CN112039453A - Automatic level control circuit for low-frequency signal - Google Patents
Automatic level control circuit for low-frequency signal Download PDFInfo
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- CN112039453A CN112039453A CN202010770042.9A CN202010770042A CN112039453A CN 112039453 A CN112039453 A CN 112039453A CN 202010770042 A CN202010770042 A CN 202010770042A CN 112039453 A CN112039453 A CN 112039453A
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- 238000001514 detection method Methods 0.000 claims abstract description 70
- 238000001914 filtration Methods 0.000 claims abstract description 62
- 230000003321 amplification Effects 0.000 claims abstract description 8
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 8
- 230000003044 adaptive effect Effects 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000013480 data collection Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers without distortion of the input signal
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
- H03G3/3005—Automatic control in amplifiers having semiconductor devices in amplifiers suitable for low-frequencies, e.g. audio amplifiers
- H03G3/3026—Automatic control in amplifiers having semiconductor devices in amplifiers suitable for low-frequencies, e.g. audio amplifiers the gain being discontinuously variable, e.g. controlled by switching
Abstract
The invention discloses a low-frequency signal automatic level control circuit, and relates to the field of low-frequency signal automatic level control. The low-frequency signal automatic level control circuit comprises a filtering detection circuit, wherein the filtering detection circuit comprises four groups of detection and filtering bandwidths, a PNP (plug-and-play) broadband transistor is connected to each group of detection and filtering bandwidths, the PNP broadband transistor controls the selection of the detection bandwidths through the switching of high and low levels, a detection signal is subjected to detection and filtering of the detection bandwidths and then is subjected to detection and amplification, and the detection signal is output to an ALC (automatic level control) board after the detection and amplification. In the four groups of detection filtering bandwidths, one group of detection filtering bandwidths is suitable for carrying out segmented filtering on the frequency below 100kHz, namely, narrow-band filtering is adopted for low-frequency signals, and the other group of detection filtering bandwidths is suitable for carrying out segmented filtering on the frequency above 100 kHz. The circuit adopts a four-section detection filter circuit to realize the automatic level control of the full wave band.
Description
Technical Field
The invention relates to the field of low-frequency signal automatic level control, in particular to a low-frequency signal automatic level control circuit.
Background
For the signal generator, the frequency range is generally from a direct current signal to a millimeter wave frequency band, and the span is large, so that a detector in the signal generator adopts a broadband detector. For a diode detector, when the frequency range is large, each index of the diode detector is rapidly deteriorated.
A traditional detection circuit adopts a broadband detector, if the same filter is adopted for filtering, the quality of a high-frequency signal and the quality of a low-frequency signal cannot be considered simultaneously, and therefore the mode of firstly detecting and then filtering in sections is adopted. Because the frequency characteristic difference between the low-frequency signal and the high-frequency signal is large, how to divide the frequency band for detection and filtering is particularly critical.
When the frequency coverage range of the traditional broadband diode detector is large, various performance parameters are reduced to different degrees, and in order to ensure that the detected signal has excellent performance at high and low levels, a segmented detection filtering mode is adopted to improve the automatic level control of the signal. Because the characteristic difference of the low-frequency signal and the high-frequency signal in the radio frequency circuit is large, the existing three-segment segmented detection filtering mode is not friendly to the low-frequency signal, the automatic level control precision is low, and the performance is poor.
The noise of the detection tube includes resistance thermal noise, current dispersion noise, flicker noise, and the like. In addition, there is noise in the system, and in order to accurately obtain the frequency band range of the original signal, the automatic level control circuit needs to adopt a filter circuit to effectively filter noise interference outside the frequency band and reduce signal distortion. The filtering technique can pass the signal through a proper passband, thereby minimizing the interference of full-band noise. In addition, the working frequency range of the signal generator is large, generally between 9kHz and 6GHz, so that the detection circuit is required to be capable of collecting signals in a wide frequency band range, and meanwhile, the data collection precision is also required to be considered. For low-frequency signals and high-frequency signals, the influence of noise in a system on the low-frequency signals and the high-frequency signals is greatly different, and the full-band filtering performance cannot be considered by adopting broadband diode detection, so that a segmented filtering technology is selected. The problem that follows is how large the band range of the filter is set to be appropriate.
In the frequency band range of 9kHz-6GHz, at present, three sections of detection filter circuits are adopted, direct filtering is used for high-frequency signals, broadband detection is used for intermediate-frequency signals, and narrow-band detection is used for low-frequency signals. The actual test result basically meets the requirement, but the automatic level control index of the low-frequency signal is slightly worse. The frequency range division in this frequency band needs to be more careful due to the poor noise immunity of low frequency signals.
Disclosure of Invention
The invention aims to overcome the defects, and provides a low-frequency signal automatic level control circuit which improves the precision of four groups of detection filter circuits by increasing a group of detection filter bandwidths, wherein the circuit is in the form of four groups of detection filter bandwidths, and different filters are selected according to different frequencies.
The invention specifically adopts the following technical scheme:
the automatic level control circuit for the low-frequency signal comprises a wave detection circuit, wherein the wave detection circuit comprises four groups of wave detection and filtering bandwidths, each group of wave detection and filtering bandwidths is connected with a broadband transistor, the broadband transistor controls the selection of the wave detection bandwidths through the switching of high and low levels, the wave detection signal is subjected to wave detection and filtering of the wave detection bandwidths and then subjected to wave detection and amplification, and the wave detection signal is output to an ALC (adaptive logic level) board after the wave detection and amplification.
Preferably, one of the four detection filter bandwidths is suitable for piecewise filtering frequencies below 100kHz, i.e., applying narrow-band filtering to low-frequency signals.
Preferably, there are three of the four detection filter bandwidths suitable for piecewise filtering frequencies above 100 kHz.
Preferably, the broadband transistor is a PNP broadband transistor.
The invention has the following beneficial effects:
on the basis of a circuit which is divided into three sections for filtering, a group of detection bandwidths are added, narrow-band filtering is used, and the detection bandwidths and the three sections of filtering circuits form a full-band detection filtering circuit, four groups of detection filtering bandwidths are totally calculated, and the automatic level control precision and range of low-frequency signals are improved.
The low-frequency signal detection filtering is divided into two sections, and a narrow-band filter and an ultra-narrow-band filter are adopted for filtering; the high-frequency signal is divided into two sections, and broadband filtering and direct filtering are respectively adopted, so that the performance of full-band automatic level control is improved.
The detection bandwidth is selected according to the frequency by switching high and low levels by adopting a broadband transistor as a switch for selecting the detection bandwidth.
The whole circuit is simple to realize, low in cost, obvious in effect and excellent in performance, and is changed on the basis of the existing circuit.
Drawings
FIG. 1 is a schematic diagram of a detector circuit.
Detailed Description
The following description of the embodiments of the present invention will be made with reference to the accompanying drawings:
referring to fig. 1, the automatic level control circuit for low frequency signals includes a filtering and wave detecting circuit, the filtering and wave detecting circuit includes four sets of wave detecting and wave filtering bandwidths, each set of wave detecting and wave filtering bandwidths is connected with a PNP wide-band transistor, the PNP wide-band transistor controls the selection of the wave detecting bandwidth through the switching of high and low levels, the wave detecting signals are subjected to wave detecting and wave filtering of the wave detecting bandwidths and then subjected to wave detecting and amplification, and the wave detecting and amplification signals are output to an ALC board.
In the four groups of detection filtering bandwidths, one group of detection filtering bandwidths is suitable for carrying out segmented filtering on the frequency below 100kHz, namely, narrow-band filtering is adopted for low-frequency signals, and the other group of detection filtering bandwidths is suitable for carrying out segmented filtering on the frequency above 100 kHz.
The low-frequency signal automatic level control circuit further divides the detection and filtering range of the low-frequency signal, a group of detection bandwidths are added on the basis of a circuit for filtering by three sections, narrow-band filtering is used, and the detection and filtering circuits and the three sections of filtering circuits form a full-band detection and filtering circuit, four groups of detection and filtering bandwidths are totally calculated, and the automatic level control precision and range of the low-frequency signal are improved.
The selection of the detection bandwidth is controlled by switching high and low levels by utilizing the switching action of a PNP broadband transistor, and when different frequencies are used, software can automatically identify the detection bandwidth corresponding to the frequency and control the enabling level of the transistor, thereby realizing the detection filtering function of different wave bands.
It is to be understood that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make modifications, alterations, additions or substitutions within the spirit and scope of the present invention.
Claims (4)
1. The automatic level control circuit for the low-frequency signal is characterized by comprising a filtering detection circuit, wherein the filtering detection circuit comprises four groups of detection filtering bandwidths, each group of detection filtering bandwidths is connected with a broadband transistor, the broadband transistor controls the selection of the detection bandwidths through switching of high and low levels, a detection signal is subjected to detection filtering of the detection bandwidths and then subjected to detection amplification, and the detection signal is output to an ALC board after the detection amplification.
2. The automatic level control circuit for low frequency signals of claim 1 wherein one of the four detector filter bandwidths is adapted to perform segmented filtering for frequencies below 100kHz, i.e. applying narrow band filtering to low frequency signals.
3. The automatic level control circuit for low frequency signals of claim 1 wherein of the four detector filter bandwidths, there are three detector filter bandwidths available for piecewise filtering frequencies above 100 kHz.
4. The automatic level control circuit for low frequency signals as claimed in claim 1, wherein the wide band transistor is a PNP wide band transistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010770042.9A CN112039453A (en) | 2020-08-04 | 2020-08-04 | Automatic level control circuit for low-frequency signal |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010770042.9A CN112039453A (en) | 2020-08-04 | 2020-08-04 | Automatic level control circuit for low-frequency signal |
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Citations (8)
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|---|---|---|---|---|
| EP1067400A2 (en) * | 1999-07-09 | 2001-01-10 | General Electric Company | Method and apparatus for adaptive wall filtering in spectral doppler ultrasound imaging |
| US20040119543A1 (en) * | 2002-11-26 | 2004-06-24 | Denoyer Gilles P. | Wide dynamic range transimpedance amplifier with a controlled low frequency cutoff at high optical power |
| CN104009765A (en) * | 2014-06-13 | 2014-08-27 | 东南大学 | High-performance radio frequency transmitter of LTE channel simulator |
| CN105049106A (en) * | 2014-12-15 | 2015-11-11 | 佳律通信设备(上海)有限公司 | Bandwidth-selectable repeater and method for controlling the same |
| CN105162478A (en) * | 2015-07-16 | 2015-12-16 | 中国电子科技集团公司第四十一研究所 | Short-wave receiver preselecting filter circuit and method |
| CN109521385A (en) * | 2018-11-22 | 2019-03-26 | 北京东方计量测试研究所 | A kind of signal source module and signal generating method for oscillograph calibrating |
| CN210893160U (en) * | 2019-12-24 | 2020-06-30 | 成都前锋电子仪器有限责任公司 | Intermediate frequency signal generating circuit for portable communication and navigation tester |
| CN210927640U (en) * | 2020-03-09 | 2020-07-03 | 深圳市航达微电子技术有限公司 | Hand-held C wave band signal detector |
-
2020
- 2020-08-04 CN CN202010770042.9A patent/CN112039453A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1067400A2 (en) * | 1999-07-09 | 2001-01-10 | General Electric Company | Method and apparatus for adaptive wall filtering in spectral doppler ultrasound imaging |
| US20040119543A1 (en) * | 2002-11-26 | 2004-06-24 | Denoyer Gilles P. | Wide dynamic range transimpedance amplifier with a controlled low frequency cutoff at high optical power |
| CN104009765A (en) * | 2014-06-13 | 2014-08-27 | 东南大学 | High-performance radio frequency transmitter of LTE channel simulator |
| CN105049106A (en) * | 2014-12-15 | 2015-11-11 | 佳律通信设备(上海)有限公司 | Bandwidth-selectable repeater and method for controlling the same |
| CN105162478A (en) * | 2015-07-16 | 2015-12-16 | 中国电子科技集团公司第四十一研究所 | Short-wave receiver preselecting filter circuit and method |
| CN109521385A (en) * | 2018-11-22 | 2019-03-26 | 北京东方计量测试研究所 | A kind of signal source module and signal generating method for oscillograph calibrating |
| CN210893160U (en) * | 2019-12-24 | 2020-06-30 | 成都前锋电子仪器有限责任公司 | Intermediate frequency signal generating circuit for portable communication and navigation tester |
| CN210927640U (en) * | 2020-03-09 | 2020-07-03 | 深圳市航达微电子技术有限公司 | Hand-held C wave band signal detector |
Non-Patent Citations (1)
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Application publication date: 20201204 |