CN111225167A - Electric signal conversion circuit, chip and tuner - Google Patents
Electric signal conversion circuit, chip and tuner Download PDFInfo
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- CN111225167A CN111225167A CN201811404474.7A CN201811404474A CN111225167A CN 111225167 A CN111225167 A CN 111225167A CN 201811404474 A CN201811404474 A CN 201811404474A CN 111225167 A CN111225167 A CN 111225167A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
- H04N5/50—Tuning indicators; Automatic tuning control
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N7/00—Television systems
- H04N7/20—Adaptations for transmission via a GHz frequency band, e.g. via satellite
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Abstract
The invention discloses an electric signal conversion circuit, a chip and a tuner, wherein the electric signal conversion circuit comprises: the device comprises a driving module, a signal amplification module and a filtering module, wherein the signal amplification module comprises a differential amplifier; the input end of the driving module receives an electric signal, and the electric signal is output through the output end of the driving module to obtain a signal to be converted with driving capability; the input end of the filtering module is connected with the output end of the driving module, and the filtering module is used for filtering alternating current signals in the signals to be converted and reserving direct current signals; the first input end of the differential amplifier is connected with the output end of the driving module, the second input end of the differential amplifier is connected with the output end of the filtering module, and the differential amplifier is used for amplifying alternating current signals in the signals to be converted and keeping direct current signals in the signals to be converted unchanged. According to the embodiment of the invention, the distortion of the waveform of the electric signal can be avoided, and the use of a coupling capacitor with larger volume is avoided, so that the space and the cost of the PCB are saved.
Description
Technical Field
The invention belongs to the technical field of circuits, and particularly relates to an electric signal conversion circuit, a chip and a high-frequency tuner.
Background
An electric signal received by a Low Noise Block (LNB) system is a square wave signal whose dc level cannot be predicted. As shown in fig. 1, the square wave signal with the dc level of 18V is on the top, and the square wave signal with the dc level of 13V is on the bottom. The range of DC level falls between 13-18V, but specific level value cannot be predicted in advance.
The 13-18V square wave signals are output to the chip, and the power supply voltage of the chip is generally 3-5V, so the 13-18V square wave signals cannot be directly connected to the chip and need direct current level conversion. The prior art uses a circuit as shown in fig. 2 for dc level conversion. In fig. 2, an electrical Signal is divided by a voltage dividing module on a Printed Circuit Board (PCB) to obtain a lower dc level suitable for a chip voltage, and an ac square wave Signal is transmitted through a coupling capacitor, and the two signals are superimposed and then sent to an input terminal of the chip. Thus, the direct current voltage input to the chip is relatively small, and the alternating current component in the electric Signal is reserved in the Signal input to the chip.
The signal at the chip input has a dc level suitable for the chip voltage, the amplitude-frequency characteristic of which is shown in fig. 3, and the frequency components below the signal band are filtered out. However, as can be seen from fig. 4, the signal input to the chip has high-pass characteristics, and the time domain signal waveform thereof is distorted and appears jagged.
In addition, the coupling capacitor occupies a larger area of the PCB due to large volume and high cost, and the cost of the whole system is increased.
Disclosure of Invention
The embodiment of the invention provides an electric signal conversion circuit, a chip and a high-frequency tuner, which can solve the technical problems that the waveform of a time domain signal input to the chip is distorted, a coupling capacitor occupies a large area of a PCB (printed circuit board) and the system cost is high.
In one aspect, an embodiment of the present invention provides an electrical signal conversion circuit, including: the device comprises a driving module, a signal amplification module and a filtering module, wherein the signal amplification module comprises a differential amplifier;
the input end of the driving module receives an electric signal, and the electric signal is output through the output end of the driving module to obtain a signal to be converted with driving capability;
the input end of the filtering module is connected with the output end of the driving module, and the filtering module is used for filtering alternating current signals in the signals to be converted and reserving direct current signals;
the first input end of the differential amplifier is connected with the output end of the driving module, the second input end of the differential amplifier is connected with the output end of the filtering module, and the differential amplifier is used for amplifying the alternating current signals in the signals to be converted and keeping the direct current signals in the signals to be converted unchanged.
In another aspect, an embodiment of the present invention provides a chip including the electrical signal conversion circuit described above.
In another aspect, an embodiment of the present invention provides a tuner including the chip as described above.
The electric signal conversion circuit, the chip and the high-frequency head of the embodiment of the invention can improve the driving capability of the electric signal, thereby avoiding the distortion of the time domain signal waveform of the electric signal. And a device with lower price and smaller volume is used for replacing the coupling capacitor, thereby saving precious space for the PCB and saving cost.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments of the present invention will be briefly described below, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 shows a schematic diagram of a prior art 13-18V square wave signal;
fig. 2 is a schematic diagram showing a structure of an electric signal conversion circuit in the prior art;
fig. 3 shows a graph of amplitude-frequency characteristics of an output signal of an electric signal conversion circuit in the prior art;
FIG. 4 is a time domain waveform diagram of an output signal of an electrical signal conversion circuit in the prior art;
fig. 5 is a schematic structural diagram of an electrical signal conversion circuit according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of an electrical signal conversion circuit according to another embodiment of the present invention;
FIG. 7 is a graph illustrating the amplitude-frequency characteristics of a signal input to a driver module according to an embodiment of the present invention;
FIG. 8 illustrates a time domain waveform diagram of a signal input to a driver module provided by an embodiment of the present invention;
FIG. 9 is a graph illustrating the amplitude-frequency characteristics of the signal output by the filtering module according to an embodiment of the present invention;
FIG. 10 is a time domain waveform diagram of a signal output by the filtering module provided by an embodiment of the invention;
FIG. 11 is a graph showing the amplitude-frequency characteristics of the signal output from the differential amplifier provided by the embodiment of the present invention;
fig. 12 shows a time domain waveform diagram of a signal output by a differential amplifier provided by an embodiment of the invention.
Detailed Description
Features and exemplary embodiments of various aspects of the present invention will be described in detail below, and in order to make objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not to be construed as limiting the invention. It will be apparent to one skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
In order to solve the problems in the prior art, embodiments of the present invention provide an electrical signal conversion circuit, a chip, and a tuner. First, an electrical signal conversion circuit provided in an embodiment of the present invention will be described.
Fig. 5 is a schematic structural diagram of an electrical signal conversion circuit according to an embodiment of the present invention. As shown in fig. 5, the electric signal conversion circuit includes: the device comprises a driving module, a signal amplification module and a filtering module, wherein the signal amplification module comprises a differential amplifier.
The input end of the driving module receives the electric signal, and the electric signal is output through the output end of the driving module to obtain a signal V1 to be converted with driving capability.
It should be noted that the function of the driving module is to duplicate the input electrical signal, i.e. the input electrical signal of the driving module is the same as the output electrical signal, except that the output signal to be converted V1 has stronger driving capability, so that the output signal to be converted V1 will not be changed in signal characteristics by the loads in the filtering module and the signal amplifying module.
The input end of the filtering module is connected with the output end of the driving module, and the filtering module is used for filtering alternating current signals in the signals to be converted and reserving direct current signals.
The first input end of the differential amplifier is connected with the output end of the driving module, the second input end of the differential amplifier is connected with the output end of the filtering module, and the differential amplifier is used for amplifying alternating current signals in the signals to be converted and keeping direct current signals in the signals to be converted unchanged.
It should be noted that the signal to be converted V1 output by the driving module includes both a dc signal and an ac signal, the signal to be converted V1 is divided into two paths, one path is input to the filtering module, and the other path is input to the first end of the differential amplifier. The filtering module filters the alternating current signal in the signal to be converted V1, reserves the direct current signal in the signal to be converted V1, namely the electrical signal V2, and outputs the electrical signal V2 to the second end of the differential amplifier. According to the general feature of the differential amplifier, the electrical signal V2 input to the second input terminal of the differential amplifier is the same as the dc signal in the signal to be converted V1 input to the first terminal, so that the dc signal in the signal to be converted V1 can be kept unchanged. . For example, in the electrical signal V3 output by the differential amplifier, the ac signal is 8 times the ac signal in V1, and the dc signal is equal to the dc signal in V1.
According to the electric signal conversion circuit provided by the embodiment of the invention, the driving capability of the electric signal can be improved through the driving module, so that the distortion of the time domain signal waveform of the electric signal is avoided. Through the amplification of the differential amplifier, for example, the original electric signal is subjected to voltage division by the voltage division module, the divided electric signal enters the electric signal conversion circuit, namely, the divided electric signal sequentially passes through the driving module and the differential amplifier, the differential amplifier amplifies the signal, the alternating current signal contained in the electric signal V3 output by the output end of the differential amplifier is recovered to the amplitude of the alternating current signal of the original signal before voltage division, the use of a coupling capacitor with a large volume is avoided, precious space is saved for a PCB (printed circuit board), and a device with a low price is used for replacing the coupling capacitor, so that the cost is saved.
Fig. 6 is a schematic structural diagram of an electrical signal conversion circuit according to another embodiment of the present invention. As shown in fig. 6, the electric signal conversion circuit includes: the circuit comprises a buffer, a differential amplifier, a resistor R0, a capacitor C0, a resistor R1 and a resistor R2.
The input end of the buffer receives the electric signal IN, the output end of the buffer outputs an electric signal V1, and the alternating current frequency, the alternating current amplitude and the direct current level between the electric signal IN and the electric signal V1 are the same.
The output of the buffer is connected to one end of a resistor R1, and the other end of the resistor R1 is connected to a first input of a differential amplifier.
The output end of the buffer is also connected with one end of a resistor R0, the other end of the resistor R0 is connected with the second input end of the differential amplifier, one end of a capacitor C0 is connected with the other end of the resistor R0, and the other end of the capacitor C0 is grounded.
One end of the resistor R2 is connected to the first input terminal of the differential amplifier, and the other end of the resistor R2 is connected to the output terminal of the differential amplifier.
Based on the above electric signal conversion circuit, the principle of the electric signal conversion circuit will be described in detail below.
Since the electrical signal IN does not have a driving capability, if the electrical signal IN directly drives the resistive load, the transmission characteristics and the waveform of the electrical signal IN are changed, and thus the electrical signal V1 having the driving capability is obtained after passing the electrical signal IN through the Buffer.
The Buffer functions to make the electrical signal V1 duplicate the electrical signal IN, and at the same time, provides sufficient driving capability to drive the resistance of the subsequent stage without the resistance load changing the characteristics of the electrical signal V1.
The electrical signal V1 output from the Buffer is divided into two paths:
(1) the electric signal V1 of the path passes through the resistor R0 and the capacitor C0, the alternating current signal in the electric signal V1 is filtered, only the direct current signal in the electric signal V1 is retained, that is, the electric signal V2 only contains the direct current level in the electric signal V1, and the electric signal V2 is used as the virtual ground end of the differential amplifier and is input to the second end of the differential amplifier.
(2) The other path of the electric signal V1 passes through the resistor R1 and the resistor R2, and under the action of the differential amplifier, the alternating current signal in the electric signal V1 is amplified, wherein the amplification factor of the alternating current signal is R2/R1. For example, an ac square wave signal with an amplitude of 25mV is amplified to an ac square wave signal with an amplitude of 200 mV.
Since the voltages V2 and V1 at one input of the differential amplifier are the same dc voltage, again according to the general characteristics of the differential amplifier, the dc voltage at the other input of the differential amplifier remains the same as V2, i.e. equal to V1. According to kirchhoff's current law, the direct current voltage across the resistor R1 and the direct current voltage across the resistor R2 are both 0, so that the direct current voltage of the electrical signal V3 is the same as the direct current voltage of the electrical signal V1, that is, the differential amplifier keeps the input direct current signal unchanged.
In conclusion, the differential amplifier realizes the amplification of the alternating current signal and keeps the input direct current signal unchanged.
The above-described scheme is explained in detail below by a specific example.
For example, the original electrical signal is divided by the voltage dividing module, the voltage dividing module divides the original signal by 1/8 ratio, and the divided electrical signal IN enters the electrical signal conversion circuit. The amplitude-frequency characteristics of the electric signal IN are as shown IN fig. 7, and the gains of the frequency components are-18 dB, and no frequency selection is performed.
Taking the original signal dc voltage 18v, the frequency of the ac signal is 22kHZ, and the amplitude is 200mv as an example, the original signal is divided by the outer voltage division module to obtain the electrical signal IN, and the time domain waveform of the electrical signal IN is shown IN fig. 8.
2. After the electric signal IN passes through the Buffer, the electric signal V1 is obtained. Since the buffer does not change the signal characteristics, the amplitude-frequency transmission characteristics and the signal waveform of the electrical signal V1 are the same as those of the electrical signal IN, and thus the description thereof is not repeated.
3. The electric signal V1 passes through the resistor R0 and the capacitor C0, and then the obtained electric signal V2 is obtained.
(1) Fig. 9 shows a magnitude-frequency characteristic diagram of the electrical signal V2 in which signals above 100Hz are attenuated to different degrees, the higher the frequency, the more the attenuation. It can be seen that the electrical signal V2 filters out the ac signal of the electrical signal V1 and only retains the dc signal of the electrical signal V1, i.e., the electrical signal V2 only contains the dc level of the electrical signal V1.
(2) Fig. 10 shows a time domain waveform diagram of the electrical signal V2, in which the electrical signal V2 is a dc signal and does not change with time.
4. The electric signal V1 passes through the resistors R1 and R2, and under the action of the differential amplifier, the ac signal of the electric signal V1 is amplified by 8 times, that is, the amplitude of the ac signal is restored to the amplitude of the ac signal before being divided by the voltage dividing module.
This completes the dc level conversion, and converts the square wave signal IN having an ac frequency of 22KHZ, an ac amplitude of 25mV, and a dc level of 2.25V into the square wave signal V3 having an ac frequency of 22KHZ, an ac amplitude of 200mV, and a dc level of 2.25V.
In one embodiment of the present invention, the electrical signal conversion circuit may further include: the capacitor C2 and the capacitor C2 are connected in parallel to two ends of the resistor R2.
Through the combination of the resistor R2, the capacitor C2 and the differential amplifier, primary filtering is performed at a proper frequency position outside a signal frequency band, so that the transmission characteristic of the whole system is changed from 'high-pass characteristic' in the prior art scheme into 'band-pass characteristic' in the embodiment of the invention, and high-frequency interference signals except for the frequency band are filtered, so that false detection caused by the high-frequency interference signals is avoided, and the stability and the reliability of the system are further enhanced.
Fig. 11 shows an amplitude-frequency characteristic diagram of the electrical signal V3, which transmits signals (including signals in a signal frequency band) in a certain frequency range, and high-frequency interference components outside the signal frequency band are filtered out.
Fig. 12 shows a time domain waveform diagram of the electrical signal V3, and the output waveform of the electrical signal V3 is close to an ideal square wave, and compared with the prior art, the dc level conversion and the ac signal transmission are better performed on the received signal, so that the signal transmission characteristics are better, and the output waveform is closer to the original signal waveform.
An embodiment of the present invention provides a chip, including the electrical signal conversion circuit in any one of the above technical solutions.
In one embodiment of the invention, the chip further comprises an analog-to-digital converter; an input terminal of an Analog to digital Converter (ADC) is connected to an output terminal of the differential amplifier.
The differential amplifier outputs the electrical signal V3 to an analog-to-digital converter, which performs analog-to-digital conversion on the electrical signal V3.
The embodiment of the invention provides a tuner, which comprises the chip in any one of the technical schemes.
In one embodiment of the present invention, the electric signal conversion circuit further includes:
and the output end of the voltage division module is connected with the input end of the driving module and is used for dividing the received electric signal and outputting the divided electric signal to the driving module.
The differential amplifier is used for amplifying the alternating current signal in the signal to be converted, and the amplitude of the amplified alternating current signal is equal to the amplitude of the alternating current signal in the electric signal before voltage division by the voltage division module.
It should be noted that, the original electrical signal is divided by the voltage dividing module, the divided electrical signal sequentially passes through the driving module and the differential amplifier, and the ac signal contained in the electrical signal output by the output end of the differential amplifier is restored to the amplitude of the ac signal of the original signal before voltage division.
In one embodiment of the present invention, the voltage dividing module includes: a fourth resistor (i.e., RB1 in fig. 6) and a fifth resistor (i.e., RB2 in fig. 6) in series.
One end of a circuit formed by connecting the fourth resistor and the fifth resistor in series is used as the input end of the voltage division module, the other end of the circuit is grounded, and a point between the fourth resistor and the fifth resistor is used as the output end of the voltage division module.
For example, the electrical Signal input to the voltage division module is a square wave Signal with an ac amplitude of 200mV and a dc level of 13V to 18V. The voltage division module is used for dividing voltage, and the alternating current amplitude and the direct current level of the electric Signal are both reduced to 1/8, namely the voltage division module outputs square wave signals with the alternating current amplitude of 25mV and the direct current level of 1.625V-2.25V.
However, an electrical signal with an ac amplitude of 200mV and a dc level of 1.625V-2.25V needs to be input to the analog-to-digital converter of the chip, i.e., the ac amplitude needs to be amplified while keeping the dc level unchanged.
By using the electric Signal conversion circuit in the embodiment of the invention, the direct current level can be kept unchanged, the alternating current amplitude can be amplified by 8 times, namely the electric Signal with the alternating current amplitude of 200mV and the direct current level of 1.625V-2.25V is obtained, the alternating current amplitude of the electric Signal Signal is recovered by the electric Signal, and the direct current level is reduced to the range which can be borne by a chip.
As described above, only the specific embodiments of the present invention are provided, and it can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working processes of the system, the module and the unit described above may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again. It should be understood that the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive various equivalent modifications or substitutions within the technical scope of the present invention, and these modifications or substitutions should be covered within the scope of the present invention.
Claims (10)
1. An electrical signal conversion circuit, comprising: the device comprises a driving module, a signal amplification module and a filtering module, wherein the signal amplification module comprises a differential amplifier;
the input end of the driving module receives an electric signal, and the electric signal is output through the output end of the driving module to obtain a signal to be converted with driving capability;
the input end of the filtering module is connected with the output end of the driving module, and the filtering module is used for filtering alternating current signals in the signals to be converted and reserving direct current signals;
the first input end of the differential amplifier is connected with the output end of the driving module, the second input end of the differential amplifier is connected with the output end of the filtering module, and the differential amplifier is used for amplifying the alternating current signals in the signals to be converted and keeping the direct current signals in the signals to be converted unchanged.
2. The electrical signal conversion circuit of claim 1, wherein the signal amplification module further comprises:
the two ends of the first resistor are respectively connected with the output end of the driving module and the first input end of the differential amplifier;
and two ends of the second resistor are respectively connected with the first input end of the differential amplifier and the output end of the differential amplifier.
3. The electrical signal conversion circuit of claim 2, wherein the signal amplification module further comprises:
and the first capacitor is connected in parallel with two ends of the second resistor.
4. The electrical signal conversion circuit of claim 1, wherein the filtering module comprises:
one end of the third resistor is used as the input end of the filter module, and the other end of the third resistor is used as the output end of the filter module;
and one end of the second capacitor is connected with the other end of the third resistor, and the other end of the second capacitor is grounded.
5. The electrical signal conversion circuit of claim 1, wherein the driver module comprises a buffer.
6. A chip, comprising: the electrical signal conversion circuit of any of claims 1-5.
7. The chip of claim 6, further comprising an analog-to-digital converter;
and the input end of the analog-to-digital converter is connected with the output end of the differential amplifier.
8. A tuner, comprising: a chip as claimed in claim 6 or 7.
9. The tuner of claim 8, further comprising:
the output end of the voltage division module is connected with the input end of the driving module and is used for dividing the voltage of the received electric signal and outputting the divided electric signal to the driving module;
the differential amplifier is used for amplifying the alternating current signals in the signals to be converted, and the amplitude of the amplified alternating current signals is equal to the amplitude of the alternating current signals in the electric signals before voltage division of the voltage division module.
10. The tuner of claim 9, wherein the voltage divider module comprises: a fourth resistor and a fifth resistor connected in series;
one end of a circuit formed by connecting the fourth resistor and the fifth resistor in series is used as the input end of the voltage division module, the other end of the circuit is grounded, and a point between the fourth resistor and the fifth resistor is used as the output end of the voltage division module.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811404474.7A CN111225167A (en) | 2018-11-23 | 2018-11-23 | Electric signal conversion circuit, chip and tuner |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811404474.7A CN111225167A (en) | 2018-11-23 | 2018-11-23 | Electric signal conversion circuit, chip and tuner |
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| Publication Number | Publication Date |
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| CN111225167A true CN111225167A (en) | 2020-06-02 |
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| CN201811404474.7A Pending CN111225167A (en) | 2018-11-23 | 2018-11-23 | Electric signal conversion circuit, chip and tuner |
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