A displacement sensor circuit

Abstract

The application discloses a displacement sensor circuit, belonging to the field of analog integrated circuits, comprising a primary part and a secondary part which are independent of each other. + and V ‑ , which drives a primary coil of an external LVDT; when the axis of the LVDT is displaced, the secondary coil outputs two corresponding changed sinusoidal signals V A and V B to the secondary part; the secondary part decodes and processes the sinusoidal signals V A and V B and outputs a direct current voltage representing displacement, so that high-precision displacement detection can be achieved and the domestic displacement sensor blank is filled.

Description

Technical Field

[0001] This invention relates to the field of analog integrated circuit technology, and in particular to a displacement sensor circuit. Background Technology

[0002] With the advent of sensors, science and technology have further developed, and various sensor circuits have been designed and rapidly applied. Current sensor technology designs are mainly divided into two categories: one where the circuit itself carries a sensing module, and the data is collected, processed, and converted by the circuit itself; and the other where the circuit uses external devices to collect data and feeds the collected data back to the circuit for processing and conversion.

[0003] Sensor technology involves collecting and processing data, converting it into the required information, and ultimately completing data detection. Currently, research on general-purpose sensor technology is relatively extensive in China, with common products including temperature sensors, sound sensors, and light sensors. However, research in the field of specialized sensors, especially specialized displacement sensors, is scarce. Summary of the Invention

[0004] The purpose of this invention is to provide a displacement sensor circuit to solve the problem.

[0005] To solve the above-mentioned technical problems, the present invention provides a displacement sensor circuit, including a primary side portion and a secondary side portion that are independent of each other;

[0006] The primary side generates a pair of differential signals V with exactly the same frequency and amplitude. + and V - , drives the first stage coil of the external LVDT;

[0007] When the axis of the LVDT is displaced, its secondary coil outputs two correspondingly changing sinusoidal signals V. A and V B To the secondary side portion;

[0008] The secondary side portion corresponds to the sinusoidal signal V. A and V B The code decodes and processes the data, outputting a DC voltage value V representing the displacement. OUT .

[0009] In one embodiment, the primary side portion includes a connected oscillator and a differential amplifier;

[0010] The oscillator generates a pair of clock signals with an external starting capacitor. The signal frequencies are 180 degrees apart. The signals are converted into differential triangular waves by the primary circuit and combined with the sine wave generation circuit to output a pair of stable differential sine wave signals.

[0011] The differential amplifier uses two completely symmetrical amplifier modules to amplify the differential sine wave signal output from the pre-stage oscillator, which is then used as the first-stage coil to drive the LVDT.

[0012] In one embodiment, the secondary side portion includes a connected decoder, filter, and DC amplifier;

[0013] The decoder processes the two sinusoidal signals output by the LVDT, and modulates the changing sinusoidal signals into DC signals;

[0014] The filter filters the DC signal output by the decoder, eliminating noise carried in the signal and reducing the distortion of the output signal.

[0015] The DC amplifier amplifies the filtered DC signal and increases the driving capability of the output signal.

[0016] In one embodiment, the front part of the decoder consists of two identical structures, which respectively include a voltage-to-current circuit, a comparator, a four-quadrant multiplier, a filter circuit, and a two-quadrant multiplier.

[0017] Sine wave signal V A and V B After entering the decoder, the signal simultaneously enters the voltage-to-current circuit and the comparator to perform voltage-to-current conversion and comparison. The voltage signal V A V B It is converted into a current signal and compared with GND. When the voltage signal is greater than GND, it outputs 1, and when it is less than GND, it outputs -1. The comparison result is then multiplied by the converted current signal.

[0018] Then, the signal is multiplied by the binary signal fed back from the subsequent circuit through a filtering circuit. The two sets of signals obtained after multiplication are then subtracted, filtered, integrated, rounded, and compared before outputting a binary signal n, i.e., n = B / (A + B), where A and B are voltage signals V. A V B The amplitude is fed back to the previous stage circuit and simultaneously output to the next stage circuit.

[0019] In one embodiment, the decoder includes a high-precision bandgap reference circuit to provide a stable reference current I. REF , will I REF The signal is multiplied by the binary signals n and 1-n fed back from the two channels respectively, and the result of the multiplication is subtracted to output a DC voltage signal. This signal is generated by I. REF The DC voltage signal is characterized by ×(AB) / (A+B); finally, the DC voltage signal is filtered, integrated, rounded, and summed using feedback to obtain a stable DC voltage signal V.OUT .

[0020] In one embodiment, the oscillator's output frequency and amplitude are controlled by an external capacitor and resistor.

[0021] In one embodiment, a common-mode feedback loop is provided between the two completely symmetrical amplifier modules in the differential amplifier. At the same time, two external ports are designed at both ends of the feedback resistor in the common-mode feedback loop. Resistors are connected through the two external ports to change the equivalent resistance in the common-mode feedback loop, thereby changing the resistance ratio of the common-mode feedback loop and thus realizing the gain adjustment of the differential amplifier.

[0022] In one implementation, the decoder is capable of processing multiple types of LVDT feedback signals.

[0023] In one implementation, the filter can adjust the size of the external capacitor to achieve filtering standards for different needs.

[0024] In one embodiment, the DC amplifier can achieve different output ranges by changing the resistance of the feedback loop.

[0025] In a displacement sensor circuit provided by the present invention, there are two independent primary and secondary sides; the primary side generates a pair of differential signals V with exactly the same frequency and amplitude. + and V - The primary coil of the external LVDT is driven; when the axis of the LVDT is displaced, its secondary coil outputs two correspondingly changing sinusoidal signals V. A and V B To the secondary side portion; the secondary side portion corresponds to the sinusoidal signal V A and V B By decoding and processing, a DC voltage representing displacement is output, enabling high-precision displacement detection and filling the gap in domestic displacement sensors. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the principle structure of a displacement sensor circuit proposed in this invention.

[0027] Figure 2 This is a diagram of the oscillator signal transmission and conversion process.

[0028] Figure 3 This is a schematic diagram of the decoder structure in a displacement sensor circuit. Detailed Implementation

[0029] The displacement sensor circuit proposed in this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of this invention will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of this invention.

[0030] This invention provides a displacement sensor circuit that uses an external LVDT (Linear Variable Displacement Transducer) to sample displacement. After internal decoding, the circuit outputs a DC voltage representing the displacement, enabling high-precision displacement detection. The overall circuit is designed using bipolar semiconductor technology and mainly includes an oscillator, differential amplifier, decoder, filter, and DC amplifier.

[0031] like Figure 1 The diagram shown is a functional block diagram of a displacement sensor circuit provided by the present invention. The displacement sensor circuit outputs a pair of differential signals V with completely equal frequency and amplitude. + and V - The primary coil drives the LVDT. When the LVDT's shaft shifts, the secondary coil outputs two corresponding changing AC voltage signals V. A and V B The AC signal is input to the displacement sensor circuit for decoding and processing. The overall displacement sensor circuit consists of two independent parts: a primary side and a secondary side. The primary side comprises an oscillator and a differential amplifier, outputting a pair of stable differential signals whose amplitude and frequency are controlled by external resistors and capacitors to drive an external LVDT. The secondary side includes a decoder, a filter, and a DC amplifier, processing the two AC signals from the LVDT feedback that vary with displacement, ultimately outputting a DC signal V corresponding to the LVDT's axis displacement. OUT .

[0032] like Figure 2 The diagram shows the output waveforms of key nodes in the primary side section. The oscillator generates a pair of clock signals with a frequency difference of 180 degrees using an external starting capacitor. These clock signals are then converted into triangular wave signals by a triangular wave converter circuit. The triangular wave signals are then converted into a set of differential sine waves with equal amplitude and frequency by a sine wave generator circuit. To provide the differential signals with a certain load driving capability, an adjustable gain differential amplifier is added to the oscillator's output stage. Finally, the primary side section outputs a pair of differential signals V with adjustable amplitude and frequency. + and V - It can drive the first stage coil of the LVDT.

[0033] like Figure 3The diagram shown is a functional implementation block diagram of the decoder in the secondary side section. A V B These are sinusoidal signals output from the LVDT's second-stage coil; the amplitudes of both signals change with the displacement of the LVDT's axis. The decoder's front end consists of two identical structures, including a voltage-to-current converter, a comparator, a four-quadrant multiplier, a filter circuit, and a two-quadrant multiplier. V A V B After entering the decoder, the signal simultaneously enters the voltage-to-current conversion circuit and the comparator to perform voltage-to-current conversion and comparison. Voltage signal V A V B The voltage signal is converted into a current signal and compared with GND. When the voltage signal is greater than GND, it outputs 1; when it is less than GND, it outputs -1. The comparison result is then multiplied by the converted current signal. After passing through a filter circuit, it is multiplied by the binary signals fed back from the subsequent circuit. The two sets of signals obtained after multiplication are subtracted, then filtered, integrated, rounded, and compared before outputting a binary signal n, i.e., n = B / (A + B), where A and B are the voltage signals V. A V B The amplitude is fed back to the preceding circuit and simultaneously output to the next stage circuit. The decoder incorporates a high-precision bandgap reference circuit, which can provide a stable reference current I. REF , will I REF The signal is multiplied by the binary signals n and 1-n fed back from the two channels respectively, and the result of the multiplication is subtracted to output a DC voltage signal. This signal is generated by I. REF The DC voltage signal is represented by ×(AB) / (A+B); finally, the DC voltage signal is filtered, integrated, rounded, and summed using feedback to obtain a stable DC voltage signal. To ensure the accuracy and stability of the final output signal, a filter and a DC amplifier are added to the output of the decoder. The closed-loop gain of the DC amplifier can be adjusted to determine the magnitude of the final output voltage.

[0034] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A displacement sensor circuit, characterized in that, It includes mutually independent primary and secondary edge components; The primary side generates a pair of differential signals V with exactly the same frequency and amplitude. + and V - , drives the first stage coil of the external LVDT; When the axis of the LVDT is displaced, its secondary coil outputs two correspondingly changing sinusoidal signals V. A and V B To the secondary side portion; The secondary side portion corresponds to the sinusoidal signal V. A and V B The code decodes and processes the data, outputting a DC voltage value V representing the displacement. OUT ; The primary side includes a connected oscillator and a differential amplifier; the oscillator generates a pair of clock signals with a frequency difference of 180 degrees using an external starting capacitor, which are converted into differential triangular waves by the primary side and combined with a sine wave generation circuit to output a pair of stable differential sine wave signals. The differential amplifier uses two completely symmetrical amplifier modules to amplify the differential sine wave signal output from the pre-stage oscillator, which is then used as the first-stage coil to drive the LVDT. The secondary side includes a connected decoder, filter, and DC amplifier; the decoder processes the two sinusoidal signals output by the LVDT and modulates the changing sinusoidal signals into DC signals. The filter filters the DC signal output by the decoder, eliminating noise carried in the signal and reducing the distortion of the output signal. The DC amplifier amplifies the filtered DC signal and increases the driving capability of the output signal.

2. The displacement sensor circuit as described in claim 1, characterized in that, The front part of the decoder consists of two identical structures, which respectively include a voltage-to-current circuit, a comparator, a four-quadrant multiplier, a filter circuit, and a two-quadrant multiplier. Sine wave signal V A and V B After entering the decoder, the signal simultaneously enters the voltage-to-current circuit and the comparator to perform voltage-to-current conversion and comparison. The voltage signal V A V B It is converted into a current signal and compared with GND. When the voltage signal is greater than GND, it outputs 1, and when it is less than GND, it outputs -1. The comparison result is then multiplied by the converted current signal. Then, the signal is multiplied by the binary signal fed back from the subsequent circuit through a filtering circuit. The two signals obtained after multiplication are then subtracted, filtered, integrated, rounded, and compared before outputting a binary signal n, i.e., n = B / (A + B), where A and B are voltage signals V. A V B The amplitude is fed back to the previous stage circuit and simultaneously output to the next stage circuit.

3. The displacement sensor circuit as described in claim 2, characterized in that, The decoder incorporates a high-precision bandgap reference circuit to provide a stable reference current I. REF , will I REF The signal is multiplied by the binary signals n and 1-n fed back from the two channels respectively, and the result of the multiplication is subtracted to output a DC voltage signal. This signal is generated by I. REF The DC voltage signal is characterized by ×(AB) / (A+B); finally, the DC voltage signal is filtered, integrated, rounded, and summed using feedback to obtain a stable DC voltage signal V. OUT .

4. The displacement sensor circuit as described in claim 1, characterized in that, The oscillator's output frequency and amplitude are controlled by an external capacitor and resistor.

5. The displacement sensor circuit as described in claim 1, characterized in that, The differential amplifier has a common-mode feedback loop between the two completely symmetrical amplifier modules. At the same time, two external ports are designed at both ends of the feedback resistor in the common-mode feedback loop. Resistors are connected through the two external ports to change the equivalent resistance in the common-mode feedback loop, thereby changing the resistance ratio of the common-mode feedback loop and thus realizing the gain adjustment of the differential amplifier.

6. The displacement sensor circuit as described in claim 1, characterized in that, The decoder can process various types of LVDT feedback signals.

7. The displacement sensor circuit as described in claim 1, characterized in that, The filter can adjust the size of the external capacitor to achieve different filtering standards.

8. The displacement sensor circuit as described in claim 1, characterized in that, The DC amplifier can achieve different output ranges by changing the resistance of the feedback loop.

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