High-bandwidth Hall current sensor chip and circuit structure thereof

Abstract

The utility model 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 sensor, in particular to a high-bandwidth Hall current sensor chip and its circuit structure. BACKGROUND

[0002] The Hall current sensor is a commonly used current sensor, which works on the principle of the Hall effect. The basic working principle is as follows: 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 across the Hall element; after amplification and processing, a voltage signal proportional to the measured current is output, thereby realizing non-contact measurement of the current. The commonly used Hall current sensor includes open-loop and closed-loop types.

[0003] Referring to Figure 1 , the basic working principle of the open-loop Hall current sensor is shown. The open-loop Hall current sensor adopts the principle of Hall direct amplification. When alternating or direct current (Ip) passes through a wire, a magnetic field proportional to the strength of the current will be generated around the wire; the generated magnetic field is concentrated 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 alternating or direct current, and by measuring the output signal of the Hall element, the size of the alternating or direct current passing through the wire can be accurately measured.

[0004] Referring to Figure 2 , the basic working principle of the closed-loop Hall current sensor is shown. The closed-loop Hall current sensor adopts the principle of magnetic balance and belongs to a compensating sensor. Unlike Figure 1 , in 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 the 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 as follows: when there is a current Ip passing through the main circuit, the magnetic field generated on the wire is concentrated by the magnetic ring and sensed by the Hall element, and the generated signal output is used to drive the power tube and make it conductive, thereby obtaining a compensation current Is; this current Is generates a magnetic field through the multiple turns of the secondary coil, 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 a role of indicating zero magnetic flux, and at this time, Ip can be tested through Is. A measurement resistor is usually 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 increasingly widespread, and the requirement for frequency response is also increasingly high, especially in high-speed rotating equipment such as brushless motors, the requirement for frequency response of Hall sensors ranges from several Hz to tens of kHz. The frequency of alternating current, i.e. the number of periodic changes per unit time, is measured in hertz (Hz), and the working frequency of 220V alternating current is usually 50Hz or 60Hz. However, in power electronic applications such as rectification or inverter circuits, the switching frequency can reach several hundred kHz. With the advent of semiconductor switching devices such as silicon carbide (SiC) and gallium nitride (GaN), the switching frequency can even reach MHz or above.

[0006] The existing ACS7xx series chips are commonly used Hall effect linear current sensors, which provide effective solutions for alternating current or direct current measurement in industrial, commercial and communication systems, but it is difficult to meet the higher requirements for frequency response at present.

[0007] Therefore, it is an urgent technical problem to provide a Hall sensor with greater bandwidth. Invention content

[0008] The present application provides 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 for inductive detection of current, generating a differential voltage signal related to the detection current, the differential voltage signal comprising 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 chopper module is used for high-precision amplification and ripple and offset elimination of the differential signal, comprising a high-bandwidth fully differential amplifier input stage and a high-bandwidth fully differential amplifier output stage, the high-bandwidth fully differential amplifier input stage comprising a first operational amplifier for inverting amplification of the low-level signal and a second operational amplifier for non-inverting amplification of the high-level signal.

[0012] The comparator is used for comparing the amplified signal output by the three-stage low-frequency amplification chopper module with a reference signal to generate a final output signal.

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

[0014] In some alternative embodiments, further comprising: a wire circuit, a first voltage regulator, a second voltage regulator, and a temperature sensor;

[0015] The wire circuit is configured to serve as a current flow path for the detection current;

[0016] The first voltage regulator is configured to provide a first power 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 to adjust the first power voltage according to a temperature compensation signal provided by the temperature sensor;

[0017] The second voltage regulator is configured to provide a second power voltage to the programmer;

[0018] The temperature sensor is configured to provide a temperature compensation signal to the first voltage regulator, and to control the first voltage regulator to stop providing the first power voltage when the operating environment temperature is out of a set range.

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

[0020] In some alternative embodiments, the programmer is further configured to connect an external MCU program burner.

[0021] In some alternative embodiments, the reference signal used by the comparator includes:

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

[0023] a second reference signal from the high-bandwidth fully differential amplifier input stage.

[0024] In some alternative embodiments, when the refresh speed and amplitude of the first reference signal are both greater than the second reference signal, the comparator uses the first reference signal to compare with the first comparison signal to generate the output signal.

[0025] In some alternative embodiments, when no program is 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 alternative embodiments, the bandwidth is not less than 120 KHz, and the maximum input reference offset voltage is not more than 3 μV.

[0027] In some alternative embodiments, the working temperature range of the comparator is -50℃-85℃.

[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 according to the first aspect.

[0029] In summary, the present application provides a circuit structure of a high-bandwidth Hall current sensor chip and a high-bandwidth Hall current sensor chip comprising the circuit structure. The present application adopts a double-channel signal transmission structure, and a three-stage low-frequency amplification chopper module composed of a high-bandwidth fully differential amplifier input stage and a high-bandwidth fully differential amplifier output stage to amplify the differential signal sensed by the Hall element with high precision and eliminate the ripple and imbalance. In this way, high bandwidth can be achieved to meet the growing frequency demand and solve the trade-off between residual imbalance and residual ripple amplitude. In addition, while optimizing for low imbalance or high bandwidth, the present application can also achieve fast response of the high-bandwidth current sensor, for example, the rise time of the high-bandwidth current sensor is less than 1 microsecond, while the bandwidth of the voltage sensor is generally controlled within 15 kHz. In addition, the present application can also improve the anti-interference ability, improve the output precision, improve the output stability, and can adjust the output sensitivity and / or static output voltage. BRIEF DESCRIPTION OF DRAWINGS

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

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

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

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

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

[0035] Figure 5 is Figure 4 is a schematic diagram of the emitter decoupling time junction capacitance of the amplifier shown in

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

[0037] Figure 7 is a structural schematic diagram of a differential amplifier based on Figure 6A schematic diagram of a differential amplifier with common mode input signal according to the present application;

[0038] Figure 8 A schematic diagram of the gain versus frequency of an OPA111 type operational amplifier according to the present application;

[0039] Figure 9 A gain bandwidth plot of an OPA111 type operational amplifier according to the present application;

[0040] Figure 10 A schematic diagram of a two stage fully differential amplifier with gain bootstrapping according to the present application;

[0041] Figure 11 A schematic diagram of the overall circuit structure of a chip of a two stage fully differential amplifier with gain bootstrapping according to the present application;

[0042] Figure 12 A schematic diagram of the circuit structure of a fully differential operational amplifier with gain bootstrapping and with common mode feedback circuit according to the present application;

[0043] Figures 13-15 A process structure diagram generated from the circuit specific to the Hall current sensor chip according to the present application. DETAILED DESCRIPTION

[0044] The application will be further described below in conjunction with the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related application, and not to limit the application. In addition, it should be noted that, for the sake of description, only the parts related to the application are shown in the 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" and the like indicate the orientation or positional relationship, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0046] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0047] In the description of the present application, it should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[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 chip

[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 of the current sensor is a frequency interval, which can be referred to as frequency bandwidth or frequency range. As the frequency of the measured current rises or falls, the output signal of the current sensor will attenuate, and when the output signal attenuates to a certain value (see the definition of -3dB below), the frequency is the upper limit frequency and the lower limit frequency, and the difference between the upper and lower limit frequencies is the bandwidth of the current sensor. Therefore, the bandwidth is the frequency range Hz that the circuit can effectively process the signal; the response time, which is the inverse of the frequency, is the reaction speed of the circuit to the change of the input signal, represented by f.

[0052] As shown in Table 1, the existing ACS7xx series Hall current sensor chip has an upper limit of the bandwidth range of about 120KHz, which is difficult to meet the current growing frequency requirements.

[0053] The main purpose of the present application is to provide a high-bandwidth Hall current sensor chip and its circuit structure, which can meet the growing frequency requirements 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 Diffusion Metal Oxide Semiconductor) process, the bandwidth of the Hall current sensor is expanded from several Hz to several hundred kHz or more.

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

[0055] In order to realize the separation of the Hall voltage and the Hall offset voltage, the application can adopt a double-channel signal transmission structure to improve the overall system bandwidth. In the design, the low-frequency path and the high-frequency path adopt the same operational amplifier and Hall element. On the low-frequency path, high-precision differential technology and chopping filter technology are adopted to solve the trade-off between residual offset and residual ripple amplitude. In addition, while the input stage transconductance is introduced, a three-stage ripple elimination loop (RRL) is introduced, that is, a three-stage low-frequency amplification chopping technology is introduced, and a three-stage low-frequency amplification chopping module is formed by using a multi-stage amplifier to eliminate the ripple and the offset.

[0056] Reference Figure 3 , the circuit structure of the high-bandwidth Hall current sensor chip of the application is shown. As Figure 3 shown, the circuit structure of the high-bandwidth Hall current sensor chip of the application includes:

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

[0058] The first Hall element U4 and the second Hall element U5 are used to inductively detect the current and generate a differential voltage signal related to the detected current, the differential voltage signal including: a low-level signal generated by the first Hall element U4, and a high-level signal generated by the second Hall element U5;

[0059] The three-stage low-frequency amplification chopping module is used to amplify the differential signal with high precision and eliminate the ripple and the offset, including a high-bandwidth fully differential amplifier input stage U6 and a high-bandwidth fully differential amplifier output stage U7, the high-bandwidth fully differential amplifier input stage U6 further including a first operational amplifier for inverting amplification of the low-level signal and a second operational amplifier for non-inverting amplification of the high-level signal;

[0060] The comparator U11 is used to compare the amplified signal output by the three-stage low-frequency amplification chopping 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] Further, the circuit structure of the high-bandwidth Hall current sensor chip of the application can further include: a wire circuit U2, a first voltage stabilizer U1, a second voltage stabilizer U3 and a temperature sensor U10; wherein,

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

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

[0065] A second voltage stabilizer U3 is used to provide a second power voltage to the programmer U8;

[0066] The temperature sensor U10 is used to provide a temperature compensation signal to the first voltage stabilizer U1 (pin 2 of U10 can be connected to pin 3 of U1), and control the first voltage stabilizer U1 to stop providing the first power 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 voltages, such as 5V / 3.3V / 1.8V, for the circuit structure of the entire chip and the programmer for burning, etc.

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

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

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

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

[0072] a second reference signal from the high-bandwidth full-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 embodiments, when the refresh speed and amplitude of the first reference signal are both greater than those of the second reference signal, the comparator uses the first reference signal to compare with the first comparison signal to generate an output signal.

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

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

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

[0077] As described above, in the circuit structure of the present application, the wire circuit U2 is an input IP+ for detecting current and a wire circuit for outputting current IP-, the performance and area of which are determined by the material produced by wafer production. The wire circuit U2 serves as an AC or DC input / output terminal, in which 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, and the main function is to sense the current size through the Ip+ / Ip- wire of the wire circuit U2. Of course, the strength of the current passing through the wire can also be sensed, and the output can be an mV digital signal.

[0079] U6 is a high-bandwidth full-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 a certain required sensitivity, and outputting through pin 1, i.e. OutA (OuA). The other is responsible for non-inverting and amplifying the high-level signal collected by U5 to a certain required sensitivity, and outputting through pin 7, i.e. OutB (OuB).

[0080] U7 is a high-bandwidth full-differential amplifier output stage, which, together with U6, constitutes the core of the three-stage low-frequency amplification chopper technology, and is also the technical core of the high-bandwidth design of the present 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 also adjust the static output voltage.

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

[0083] U10 is a temperature sensor, which, as an example, can provide a temperature rise curve in the range of -40 to 150 degrees.

[0084] U11 is a high-precision comparator that compares the amplified signal output by U7, and the reference signal can be the complete signal of the previous stage, to identify whether the U3 / U4 signal is correct, so as to determine the current transformation of the Ip+ / Ip- wire and further determine whether the chip is stable or defective. U11 determines the final output precision after comparing the input of U7. U11 can work 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, amplifiers (including high bandwidth fully differential amplifier input stage U6 and high bandwidth fully differential amplifier output stage U7) are required in the current sensor to amplify the signal. The amplifier technology is further described below.

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

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

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

[0089] In the process of bandwidth control, any amplifier should have a bandwidth suitable for the frequency range it wants to amplify, too narrow bandwidth will result in the loss of some signal frequencies, too wide bandwidth will result in the introduction of unwanted signals, for example, an audio amplifier will include low frequency hum and possible mechanical noise, and a hissing sound can be heard at high frequencies.

[0090] Reference Figure 4 shows the circuit structure of a single common emitter amplifier. The alternating current (AC) component in the common emitter amplifier can refer to Figure 3 . Figure 3 The common emitter amplifier circuit shown has a direct current (DC) bias component and adds an AC component (capacitors C1 to C4), which is necessary for using AC signals and achieving control over gain and bandwidth.

[0091] The signal must pass through the input and output coupling capacitors C1 and C2 from input to output. The main function of these capacitors is to provide DC isolation for the voltage in the front and rear circuits. However, since the effect of the capacitor is related to the frequency, they will also affect the bandwidth of the amplifier.

[0092] C1 and R1, R2 and the input resistance of the transistor form a high-pass filter, C1 usually has a fairly large capacitance value, so that the filter's corner frequency is very low. However, at frequencies below this point, the amplifier gain will decrease.

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

[0094] Reference Figure 5 shows a schematic diagram of the junction capacitance when the emitter is decoupled. The junction Figure 4The emitter decoupling capacitor C3 is connected across the emitter stabilizing resistor R4, and is intended to prevent any AC signal from appearing on the emitter, which would otherwise act as negative feedback, thus severely reducing the gain of the amplifier. The relatively large value of C3 almost completely eliminates any AC current in the emitter, but it does create some reactance at the lowest frequencies, thus allowing some very low frequency signals to appear on the emitter, (assuming these frequencies are not removed by the emitter), which is the role of C1 and C2 (as described above), while C3 helps to increase the gain over most of the bandwidth, the gain at very low frequencies can not be improved.

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

[0096] At high frequencies, however, the amplifier gain tends to decrease somewhat due to the small inductive reactance present in the circuit wiring and components (which increases with frequency). But the more dominant factor is the stray capacitance. These are not necessarily identifiable capacitor components, but can be the unavoidable capacitive effects within the circuit wiring and components themselves. CMOS and bipolar transistors both have capacitances in their junctions. As shown in Figure 3 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 back the inverse signal between the collector and base, and the non-inverted signal across the base-emitter junction. Thus, each transistor has a limit to its high frequency current gain, which is usually indicated in the transistor's data sheet as the cutoff frequency fT, the frequency at which the small signal current gain hfe drops to 1. Before fT is reached, the gain starts to drop at a rate of 6dB per octave (i.e. the gain halves when the frequency is doubled), and the transistor needs to be operated at frequencies well below fT. Due to the relationship between frequency and gain in a transistor, fT is often also referred to as the "gain-bandwidth product".

[0097] Stray capacitance between dense wiring and components not only reduces the high frequency gain, but can also cause problems such as instability and oscillation, so the practical upper operating limit of an amplifier is influenced by a number of factors. However, in many practical amplifier circuits, these very high frequency limits are not reached. It makes no sense to design an amplifier with appreciable gain at frequencies higher than the highest signal frequency required, as this would mean that the amplifier is mainly amplifying high frequency noise in that frequency region (which can result in a hissing sound in the case of an audio amplifier, for example).

[0098] A differential amplifier is an electronic circuit that amplifies the difference between two input voltages while rejecting the common-mode voltage (i.e., the voltage common to both inputs). Due to its strong rejection of common-mode signals, differential amplifiers are widely used in noise-sensitive circuits such as sensor signal processing, data acquisition, current sensing, and audio amplification.

[0099] The basic principle of a differential amplifier is to amplify the difference between two input signals while rejecting their common-mode components. The input signals have two ports, which can be defined as Vin1 (V1) and Vin2 (V2). The output signal of a differential amplifier is proportional to the difference between the input signals.

[0100] Reference Figure 6 To reject common-mode signals, the common-mode gain Ac of a differential amplifier should be as small as possible. The common-mode rejection ratio (CMRR) is an important measure of a differential amplifier's performance, defined as the ratio of the differential gain Ad to the common-mode gain Ac, with the formula:

[0101] CMMR = Ad / Ac

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

[0103] As shown in Figure 6 A typical structure of a differential amplifier consists of two input ports, one output port, and a feedback circuit, usually using a resistor network to set the gain. Figure 7 The structure of a differential amplifier with a common-mode input signal is shown.

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

[0105]

[0106] As can be seen from the above, a differential amplifier amplifies the difference between two input signals (V1-V2) and rejects their common-mode components. 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 a differential amplifier is its ability to reject noise. When external noise produces the same voltage at both input ports, a differential amplifier can effectively filter out these common-mode noises and only amplify the useful differential signals.

[0108] Differential amplifier has multiple operating modes, it can run 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, with excellent common-mode rejection capability. Application scenarios can include sensor output signal processing, arithmetic circuits, etc.

[0111] 2. Common-mode mode

[0112] When the signals at both input terminals are equal, the differential amplifier operates in common-mode mode. Ideally, the differential amplifier will not amplify the common-mode signal, and the output will be zero. But in actual circuits, the common-mode signal may cause a small output, so a high CMRR (common-mode rejection ratio) is needed to suppress the common-mode signal.

[0113] 3. Single-ended input mode

[0114] In single-ended input mode, one input terminal is connected to ground and the other input terminal inputs a signal. At this time, the differential amplifier will still amplify the input signal, but compared to full-differential mode, the effect of suppressing common-mode noise is not as good as differential input mode.

[0115]

[0116] The ratio of the output voltage of the operational amplifier (op-amp) to the voltage difference between the positive and negative input terminals. Within a certain frequency range, the open-loop gain and frequency of the op-amp are basically linear, i.e. 20dB / 10 times frequency. For example, Figure 8 shows the relationship between the gain and frequency of an OPA111 type operational amplifier.

[0117] Gain-bandwidth product and -3dB bandwidth:

[0118] The open-loop voltage gain curve of the op-amp indicates that if the op-amp can achieve a certain gain, the signal frequency must be within the frequency corresponding to that gain. The bandwidth indicator of the op-amp - gain-bandwidth product (GBW): refers to the product of the open-loop gain and the frequency at a certain frequency point.

[0119] Taking the OPA111 type operational amplifier as an example, the gain-bandwidth product at G=1 is 45MHz, if the actual closed-loop amplification factor designed is 10v / v, then the bandwidth of the circuit can be roughly estimated to be 4.5MHz.

[0120] Referring to the gain-bandwidth diagram of the OPA111 type operational amplifier as shown in Figure 9 , the -3dB bandwidth is based on a certain fixed gain of the closed-loop circuit, and the frequency at which the gain is measured to drop to 0.707 times.

[0121] Advantages and limitations of differential amplifier Advantages:

[0122] Advantages:

[0123] Excellent common-mode rejection: Differential amplifiers can effectively suppress common-mode noise, improving signal-to-noise ratio.

[0124] Differential signal amplification: Can handle differential signals output by sensors, widely used in precision signal measurement.

[0125] High linearity: Differential amplifiers have good linearity and can provide high-precision signal amplification.

[0126] Limitations:

[0127] High circuit complexity: Differential amplifier circuits are relatively complex, and the precision matching of multiple resistors needs to be considered during design.

[0128] High power consumption: Differential amplifier design usually requires high power consumption, especially in high-speed and high-precision applications.

[0129] Reference Figure 10 , shows the structure design of the 2-stage full-differential amplifier with gain bootstrap of the present application.

[0130] Reference Figure 11 , shows the overall circuit structure design of the chip of the full-differential operational amplifier with gain bootstrap circuit (e.g.

[0131] Reference Figure 12 , shows the circuit structure design of the full-differential operational amplifier with gain bootstrap circuit (e.g. Figure 11

[0132] It should be noted that the amplifier part in the circuit structure of the high-bandwidth Hall current sensor chip provided by the present application as shown in Figure 3 may adopt the full-differential operational amplifier according to Figure 12 .

[0133] In some optional embodiments, the Hall current sensor chip of the present application also provides an internal control clock mechanism to intermittently power the Hall element and the analog signal processing circuit. The device periodically "wakes up" through internal logic, compares the magnetic flux density passing through the Hall element with the predefined threshold value. If the magnetic flux density is higher or lower than the BOP / BRP threshold value, the output driver tube is driven to change the state accordingly.

[0134] Continuing to refer to Figure 3 , the present application also provides a high-bandwidth Hall current sensor chip, which includes as Figure 3 ​The circuit structure of the high-bandwidth Hall current sensor chip is shown.

[0135] In some optional embodiments, the chip of the present application can be manufactured using, for example, a 0.18 μm Bi-CMOS process, and the working voltage can be 5.0 V. Circuit design simulation verification and layout drawing can be performed by Cadence software. For example, the overall chip area is 1.65 mm x 1.45 mm, the input reference noise power spectral density (PSD) is 15 nV / √Hz, the overall circuit -3dB bandwidth is as high as 120 kHz, the maximum input reference offset voltage is 3 μV, the ripple rejection ratio reaches 62.6 dB, the static current is about 1 mA (including the front-end Hall element and bias circuit), and the overall circuit residual offset is less than 2Gs Gauss.

[0136] Reference Figures 13-15 The process structure diagram of the circuit generation of the high-bandwidth Hall current sensor chip of the present application is shown, which represents the process level and chip performance of the chip.

[0137] In the chip, the TOP layer is the top layer 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 (poly gate), the PIMP layer is the P+Implant (P type doped implant), the NIMP layer is the N+Implant (N type doped implant), 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 Thick gate oxide (thick gate oxide), the DNW layer is the Deep NWELL (deep N well layer), the SAB layer is the Silicide block (silicide block), the CONT layer is the Contact (contact layer), the MET1 layer is the Metal1 (first metal layer), the VIA1 layer is the Via1 (first via layer), the MET2 layer is the Metal2 (second metal layer), the VIA2 layer is the Via2 (second via layer), the MET3 layer is the Metal3 (third metal layer), the POR layer is the Passivation open (passivation open layer), and the MTM layer is the MIM capacitor (metal-insulator-metal capacitor).

[0138] Here, Figures 13-15 The TOP layer (i.e. top layer) view, DIFF layer view and SAB layer view are respectively shown.

[0139] The technical solutions of the present application are described in detail above through specific embodiments. In the above embodiments, the description of each embodiment has its own focus, and the parts not described in detail in a certain embodiment can be referred to the relevant description of other embodiments.

[0140] The above description is merely preferred embodiments of the present application and a description of the principles of the applied technology. Those skilled in the art should understand that the scope of the application involved in the present application is not limited to the technical solutions formed by the specific combinations of the above technical features, and should also cover other technical solutions formed by any combinations of the above technical features or equivalent features without departing from the above inventive concept. For example, the technical solutions formed by the mutual replacement of the above features and the technical features with similar functions applied in the present application (but not limited to).

Claims

1. A circuit structure for 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 amplification and chopper module connected to the first Hall element and the second Hall element, a comparator connected to the three-stage low-frequency amplification and chopper module, and a programmer connected to the comparator. The first Hall element and the second Hall element are used to sense the detection current and generate a differential voltage signal related to the detection current. 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 chopper module is used to amplify the differential voltage signal with high precision and to eliminate ripple and offset. It includes a high-bandwidth fully differential amplifier input stage and a high-bandwidth fully differential amplifier output stage. The high-bandwidth fully differential amplifier input stage includes a first operational amplifier for inverting the low-level signal and a second operational amplifier for non-inverting the high-level signal. The comparator is used to compare the amplified signal output by the three-stage low-frequency amplification and chopper module with the reference signal to generate the 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: The circuit consists of a wire circuit, a first voltage regulator, a second voltage regulator, and a temperature sensor. The wire circuit serves as the path through which the detected current flows; The first voltage regulator is used to provide a first power supply voltage to the first Hall element, the second Hall element, the input stage of the high-bandwidth fully differential amplifier, the output stage of the high-bandwidth fully differential amplifier, and the comparator, and to adjust the first power supply voltage according to the temperature compensation signal provided by the temperature sensor. A second voltage regulator is used to provide a second power supply voltage to the programmer; The temperature sensor is used to provide a temperature compensation signal to the first voltage regulator and to control the first voltage regulator to stop providing the first power supply voltage when the ambient temperature exceeds the 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 chopper module is equipped 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 programmer.

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: The first reference signal from the programmer; and / or The second reference signal originates from the input stage of the high-bandwidth fully differential amplifier.

6. 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 is not more than 3μV.

7. The circuit structure of the high-bandwidth Hall current sensor chip according to claim 1, characterized in that, The comparator operates in a temperature range of -50℃ to 85℃.

8. A high-bandwidth Hall current sensor chip, characterized in that, The circuit structure includes the high-bandwidth Hall current sensor chip as described in any one of claims 1-7.

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