High-bandwidth Hall current sensor chip and circuit structure thereof

Abstract

The invention provides a high-bandwidth Hall current sensor chip and a circuit structure thereof. The circuit structure comprises a first Hall element and a second Hall element which are used for sensing a detection current and generating a differential voltage signal; the three-stage low-frequency amplification chopping module is used for carrying out high-precision amplification and ripple and offset elimination on the differential signals and comprises a high-bandwidth fully-differential amplifier input stage and a high-bandwidth fully-differential amplifier output stage, and the high-bandwidth fully-differential amplifier input stage comprises two operational amplifiers; the comparator is used for comparing the amplified signal output by the three-stage low-frequency amplifying and chopping module with a reference signal to generate a final output signal; and the programmer is used for adjusting the output sensitivity and / or the static output voltage. According to the high-bandwidth current sensor, a dual-channel signal transmission structure and a three-stage low-frequency amplification chopping module are adopted, high bandwidth can be achieved, the ever-increasing frequency requirement is met, the compromise between residual offset and residual ripple amplitude is solved, and quick response of the high-bandwidth current sensor can be achieved.

Description

Technical Field

[0001] The present application relates to the technical field of current sensors, and in particular to a high-bandwidth Hall current sensor chip and a circuit structure thereof. Background Art

[0002] The Hall current sensor is a commonly used current sensor. It works based on the Hall effect principle. The basic working principle is: when current passes through a conductor, a magnetic field proportional to the current will be generated around the conductor; the Hall element contained in the Hall current sensor will sense this magnetic field and generate a Hall voltage at both ends of the Hall element; after the Hall voltage is amplified and processed, it outputs a voltage signal proportional to the measured current, thereby realizing non-contact measurement of the current. Currently, the commonly used Hall current sensors include open-loop and closed-loop types.

[0003] refer to Figure 1 , shows the basic working principle of the open-loop Hall current sensor. The open-loop Hall current sensor adopts the Hall direct amplification principle. When an AC or DC current (Ip) passes through a wire, a magnetic field is generated around it, and the magnitude of this magnetic field is proportional to the strength of the current; the generated magnetic field is gathered in the magnetic ring, and is measured and amplified by the Hall element in the air gap of the magnetic ring; the output voltage VS of the Hall element accurately reflects the primary current Ip. The signal output by the Hall element reflects the strength and direction of the AC or DC current. By measuring the output signal of the Hall element, the magnitude of the AC or DC current passing through the wire can be accurately measured.

[0004] refer to Figure 2 , shows the basic working principle of the closed-loop Hall current sensor. The closed-loop Hall current sensor adopts the magnetic balance principle and is a compensation sensor. Figure 1 The difference is that Figure 2 The magnetic field generated by the primary current Ip at the magnetic ring is compensated by the magnetic field generated by a secondary coil current, and its compensation current Is accurately reflects the primary current Ip, so that the Hall device is in a working state of detecting zero magnetic flux. The specific working process is: when a current Ip passes through the main circuit, the magnetic field generated on the wire is gathered by the magnetic ring and induced to the Hall element, and the generated signal output is used to drive the power tube and turn it on, thereby obtaining a compensation current Is; this current Is then passes through the secondary coil multi-turn winding to generate a magnetic field, which is exactly opposite to the magnetic field generated by the measured current Ip, thereby compensating the original magnetic field. At this time, the Hall device plays the role of indicating zero magnetic flux, and Ip can be tested by Is at this time. Generally, a measuring resistor is used to convert the current Is into a voltage, and the output signal is a voltage signal.

[0005] In the field of new energy, the application of Hall sensors is becoming more and more extensive, and the requirements for frequency response are becoming higher and higher, especially in high-speed rotating equipment such as brushless motors, where the frequency response requirements for Hall sensors range from a few Hz to tens of kHz. The frequency of AC, that is, the number of periodic changes per unit time, is measured in Hertz (Hz). Usually, the operating frequency of 220V AC is 50Hz or 60Hz. However, in power electronics applications, such as rectifier or inverter circuits, the switching frequency can reach hundreds of kHz. With the emergence of new materials such as semiconductor switching devices such as silicon carbide (SiC) and gallium nitride (GaN), the switching frequency can even reach above MHz.

[0006] The existing ACS7xx series chips are commonly used Hall effect linear current sensors in the industry. They provide effective solutions for AC or DC current measurement in industrial, commercial and communication systems. However, they can hardly meet the current higher requirements for frequency response.

[0007] Therefore, providing a Hall sensor with a larger bandwidth has become a technical problem that needs to be solved urgently. Summary of the invention

[0008] The present application proposes a high-bandwidth Hall current sensor chip and its circuit structure.

[0009] In a first aspect, the present application provides a circuit structure of a high-bandwidth Hall current sensor chip, comprising: a first Hall element and a second Hall element, a three-stage low-frequency amplification chopper module connected to the first Hall element and the second Hall element, a comparator connected to the three-stage low-frequency amplification chopper module, and a programmer connected to the comparator;

[0010] The first Hall element and the second Hall element are used to sense a detection current and generate a differential voltage signal related to the detection current, wherein the differential voltage signal includes: a low level signal generated by the first Hall element and a high level signal generated by the second Hall element;

[0011] The three-stage low-frequency amplification and chopping module is used to perform high-precision amplification on the differential signal and to eliminate ripples and offsets, and includes a high-bandwidth fully differential amplifier input stage and a high-bandwidth fully differential amplifier output stage, wherein the high-bandwidth fully differential amplifier input stage includes a first operational amplifier for inverting and amplifying the low-level signal and a second operational amplifier for in-phase amplification of the high-level signal;

[0012] The comparator is used to compare the amplified signal output by the three-stage low-frequency amplification and chopping module with a reference signal to generate a final output signal;

[0013] The programmer is used to adjust the output sensitivity and / or static output voltage of the comparator.

[0014] In some optional embodiments, the device further comprises: a conductor circuit, a first voltage regulator, a second voltage regulator, and a temperature sensor;

[0015] The conductor circuit is used as a flow path for the detection current;

[0016] The first voltage regulator is used to provide a first power supply voltage to the first Hall element, the second Hall element, the high-bandwidth fully differential amplifier input stage, the high-bandwidth fully differential amplifier output stage, and the comparator, and adjust the first power supply voltage according to a temperature compensation signal provided by the temperature sensor;

[0017] A second voltage regulator, used for providing a second power supply voltage to the programmer;

[0018] The temperature sensor is used to provide a temperature compensation signal to the first voltage stabilizer, and control the first voltage stabilizer to stop providing the first power supply voltage when the working environment temperature exceeds a set range.

[0019] In some optional implementations, the three-stage low-frequency amplification and chopping module is provided with a gain bootstrap circuit and a common-mode feedback circuit.

[0020] In some optional implementations, the programmer is also used to connect to an external MCU program burner.

[0021] In some optional implementations, the reference signal used by the comparator includes:

[0022] a first reference signal from the programmer; and / or

[0023] A second reference signal is derived from the high bandwidth fully differential amplifier input stage.

[0024] In some optional implementations, when the refresh rate and amplitude of the first reference signal are both greater than those of the second reference signal, the comparator compares the first reference signal with the first comparison signal to generate the output signal.

[0025] In some optional implementations, when the program has not been burned into the programmer, the comparator uses the second reference signal to compare with the first comparison signal to generate the output signal.

[0026] In some optional implementations, the bandwidth is not less than 120 KHz, and the maximum input reference offset voltage does not exceed 3 μV.

[0027] In some optional embodiments, the operating temperature range of the comparator is -50°C-85°C.

[0028] In a second aspect, the present application provides a high-bandwidth Hall current sensor chip, comprising the circuit structure of the high-bandwidth Hall current sensor chip as described in the first aspect.

[0029] As mentioned above, the present application proposes a circuit structure of a high-bandwidth Hall current sensor chip and a high-bandwidth Hall current sensor chip including the circuit structure. The present application adopts a dual-channel signal transmission structure, and a high-bandwidth fully differential amplifier input stage and a high-bandwidth fully differential amplifier output stage form a three-stage low-frequency amplification and chopping module to amplify the differential signal sensed by the Hall element with high precision and eliminate ripples and offsets. In this way, high bandwidth can be achieved to meet the growing frequency requirements and solve the compromise between residual offset and residual ripple amplitude. In addition, while optimizing low offset or high bandwidth, the present application can also achieve fast response of high-bandwidth current sensors. For example, the rise time of high-bandwidth current sensors is less than 1 microsecond, while the bandwidth of voltage sensors is generally controlled within 15kHz. In addition, the present application can also improve anti-interference capability, output accuracy, output stability, and can adjust output sensitivity and / or static output voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0031] Figure 1 This is a schematic diagram of the basic working principle of an open-loop Hall current sensor;

[0032] Figure 2 This is a schematic diagram of the basic working principle of a closed-loop Hall current sensor;

[0033] Figure 3 It is a structural schematic diagram of an embodiment of a circuit structure of a high-bandwidth Hall current sensor chip according to the present application;

[0034] Figure 4 It is a schematic diagram of the circuit structure of a single-stage common emitter amplifier;

[0035] Figure 5 yes Figure 4 Schematic diagram of the junction capacitance when the emitter of the amplifier is decoupled;

[0036] Figure 6 It is a structural diagram of a differential amplifier;

[0037] Figure 7 is based on Figure 6A structural schematic diagram of a differential amplifier with a common-mode input signal;

[0038] Figure 8 It is a schematic diagram of the relationship between the gain and frequency of an OPA111 operational amplifier;

[0039] Fig. 9 This is a gain-bandwidth diagram of an OPA111 operational amplifier;

[0040] Fig.10 It is a structural schematic diagram of a two-stage fully differential amplifier with gain bootstrapping of the present application;

[0041] Fig.11 The circuit structure of the chip of the two-stage fully differential amplifier with gain bootstrapping of the present application is as a whole;

[0042] Fig.12 It is a circuit structure diagram of a fully differential operational amplifier with gain bootstrapping and a common-mode feedback circuit of the present application;

[0043] Figure 13-Figure 15 This is a process structure diagram generated according to the proprietary circuit of the Hall current sensor chip of this application. DETAILED DESCRIPTION

[0044] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It should also be noted that, for ease of description, only the parts related to the relevant invention are shown in the accompanying drawings.

[0045] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating directions or positional relationships, are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0046] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", etc. should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0047] In the description of the present application, it should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other.

[0048] The bandwidth design and amplifier frequency of the existing ACS7xx series Hall current sensor chip circuit are shown in Table 1 below.

[0049] Table 1 Parameters and bandwidth of ACS7xx series Hall current sensor chips

[0050]

[0051] The relationship between the bandwidth marked in the general current sensor specification (such as Table 1) and the frequency of the measured signal is as follows: There is a correlation between the two, but it cannot be said that the frequency of the measured signal is the bandwidth of the sensor. The bandwidth (Frequency bandwidth) of the current sensor is a frequency range, which can be called the bandwidth or frequency range. As the frequency of the measured current continues to rise or fall, the output signal of the current sensor will attenuate. When the output signal attenuates to a certain value (refer to the -3dB definition below), the frequency is the upper and lower limits of the frequency, and the difference between the upper and lower limits is the bandwidth of the current sensor. Therefore, the bandwidth is the frequency range in Hz that the circuit can effectively process the signal; the response time, which is the reciprocal of the frequency, is the speed at which the circuit reacts to changes in the input signal, represented by f.

[0052] As shown in Table 1, the upper limit of the bandwidth range of the existing ACS7xx series Hall current sensor chips is approximately 120KHz, which is difficult to meet the current increasing frequency requirements.

[0053] The main purpose of this application is to provide a high-bandwidth Hall current sensor chip and its circuit structure, which can meet the growing frequency demand by enhancing the working bandwidth of the Hall current sensor chip. For example, under the Bi-CMOS (Bipolar-Bipolar-CMOS-DMOS, "Bipolar-Complementary Metal Oxide Semiconductor-Double Diffused Metal Oxide Semiconductor) process, the bandwidth of the Hall current sensor is extended from a few Hz to more than hundreds of kHz.

[0054] The present application can use CMOS magnetic sensor chip design technology to optimize for low offset or high bandwidth while achieving fast response of high-bandwidth current sensors. For example, the rise time of a high-bandwidth current sensor is less than 1 microsecond (μs), while the bandwidth of a voltage sensor is generally controlled within 15kHz. For example, for a 6400Vrms high voltage sensor, the rise time is about 500 microseconds (μs) and the bandwidth is about 700Hz.

[0055] In order to achieve the separation of Hall voltage and Hall offset voltage, the present application can adopt a dual-channel signal transmission structure to improve the overall system bandwidth. In the design, the low-frequency path and the high-frequency path use the same op amp and Hall element. In the low-frequency path, high-precision differential technology and chopping filtering technology are used to solve the compromise between residual offset and residual ripple amplitude. In addition, while the input stage transconductance is being adjusted, a three-stage ripple elimination loop (RRL) is introduced, that is, a three-stage low-frequency amplification chopping technology is introduced, and a multi-stage amplifier is used to form a three-stage low-frequency amplification chopping module to eliminate ripples and offsets.

[0056] refer to Figure 3 , shows the circuit structure of the high-bandwidth Hall current sensor chip of the present application. Figure 3 As shown, the circuit structure of the high-bandwidth Hall current sensor chip of the present application includes:

[0057] A first Hall element U4 and a second Hall element U5, a three-stage low-frequency amplifying and chopping module connected to the first Hall element U4 and the second Hall element U5, a comparator U11 connected to the three-stage low-frequency amplifying and chopping module, and a programmer U8 connected to the comparator U11; wherein:

[0058] The first Hall element U4 and the second Hall element U5 are used to sense the detection current and generate a differential voltage signal related to the detection current, wherein the differential voltage signal includes: a low level signal generated by the first Hall element U4 and a high level signal generated by the second Hall element U5;

[0059] A three-stage low-frequency amplification chopper module, used for high-precision amplification of differential signals and ripple and offset elimination, including a high-bandwidth fully differential amplifier input stage U6 and a high-bandwidth fully differential amplifier output stage U7, wherein the high-bandwidth fully differential amplifier input stage U6 further includes a first operational amplifier for inverting amplification of low-level signals and a second operational amplifier for in-phase amplification of high-level signals;

[0060] The comparator U11 is used to compare the amplified signal output by the three-stage low-frequency amplification chopper module with the reference signal to generate a final output signal;

[0061] The programmer U8 is used to adjust the output sensitivity and / or static output voltage of the comparator U11.

[0062] Furthermore, the circuit structure of the high-bandwidth Hall current sensor chip of the present application may also include: a wire circuit U2, a first voltage regulator U1, a second voltage regulator U3 and a temperature sensor U10; wherein,

[0063] The conductor circuit U2 is used as a flow path for the detection current;

[0064] A first voltage regulator U1 is used to provide a first power supply voltage to the first Hall element U4, the second Hall element U5, the high-bandwidth fully differential amplifier input stage U6, the high-bandwidth fully differential amplifier output stage U7, and the comparator U11, and adjust the first power supply voltage according to a temperature compensation signal provided by the temperature sensor U10;

[0065] A second voltage regulator U3, used for providing a second power supply voltage to the programmer U8;

[0066] The temperature sensor U10 is used to provide a temperature compensation signal to the first regulator U1 (pin 2 of U10 can be connected to pin 3 of U1), and control the first regulator U1 to stop providing the first power supply voltage when the working environment temperature exceeds a set range.

[0067] Here, the first voltage stabilizer U1 and the second voltage stabilizer U3 can provide various stabilized power supply voltages, such as 5V / 3.3V / 1.8V, for the circuit structure of the entire chip and the programmer for burning.

[0068] In some optional implementations, the three-stage low-frequency amplifier chopper module is provided with a gain bootstrap circuit and a common-mode feedback circuit.

[0069] In some optional implementations, the programmer U8 is also used to connect to an external MCU program burner U9.

[0070] In some optional implementations, the reference signal used by the comparator includes:

[0071] A first reference signal from programmer U8 (pin 7 of U8 may be connected to pin 3 of U11); and / or

[0072] The second reference signal comes from the high bandwidth fully differential amplifier input stage U6 (pin 7 of U6 can be connected to pin 3 of U11 through resistors R1 and R2 and capacitor C3).

[0073] In some optional implementations, when the refresh rate and amplitude of the first reference signal are both greater than those of the second reference signal, the comparator compares the first reference signal with the first comparison signal to generate an output signal.

[0074] In some optional implementations, when the program has not been burned into the programmer U8, the comparator U11 may use the second reference signal to compare with the first comparison signal to generate an output signal.

[0075] In some optional implementations, the adjustable range of the static output voltage of the comparator U11 is 2.5V±0.2V or 50% of the power supply voltage, and the adjustable range of the output sensitivity is 1.8-30mV / Gs.

[0076] In some optional implementations, the operating temperature range of the comparator U11 is -50°C-85°C.

[0077] As described above, in the circuit structure of the present application, the conductor circuit U2 is a conductor circuit for detecting the input IP+ of the current and the current output terminal IP-, and its performance and area are determined by the materials produced by the wafer. The conductor circuit U2 is used as an AC or DC input / output terminal, where G1 is positive and G2 is negative, and the direction can be reversed without affecting the performance.

[0078] U4 and U5 are Hall elements that can output differential signals. Their main function is to sense the current passing through the Ip+ / Ip- wires in the wire circuit U2. Of course, they can also sense the strength of the current passing through the wires, and the output can be a mV digital signal.

[0079] U6 is a high-bandwidth fully differential amplifier input stage, which includes two operational amplifiers (OP). One is responsible for inverting and amplifying the low-level signal collected by U4 to achieve a certain sensitivity requirement, and outputting it through pin 1, OutA (OuA). The other is responsible for in-phase amplifying the high-level signal collected by U5 to achieve a certain sensitivity requirement, and outputting it through pin 7, OutB (OuB).

[0080] U7 is a high-bandwidth fully differential amplifier output stage, which together with U6 forms the core of the three-stage low-frequency amplification chopping technology, and is also the technical core of the high-bandwidth design of this application.

[0081] U8 is the entire chip output programmer, which can program the output sensitivity range and determine the final required sensitivity value; and can adjust the static output voltage.

[0082] U9 is an external MCU program burner, represented by a dotted line.

[0083] U10 is a temperature sensor, which can provide a temperature rise curve ranging from -40 to 150 degrees by way of example.

[0084] U11 is a high-precision comparator that compares the amplified signal output by U7. The reference signal can be the complete signal of the previous level to identify whether the U3 / U4 signal is correct, so as to judge the current conversion of the Ip+ / Ip- wires, and then determine whether the chip is stable or defective. U11 determines the final output accuracy after comparing the input of U7. U11 can operate in the range of -50 degrees to 85 degrees, and has obvious low-temperature characteristics. Before the program is burned, the reference signal of U11 can come from U6, and the reference voltage can be obtained by adjusting the value of C3. After the program is burned, the reference signal of U11 can come from U8.

[0085] As mentioned above, an amplifier (including a high-bandwidth fully differential amplifier input stage U6 and a high-bandwidth fully differential amplifier output stage U7) is required in the current sensor to amplify the signal. The amplifier technology is further introduced below.

[0086] In the use of low-frequency amplifier technology, the main factors affecting the bandwidth of a single-stage common-emitter amplifier are as follows:

[0087] a. Stray capacitance and inductance in circuits and components;

[0088] b. Gain bandwidth product, cut-off frequency fT.

[0089] In the bandwidth control process, any amplifier should have a bandwidth suitable for the frequency range it is to amplify. Too narrow a bandwidth will result in the loss of some signal frequencies, and too wide a bandwidth will result in the introduction of unwanted signals. For example, an audio amplifier will include low-frequency hum and possible mechanical noise, as well as audible hiss at high frequencies.

[0090] refer to Figure 4 , shows the circuit structure of a single-stage common emitter amplifier. The alternating current (AC) component in the common emitter amplifier can be referred to Figure 3 . Figure 3 The common emitter amplifier circuit shown has a direct current (DC) bias component and adds AC components (capacitors C1 to C4) that are necessary to use AC signals and achieve control over gain and bandwidth.

[0091] The signal must pass through the input and output coupling capacitors C1 and C2 when going from input to output. The main function of these capacitors is to provide DC isolation for the voltage in the circuits before and after. However, because the action of capacitors is frequency-dependent, they also have an impact on the bandwidth of the amplifier.

[0092] C1 forms a high-pass filter with R1, R2, and the input resistance of the transistor. C1 is usually of a fairly large capacitance value, which makes the filter's corner frequency very low. However, at frequencies below this point, the amplifier gain will be reduced.

[0093] C2 will act in a similar way on the input impedance of any subsequent circuitry, also causing a reduction in low frequency gain.

[0094] refer to Figure 5 , shows a schematic diagram of the junction capacitance when the emitter is decoupled. Figure 4, the emitter decoupling capacitor C3 is connected across the emitter stabilizing resistor R4 and is designed to prevent any AC signals from appearing at the emitter, which would otherwise act as negative feedback and severely reduce the gain of the amplifier. The relatively large value of C3 almost completely eliminates any AC in the transmitter, but it will create some reactance at the lowest frequencies and therefore allow some very low frequency signals to appear at the transmitter, (assuming these frequencies are not removed by the transmitter), which is the role of C1 and C2 (as described above), and while C3 will help improve gain over most of the bandwidth, the gain at very low frequencies may not be improved.

[0095] The values ​​of C1, C2 and C3 can therefore be chosen to give the required gain reduction at the low frequency end of the bandwidth.

[0096] At high frequencies, amplifier gain tends to be reduced somewhat due to a small amount of inductive reactance (which increases with frequency) in the circuit wiring and components. But a more significant contributing factor is stray capacitance. These are not necessarily identifiable capacitor components, but may be unavoidable capacitive effects within the circuit wiring and components themselves. Both CMOS and bipolar transistors have capacitance in their junctions. Figure 3 As shown, the base-collector and base-emitter junctions of a bipolar transistor actually form very small capacitors due to the (insulating) depletion layers on either side of the base. At very high frequencies (typically in the hundreds of megahertz), these tiny "capacitors" will form a negative feedback path by feeding an anti-phase signal between the collector and base and a non-phase signal across the base-emitter junction. Therefore, every transistor has a limit on its high-frequency current gain, which is usually expressed in the transistor's data sheet as a cutoff frequency fT, which is the frequency at which the small signal current gain hfe drops to 1. Before fT is reached, the gain begins to drop at a rate of 6dB per octave (i.e., the gain halves when the frequency doubles), and the transistor needs to operate at frequencies much lower than fT. Due to the relationship between frequency and gain in transistors, fT is also often referred to as the "gain bandwidth product."

[0097] Dense wiring and stray capacitance between components not only reduce high-frequency gain, but can also cause problems such as instability and oscillation, so the actual upper limit of an amplifier's operation is affected by a variety of factors. However, in many practical amplifier circuits, these extremely high frequency limits cannot be achieved. It makes no sense to design an amplifier with considerable gain at frequencies above the highest desired signal frequency, because this would mean that the amplifier would mainly amplify high-frequency noise in this frequency region (for example, in the case of an audio amplifier, this might produce a hissing sound).

[0098] A differential amplifier can amplify the difference between two input signals and suppress the common mode part of the input signal (i.e., the same signal at both input ends). Due to its strong ability to suppress common mode signals, differential amplifiers are widely used in noise-sensitive circuits, such as sensor signal processing, data acquisition, current detection, and audio amplification.

[0099] The basic principle of the differential amplifier is to suppress the common-mode component of the input signals by amplifying their differences. The input signals have two ports, which can be defined as Vin1 (V1) and Vin2 (V2). The output signal of the differential amplifier is proportional to the difference of the input signals.

[0100] refer to Figure 6 In order to suppress the common-mode signal, the common-mode gain Ac of the differential amplifier should be as small as possible. The common-mode rejection ratio (CMRR) is an important indicator for measuring the performance of the differential amplifier. It is defined as the ratio of the differential gain Ad to the common-mode gain Ac, and the formula is:

[0101] CMMR=Ad / Ac

[0102] The higher the CMRR, the better the differential amplifier's ability to reject common-mode signals.

[0103] like Figure 6 As shown in Figure 1, the typical structure of a differential amplifier consists of two input terminals, an output terminal, and a feedback circuit, and a resistor network is usually used to set the gain. Figure 7 The structure of a differential amplifier with a common-mode input signal is shown.

[0104] like Figure 5 The relationship between the output signal Vout and other parameters (input signals V1 and V2, and resistors R3 and R4) of the differential amplifier shown is calculated as follows:

[0105]

[0106] As can be seen above, the differential amplifier amplifies the difference between the two input signals (V1-V2) and suppresses their common-mode portion. Feedback resistors R3 and R4 are used to determine the gain of the amplifier. By adjusting the resistance values ​​of R3 and R4, the differential gain of the circuit can be controlled.

[0107] The advantage of the differential amplifier lies in its ability to suppress noise. When external noise generates the same voltage at the two input terminals, the differential amplifier can effectively filter out the common-mode noise and only amplify the useful differential signal.

[0108] The differential amplifier has multiple operating modes. It can operate in the following operating modes:

[0109] 1. Differential mode

[0110] In differential mode, the differential amplifier amplifies the difference between two input signals. This is the main operating mode of the differential amplifier, which has excellent common-mode rejection. Application scenarios can include sensor output signal processing, operational circuits, etc.

[0111] 2. Common mode

[0112] When the signals at the two inputs are equal, the differential amplifier operates in common mode. Ideally, the differential amplifier does not amplify the common mode signal and the output is zero. However, in actual circuits, the common mode signal may cause a small amount of output, so a high CMRR (common mode rejection ratio) is required to suppress the common mode signal.

[0113] 3. Single-ended input mode

[0114] In single-ended input mode, one input is grounded and the other input is connected to the signal. In this case, the differential amplifier still amplifies the input signal, but the effect of suppressing common-mode noise is not as good as in the differential input mode compared to the fully differential mode.

[0115]

[0116] Open loop voltage gain:

[0117] It is the ratio of the output voltage of the operational amplifier (operational amplifier) ​​to the voltage difference between the positive and negative input terminals. In a frequency range, the open-loop gain of the operational amplifier is basically linear with the frequency, that is, 20dB / 10 times the frequency. Figure 8 , which shows the relationship between gain and frequency for an OPA111 operational amplifier.

[0118] Gain-Bandwidth Product and -3dB Bandwidth:

[0119] The open-loop voltage gain curve of an op amp shows that if the op amp can achieve a certain gain, the signal frequency must be within the frequency corresponding to the gain. The op amp bandwidth indicator - gain bandwidth product (GBW): refers to the product of the open-loop gain and the frequency at a certain frequency point.

[0120] Taking the OPA111 operational amplifier as an example, when G=1, the gain-bandwidth product is 45MHz. If the actual closed-loop gain of the design is 10v / v, then the bandwidth of the circuit can be roughly estimated to be 4.5MHz.

[0121] References Fig. 9The gain-bandwidth diagram of the OPA111 operational amplifier shown in the figure shows that the -3dB bandwidth is based on the frequency at which the gain drops to 0.707 times at a fixed gain in the closed-loop circuit.

[0122] Advantages and limitations of differential amplifiersAdvantages:

[0123] Advantages:

[0124] Excellent common-mode rejection capability: The differential amplifier can effectively suppress common-mode noise and improve the signal-to-noise ratio.

[0125] Differential signal amplification: It can process differential signals output by sensors, etc. and is widely used in precision signal measurement.

[0126] High linearity: The differential amplifier has good linearity and can provide high-precision signal amplification.

[0127] Limitations:

[0128] High circuit complexity: The differential amplifier circuit is relatively complex, and the design requires attention to the precision matching of multiple resistors.

[0129] High power consumption: The design of differential amplifiers usually requires high power consumption, especially in high-speed and high-precision applications.

[0130] refer to Fig.10 , showing the structural design of the two-stage fully differential amplifier with gain bootstrapping of the present application.

[0131] refer to Fig.11 , showing the overall circuit structure design of the chip of the two-stage fully differential amplifier with gain bootstrapping of the present application.

[0132] refer to Fig.12 , showing the present application with a gain bootstrap circuit (eg Fig.11 As shown in the figure, the circuit structure design of a fully differential operational amplifier with a common-mode feedback circuit is described.

[0133] It should be noted that if Figure 3 The amplifier part of the circuit structure of the high-bandwidth Hall current sensor chip provided by the present application can be based on Fig.12 The fully differential operational amplifier shown.

[0134] In some optional embodiments, the Hall current sensor chip of the present application also provides an internally controlled clock mechanism to intermittently power the Hall element and the analog signal processing circuit. The device periodically "wakes up" through internal logic to compare the magnetic flux density passing through the Hall element with a predefined threshold. If the magnetic flux density is higher or lower than the BOP / BRP threshold, the output driver tube changes state accordingly.

[0135] Continue to refer Figure 3 The present application also provides a high-bandwidth Hall current sensor chip, including: Figure 3 The circuit structure of the high-bandwidth Hall current sensor chip is shown.

[0136] In some optional embodiments, the chip of the present application can be manufactured using, for example, a 0.18μm Bi-CMOS process, and its operating voltage can be 5.0V. Circuit design simulation verification and layout drawing can be performed using Cadence software. Exemplarily, the overall chip area is 1.65mm×1.45mm, the input reference noise power spectral density (PSD) is 15nV / √Hz, the overall circuit -3dB bandwidth is up to 120kHz, the input reference offset voltage is a maximum of 3μV, the ripple rejection ratio reaches 62.6dB, the quiescent current is about 1mA (including the front-end Hall element and the bias circuit), and the overall circuit residual offset is less than 2Gs Gauss.

[0137] refer to Figure 13-Figure 15 The figure shows the process structure diagram of the circuit generation of the proprietary high-bandwidth Hall current sensor chip of the present application, which represents the process level and chip performance of the chip.

[0138] In the chip, the TOP layer is the top view of the chip, the PWELL layer is the Core device PWELL (core device P well), the NWELL layer is the Core device NWELL (core device N well), the DIFF layer is the Active region (active region), the POLY layer is the Poly gate (polysilicon gate), the PIMP layer is the P+Implant (P-type doping implantation), the NIMP layer is the N+Implant (N-type doping implantation), the SDPW layer is the SD PWELL (shallow P well), the SDNW layer is the SD NWELL (shallow N well), the TGOX layer is the Thickgate oxide (thick gate oxide layer), the DNW layer is the Deep NWELL (deep N well layer), and the SAB layer is the Silicide block (silicide barrier layer), CONT layer is Contact (contact layer), MET1 layer is Metal1 (first metal layer), VIA1 layer is Via1 (first via layer), MET2 layer is Metal2 (second metal layer), VIA2 layer is Via2 (second via layer), MET3 layer is Metal3 (third metal layer), POR layer is Passivation open (passivation opening layer), and MTM layer is MIM capacitor (metal-insulator-metal capacitor).

[0139] here, Figure 13-Figure 15The TOP layer (ie, top layer) view, the DIFF layer view, and the SAB layer view are exemplarily shown respectively.

[0140] In the above, the technical solution of the present application is described in detail through specific embodiments. In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the relevant description of other embodiments.

[0141] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above invention concept. For example, the above features are replaced with (but not limited to) technical features with similar functions applied in this application.

Claims

1. A circuit structure of a high-bandwidth Hall current sensor chip, characterized in that: include: A first Hall element and a second Hall element, a three-stage low-frequency amplifying and chopping module connected to the first Hall element and the second Hall element, a comparator connected to the three-stage low-frequency amplifying and chopping module, and a programmer connected to the comparator; The first Hall element and the second Hall element are used to sense a detection current and generate a differential voltage signal related to the detection current, wherein the differential voltage signal includes: a low level signal generated by the first Hall element and a high level signal generated by the second Hall element; The three-stage low-frequency amplification and chopping module is used to perform high-precision amplification on the differential signal and to eliminate ripples and offsets, and includes a high-bandwidth fully differential amplifier input stage and a high-bandwidth fully differential amplifier output stage, wherein the high-bandwidth fully differential amplifier input stage includes a first operational amplifier for inverting and amplifying the low-level signal and a second operational amplifier for in-phase amplification of the high-level signal; The comparator is used to compare the amplified signal output by the three-stage low-frequency amplification and chopping module with a reference signal to generate a final output signal; The programmer is used to adjust the output sensitivity and / or static output voltage of the comparator.

2. The circuit structure of the high-bandwidth Hall current sensor chip according to claim 1, characterized in that: Also includes: A conductor circuit, a first voltage regulator, a second voltage regulator, and a temperature sensor; The conductor circuit is used as a flow path for the detection current; The first voltage regulator is used to provide a first power supply voltage to the first Hall element, the second Hall element, the high-bandwidth fully differential amplifier input stage, the high-bandwidth fully differential amplifier output stage, and the comparator, and adjust the first power supply voltage according to a temperature compensation signal provided by the temperature sensor; A second voltage regulator, used for providing a second power supply voltage to the programmer; The temperature sensor is used to provide a temperature compensation signal to the first voltage stabilizer, and control the first voltage stabilizer to stop providing the first power supply voltage when the working environment temperature exceeds a set range.

3. The circuit structure of the high-bandwidth Hall current sensor chip according to claim 1, characterized in that: The three-stage low-frequency amplification chopping module is provided with a gain bootstrap circuit and a common-mode feedback circuit.

4. The circuit structure of the high-bandwidth Hall current sensor chip according to claim 1, characterized in that: The programmer is also used to connect to an external MCU program burner.

5. The circuit structure of the high-bandwidth Hall current sensor chip according to claim 2, characterized in that: The reference signal used by the comparator includes: a first reference signal from the programmer; and / or A second reference signal is derived from the high bandwidth fully differential amplifier input stage.

6. The circuit structure of the high-bandwidth Hall current sensor chip according to claim 5, characterized in that: When the refresh rate and amplitude of the first reference signal are both greater than those of the second reference signal, the comparator compares the first reference signal with the first comparison signal to generate the output signal.

7. The circuit structure of the high-bandwidth Hall current sensor chip according to claim 5, characterized in that: When the program is not burned into the programmer, the comparator compares the second reference signal with the first comparison signal to generate the output signal.

8. The circuit structure of the high-bandwidth Hall current sensor chip according to claim 1, characterized in that: The bandwidth is not less than 120KHz, and the maximum input reference offset voltage does not exceed 3μV.

9. The circuit structure of the high-bandwidth Hall current sensor chip according to claim 1, characterized in that: The operating temperature range of the comparator is -50°C to 85°C.

10. A high-bandwidth Hall current sensor chip, characterized in that: A circuit structure comprising a high-bandwidth Hall current sensor chip as described in any one of claims 1-9.

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