible with CMOS semiconductor processes, do not require the addition of additional mask layers, are economical and efficient, and are very ideal capacitor elements in most low-voltage applications. However, the capacitance value of CMOS capacitors is related to the voltage drop across the capacitors. When the voltage polarity across the capacitors is positive and the voltage difference is high, their capacitance value remains stable; when the voltage difference is reduced to near or below the threshold voltage, or when the voltage polarity is reversed, their capacitance value decreases rapidly. Although most semiconductor processes usually adjust the threshold voltage of CMOS capacitors to 0V or less than 0V to improve the capacitance characteristics at low voltage, the capacitance value of CMOS capacitors has begun to decline significantly near 0V or when the voltage drop is negative. Due to this characteristic of CMOS capacitors, they cannot be used in some filters that are sensitive to distortion.

[0034] See also Figure 1 , Figure 1 is a typical first-order active low-pass filter, where C is a CMOS capacitor. Figure 1 In the circuit shown, the filter input and output operate at a common-mode voltage V refNearby, the reference operational amplifier U uses the reference feedback resistor r1 and the CMOS capacitor C as feedback to achieve a first-order low-pass filter characteristic. The positive plate terminal voltage V A Equal to the reference voltage V at the non-inverting input of the operational amplifier ref , the voltage at the negative plate of C is equal to the voltage V at the output port of the operational amplifier out Please see further Figure 2 , Figure 2 Shows V ref With V out The waveform state under typical working conditions. Figure 2 It can be seen that the voltages at both ends of the CMOS capacitor C are fixed voltages V ref and the changing voltage V out , the voltage across C is positive in the first half of the cycle and negative in the second half of the cycle. It can be seen that when the voltage across C is positive, the capacitance value is normal, and when the voltage is negative, the capacitance value will decrease sharply. This characteristic of the capacitance value changing with the voltage will cause the output signal to produce a nonlinear error voltage, which worsens the distortion and cannot meet the needs of audio applications.

[0035] In order to solve the above problems, the present application proposes a filter to solve the above problems existing in CMOS capacitors.

[0036] The filter in the implementation manner of the present application includes an original filter component and a potential translation branch, and the original filter component includes a target capacitor;

[0037] The potential shifting branch is configured to increase or decrease the output voltage of the original filter component within a preset range to control the target capacitor to always work in the linear region.

[0038] Specifically, the filter proposed in the embodiment of the present application is improved based on various types of filters currently available using CMOS capacitors, and the main improvement idea is to connect one or more groups of potential shift branches additionally on the basis of the existing filter. The most important function of the potential shift branch is to shift the voltage of one of the plate ends of the target capacitor in the direction of increase or decrease, so that when the voltage of the other plate end remains unchanged, the voltage between the two plates of the target capacitor can be directly adjusted by the above-mentioned shift, so that the target capacitor can maintain a working state in the linear region, thereby ensuring the overall distortion requirements of the filter circuit. In order to achieve the above-mentioned purpose, illustratively, the above-mentioned potential shift branch is generally connected to the controlled end of the target capacitor to directly intervene in and control the voltage of the controlled end.

[0039] In some embodiments, the original filter component includes an operational amplifier, the potential shifting branch is connected between an output port of the operational amplifier and a second electrode of the target capacitor, and a first electrode of the target capacitor is connected to an inverting input port of the operational amplifier.

[0040] In some embodiments, the potential shifting branch includes a level shifter, a first electrode of the level shifter is connected to a second electrode of the target capacitor, and a second electrode of the level shifter is connected to an output port of the operational amplifier.

[0041] In some implementations, the polarity direction of the target capacitor and the polarity direction of the level shifter meet a preset condition to reduce or increase the output voltage of the output port of the operational amplifier within a preset range.

[0042] In some embodiments, the original filter component further includes a feedback resistor connected between the inverting input port of the operational amplifier and the output port of the operational amplifier.

[0043] Specifically, let's take a first-order low-pass filter as an example. Figure 3 , Figure 3 A first-order low-pass filter with a potential shifting branch is shown. The filter includes a first operational amplifier Ua, an input resistor R1, a feedback resistor R2, a target capacitor C1 and a level shifter L. Figure 1 Compared with the situation shown, the above-mentioned first operational amplifier Ua, input resistor R1, feedback resistor R2 and target capacitor C1 are connected together to form an original filter component, the input resistor R1 is connected to the inverting input port of the first operational amplifier Ua, the feedback resistor R2 is connected between the inverting input port of the first operational amplifier Ua and the output port of the first operational amplifier Ua, and the target capacitor C1 is also connected between the inverting input port of the first operational amplifier Ua and the output port of the first operational amplifier Ua, wherein the positive plate end of the target capacitor C1 is connected to the inverting input port of the first operational amplifier Ua, and the negative plate end of the target capacitor C1 is connected to the output port of the first operational amplifier Ua. In addition, the positive input port of the first operational amplifier Ua is connected to the reference voltage V ref Based on the circuit structure of the first operational amplifier, the voltage V A With reference voltage V ref The voltage V at the negative plate of the target capacitor C2 is equal to B The output voltage V of the first operational amplifier Ua out equal.

[0044] On this basis, the level shifter L itself serves as a potential shifting branch of the filter in the embodiment of the present application, wherein the positive electrode of the level shifter L is connected to the output port of the first operational amplifier Ua, and the negative electrode of the level shifter L is directly connected to the negative plate end of the target capacitor C1. Figure 3 The circuit shown in the figure is used to convert the negative plate voltage V B Shift downwards, the degree of shift is V S It is determined by the properties of the level shifter L itself, but the purpose of the shift is to make V B Always below V ref , thereby controlling the voltage across the target capacitor C1 to always be maintained within a positive range, thereby maintaining the target capacitor C1 within a working range with good linearity as much as possible, avoiding nonlinear operation and thus causing negative impact on the filter performance.

[0045] according to Figure 3 In the example shown, in the filter in this example, the output voltage at the output port of the first operational amplifier is shifted downward by V S The output signal after translation is fed back to the input end side of the first operational amplifier Ua through the target capacitor C1, while the output signal without translation is fed back to the input end side of the first operational amplifier Ua through the feedback resistor R2.

[0046] Then please refer to Figure 4 , illustratively, Figure 4 Shows V ref With V out In the level shifter L to V out The waveform state of the voltage at each port when the filter is working before and after the translation. It can be seen that under the translation effect of the level shifter L, V out Shifted downward by V S After V B equal, thus ensuring that the V out Always less than V ref , thereby ensuring that the target capacitor C1 can always operate in the linear region, avoiding nonlinear operation and thus causing negative impact on the filter performance.

[0047] In addition, in addition to reducing the output voltage of the output port of the first operational amplifier Ua, in some examples, in order to adapt to different connection methods of the target capacitor C1, the output voltage of the output port of the first operational amplifier Ua can also be increased to maintain the target capacitor C1 within a working range with good linearity. In this example, see Figure 5 , Figure 5A first-order low-pass filter with a potential shifting branch is shown. The filter includes a first operational amplifier Ua, an input resistor R1, a feedback resistor R2, a target capacitor C1 and a level shifter L. Figure 1 Compared with the situation shown in the figure, the first operational amplifier Ua, input resistor R1, feedback resistor R2 and target capacitor C1 are connected together to form an original filter component, the input resistor R1 is connected to the inverting input port of the first operational amplifier Ua, the feedback resistor R2 is connected between the inverting input port of the first operational amplifier Ua and the output port of the first operational amplifier Ua, and the target capacitor C1 is also connected between the inverting input port of the first operational amplifier Ua and the output port of the first operational amplifier Ua, wherein the positive plate end of the target capacitor C1 is connected to the output port of the first operational amplifier Ua. In addition, the positive input port of the first operational amplifier Ua is connected to the reference voltage V ref Based on the circuit structure of the first operational amplifier, the voltage V A With reference voltage V ref The voltage V at the positive plate of the target capacitor C2 is equal to B The output voltage V of the first operational amplifier Ua out equal.

[0048] On this basis, the level shifter L itself serves as a potential shift branch of the filter in the embodiment of the present application, wherein the negative electrode of the level shifter L is connected to the output port of the first operational amplifier Ua, and the positive electrode of the level shifter L is directly connected to the positive plate end of the target capacitor C1. Figure 3 The circuit shown in the figure is used to convert the positive plate voltage V B Upward translation, translation degree V S It is determined by the properties of the level shifter L itself, but the purpose of the shift is to make V B Always higher than V ref , thereby controlling the voltage across the target capacitor C1 to always be maintained within a positive range, thereby maintaining the target capacitor C1 within a working range with good linearity as much as possible, avoiding nonlinear operation and thus causing negative impact on the filter performance.

[0049] according to Figure 5 In the example shown, in the filter in this example, the output voltage at the output port of the first operational amplifier is shifted upward by V S The output signal after translation is fed back to the input end side of the first operational amplifier Ua through the target capacitor C1, while the output signal without translation is fed back to the input end side of the first operational amplifier Ua through the feedback resistor R2.

[0050] Then please refer to Figure 6 , illustratively, Figure 6 Shows V ref With V out In the level shifter L to V out The waveform state of the voltage at each port when the filter is working before and after the translation. It can be seen that under the translation effect of the level shifter L, V out Shifted upward by V S After V B equal, thus ensuring that the V out Always greater than V ref , thereby ensuring that the target capacitor C1 can always operate in the linear region, avoiding nonlinear operation and thus causing negative impact on the filter performance.

[0051] In some embodiments, the original filter component includes an operational amplifier, a first potential shifting branch connected between a first output port of the operational amplifier and a second pole of the first target capacitor, and a second potential shifting branch connected between a second output port of the operational amplifier and a first pole of the second target capacitor;

[0052] A first electrode of the first target capacitor is connected to a non-inverting input port of the operational amplifier, and a second electrode of the second target capacitor is connected to an inverting input port of the operational amplifier.

[0053] In some embodiments, the first potential shifting branch includes a first level shifter, a first electrode of the first level shifter is connected to a second electrode of the first target capacitor, and a second electrode of the first level shifter is connected to a first output port of the operational amplifier;

[0054] The second potential translation branch includes a second level shifter, a second electrode of the second level shifter is connected to a second electrode of the second target capacitor, and a first electrode of the second level shifter is connected to a second output port of the operational amplifier.

[0055] In some embodiments, the polarity direction of the first target capacitor and the polarity direction of the first level shifter satisfy a first preset condition to reduce or increase the output voltage of the first output port of the operational amplifier within a preset range;

[0056] The polarity direction of the second target capacitor and the polarity direction of the second level shifter satisfy a second preset condition, so as to increase or decrease the output voltage of the second output port of the operational amplifier within a preset range.

[0057] In some embodiments, the original filter component also includes a first feedback resistor and a second feedback resistor, the first feedback resistor is connected between the non-inverting input port of the operational amplifier and the first output port of the operational amplifier, and the second feedback resistor is connected between the inverting input port of the operational amplifier and the second output port of the operational amplifier.

[0058] Specifically, take the first-order differential active low-pass filter as an example, see Figure 7 , Figure 7 A first-order differential active low-pass filter with a potential shifting branch is shown, wherein the filter includes a second operational amplifier Ub, a first input resistor R1+, a second input resistor R1-, a first feedback resistor R2+, a second feedback resistor R2-, a first target capacitor C1+, a second target capacitor C1-, a first level shifter L1, and a second level shifter L2.

[0059] Among them, for the branch where the first target capacitor C1+ is located, the first input resistor R1+ is connected to the non-inverting input port of the second operational amplifier Ub, the first feedback resistor R2+ is connected between the non-inverting input port of the second operational amplifier Ub and the first output port of the second operational amplifier Ub, and the first target capacitor C1+ is also connected between the non-inverting input port of the second operational amplifier Ub and the output port of the second operational amplifier Ub, wherein the positive plate end of the first target capacitor C1+ is connected to the non-inverting input port of the second operational amplifier Ub, the negative plate end of the first target capacitor C1+ is connected to the first output port of the second operational amplifier Ub, and the voltage V at the negative plate end of the first target capacitor C1+ is B+ The output voltage V of the first output port of the second operational amplifier Ub out- equal.

[0060] On this basis, illustratively, the first level shifter L1 itself serves as the first potential shifting branch of the filter in the embodiment of the present application, wherein the positive electrode of the first level shifter L1 is connected to the first output port of the second operational amplifier Ub, and the negative electrode of the first level shifter L1 is directly connected to the negative plate end of the first target capacitor C1+. Figure 7 The circuit shown in the figure is used to convert the negative plate terminal voltage V B+ The output signal after translation is fed back to the input end of the second operational amplifier Ub through the first target capacitor C1+, while the output signal without translation is fed back to the input end of the second operational amplifier Ub through the first feedback resistor R2+. The degree of translation V S The first level shifter L1 itself determines the properties of the first level shifter L1, but the purpose of the shift is to make the negative plate terminal voltage V B+Always lower than the positive plate voltage V of the first target capacitor C1+ A+ , thereby controlling the voltage across the first target capacitor C1+ to always be maintained within a positive range, thereby maintaining the first target capacitor C1+ within a working range with good linearity as much as possible, avoiding nonlinear operation and thus negatively affecting the filter performance.

[0061] As for the branch where the second target capacitor C1- is located, the second input resistor R1- is connected to the non-inverting input port of the second operational amplifier Ub, the second feedback resistor R2- is connected between the inverting input port of the second operational amplifier Ub and the second output port of the second operational amplifier Ub, and the second target capacitor C1- is also connected between the inverting input port of the second operational amplifier Ub and the second output port of the second operational amplifier Ub, wherein the negative plate end of the second target capacitor C1- is connected to the inverting input port of the second operational amplifier Ub, and the positive plate end of the second target capacitor C1- is connected to the second output port of the second operational amplifier Ub, and the voltage V B- The output voltage V of the second output port of the second operational amplifier Ub out+ equal.

[0062] On this basis, the second level shifter L2 itself serves as the potential shift branch of the filter in the embodiment of the present application, wherein the negative electrode of the second level shifter L2 is connected to the second output port of the second operational amplifier Ub, and the positive electrode of the second level shifter L2 is directly connected to the positive plate end of the target capacitor C1-. Figure 7 The circuit shown in the figure is used to convert the positive plate terminal voltage V B- The output signal after translation is fed back to the input end of the second operational amplifier Ub through the second target capacitor C1-, while the output signal without translation is fed back to the input end of the second operational amplifier Ub through the second feedback resistor R2-. The degree of translation V S The second level shifter L2 itself determines the nature of the second level shifter L2, but the purpose of the shift is to make the positive plate terminal voltage V B- Always higher than the negative plate terminal voltage V of the second target capacitor C1- A- , thereby controlling the voltage across the second target capacitor C1- to always be maintained within a positive range, thereby maintaining the second target capacitor C1- within a working range with good linearity as much as possible, avoiding nonlinear operation and thus negatively affecting the filter performance.

[0063] In addition, in some other examples, the polarity connection mode of the first target capacitor C1+ and the first level shifter L1, and the polarity connection mode of the second target capacitor C1- and the second level shifter L2 may be the same as Figure 7 The opposite connection is shown, such as Figure 8 As shown, the negative electrode of the first level shifter L1 is connected to the second output port of the second operational amplifier Ub, and the positive electrode of the first level shifter L1 is directly connected to the positive plate end of the first target capacitor C1+, while the positive electrode of the second level shifter L2 is connected to the second output port of the second operational amplifier Ub, and the negative electrode of the second level shifter L2 is directly connected to the negative plate end of the second target capacitor C1-. Then, Figure 8 In the case shown, the main function of the first level shifter L1 is to increase the voltage V at the positive plate terminal of the first target capacitor C1+. B+ , so that the voltage V B+ Always higher than the voltage V at the negative plate end of the first target capacitor C1+ A+ The main function of the second level shifter L2 is to reduce the voltage V at the negative plate end of the second target capacitor C1. B- , so that the voltage V B- Always lower than the voltage V at the positive plate end of the second target capacitor C1 A- .

[0064] In addition to the above-mentioned implementation manner, the filter in the implementation manner of the present application may also be a second-order differential active low-pass filter or a higher-order filter, and the setting of the potential shift branch may be adaptively set with reference to the above-mentioned example.

[0065] In some embodiments, the target capacitor C1 , the first target capacitor C1+, and the second target capacitor C1 − are all CMOS capacitors.

[0066] In this way, the filter in the implementation mode of the present application can increase or decrease the output voltage of the output end of the filter by setting a potential shift branch on the basis of a general filter circuit structure that uses CMOS capacitors, so that the voltage drop across the CMOS capacitor remains positive throughout the entire signal cycle, thereby controlling the CMOS capacitor to always operate in a voltage region with good capacitance linearity throughout the signal cycle, reducing the distortion characteristics of the filter, and avoiding the situation where the filter distortion exceeds the allowable range due to the CMOS capacitor operating in a nonlinear region.

[0067] In the description of this specification, the descriptions with reference to the terms "certain embodiments", "in an example", "exemplarily", etc., mean that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0068] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code that includes one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0069] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A filter, characterized in that: The filter comprises an original filter component and a potential translation branch, wherein the original filter component comprises a target capacitor; The potential shifting branch is configured to increase or decrease the output voltage of the original filter component within a preset range to control the target capacitor to always operate in a linear region.

2. The filter according to claim 1, characterized in that The original filter component includes an operational amplifier, the potential shifting branch is connected between the output port of the operational amplifier and the second pole of the target capacitor, and the first pole of the target capacitor is connected to the inverting input port of the operational amplifier.

3. The filter according to claim 2, characterized in that The potential translation branch includes a level shifter, a first electrode of the level shifter is connected to a second electrode of the target capacitor, and a second electrode of the level shifter is connected to an output port of the operational amplifier.

4. The filter according to claim 3, characterized in that The polarity direction of the target capacitor and the polarity direction of the level shifter meet a preset condition, so as to reduce or increase the output voltage of the output port of the operational amplifier within a preset range.

5. The filter according to claim 2, characterized in that The original filter component further includes a feedback resistor connected between an inverting input port of the operational amplifier and an output port of the operational amplifier.

6. The filter according to claim 1, characterized in that The original filter component includes an operational amplifier, a first potential shift branch connected between a first output port of the operational amplifier and a second pole of a first target capacitor, and a second potential shift branch connected between a second output port of the operational amplifier and a first pole of a second target capacitor; A first electrode of the first target capacitor is connected to a non-inverting input port of the operational amplifier, and a second electrode of the second target capacitor is connected to an inverting input port of the operational amplifier.

7. The filter according to claim 6, characterized in that The first potential translation branch comprises a first level shifter, a first electrode of the first level shifter is connected to a second electrode of the first target capacitor, and a second electrode of the first level shifter is connected to a first output port of the operational amplifier; The second potential shifting branch includes a second level shifter, a second electrode of the second level shifter is connected to a second electrode of the second target capacitor, and a first electrode of the second level shifter is connected to a second output port of the operational amplifier.

8. The filter according to claim 7, characterized in that The polarity direction of the first target capacitor and the polarity direction of the first level shifter satisfy a first preset condition, so as to reduce or increase the output voltage of the first output port of the operational amplifier within a preset range; The polarity direction of the second target capacitor and the polarity direction of the second level shifter satisfy a second preset condition, so as to increase or decrease the output voltage of the second output port of the operational amplifier within a preset range.

9. The filter according to claim 6, characterized in that The original filter component also includes a first feedback resistor and a second feedback resistor, wherein the first feedback resistor is connected between the non-inverting input port of the operational amplifier and the first output port of the operational amplifier, and the second feedback resistor is connected between the inverting input port of the operational amplifier and the second output port of the operational amplifier.

10. The filter according to any one of claims 1 to 9, characterized in that: The target capacitor, the first target capacitor and / or the second target capacitor are CMOS capacitors.

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