Current sampling circuit and chip

Abstract

The invention discloses a current sampling circuit and a chip. The current sampling circuit is used for executing current sampling on an inductor in the power amplifier and comprises an operation sub-circuit and a filtering sub-circuit, the operation sub-circuit is connected to the two ends of the inductor, and the filtering sub-circuit is connected with the operation sub-circuit; the operation sub-circuit is configured to calculate a voltage difference between the two ends of the inductor, and the filtering sub-circuit is configured to determine a sampling current of the inductor according to the voltage difference. According to the current sampling circuit provided by the embodiment of the invention, through the arrangement of the operation sub-circuit and the filtering sub-circuit, the voltage difference between the two ends of the inductor is directly obtained by using the operation sub-circuit; and further executing equivalent low-pass filtering by using a filtering sub-circuit according to the obtained voltage difference so as to output a sampling current which is equal to the alternating current flowing through the inductor, so that the alternating current sampling current flowing through the inductor is directly sampled and obtained under the condition that the power consumption efficiency of the power amplifier is kept unchanged. And the negative influence on the function of the power amplifier is avoided.

Description

Technical Field

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

[0002] In current technology, inductors are considered ideal devices for energy storage or conversion in Class D audio power amplifiers. In certain closed-loop control systems, it's necessary to sample the current flowing through the inductor. This is typically done indirectly by connecting a sampling resistor in series with the inductor and measuring the voltage across it. However, this approach increases the power consumption of the entire power amplifier due to the insertion of the sampling resistor, which in turn reduces the amplifier's efficiency when performing certain power-related operations. Summary of the Invention

[0003] The present application provides a current sampling circuit.

[0004] The current sampling circuit involved in the embodiments of the present application is used to perform AC current sampling on an inductor in a power amplifier. The circuit includes an operation subcircuit and a filter subcircuit. The operation subcircuit is connected to both ends of the inductor, and the filter subcircuit is connected to the operation subcircuit.

[0005] The operation subcircuit is configured to operate a voltage difference across the inductor, and the filtering subcircuit is configured to determine an AC sampling current of the inductor according to the voltage difference.

[0006] In this way, the current sampling circuit in the embodiment of the present application uses the operation subcircuit and the filtering subcircuit to directly obtain the voltage difference across the inductor using the operation subcircuit, and further uses the filtering subcircuit to perform equivalent low-pass filtering based on the obtained voltage difference to output a sampling current equal to the AC current flowing through the current meter, thereby achieving direct sampling and obtaining of the AC sampling current flowing through the current meter while maintaining the power consumption efficiency of the power amplifier unchanged, thereby avoiding negative impact on the function of the power amplifier.

[0007] In certain embodiments, the operation subcircuit includes a voltage operation module configured as a subtractor based on an operational amplifier;

[0008] The first end of the inductor is connected to the non-inverting input terminal of the operational amplifier, the second end of the inductor is connected to the inverting input terminal of the operational amplifier, and the output terminal of the operational amplifier is connected to the filter sub-circuit.

[0009] In some embodiments, the filtering subcircuit includes a filtering resistor and a filtering capacitor, the first end of the filtering resistor is connected to the output end of the operational amplifier, the second end of the filtering resistor is connected to the first end of the filtering capacitor, the second end of the filtering capacitor is connected to a preset equipotential end, and the sampling current is output from the second end of the filtering resistor.

[0010] In some embodiments, the power amplifier includes a first inductor, a second inductor, and a load, wherein a first end of the load is connected to the first inductor, and a second end of the load is connected to the second inductor;

[0011] The current sampling circuit includes a first operation subcircuit, a first filtering subcircuit, a second operation subcircuit, and a second filtering subcircuit. The first operation subcircuit and the first filtering subcircuit are connected to the first inductor, and the second operation subcircuit and the second filtering subcircuit are connected to the second inductor.

[0012] In some embodiments, the first operation subcircuit includes a first voltage operation module, which is configured as a subtractor based on a first operational amplifier;

[0013] A first end of the first inductor is connected to a non-inverting input of the first operational amplifier, a second end of the first inductor is connected to an inverting input of the first operational amplifier, and an output of the first operational amplifier is connected to the first filtering sub-circuit.

[0014] In some embodiments, the first filtering subcircuit includes a first filtering resistor and a first filtering capacitor, the first end of the first filtering resistor is connected to the output end of the first operational amplifier, the second end of the first filtering resistor is connected to the first end of the first filtering capacitor, the second end of the first filtering capacitor is connected to a preset equipotential end, and the AC sampling current of the first inductor is output from the second end of the first filtering resistor.

[0015] In some embodiments, the second operation subcircuit includes a second voltage operation module, and the second voltage operation module is configured as a subtractor based on a second operational amplifier;

[0016] A first end of the second inductor is connected to a non-inverting input of the second operational amplifier, a second end of the second inductor is connected to an inverting input of the second operational amplifier, and an output of the second operational amplifier is connected to the second filter sub-circuit.

[0017] In some embodiments, the second filtering subcircuit includes a second filtering resistor and a second filtering capacitor, the first end of the second filtering resistor is connected to the output end of the second operational amplifier, the second end of the second filtering resistor is connected to the first end of the second filtering capacitor, the second end of the second filtering capacitor is connected to a preset equipotential end, and the AC sampling current of the second inductor is output from the second end of the second filtering resistor.

[0018] In some embodiments, the first operation subcircuit includes a third resistor and a fourth resistor, and the first filtering subcircuit includes the third resistor, the fourth resistor, and a third filtering capacitor;

[0019] The first end of the third resistor is connected to the first end of the first inductor, the first end of the fourth resistor is connected to the second end of the second inductor, the second end of the third resistor and the second end of the fourth resistor are both connected to the first end of the third filter capacitor, the second end of the third filter capacitor is connected to the preset equipotential terminal, and the AC sampling current of the first inductor is output from the first end of the third filter capacitor.

[0020] In some embodiments, the second operation subcircuit includes a fifth resistor and a sixth resistor, and the first filtering subcircuit includes the fifth resistor, the sixth resistor, and a fourth filtering capacitor;

[0021] The first end of the fifth resistor is connected to the first end of the second inductor, the first end of the sixth resistor is connected to the second end of the first inductor, the second end of the fifth resistor and the second end of the sixth resistor are both connected to the first end of the fourth filter capacitor, the second end of the fourth filter capacitor is connected to the preset equipotential terminal, and the AC sampling current of the second inductor is output from the first end of the fourth filter capacitor.

[0022] The chip in the embodiment of the present application includes the above-mentioned current sampling circuit.

[0023] 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 obvious from the description below, or will be learned through practice of the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] 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:

[0025] Figure 1 This is one of the circuit structure diagrams of the current sampling circuit in the embodiment of the present application;

[0026] Figure 2Schematic diagram of the circuit structure of the voltage operation module / first voltage operation module / second voltage operation module in the embodiment of the present application;

[0027] Figure 3 This is the second circuit structure diagram of the current sampling circuit in the embodiment of the present application;

[0028] Figure 4 This is the third circuit structure diagram of the current sampling circuit in the embodiment of this application.

[0029] Where: V1, voltage source; L, inductor; C L , amplifier capacitance; R L , load; 100, current sampling circuit; 101, operation subcircuit; 102, filtering subcircuit; A, voltage operation module; U A , operational amplifier; R a , reverse resistor; R b , common-phase resistor; R F , feedback resistor; R c , grounding resistor; R, filter resistor; C, filter capacitor; VCC, power supply terminal; M1, first switch tube; M2, second switch tube; L1, first inductor; C L1 , first amplifier capacitor; A1, first voltage operation module; U A1 , first operational amplifier; R1, first filter resistor; C1, first filter capacitor; M3, third switch tube; M4, fourth switch tube; L2, second inductor; C L2 , second amplifier capacitor; A2, second voltage operation module; U A2 , second operational amplifier; R2, second filter resistor; C2, second filter capacitor; R3, third resistor;

[0030] R4, the fourth resistor; C3, the third filter capacitor; R5, the fifth resistor; R6, the sixth resistor; C4, the fourth filter capacitor. DETAILED DESCRIPTION

[0031] The embodiments of the present application are described in detail below. 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 throughout. 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 should not be understood as limiting the embodiments of the present application.

[0032] See also Figure 1 The current sampling circuit 100 in the embodiment of the present application is used to perform current sampling on an inductor L in a power amplifier. The circuit includes an operation subcircuit and a filter subcircuit. The operation subcircuit is connected to both ends of the inductor L, and the filter subcircuit is connected to the operation subcircuit.

[0033] The operation sub-circuit is configured to operate the voltage difference between the two ends of the inductor L, and the filtering sub-circuit is configured to determine the AC sampling current of the inductor L according to the voltage difference.

[0034] Specifically, the current sampling circuit 100 in the embodiment of the present application is mainly used in conjunction with a power amplifier circuit, and its main function is to perform current sampling on the inductor L in the power amplifier circuit. For example, see Figure 1 ,exist Figure 1 In the example shown, the voltage source V1, the inductor L, the amplifier capacitor C L and load R L Together they form a power amplifier circuit, and the current sampling circuit 100 cooperates with the power amplifier circuit to collect the magnitude of the current flowing through the inductor L.

[0035] The current sampling circuit 100 in the embodiment of the present application generally includes two parts: an operation subcircuit 101 and a filtering subcircuit 102. The operation subcircuit 101 is directly connected to the two ends of the inductor L. Its main function is to obtain the voltage difference between the two ends of the inductor L. The operation subcircuit 101 and the filtering subcircuit 102 are connected. The voltage difference obtained by the operation subcircuit 101 will be transmitted to the filtering subcircuit 102 through the connection relationship. The filtering subcircuit 102 performs filtering calculations on this voltage difference to obtain a current signal equal to the current currently flowing through the inductor L.

[0036] In this way, the current sampling circuit 100, which is composed of the operation sub-circuit 101 and the filtering sub-circuit 102, is not directly connected to the loop of the power amplifier. This does not affect the power function of the power amplifier circuit itself. When the power amplifier circuit performs certain power-related operations, its power consumption will not be reduced due to the configuration of the current sampling circuit 100. This achieves the goal of maintaining the power consumption efficiency of the power amplifier as much as possible when performing current sampling on the inductor L.

[0037] In this way, the current sampling circuit 100 in the embodiment of the present application, through the configuration of the operation sub-circuit 101 and the filtering sub-circuit 102, uses the operation sub-circuit 101 to directly obtain the voltage difference across the inductor L, and further uses the filtering sub-circuit 102 to perform equivalent low-pass filtering based on the obtained voltage difference to output a sampling current equal to the AC current flowing through the current meter, thereby achieving direct sampling and obtaining of the AC sampling current flowing through the current meter while maintaining the power consumption efficiency of the power amplifier unchanged, thereby avoiding negative impact on the function of the power amplifier.

[0038] In certain embodiments, see Figure 1 and Figure 2, the operation sub-circuit 101 includes a voltage operation module A, and the voltage operation module A is configured as a subtractor based on an operational amplifier;

[0039] The first end of the inductor L is connected to the operational amplifier U A The second end of the inductor L is connected to the non-inverting input terminal of the operational amplifier U A The inverting input terminal of the operational amplifier U A The output end of is connected to the filtering sub-circuit 102.

[0040] In some embodiments, please see Figure 1 and Figure 2 The filter subcircuit 102 includes a filter resistor R and a filter capacitor C. The first end of the filter resistor R is connected to the operational amplifier U A The output end of the filter resistor R is connected to the first end of the filter capacitor C, the second end of the filter capacitor C is connected to the preset equipotential end, and the sampling current is output from the second end of the filter resistor R.

[0041] Specifically, see Figure 1 , Figure 1 FIG. 1 shows an example of a current sampling circuit 100 and a power amplifier circuit used in conjunction with the current sampling circuit 100 in the embodiment of the present application. Figure 1 In the example shown, the power amplifier circuit includes a voltage source V1, an inductor L, an amplifier capacitor C L and load R L , where the inductor L and the amplifier capacitor C L Together they form an LC filter structure, which filters the voltage generated by the voltage source V1 and supplies it to the load R L , and the operator circuit 101 is directly connected across the inductor L.

[0042] For example, the operation subcircuit 101 includes a set of voltage operation modules A. Generally, the voltage operation module A can be implemented as a subtractor based on an operational amplifier. Figure 2 , operational amplifier U A The non-inverting input terminal is connected to the non-inverting resistor R b Connected to the first end of the inductor L and connected to the ground through the resistor R c To achieve grounding, the operational amplifier U A The inverting input is connected to the inverting resistor R a Connected to the second end of the inductor L, the operational amplifier U A The output terminal passes through the feedback resistor R F It is connected to the inverting input terminal and also connected to the filtering sub-circuit 102 .

[0043] Then according to the nature of the subtractor, the in-phase resistor R b Equal to the inverting resistor Ra , grounding resistance R c Equal to the feedback resistor R F In this case, the voltage at the output terminal satisfies the following formula:

[0044]

[0045] in:

[0046] Uo is the operational amplifier U A The voltage at the output,

[0047] U b For the operational amplifier U A The voltage at the non-inverting input terminal, which corresponds to the voltage at the first terminal of the inductor L,

[0048] U a For the operational amplifier U A The voltage at the inverting input terminal, which corresponds to the voltage at the second terminal of the inductor L,

[0049] Then the feedback resistor R F With the inverting resistor R a It is known that the operational amplifier U A The proportionality coefficient between the voltage at the output terminal and the voltage difference across the inductor L is also known, so the voltage difference across the inductor L can be obtained by using the above subtractor. More specifically, if the in-phase resistor R b , reverse resistor R a , grounding resistance R c And the feedback resistor R F When all four are equal, the operational amplifier U A The output voltage is equal to the voltage difference across the inductor L, so an equal in-phase resistor R can be set in the voltage operation module A. b , reverse resistor R a , grounding resistance R c And the feedback resistor R F , thus, based on the above subtractor structure, the voltage across the inductor L can be obtained in an equivalent manner.

[0050] Furthermore, according to the characteristics of inductance, the current I flowing through the inductor L is L Equal to the voltage U across the inductor L L and the inductive reactance Z of the inductor L L The ratio of:

[0051]

[0052] in:

[0053] s is the Laplace variable, and L is the inductance of the inductor L.

[0054] The RC filter circuit is used to filter the current I flowing through the inductor L. L Performing a first-order high-pass filter can remove I L The DC component in I L The AC component I L (AC):

[0055]

[0056] in:

[0057] HPF(s) is the transfer function of the first-order high-pass filter,

[0058] s is the Laplace variable,

[0059] L is the inductance of the inductor L,

[0060] ω c is the cut-off frequency, which is equal to the inverse of the product of the resistance and capacitance in the RC filter circuit.

[0061] Then, according to the above high-pass filtering formula, it is equivalent to performing low-pass filtering on the voltage difference across the inductor L to obtain the AC current flowing through the inductor L. The equivalent low-pass filtering process is:

[0062]

[0063] Where LPF(s) is the transfer function of the first-order low-pass filter:

[0064]

[0065] Then, according to the above derivation process, we can directly use the operational amplifier U A The output end of the filter sub-circuit 102 is connected to the filter sub-circuit 102, see Figure 1 as well as Figure 2 , wherein the filter sub-circuit 102 is an RC filter circuit, wherein the first end of the filter resistor R is connected to the operational amplifier U A The output end of the filter resistor R is connected to the first end of the filter capacitor C, the second end of the filter capacitor C is connected to the preset equipotential end, and the current output from the second end of the filter resistor R is equal to the AC current flowing through the inductor L, thereby completing the sampling process of the AC current flowing through the inductor L.

[0066] It should also be noted that the voltage operation module A can also adopt a circuit structure for obtaining the voltage difference in the current related technology other than the above-mentioned operational amplifier-based subtractor method, and the above content about the subtractor is only an exemplary description.

[0067] See also Figure 3 In some embodiments, the power amplifier includes a first inductor L1, a second inductor L2, and a load R L , load R L The first end of the first inductor L1 is connected to the load R L The second end of the second inductor L2 is connected;

[0068] The current sampling circuit includes a first operation subcircuit, a first filtering subcircuit, a second operation subcircuit and a second filtering subcircuit. The first operation subcircuit and the first filtering subcircuit are connected to the first inductor L1, and the second operation subcircuit and the second filtering subcircuit are connected to the second inductor L2.

[0069] Specifically, based on the above implementation, for example, please refer to Figure 4 , Figure 4 The power amplifier shown adopts a bridge output circuit structure, including two groups of inductors, namely the first inductor L1 and the second inductor L2. The two groups of inductors belong to two different LC filter structures. The first end of the first inductor L1 is connected to the power supply terminal VCC and the preset equal potential terminal through the first switch tube M1 and the second switch tube M2. The voltage at the first end of the first inductor L1 is the first switch output SW+. Similarly, the second end of the second inductor L2 is connected to the power supply terminal VCC and the preset equal potential terminal through the third switch tube M3 and the fourth switch tube M4. The voltage at the first end of the second inductor L2 is the second switch output SW-. The first switch output SW+ passes through the first inductor L1 and the first amplifier capacitor C L1 The LC filter structure formed by the first output voltage OUT+ is obtained. Similarly, the second switch output SW- is connected to the second inductor L2 and the second amplifier capacitor C L2 The LC filter structure formed by the second output voltage OUT- is output to the load R L .

[0070] Based on the above-described power amplifier structure, the current sampling circuit in the embodiments of the present application illustratively includes two parts, one for sampling the first inductor L1 and the other for sampling the second inductor L2. The part sampling the first inductor L1 includes a first operator subcircuit and a first filter subcircuit, while the part sampling the second inductor L2 includes a second operator subcircuit and a second filter subcircuit.

[0071] Please continue reading Figure 3 In some embodiments, the first operation sub-circuit includes a first voltage operation module A1, which is configured based on a first operational amplifier U A1 The subtractor;

[0072] The first end of the first inductor L1 is connected to the first operational amplifier U A1 The second end of the first inductor L1 is connected to the non-inverting input terminal of the first operational amplifier U A1 The inverting input terminal of the first operational amplifier U A1 The output end is connected to the first filtering sub-circuit.

[0073] In some embodiments, the first filtering subcircuit includes a first filtering resistor R1 and a first filtering capacitor C1. The first end of the first filtering resistor R1 is connected to the first operational amplifier U A1 The output end of the first filter resistor R1 is connected to the first end of the first filter capacitor C1, the second end of the first filter capacitor C1 is connected to the preset equipotential end, and the sampling current of the first inductor L1 is output from the second end of the first filter resistor R1.

[0074] Specifically, based on the above embodiment, for the structure of the first operator sub-circuit and the first filter sub-circuit, reference can be made to the circuit structure and connection method of the operator sub-circuit and the filter sub-circuit for performing current sampling on a single inductor in the above embodiment. The logic for performing current sampling is the same as the logic for performing current sampling on a single inductor based on the operator sub-circuit and the filter sub-circuit in the above embodiment.

[0075] For example, the first operation sub-circuit includes a first voltage operation module A1. The first voltage operation module A1 can be implemented as a subtractor based on an operational amplifier. For a specific structure, please refer to Figure 2 , the first operational amplifier U A1 The non-inverting input terminal is connected to the non-inverting resistor R b connected to the first end of the first inductor L1 and connected to the ground through the resistor R c To achieve grounding, the first operational amplifier U A1 The inverting input is connected to the inverting resistor R a Connected to the second end of the first inductor L1, the first operational amplifier U A1 The output terminal passes through the feedback resistor R F The inverting input terminal is connected to the first filtering sub-circuit.

[0076] The first filter sub-circuit is an RC filter circuit, wherein the first end of the first filter resistor R1 is connected to the first operational amplifier U A1 The output end of the first filter resistor R1, the second end of the first filter capacitor C1 is connected to the first end of the first filter capacitor C1, the second end of the first filter capacitor C1 is connected to the preset equipotential end, and the current I output by the second end of the first filter resistor R1 sense1 That is, it is equal to the AC current flowing through the first inductor L1 , thereby completing the sampling process of the current flowing through the first inductor L1 .

[0077] Please continue reading Figure 3 In some embodiments, the second operation sub-circuit includes a second voltage operation module A2, which is configured based on the second operational amplifier U A2 The subtractor;

[0078] The first end of the second inductor L2 is connected to the second operational amplifier U A2 The second end of the second inductor L2 is connected to the non-inverting input terminal of the second operational amplifier U A2 The inverting input terminal of the second operational amplifier U A2 The output end is connected to the second filtering sub-circuit.

[0079] In some embodiments, the second filtering subcircuit includes a second filtering resistor R2 and a second filtering capacitor C2. The first end of the second filtering resistor R2 is connected to the second operational amplifier U A2 The output end of the second filter resistor R2 is connected to the first end of the second filter capacitor C2, the second end of the second filter capacitor C2 is connected to the preset equipotential end, and the sampling current of the second inductor L2 is output from the second end of the second filter resistor R2.

[0080] Specifically, based on the above embodiment, for the structure of the second operator sub-circuit and the second filter sub-circuit, reference can be made to the circuit structure and connection method of the operator sub-circuit and the filter sub-circuit for performing current sampling on a single inductor in the above embodiment. The logic for performing current sampling is the same as the logic for performing current sampling on a single inductor based on the operator sub-circuit and the filter sub-circuit in the above embodiment.

[0081] For example, the second operation sub-circuit includes a second voltage operation module A2. The second voltage operation module A2 can be implemented by a subtractor based on an operational amplifier. For a specific structure, please refer to Figure 2 , the second operational amplifier U A2 The non-inverting input terminal is connected to the non-inverting resistor R b connected to the first end of the second inductor L2 and connected to the ground through the resistor R c To achieve grounding, the second operational amplifier U A2 The inverting input is connected to the inverting resistor R a connected to the second end of the second inductor L2, the second operational amplifier U A2 The output terminal passes through the feedback resistor R F The inverting input terminal is connected to the second filtering sub-circuit.

[0082] The second filter sub-circuit is an RC filter circuit, wherein the first end of the second filter resistor R2 is connected to the second operational amplifier U A2The output end of the second filter resistor R2 is connected to the first end of the second filter capacitor C2, the second end of the second filter capacitor C2 is connected to the preset equipotential end, and the current I output by the second end of the second filter resistor R2 sense2 That is, it is equal to the AC current flowing through the second inductor L2, thereby completing the sampling process of the current flowing through the second inductor L2.

[0083] See also Figure 4 In some embodiments, the first operation subcircuit includes a third resistor R3 and a fourth resistor R4, and the first filtering subcircuit includes a third resistor R3, a fourth resistor R4, and a third filtering capacitor C3;

[0084] A first end of the third resistor R3 is connected to the first end of the first inductor L1, a first end of the fourth resistor R4 is connected to the second end of the second inductor L2, a second end of the third resistor R3 and a second end of the fourth resistor R4 are both connected to the first end of the third filter capacitor C3, a second end of the third filter capacitor C3 is connected to the preset equipotential end, and the sampling current of the first inductor L1 is output from the first end of the third filter capacitor C3.

[0085] In some embodiments, the second operation subcircuit includes a fifth resistor R5 and a sixth resistor R6, and the first filtering subcircuit includes a fifth resistor R5, a sixth resistor R6, and a fourth filtering capacitor C4;

[0086] A first end of the fifth resistor R5 is connected to the first end of the second inductor L2, a first end of the sixth resistor R6 is connected to the second end of the first inductor L1, a second end of the fifth resistor R5 and a second end of the sixth resistor R6 are both connected to the first end of the fourth filter capacitor C4, a second end of the fourth filter capacitor C4 is connected to the preset equipotential end, and the sampling current of the second inductor L2 is output from the first end of the fourth filter capacitor C4.

[0087] Specifically, based on the above embodiment, since the power amplifier circuit, the operation subcircuit and the filter subcircuit in the above embodiment adopt a differential output structure, the voltage amplitudes of the first output voltage OUT+ and the second output voltage OUT- obtained by the two sets of LC filter structures are equal but the polarities are opposite. Figure 4 In the circuit shown, the voltage U across the first inductor L1 is L1 and the voltage U across the second inductor L2 L2 Satisfies the following equality relationship:

[0088] U L1 =(SW+)-(OUT+)=(SW+)+(OUT-)

[0089] U L2 =(SW-)-(OUT-)=(SW-)+(OUT+)

[0090] According to the above equation, except Figure 3 In addition to the method of using a subtractor to obtain the voltage across the corresponding inductor, the voltage across the corresponding inductor can also be obtained by using an adder circuit by changing the connection structure.

[0091] Therefore, see Figure 4 , Figure 4 Another current sampling circuit used in conjunction with a power amplifier circuit is shown. First of all, it should be noted that Figure 4 The current sampling circuit shown in Figure 3 The current sampling circuit in the same power amplifier circuit is used with the Figure 3 The current sampling circuit in the example is different in that: Figure 4 The circuit shown needs to rely on at least two inductors to obtain the voltages across the two inductors and thus to sample the currents of the two inductors. However, for a power amplifier circuit with only a single inductor, Figure 4 The current sampling circuit shown is not suitable.

[0092] According to the above equation, Figure 4 In the current sampling circuit shown, for the first operation sub-circuit and the first filtering sub-circuit corresponding to the first inductor L1, the first operation sub-circuit includes a third resistor R3 and a fourth resistor R4, wherein the first end of the third resistor R3 is connected to the first end of the first inductor L1, but the first end of the fourth resistor R4 is connected to the second end of the second inductor L2. The purpose of this connection method is to use the third resistor R3 to introduce the first switch output SW+, and use the fourth resistor R4 to introduce the second output voltage OUT-. In this way, the first switch output SW+ and the second output voltage OUT- can be added together, thereby directly converting the voltage U across the first inductor L1 to L1 In the first filtering sub-circuit, the parallel equivalent resistance of the third resistor R3 and the fourth resistor R4 is used as the filtering resistor, and a third filtering capacitor C3 is provided. The second end of the third resistor R3 is connected to the second end of the fourth resistor R4, and the first end of the third filtering capacitor C3 is connected to the connection point of the second end of the third resistor R3 and the second end of the fourth resistor R4, while the second end of the third filtering capacitor C3 is connected to the preset equipotential terminal. In this way, the connection relationship between the third resistor R3 and the first end of the fourth resistor R4 reduces the voltage U across the first inductor L1. L1 The RC filter structure formed by the parallel equivalent resistance of the third resistor R3 and the fourth resistor R4 and the third filter capacitor C3 is further derived according to U L1 Determine a current signal I that is equal to the current flowing through the first inductor L1 sense1, thereby realizing AC current sampling for the first inductor L1.

[0093] Similarly, for the second operation sub-circuit and the second filtering sub-circuit corresponding to the second inductor L2, the second operation sub-circuit includes a fifth resistor R5 and a sixth resistor R6, wherein the first end of the fifth resistor R5 is connected to the first end of the second inductor L2, but the first end of the sixth resistor R6 is connected to the second end of the second inductor L2. The purpose of this connection method is to use the fifth resistor R5 to introduce the second switch output SW-, and use the sixth resistor R6 to introduce the first output voltage OUT+. In this way, the second switch output SW- and the first output voltage OUT+ can be added together, thereby directly increasing the voltage U across the second inductor L2. L2 In the first filtering sub-circuit, the parallel equivalent resistance of the fifth resistor R5 and the sixth resistor R6 is used as the filtering resistor, and a fourth filtering capacitor C4 is provided. The second end of the fifth resistor R5 is connected to the second end of the sixth resistor R6, while the first end of the fourth filtering capacitor C4 is connected to the connection point of the second end of the fifth resistor R5 and the second end of the sixth resistor R6, and the second end of the fourth filtering capacitor C4 is connected to the preset equipotential terminal. In this way, the connection relationship between the fifth resistor R5 and the first end of the sixth resistor R6 reduces the voltage U across the second inductor L2. L2 The RC filter structure formed by the parallel equivalent resistance of the fifth resistor R5 and the sixth resistor R6 and the fourth filter capacitor C4 is further used according to U L2 Determine the current signal I that is equal to the current flowing through the second inductor L2 sense2 , thereby realizing AC current sampling for the second inductor L2.

[0094] For example, for the sake of simplicity in circuit construction, the resistance values of the third resistor R3, the fourth resistor R4, the fifth resistor R5, and the sixth resistor R6 can be set to be completely equal. In this way, the process of obtaining the voltage across the corresponding inductor can avoid artificially introducing unnecessary proportional coefficients as much as possible, reduce the probability of error, and thus improve the accuracy of introducing the voltage across the corresponding inductor.

[0095] The chip in the embodiment of the present application includes the above-mentioned current sampling circuit.

[0096] In the description of this specification, the reference 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 mutually inconsistent.

[0097] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code comprising 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 be performed out of 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 those skilled in the art to which the embodiments of the present application belong.

[0098] 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 current sampling circuit, characterized in that: The circuit is used to perform current sampling on an inductor in a class D power amplifier, and the circuit includes an operation subcircuit and a filtering subcircuit, wherein the operation subcircuit is connected to both ends of the inductor, and the filtering subcircuit is connected to the operation subcircuit; The operation subcircuit is configured to operate a voltage difference across the inductor, and the filtering subcircuit is configured to determine an AC sampling current of the inductor according to the voltage difference.

2. The circuit according to claim 1, characterized in that The operation subcircuit includes a voltage operation module, and the voltage operation module is configured as a subtractor based on an operational amplifier; The first end of the inductor is connected to the non-inverting input terminal of the operational amplifier, the second end of the inductor is connected to the inverting input terminal of the operational amplifier, and the output terminal of the operational amplifier is connected to the filter sub-circuit.

3. The circuit according to claim 2, characterized in that The filtering subcircuit includes a filtering resistor and a filtering capacitor, wherein the first end of the filtering resistor is connected to the output end of the operational amplifier, the second end of the filtering resistor is connected to the first end of the filtering capacitor, the second end of the filtering capacitor is connected to a preset equipotential end, and the sampling current is output from the second end of the filtering resistor.

4. The circuit according to claim 1, wherein: The power amplifier includes a first inductor, a second inductor, and a load, wherein a first end of the load is connected to the first inductor, and a second end of the load is connected to the second inductor; The current sampling circuit includes a first operation subcircuit, a first filtering subcircuit, a second operation subcircuit, and a second filtering subcircuit. The first operation subcircuit and the first filtering subcircuit are connected to the first inductor, and the second operation subcircuit and the second filtering subcircuit are connected to the second inductor.

5. The circuit according to claim 4, characterized in that The first operation subcircuit includes a first voltage operation module, which is configured as a subtractor based on a first operational amplifier; A first end of the first inductor is connected to a non-inverting input of the first operational amplifier, a second end of the first inductor is connected to an inverting input of the first operational amplifier, and an output of the first operational amplifier is connected to the first filtering sub-circuit.

6. The circuit according to claim 5, characterized in that The first filtering subcircuit includes a first filtering resistor and a first filtering capacitor, wherein a first end of the first filtering resistor is connected to the output end of the first operational amplifier, a second end of the first filtering resistor is connected to the first end of the first filtering capacitor, and a second end of the first filtering capacitor is connected to a preset equipotential end. The AC sampling current of the first inductor is output from the second end of the first filtering resistor.

7. The circuit according to claim 4, characterized in that The second operation subcircuit includes a second voltage operation module, and the second voltage operation module is configured as a subtractor based on a second operational amplifier; A first end of the second inductor is connected to a non-inverting input of the second operational amplifier, a second end of the second inductor is connected to an inverting input of the second operational amplifier, and an output of the second operational amplifier is connected to the second filter sub-circuit.

8. The circuit according to claim 7, characterized in that The second filtering subcircuit includes a second filtering resistor and a second filtering capacitor, wherein a first end of the second filtering resistor is connected to the output end of the second operational amplifier, a second end of the second filtering resistor is connected to the first end of the second filtering capacitor, and a second end of the second filtering capacitor is connected to a preset equipotential end. The AC sampling current of the second inductor is output from the second end of the second filtering resistor.

9. The circuit according to claim 4, characterized in that The first operation sub-circuit includes a third resistor and a fourth resistor, and the first filtering sub-circuit includes the third resistor, the fourth resistor and a third filtering capacitor; The first end of the third resistor is connected to the first end of the first inductor, the first end of the fourth resistor is connected to the second end of the second inductor, the second end of the third resistor and the second end of the fourth resistor are both connected to the first end of the third filter capacitor, the second end of the third filter capacitor is connected to the preset equipotential terminal, and the AC sampling current of the first inductor is output from the first end of the third filter capacitor.

10. The circuit according to claim 4, characterized in that The second operation sub-circuit includes a fifth resistor and a sixth resistor, and the first filtering sub-circuit includes the fifth resistor, the sixth resistor and a fourth filtering capacitor; The first end of the fifth resistor is connected to the first end of the second inductor, the first end of the sixth resistor is connected to the second end of the first inductor, the second end of the fifth resistor and the second end of the sixth resistor are both connected to the first end of the fourth filter capacitor, the second end of the fourth filter capacitor is connected to the preset equipotential terminal, and the AC sampling current of the second inductor is output from the first end of the fourth filter capacitor.

11. A chip, characterized in that: The chip includes the current sampling circuit according to any one of claims 1 to 10.

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