CN111308196B - Frequency detector - Google Patents
Frequency detector Download PDFInfo
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- CN111308196B CN111308196B CN201811509609.6A CN201811509609A CN111308196B CN 111308196 B CN111308196 B CN 111308196B CN 201811509609 A CN201811509609 A CN 201811509609A CN 111308196 B CN111308196 B CN 111308196B
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
- G01R23/02—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage
- G01R23/06—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage by converting frequency into an amplitude of current or voltage
Abstract
A frequency detector for detecting a frequency difference of a signal to be detected from a first time point to a second time point, the frequency detector comprising: an AC coupling capacitor for receiving the signal to be measured; a rectification circuit electrically connected to the AC coupling capacitor; an analog-digital converter electrically connected to the rectifying circuit; a control unit electrically connected to the analog-to-digital converter; and a counter electrically connected to the rectifying circuit and the control unit, wherein the control unit calculates the frequency difference of the signal to be measured from the first time point to the second time point according to the output of the analog-to-digital converter and the output of the counter.
Description
Technical Field
The present disclosure relates to the field of frequency detection technologies, and more particularly, to a frequency detector.
Background
The conventional frequency detector detects the frequency of a circuit to be detected by using the count value of the counter in a period of the circuit to be detected and the count frequency of the counter.
In addition, the operating frequency of many circuits needs to be fixed and cannot vary too much, so it is very important to detect the frequency difference (variation) of the circuits. However, when the frequency difference of the circuit to be detected is detected only by using the counter, if the accuracy of detecting the frequency difference needs to be improved, for example, from 10KHz (10 kilohertz,10 KHz) to 1KHz, the counter needs a longer counting time, which results in a slower speed of detecting the frequency difference. Alternatively, a counter with a higher counting frequency can be used to increase the accuracy of detecting the frequency difference, which may cause the problem of increased power.
There is therefore a need to provide a solution to the above-mentioned problems of the prior art.
Disclosure of Invention
The present disclosure provides a frequency detector that solves the problems of the prior art.
The frequency detector of the present disclosure is used for detecting a frequency difference of a signal to be detected from a first time point to a second time point, the frequency detector comprising: an AC coupling capacitor for receiving the signal to be measured; a rectification circuit electrically connected to the AC coupling capacitor; an analog-digital converter electrically connected to the rectifying circuit; a control unit electrically connected to the analog-to-digital converter; and a counter electrically connected to the rectifying circuit and the control unit, wherein the control unit calculates the frequency difference of the signal to be measured from the first time point to the second time point according to the output of the analog-to-digital converter and the output of the counter.
The frequency detector of the present disclosure is used for detecting a frequency difference of a signal to be detected from a first time point to a second time point, the frequency detector comprising: an AC coupling capacitor for receiving the signal to be measured; a rectifying circuit electrically connected to the AC coupling capacitor; a time-to-digital converter electrically connected to the rectifying circuit; a control unit electrically connected to the time-to-digital converter; and a counter electrically connected to the rectifying circuit and the control unit, wherein the control unit calculates the frequency difference of the signal to be measured from the first time point to the second time point according to the output of the time-to-digital converter and the output of the counter.
The frequency detector of the present disclosure converts different frequencies of the signal to be measured into voltages, thereby calculating the frequency difference, which is different from the prior art that directly uses a counter to calculate the frequency difference. Furthermore, the frequency detector of the present embodiment includes an analog-to-digital converter or a time-to-digital converter, so that the accuracy of detecting the frequency difference can be improved. That is, the frequency detector of the present embodiment does not need to have a longer counting time or increase the counting frequency of the counter to increase the accuracy of detecting the frequency difference.
In order to make the aforementioned and other aspects of the present disclosure more comprehensible, preferred embodiments accompanied with figures are described in detail below:
drawings
Fig. 1 shows a schematic diagram of a frequency detector according to an embodiment of the present disclosure.
Fig. 2 to 4 are schematic diagrams showing waveforms of the signal to be measured, the output waveform of the ac coupling capacitor, and the output waveform of the rectifier circuit, respectively.
Fig. 5 shows a schematic diagram of a first rectified signal output by a rectifier circuit at a first point in time and a second rectified signal output by the rectifier circuit at a second point in time.
FIG. 6 is a schematic diagram of a frequency detector according to another embodiment of the disclosure.
Detailed Description
In order to make the objects, technical solutions and effects of the present disclosure clearer and clearer, the present disclosure is further described in detail below with reference to the drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the disclosure and that the word "embodiment" as used in this disclosure is intended to serve as an example, instance, or illustration and is not intended to limit the disclosure. In addition, the articles "a" and "an" as used in this disclosure and the appended claims may generally be construed to mean "one or more" unless specified otherwise or clear from context to be directed to a singular form. Also, in the drawings, elements having similar or identical structures, functions, and the like are referred to by the same element numbers.
Referring to fig. 1, fig. 1 shows a schematic diagram of a frequency detector according to an embodiment of the disclosure.
The frequency detector includes an ac coupling capacitor 10, a rectifying circuit 12, an Analog-to-Digital Converter (ADC) 14, a control unit 16, and a counter 18. The frequency detector is used for detecting a frequency difference of a detected signal VIN from a first time point to a second time point. The signal to be measured VIN is from a circuit to be measured.
The ac coupling capacitor 10 is configured to receive the signal to be measured VIN and filter out low-frequency components of the signal to be measured VIN. More specifically, one end of the ac coupling capacitor 10 is electrically connected to the signal to be measured VIN.
The rectifying circuit 12 is electrically connected to the ac coupling capacitor 10. More specifically, the input terminal of the rectifying circuit 12 is electrically connected to the other terminal of the AC coupling capacitor 10.
The analog-to-digital converter 14 is electrically connected to the rectifying circuit 12. More specifically, the input terminal of the analog-to-digital converter 14 is electrically connected to the output terminal of the rectifying circuit 12.
The control unit 16 is electrically connected to the adc 14. More specifically, an input terminal of the control unit 16 is electrically connected to the output terminal of the analog-to-digital converter 14.
The counter 18 is electrically connected to the rectifying circuit 12 and the control unit 16. More specifically, an input terminal of the counter 18 is electrically connected to an output terminal of the analog-to-digital converter 14, and an output terminal of the counter 18 is electrically connected to another input terminal of the control unit 16.
The control unit 16 calculates the frequency difference of the signal to be measured from the first time point to the second time point according to the output of the adc 14 and the output of the counter 18.
For a first time point, the ac coupling capacitor 10 filters a low frequency component of the signal to be measured VIN at the first time point and outputs a first filtered signal, the rectifier circuit 12 rectifies the first filtered signal and outputs a first rectified signal, and the analog-to-digital converter 14 performs analog-to-digital conversion on the first rectified signal and outputs a first digital signal.
For a second time point, the ac coupling capacitor 10 filters out a low frequency component of the signal to be measured VIN at the second time point and outputs a second filtered signal, the rectifier circuit 12 rectifies the second filtered signal and outputs a second rectified signal, and the analog-to-digital converter 14 performs analog-to-digital conversion on the second rectified signal and outputs a second digital signal.
The counter 18 counts the first rectified signal and outputs a first count value, the counter 18 counts the second rectified signal and outputs a second count value, and the control unit 16 calculates the frequency difference between the signal to be measured VIN at a first time point and a second time point according to the first digital signal, the second digital signal, the first count value and the second count value.
Referring to fig. 1 to 4, fig. 2 to 4 respectively show waveforms of the signal to be measured VIN, the output waveform of the ac coupling capacitor 10 and the output waveform of the rectifying circuit 12.
As shown in fig. 2, the waveform of the signal to be measured VIN is a sine wave. As shown in fig. 3, the output waveform of the ac coupling capacitor 10 is the waveform with low frequency components filtered out. As shown in fig. 4, the output waveform of the rectifier circuit 12 is rectified into a dc component.
Referring to fig. 1 and 5, fig. 5 shows a schematic diagram of a first rectified signal C1 output by the rectifying circuit 12 at a first time point and a second rectified signal C2 output by the rectifying circuit 12 at a second time point.
The principle of the frequency detector of the present disclosure is as follows: the signal to be measured VIN at the first time point is converted into a dc first rectified signal C1, the control unit 16 obtains a time T2 when the first rectified signal C1 reaches the voltage V, and the counter 18 counts a count value CV1 when the first rectified signal C1 reaches the voltage V. Then, the signal to be measured VIN at the second time point is converted into a direct-current second rectified signal C2, the control unit 16 obtains a time T1 when the second rectified signal C2 reaches the voltage V, and the counter 18 counts a count value CV2 when the second rectified signal C2 reaches the voltage V. Finally, the control unit 16 obtains a frequency difference of the signal to be measured VIN from the first time point to the second time point according to the time difference (T2-T1), the counter value CV1 when the first rectified signal C1 reaches the voltage V, the counter value CV2 when the second rectified signal C2 reaches the voltage V, and the counting frequency of the counter 18. The voltage V can be designed appropriately according to the circuit to be tested.
For example, assume that the frequency of the signal to be measured VIN at the first time point is 100KHz, the frequency of the signal to be measured VIN at the first time point is 110KHz, and the counting frequency of the counter 18 is 100mhz (100megahertz, 100mhz). The difference in frequency between the first and second time points is 10KHz.
First, the control unit 16 obtains a time for the first rectified signal C1 to reach the voltage V as 6 milliseconds (ms), and the counter 18 counts the count value of the first rectified signal C1 reaching the voltage V as 100. Then, the control unit 16 obtains the time for the second rectified signal C2 to reach the voltage V as 5ms, and the counter 18 counts the count value for the second rectified signal C2 to reach the voltage V as 110. Finally, the control unit 16 obtains the frequency difference F from the first time point to the second time point of the signal VIN to be measured according to the time difference (6 ms-5ms = 1ms), the count value difference (110-100 = 10) and the count frequency (100 MHz) of the counter 18 as follows:
F＝100MHz/(10/1ms)＝10KHz。
the above description is made by calculating the frequency difference by the control unit 16 according to the first rectified signal C1 and the second rectified signal C2 outputted by the rectifying circuit 12. However, as shown in fig. 1, the frequency detector of the present disclosure further includes an adc 14, so that the control unit 16 can also calculate the frequency difference according to the first digital signal and the second digital signal outputted by the adc 14.
More specifically, the signal to be measured VIN at the first time point is converted into a first digital signal, the control unit 16 obtains a time when the first rectified signal corresponding to the first digital signal reaches the voltage V, and the counter 18 counts a count value when the first rectified signal reaches the voltage V. Then, the signal to be measured VIN at the second time point is converted into a second digital signal, the control unit 16 can obtain the time when the second rectified signal corresponding to the second digital signal reaches the voltage V, and the counter 18 counts the count value when the second rectified signal corresponding to the second digital signal reaches the voltage V. Finally, the control unit 16 obtains the frequency difference of the signal to be measured VIN from the first time point to the second time point according to the time difference, the count value of the voltage V reached by the first rectified signal corresponding to the first digital signal, the count value of the voltage V reached by the second rectified signal corresponding to the second digital signal, and the count frequency of the counter.
In the embodiment of fig. 1, the rectifying circuit 12 includes a first Schottky diode (Schottky diode) 120, a second Schottky diode 122 and a first capacitor 124.
The first schottky diode 120 includes a first anode and a first cathode. The first anode is electrically connected to a ground. The first cathode is electrically connected to the other end of the AC coupling capacitor 10.
The second schottky diode 122 includes a second anode and a second cathode. The second anode is electrically connected to the other end of the AC coupling capacitor 10. The second cathode is electrically connected to the input terminal of the analog-to-digital converter 14. The first capacitor 124 is electrically connected between the input terminal of the adc 14 and the ground.
The frequency detector of this embodiment converts different frequencies of the signal to be measured into voltages, thereby calculating the frequency difference, which is different from the prior art that directly uses a counter to calculate the frequency difference. Furthermore, the frequency detector of the present embodiment includes an analog-to-digital converter, so that the accuracy of detecting the frequency difference can be improved. That is, the frequency detector of the present embodiment does not need longer counting time or increase the counting frequency of the counter to increase the accuracy of detecting the frequency difference.
Referring to fig. 6, fig. 6 shows a schematic diagram of a frequency detector according to another embodiment of the present disclosure.
The frequency detector includes an ac coupling capacitor 60, a rectifying circuit 62, a Time-to-Digital Converter (TDC) 64, a control unit 66 and a counter 68. The frequency detector is used for detecting a frequency difference of a signal VIN to be detected from a first time point to a second time point. The signal to be measured VIN is from a circuit to be measured.
The ac coupling capacitor 60 is configured to receive the signal to be measured VIN and filter out low-frequency components of the signal to be measured VIN. More specifically, one end of the ac coupling capacitor 60 is electrically connected to the signal to be measured VIN.
The rectifying circuit 62 is electrically connected to the ac coupling capacitor 60. More specifically, the input terminal of the rectifying circuit 62 is electrically connected to the other terminal of the ac coupling capacitor 60.
The time-to-digital converter 64 is electrically connected to the rectifying circuit 62. More specifically, the input terminal of the time-to-digital converter 64 is electrically connected to the output terminal of the rectifying circuit 62.
The control unit 66 is electrically connected to the time-to-digital converter 64. More specifically, an input of the control unit 66 is electrically connected to the output of the time-to-digital converter 64.
The counter 68 is electrically connected to the rectifying circuit 62 and the control unit 66. More specifically, an input terminal of the counter 68 is electrically connected to an output terminal of the time-to-digital converter 64, and an output terminal of the counter 68 is electrically connected to another input terminal of the control unit 66.
The control unit 66 calculates the frequency difference of the signal to be measured from the first time point to the second time point according to the output of the time-to-digital converter 64 and the output of the counter 68.
For a first time point, the ac coupling capacitor 60 filters the low frequency component of the signal to be measured VIN at the first time point and outputs a first filtered signal, the rectifier circuit 62 rectifies the first filtered signal and outputs a first rectified signal, and the time-to-digital converter 64 performs time-to-digital conversion on the first rectified signal and outputs a first digital signal.
For the second time point, the ac coupling capacitor 60 filters the low frequency component of the signal to be measured VIN at the second time point and outputs a second filtered signal, the rectifier circuit 62 rectifies the second filtered signal and outputs a second rectified signal, and the time-to-digital converter 64 performs time-to-digital conversion on the second rectified signal and outputs a second digital signal.
The counter 68 counts the first rectified signal and outputs a first count value, the counter 68 counts the second rectified signal and outputs a second count value, and the control unit 66 calculates the frequency difference between the signal to be measured VIN at the first time point and the second time point according to the first digital signal, the second digital signal, the first count value and the second count value.
The waveforms of the signal to be measured VIN, the output waveforms of the ac coupling capacitor 60 and the output waveforms of the rectifying circuit 62 in this embodiment can be referred to fig. 2 to 4, which are not repeated herein.
The difference between the frequency detector of this embodiment and the frequency detector of FIG. 1 is that the frequency detector of this embodiment uses a time-to-digital converter 64.
The principle of the frequency detector of the present disclosure is as follows: the signal to be measured VIN at the first time point is converted into a first direct current rectified signal, the control unit 66 obtains a time when the first rectified signal reaches a voltage, and the counter 68 counts a first count value when the first rectified signal reaches the voltage. Then, the signal to be measured VIN at the second time point is converted into a second dc rectified signal, the control unit 66 obtains the time when the second rectified signal reaches the voltage, and the counter 68 counts a second count value when the second rectified signal reaches the voltage. Finally, the control unit 66 obtains the frequency difference between the first time point and the second time point of the signal to be measured VIN according to the time difference between the time when the first rectified signal reaches the voltage and the time when the second rectified signal reaches the voltage, the first count value when the first rectified signal reaches the voltage, the second count value when the second rectified signal reaches the voltage, and the count frequency of the counter 68. The voltage V can be designed appropriately according to the circuit to be tested.
The above description is made by the control unit 66 calculating the frequency difference according to the first rectified signal and the second rectified signal output by the rectifying circuit 62. However, as shown in fig. 6, the frequency detector of the present disclosure further includes a time-to-digital converter 64, so that the control unit 66 can also calculate the frequency difference according to the first digital signal and the second digital signal outputted by the time-to-digital converter 64.
More specifically, the signal to be measured VIN at the first time point is converted into a first digital signal, the control unit 66 obtains a time when the first rectified signal corresponding to the first digital signal reaches the voltage, and the counter 68 counts a first count value when the first rectified signal reaches the voltage. Then, the signal to be measured VIN at the second time point is converted into a second digital signal, the control unit 66 obtains a time when the second rectified signal corresponding to the second digital signal reaches the voltage, and the counter 68 counts a second count value when the second rectified signal corresponding to the second digital signal reaches the voltage. Finally, the control unit 66 obtains a frequency difference between the first time point and the second time point of the signal to be measured VIN according to a time difference between the time when the first rectified signal reaches the voltage and the time when the second rectified signal reaches the voltage, a first count value when the first rectified signal corresponding to the first digital signal reaches the voltage, a second count value when the second rectified signal corresponding to the second digital signal reaches the voltage, and a count frequency of the counter 68.
In the present embodiment, the rectifying circuit 62 includes a first Schottky diode 620, a second Schottky diode 622, and a first capacitor 624.
The first schottky diode 620 includes a first anode and a first cathode. The first anode is electrically connected to a ground. The first cathode is electrically connected to the other end of the AC coupling capacitor 10.
The second schottky diode 622 includes a second anode and a second cathode. The second anode is electrically connected to the other end of the AC coupling capacitor 60. The second cathode is electrically connected to the input terminal of the time-to-digital converter 64.
The first capacitor 624 is electrically connected between the input of the time-to-digital converter 64 and the ground.
Other portions not described in this embodiment can refer to the related description of the embodiment in fig. 1, and are not repeated herein.
The frequency detector of the present disclosure converts different frequencies of the signal to be measured into voltages, thereby calculating the frequency difference, which is different from the prior art that directly uses a counter to calculate the frequency difference. Furthermore, the frequency detector of the present embodiment includes an analog-to-digital converter or a time-to-digital converter, so that the accuracy of detecting the frequency difference can be improved. That is, the frequency detector of the present embodiment does not need longer counting time or increase the counting frequency of the counter to increase the accuracy of detecting the frequency difference.
In summary, although the present disclosure has been described with reference to the preferred embodiments, the above-described preferred embodiments are not intended to limit the present disclosure, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, so that the scope of the present disclosure is defined by the appended claims.
Claims (6)
1. A frequency detector for detecting a frequency difference of a signal to be detected from a first time point to a second time point, the frequency detector comprising:
the alternating current coupling capacitor is used for receiving the signal to be detected, outputting a first filtering signal at the first time point and outputting a second filtering signal at the second time point;
the rectifying circuit is electrically connected to the alternating current coupling capacitor, outputs a first rectifying signal at the first time point and outputs a second rectifying signal at the second time point;
the analog-digital converter is electrically connected to the rectifying circuit, outputs a first digital signal at the first time point and outputs a second digital signal at the second time point;
a control unit electrically connected to the analog-to-digital converter; and
a counter electrically connected to the rectifying circuit and the control unit,
wherein the control unit obtains the time when the first rectified signal corresponding to the first digital signal reaches a voltage, the counter counts the time when the first rectified signal corresponding to the first digital signal reaches the first count value of the voltage,
the control unit obtains the time when the second rectification signal corresponding to the second digital signal reaches the voltage, the counter counts a second count value when the second rectification signal corresponding to the second digital signal reaches the voltage,
the control unit calculates the frequency difference of the signal to be detected from the first time point to the second time point according to the time difference between the time when the first rectification signal reaches the voltage and the time when the second rectification signal reaches the voltage, the first counting value when the first rectification signal corresponding to the first digital signal reaches the voltage, the second counting value when the second rectification signal corresponding to the second digital signal reaches the voltage and the counting frequency of the counter.
2. The frequency detector of claim 1, wherein the AC-coupling capacitor filters out low frequency components of the signal to be detected at the first time point and outputs the first filtered signal, the rectifier circuit rectifies the first filtered signal and outputs the first rectified signal, the ADC converts the first rectified signal into analog-to-digital and outputs the first digital signal,
the AC coupling capacitor filters out the low-frequency component of the signal to be measured at the second time point and outputs the second filtering signal, the rectifying circuit rectifies the second filtering signal and outputs the second rectifying signal, and the analog-digital converter performs analog-to-digital conversion on the second rectifying signal and outputs the second digital signal.
3. The frequency detector of claim 1, wherein the rectifying circuit comprises:
a first Schottky diode comprising a first anode and a first cathode, wherein the first anode is electrically connected to a ground, and the first cathode is electrically connected to the AC coupling capacitor;
a second Schottky diode comprising a second anode and a second cathode, wherein the second anode is electrically connected to the AC coupling capacitor, and the second cathode is electrically connected to the analog-to-digital converter; and
the first capacitor is electrically connected between the analog-digital converter and the ground.
4. A frequency detector for detecting a frequency difference of a signal to be detected from a first time point to a second time point, the frequency detector comprising:
the alternating current coupling capacitor is used for receiving the signal to be detected, outputting a first filtering signal of the first time point and outputting a second filtering signal of the second time point;
the rectifying circuit is electrically connected to the alternating current coupling capacitor, outputs a first rectifying signal at the first time point and outputs a second rectifying signal at the second time point;
a time-to-digital converter electrically connected to the rectifying circuit, outputting a first digital signal at the first time point and outputting a second digital signal at the second time point;
a control unit electrically connected to the time-to-digital converter; and
a counter electrically connected to the rectifying circuit and the control unit,
wherein the control unit obtains the time when the first rectified signal corresponding to the first digital signal reaches a voltage, the counter counts the first count value when the first rectified signal corresponding to the first digital signal reaches the voltage,
the control unit obtains the time when the second rectification signal corresponding to the second digital signal reaches the voltage, the counter counts a second count value when the second rectification signal corresponding to the second digital signal reaches the voltage,
the control unit calculates the frequency difference of the signal to be measured from the first time point to the second time point according to the time difference between the time when the first rectification signal reaches the voltage and the time when the second rectification signal reaches the voltage, the first counting value when the first rectification signal corresponding to the first digital signal reaches the voltage, the second counting value when the second rectification signal corresponding to the second digital signal reaches the voltage and the counting frequency of the counter.
5. The frequency detector according to claim 4, wherein the AC coupling capacitor filters out low frequency components of the signal to be detected at the first time point and outputs the first filtered signal, the rectifier circuit rectifies the first filtered signal and outputs the first rectified signal, the time-to-digital converter performs analog-to-digital conversion on the first rectified signal and outputs the first digital signal,
the AC coupling capacitor filters out the low-frequency component of the signal to be measured at the second time point and outputs the second filtering signal, the rectifier circuit rectifies the second filtering signal and outputs the second rectified signal, and the time-to-digital converter converts the second rectified signal from analog to digital and outputs the second digital signal.
6. The frequency detector of claim 4, wherein the rectifying circuit comprises:
a first Schottky diode comprising a first anode and a first cathode, wherein the first anode is electrically connected to a ground, and the first cathode is electrically connected to the AC coupling capacitor;
a second Schottky diode comprising a second anode and a second cathode, wherein the second anode is electrically connected to the AC coupling capacitor, and the second cathode is electrically connected to the time-to-digital converter; and
a first capacitor electrically connected between the time-to-digital converter and the ground.
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| JPH05273266A (en) * | 1992-03-25 | 1993-10-22 | Advantest Corp | Frequency-deviation-amount measuring apparatus |
| US5394217A (en) * | 1993-09-27 | 1995-02-28 | Eastman Kodak Company | Method and apparatus for determining line frequency and detecting variable frequency light sources |
| US20060239661A1 (en) * | 2005-04-22 | 2006-10-26 | Mediatek Inc. | Frequency detection methods |
| CN201233423Y (en) * | 2008-07-29 | 2009-05-06 | 奥豪斯仪器（上海）有限公司 | Electric network voltage detection device |
| TWI356593B (en) * | 2009-06-29 | 2012-01-11 | Ind Tech Res Inst | Digital phase-locked loop and digital phase-freque |
| CN202282326U (en) * | 2011-09-28 | 2012-06-20 | 上海大学 | Digital frequency meter applied to radio frequency multipole rod |
| US20130169268A1 (en) * | 2011-12-29 | 2013-07-04 | Fluke Corporation | Schottky Diode Radio Frequency Detector Probe With Amplitude Linearity Compensation |
| CN202583320U (en) * | 2012-03-01 | 2012-12-05 | 贵航发动机设计研究所 | Frequency/voltage converter |
| CN207650273U (en) * | 2017-10-11 | 2018-07-24 | 广东电网有限责任公司佛山供电局 | A kind of sine wave freuqency harvester based on difference algorithm |
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