Narrowband tunable filter for low frequency band

A filter and low-frequency technology, applied in the field of analog signal filtering system, which can solve the problems of reduced system accuracy, reduced signal-to-noise ratio, widened bandwidth, etc., to achieve the effect of improved signal-to-noise ratio and high flexibility

Active Publication Date: 2021-06-04
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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AI Technical Summary

Problems solved by technology

On the basis of high precision, the widest possible system bandwidth is required. However, the main problem faced by traditional filters is that the signal-to-noise ratio of the signal will decrease with the widening of the system bandwidth. Directly enlarging the bandwidth will lead to the loss of the entire system. Accuracy drops
In fact, under narrow-band conditions, the accuracy can already meet the requirements, so how to achieve high-precision acquisition of filters under wide-band conditions has become a problem that must be considered to improve system performance

Method used

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  • Narrowband tunable filter for low frequency band
  • Narrowband tunable filter for low frequency band
  • Narrowband tunable filter for low frequency band

Examples

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Embodiment 1

[0069] In this example, the frequency adjustment upper limit of the LRC narrowband tunable filter It is defined as 100KHz, the lower limit of frequency adjustment It is defined as 36.25KHz, the speed of FPGA scanning user control port P1 is set to 100Hz, the values ​​of filter inductors L1 and L2 are L=25mH, and the corresponding adjustment range of voltage-controlled capacitors CC1 and CC2 is 100pF~771pF.

[0070] The program of the programmable gate array FPGA is as follows: After power-on, the self-test of the device and the initialization of the digital-to-analog converter DAC are completed. , resistors R5-R7) the center frequency is placed in After that, the FPGA scans the user control port P1 cyclically at a frequency of 100Hz to detect whether there is a control signal incoming. The control signal is defined by the filter designer. 256 cases), defined 256 groups of control signals numbered 0~255, corresponding to the linear correspondence from 100KHz to 36.25KHz, w...

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Abstract

The invention is a narrow-band adjustable filter in the low frequency band, which solves the problem that it is difficult to realize the adjustment of the low frequency signal filtering frequency band in the traditional filter circuit design. The invention solves the problem of waveform distortion caused by superposition of the control channel and the signal channel of the varactor diode by adopting a voltage-controlled capacitor chip to replace the traditional varactor diode method. At the same time, it improves and combines the LRC filter circuit to solve the problem of the quality factor of the traditional RC filter circuit. The invention has the characteristics of narrow frequency band, high quality factor, and small signal deformation after filtering. At the same time, it further expands the adjustable range of frequency band by means of the parallel design of capacitors, and can be widely used in noise filtering of low-frequency harmonic circuits and high-precision acquisition circuits. .

Description

technical field [0001] The invention relates to the field of data acquisition, in particular to an analog signal filtering system in data acquisition. Background technique [0002] With the development of electronic power technology and large-scale integration technology, the information processing system has higher and higher requirements on the performance of the data acquisition system. On the basis of high precision, the widest possible system bandwidth is required. However, the main problem faced by traditional filters is that the signal-to-noise ratio of the signal will decrease with the widening of the system bandwidth. Directly enlarging the bandwidth will lead to the loss of the entire system. Accuracy drops. In fact, under narrow-band conditions, the accuracy can already meet the requirements, so how to achieve high-precision acquisition of filters under wide-band conditions has become a problem that must be considered to improve system performance. Contents of ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H03H7/01H03H1/02
Inventor 张治国王艺璇施博文赖小松
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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