Filter circuit and method for reducing 1 / f noise of hemispherical resonator gyroscope control circuit
By designing a filter circuit of an inverting single-pole high-pass filter and a voltage cancellation circuit, the impact of 1/f noise on detection accuracy in the hemispherical resonant gyroscope control circuit is solved, and effective filtering and detection accuracy of low-frequency noise is achieved.
Patent Information
- Application Number
- CN202411960052.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2025-05-30
AI Technical Summary
There is 1/f noise in the hemispherical resonant gyroscope control circuit, which has a great impact on the detection accuracy of low-frequency gyroscopes.
A filtering circuit including an inverting single-pole high-pass filter and a voltage cancellation circuit is designed to reduce 1/f noise. The inverting single-pole high-pass filter consists of a CMOS chopping stable amplifier, resistor and capacitor. The voltage cancellation circuit realizes noise cancellation through resistor and capacitor.
Effectively filter out the low-frequency components in vibration signal noise, avoiding the influence of 1/f noise on the low-frequency gyroscope angular rate, improving the angular rate detection accuracy, and filtering without increasing the DC offset voltage.
Smart Images
Figure CN120074444A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of hemispherical resonator gyroscope detection, and particularly relates to a filtering circuit and method for reducing 1 / f noise of a control circuit of a hemispherical resonator gyroscope. Background Art
[0002] The vibration signal of the hemispherical resonator gyroscope is converted into an analog electrical signal through capacitance-voltage conversion and then collected. The analog signal is subjected to gain transformation through an integrated operational amplifier and becomes a digital quantity through an analog-to-digital converter for further operation. In this process, the analog signal is affected by noise, including 1 / f noise and Gaussian white noise. At high frequencies, the power spectral density of white noise is relatively large, and at low frequencies, the power spectral density of 1 / f noise is relatively large. As the frequency decreases, the 1 / f noise starts to exceed the relatively flat white noise at a certain frequency point between several hundred hertz and several thousand hertz and increases at a rate of 3 dB per octave (about 10 dB per decade). This frequency point is called the 1 / f corner frequency, as Figure 2 shown. For bipolar process operational amplifiers, this frequency is usually several hundred hertz; for CMOS process operational amplifiers, this frequency is usually several thousand hertz.
[0003] When the gyro angular rate changes slowly, its change frequency is much smaller than the 1 / f corner frequency, resulting in a greater impact of 1 / f noise on the detection accuracy. Summary of the Invention
[0004] The present invention aims to solve at least one of the technical problems existing in the prior art.
[0005] According to one aspect of the present invention, there is provided a filtering circuit for reducing 1 / f noise of a control circuit of a hemispherical resonator gyroscope. The filtering circuit for reducing 1 / f noise of a control circuit of a hemispherical resonator gyroscope includes: an inverting single-pole high-pass filter and a voltage cancellation circuit.
[0006] The inverting single-pole high-pass filter includes a CMOS chopper-stabilized amplifier A1, resistors R1-R3, and a capacitor C1. The analog signal of the hemispherical resonator gyroscope is input through a signal input terminal, and after passing through resistors R1 and R2 respectively, it is connected to the non-inverting input terminal and the inverting input terminal of the amplifier A1 respectively. The capacitor C1 is connected to the non-inverting input terminal of the amplifier A1 and bypassed to the common terminal of the circuit; the resistor R3 is connected to the inverting input terminal and the output terminal of the amplifier A1 respectively.
[0007] The voltage cancellation circuit includes resistors R4 and R5, a capacitor C2, and a CMOS chopper-stabilized amplifier A2. The output terminal of the amplifier A1 is connected to the non-inverting input terminal of the amplifier A2 after passing through the resistor R5 and the capacitor C2. Both ends of the resistor R4 are connected to the inverting input terminal of the amplifier A1 and the non-inverting input terminal of the amplifier A2 respectively. The inverting input terminal and the output terminal of the amplifier A2 are connected to the signal output terminal.
[0008] Furthermore, the gain of the inverting single-pole high-pass filter is 100, and the DC gain is 1.
[0009] Furthermore, the gain or attenuation coefficient of the voltage cancellation circuit is 100.
[0010] Furthermore, the capacitors C1 and C2 are polypropylene film dielectric capacitors.
[0011] Furthermore, the minimum RC time constant corresponding to the capacitors C1 and C2 is 30000 seconds.
[0012] According to another aspect of the present invention, there is provided a method for reducing 1 / f noise of a hemispherical resonator gyro control circuit. The method uses the filtering circuit for reducing 1 / f noise of a hemispherical resonator gyro control circuit as described above to achieve the filtering of 1 / f noise.
[0013] Applying the technical solution of the present invention, there is provided a filtering circuit and method for reducing 1 / f noise of a hemispherical resonator gyro control circuit. The filtering circuit includes an inverting single-pole high-pass filter and a voltage cancellation circuit, which can filter out the low-frequency components in the vibration signal noise and will not introduce a large DC offset voltage error. Using the filtering circuit of the present invention can effectively avoid the influence of 1 / f noise on the gyro angular rate at low frequencies and improve the angular rate detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The accompanying drawings included are used to provide a further understanding of the embodiments of the present invention, which form a part of the specification, are used to illustrate the embodiments of the present invention, and together with the written description are used to explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.
[0015] Figure 1 Shows a schematic structural diagram of a filtering circuit for reducing 1 / f noise of a hemispherical resonator gyro control circuit provided according to a specific embodiment of the present invention;
[0016] Figure 2 Shows a schematic diagram of 1 / f noise spectral density. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0017] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way limits the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.
[0018] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0019] Unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for the sake of convenience of description, the sizes of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and devices should be regarded as part of the specification. In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values.
[0020] As Figure 1 shown, according to a specific embodiment of the present invention, a filter circuit for reducing the 1 / f noise of a hemispherical resonant gyro control circuit is provided. The filter circuit includes: an inverting single-pole high-pass filter and a voltage cancellation circuit.
[0021] The inverting single-pole high-pass filter includes a CMOS chopper-stabilized amplifier A1, resistors R1-R3, and a capacitor C1. The analog signal of the hemispherical resonant gyro is input through the signal input terminal, and after passing through resistors R1 and R2 respectively, it is connected to the non-inverting input terminal and the inverting input terminal of the amplifier A1 respectively. The capacitor C1 is connected to the non-inverting input terminal of the amplifier A1 and bypassed to the common terminal of the circuit; the resistor R3 is connected to the inverting input terminal and the output terminal of the amplifier A1 respectively.
[0022] The voltage cancellation circuit includes resistors R4 and R5, capacitor C2, and CMOS chopper-stabilized amplifier A2. The output terminal of amplifier A1 is connected to the non-inverting input terminal of amplifier A2 via resistor R5 and capacitor C2. Both ends of resistor R4 are respectively connected to the inverting input terminal of amplifier A1 and the non-inverting input terminal of amplifier A2. The inverting input terminal and the output terminal of amplifier A2 are connected to the signal output terminal.
[0023] Applying this configuration method, a filter circuit for reducing 1 / f noise of a hemispherical resonant gyro control circuit is provided. The filter circuit includes an inverting single-pole high-pass filter and a voltage cancellation circuit, which can filter out the low-frequency components in the vibration signal noise and will not introduce a large DC offset voltage error. Using the filter circuit of the present invention can effectively avoid the influence of 1 / f noise on the gyro angular rate at low frequencies and improve the angular rate detection accuracy.
[0024] Aiming at the influence of the gyro angular rate by detection noise, the present invention analyzes the noise source and provides a filter circuit to eliminate the noise, thereby improving the detection accuracy.
[0025] The filter of the present invention is approximately a single-pole transfer function with a cut-off frequency equal to 10 MHz, providing 22 dB of attenuation for the noise voltage in the frequency band from 0.1 Hz to 10 Hz.
[0026] Preferably, Figure 1 The middle circuit is a bootstrap filter. The precision chopper-stabilized CMOS amplifier A1 is configured as an inverting single-pole high-pass filter with a gain of 100. The gain is determined by R2 / R3. C1 is bypassed to the common terminal of the circuit. The DC gain is 1 (because R2 and R1 are connected to the same DC potential). The cut-off frequency of the high-pass filter is determined by R1×C1. After the signal noise is amplified and inverted by the output of amplifier A1, it is connected to the voltage cancellation circuit through C2, and the voltage division ratio is equal to the AC gain of amplifier A1. The cancellation node is at the non-inverting input terminal of amplifier A2, and the angular frequency of the voltage cancellation circuit is determined by the time constant C2(R5 + R4).
[0027] The voltage cancellation circuit can use capacitor C2 to reduce the impact of the voltage drop across the resistor (Rl) of the first-stage RC filter on DC through a DC-blocking circuit. The voltage drop across R1 is generated by the leakage current of Cl and amplified at the output of amplifier Al. The gain / attenuation coefficient of the voltage cancellation circuit is 100, and a large-value resistor of 1 MΩ (R5) can be used to determine the time constant of the second-stage RC (R5C2). The resistor that determines the time constant of the second-stage RC is not connected in series in the DC "signal" path, and the voltage cancellation voltage-dividing resistor connected in the path is only 10 kΩ. The extremely small resistor R4 makes the voltage drop generated by the leakage current of C2 negligible. The chopper-stabilized amplifier A2 buffers its non-inverting input terminal, featuring a large input impedance and a small output impedance. When the frequency is lower than the angular frequency defined by 1 / 2[C2(R5 + R4)], the maximum DC resistance is approximately 10 kΩ. The noise source level is defined as 0 dB, and the output noise of the second amplifier A2 is very low relative to the input noise of the filter, effectively suppressing the 1 / f noise in dB.
[0028] Due to different device selections, there may be certain uncertainties in this form of circuit. DC uncertainties include the voltage drops generated by the leakage current of the signal-path capacitor and the amplifier bias current across the resistor, as well as the variation of the amplifier offset voltage. In filter design, it is necessary to appropriately select the capacitor type, and the selection of CMOS amplifiers also directly affects the uncertainty of the amplifier input current and the noise caused by the input current. The CMOS chopper-stabilized amplifier almost eliminates the offset voltage, temperature drift, and 1 / f noise of the operational amplifier. AC uncertainties stem from the noise introduced by the amplifier itself and the amplifier gain mismatch caused by the resistance ratio of the voltage cancellation network. When using a single operational amplifier, the output noise of the filter is approximately twice the input noise.
[0029] The selection of capacitors Cl and C2 is crucial. Preferably, the present invention uses polypropylene film dielectric capacitors, with a minimum RC time constant of 30,000 seconds. For a 10 μF capacitor, the leakage resistance in the worst case is 3000 MΩ. The dual operational amplifier (ADA4807) is CMOS chopper-stabilized and meets the zero-bias current requirement. For this application, the chopper-stabilized amplifier provides a noise spectrum that does not contain the 1 / f noise component, has an extremely low offset voltage and offset voltage temperature coefficient, and gives a narrowband noise. Since amplifiers Al and A2 are chopper-stabilized amplifiers, the circuit output contains switching noise and the chopping frequency, distributed between 10 kHz and 15 kHz. These high-frequency noises can be easily filtered out when needed, and the influence of this part of the noise can be ignored in most applications that require a stable reference source.
[0030] According to another aspect of the present invention, there is provided a method for reducing 1 / f noise of a hemispherical resonant gyro control circuit. The method uses the filtering circuit for reducing 1 / f noise of the hemispherical resonant gyro control circuit as described above to achieve filtering of 1 / f noise.
[0031] In the present invention, during the signal detection stage, the vibration signal of the hemispherical resonant gyro collected is converted into an analog electrical signal through a capacitance-voltage conversion circuit. This analog electrical signal is input into the filtering circuit for reducing 1 / f noise of the hemispherical resonant gyro control circuit of the present invention, and undergoes inverting amplification determined by the R3 / R2 ratio, which includes noise. It is connected through C2 to a voltage cancellation circuit composed of R4 and R5, and is buffered by a chopper-stabilized amplifier A2 for its non-inverting input terminal to obtain the output signal, which has filtered out 1 / f noise.
[0032] The filtering circuit for reducing 1 / f noise of the hemispherical resonant gyro control circuit of the present invention can achieve filtering of the vibration signal without increasing the DC offset voltage, can effectively filter out 1 / f noise, thereby improving the signal detection accuracy.
[0033] In addition, it should be noted that using terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Without additional statements, the above terms have no special meanings, so they should not be construed as limiting the protection scope of the present invention.
[0034] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.
Claims
1. A filter circuit for reducing 1 / f noise of a hemispherical resonant gyroscope control circuit, characterized in that: The filter circuit for reducing the 1 / f noise of the hemispherical resonant gyro control circuit comprises: an inverting single-pole high-pass filter and a voltage offset circuit. The inverting single-pole high-pass filter includes a CMOS chopper-stabilized amplifier A1, resistors R1-R3 and a capacitor C1. The analog signal of the hemispherical resonant gyroscope is input through the signal input terminal, and is connected to the in-phase input terminal and the inverting input terminal of the amplifier A1 respectively after passing through the resistors R1 and R2. The capacitor C1 is connected to the in-phase input terminal of the amplifier A1 and bypassed to the common terminal of the circuit; the resistor R3 is connected to the inverting input terminal and the output terminal of the amplifier A1 respectively; The voltage offset circuit includes resistors R4 and R5, capacitor C2 and CMOS chopper-stabilized amplifier A2. The output end of amplifier A1 is connected to the non-inverting input end of amplifier A2 through resistor R5 and capacitor C2. The two ends of resistor R4 are respectively connected to the inverting input end of amplifier A1 and the non-inverting input end of amplifier A2. The inverting input end and output end of amplifier A2 are connected to the signal output end.
2. The filter circuit for reducing 1 / f noise of a hemispherical resonant gyro control circuit according to claim 1, characterized in that: The inverting single-pole high-pass filter has a gain of 100 and a DC gain of 1.
3. The filter circuit for reducing 1 / f noise of a hemispherical resonant gyro control circuit according to claim 1, characterized in that: The voltage cancellation circuit has a gain or attenuation factor of 100.
4. The filter circuit for reducing 1 / f noise of a hemispherical resonant gyro control circuit according to claim 3, characterized in that: Capacitors Cl and C2 are polypropylene film dielectric capacitors.
5. The filter circuit for reducing 1 / f noise of a hemispherical resonant gyro control circuit according to claim 4, characterized in that: The minimum RC time constant corresponding to capacitors Cl and C2 is 30,000 seconds.
6. A method for reducing 1 / f noise of a hemispherical resonant gyroscope control circuit, characterized in that: The method uses the filter circuit for reducing the 1 / f noise of the hemispherical resonant gyroscope control circuit as described in claims 1 to 5 to achieve filtering of the 1 / f noise.