CN201956980U - Automatic gain adjusting circuit in high dynamic range - Google Patents
Automatic gain adjusting circuit in high dynamic range Download PDFInfo
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- CN201956980U CN201956980U CN2011200061191U CN201120006119U CN201956980U CN 201956980 U CN201956980 U CN 201956980U CN 2011200061191 U CN2011200061191 U CN 2011200061191U CN 201120006119 U CN201120006119 U CN 201120006119U CN 201956980 U CN201956980 U CN 201956980U
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Abstract
The utility model discloses an automatic gain adjusting circuit in a high dynamic range, which comprises a variable gain amplifier, a power detection circuit and an operational amplifying circuit. An input end of the power detection circuit is connected with an output end of the variable gain amplifier, the power detection circuit detects the power level output by the power detection circuit and outputs voltage signals corresponding to the detection signal power, an output end of the power detection circuit is connected with an input end of the operational amplifying circuit, the operational amplifying circuit is used for amplifying the voltage signals output by the power detection circuit, and an output end of the operational amplifying circuit is connected with a control end of the variable gain amplifier.
Description
Technical Field
The utility model relates to a big dynamic range automatic gain control circuit for radio frequency receiver.
Background
Currently, the wireless communication technology is the fastest developing and most widely applied in the field of information communication. From the popularization of 3G to the increasing popularity of WLAN applications, this technology has played an increasingly important role in people's work and life. However, wireless communication systems also present problems in communicating. Due to the influence of factors such as transmission power, communication distance, electromagnetic interference and the like, the power of a signal required to be received by a receiver in a communication system often has a large variation. In addition, in the transmission path of the signal inside the receiver, a phenomenon that the signal cannot be accurately processed by the internal device of the receiver due to the large dynamic range of the signal often occurs. Since the receiving channel can only process signals in a fixed power range, an Automatic Gain Control (AGC) circuit is usually added to the signal receiving channel in order to maintain normal communication. The AGC module in the receiver is an important component of communication equipment such as the receiver, and the dynamic range thereof is one of important technical indexes of the receiver.
The automatic gain control circuit is an automatic control circuit capable of automatically adjusting the gain of the amplification circuit in accordance with the signal intensity. The circuit module can receive signals in a certain dynamic range, and the signals are amplified to meet the requirement of subsequent processing of a receiving path. The dynamic range of the existing automatic gain control circuit is small, generally 70-80 dB, and the signal processing capability of a receiver is greatly limited. In addition, the automatic gain control circuit often uses a comparator to realize the function of outputting the feedback voltage, which is also not beneficial to the application of the automatic gain control circuit.
Disclosure of Invention
The utility model discloses the purpose is: aiming at the defects of the existing automatic gain control circuit in the receiver, the automatic gain control circuit is provided, the dynamic range of power signal adjustment can be enlarged, and the automatic gain adjustment with a large dynamic range is realized.
The technical scheme of the utility model is that: a large dynamic range automatic gain adjusting circuit comprises a variable gain amplifier, a power detection circuit and an operational amplification circuit; the input end of the power detection circuit is connected with the output end of the variable gain amplifier, and the power detection circuit detects the power level output by the variable gain amplifier and outputs a voltage signal corresponding to the detected signal power; the output end of the power detection circuit is connected with the input end of the operational amplification circuit, and the operational amplification circuit amplifies the voltage signal output by the power detection circuit; the output end of the operational amplification circuit is connected with the control end of the variable gain amplifier.
Furthermore, in the automatic gain adjusting circuit with a large dynamic range, the power detection circuit comprises a filter network, a logarithmic amplifier and a follower which are connected in sequence.
The utility model has the advantages that:
1. the adjustment of the power signal with a large dynamic range is realized, and the dynamic range can reach 100 dB;
2. the utility model has simple structure and wide application, and can be used for preprocessing the signal to be input into the receiver before the receiver; the amplitude modulation method can also be used in an internal path of a receiver and used for adjusting the output signal of the demodulator to ensure that the amplitude of the output signal meets the requirement that a subsequent circuit can accurately process the output signal;
3. the filter circuit in the power detection circuit is adjusted, so that the working frequency band of the automatic gain adjusting circuit can be adjusted;
4. the feedback voltage of the common AGC circuit is obtained by voltage comparison, and the utility model adopts the detection circuit to feed back, thereby saving a comparator, not needing to specially provide a fixed voltage signal required by voltage comparison, having simpler circuit and lower cost;
5. the power level of the received signal can be indirectly detected according to the voltage signal.
Drawings
The invention will be further described with reference to the following drawings and examples:
fig. 1 is a block diagram of an automatic gain control circuit according to an embodiment of the present invention;
fig. 2 is a block diagram of a circuit structure of a receiver according to an embodiment of the present invention;
FIG. 3 is a graph showing the relationship between the gain of the variable gain amplifier and the control voltage applied thereto;
fig. 4 is a block diagram of a power detection circuit according to an embodiment of the present invention;
FIG. 5 is a diagram illustrating the relationship between the output voltage of the logarithmic amplifier and the power of the input signal;
fig. 6 is a block diagram showing the configuration of a filter network and a logarithmic amplifier circuit in the power detection circuit.
Wherein: 1 a variable gain amplifier; 2 a power detection circuit; and 3, an operational amplifier circuit.
Detailed Description
Example (b): the utility model provides a big dynamic range automatic gain control circuit utilizes this circuit can adjust the range of signal to can calculate out the power level of this automatic gain control circuit received signal according to the control voltage size of feeding back to variable gain amplifier. The automatic gain adjustment circuit is shown in fig. 1, and includes three modules, namely, a variable gain amplifier 1, a power detection circuit 2, and an operational amplifier circuit 3. Variable Gain Amplifiers (VGAs) have the advantages of high frequency, large signal, and the ability to drive large load currents. In addition to providing accurate device-to-device gain matching, variable gain amplifiers provide excellent attenuation range and are therefore suitable for automatic gain control in communication infrastructure wireless base stations, industrial and video applications. The input end of the power detection circuit 2 is connected with the output end of the variable gain amplifier 1, the output end of the power detection circuit 2 is connected with the input end of the operational amplification circuit 3, the output end of the operational amplification circuit 3 is connected with the control end of the variable gain amplifier, and the operational amplification circuit 3 outputs a voltage signal Vc for controlling the variable gain amplifier 1. The power detection circuit 2 includes a filter network 21, a logarithmic amplifier 22, and a follower 23 connected in this order, detects the power level output from the variable gain amplifier, and outputs a voltage signal corresponding to the detected signal power. The operational amplification circuit receives the voltage signal output by the power detection circuit and amplifies the voltage signal into a voltage control signal required by the variable gain amplifier so as to accurately control the gain of the variable gain amplifier, thereby realizing the adjustment of the power signal with a large dynamic range. The filter network is composed of a plurality of resistance capacitors and is used for filtering out the interference of out-of-band signals. The logarithmic amplifier detects the filtered signal and outputs a voltage signal corresponding to the power of the detected signal to the follower. The operational amplification circuit amplifies the voltage signal output by the power detection circuit, so that the voltage signal reaches an amplitude range capable of effectively controlling the gain change of the variable gain amplifier.
As shown in fig. 2, a radio frequency signal received by an antenna is filtered by a Radio Frequency Band Pass Filter (RFBPF), amplified by a Low Noise Amplifier (LNA) and output, mixed with a local oscillator signal (LO), filtered by a low pass filter and converted into a baseband signal, and the baseband signal filtered by the Low Pass Filter (LPF) enters an automatic gain adjusting circuit for processing. A Variable Gain Amplifier (VGA) amplifies an input baseband signal. Fig. 3 is a graph showing the relationship between the gain of the variable gain amplifier and the control voltage applied thereto, and it can be seen from the graph that the gain of the variable gain amplifier is linear with the control voltage within a certain range, which can provide an accurate linear gain for the baseband signal to be processed. Most of the signals amplified by the variable gain amplifier are output to an analog-to-digital converter (ADC) for processing, and the other part of the signals enter a power detection circuit 2, which is composed of a logarithmic amplifier with a filter network at the front end, as shown in fig. 6, after the input signals are ac-coupled to the input end of the logarithmic amplifier through a capacitor Cc, the input signals enter the logarithmic amplifier through a filter composed of a capacitor and a resistor, and the capacitor Cp added by the filter should satisfy: fHP =1/(2 π RinCp)
Wherein,f HPfor the high pass angle of the low-pass filter,R inis the input resistance of the logarithmic amplifier and,C pthe capacitor is connected in parallel with the input end of the power detection circuit. The logarithmic amplifier detects the input signal and outputs a voltage amplitude that is linear with the input signal power, fig. 5 shows the logarithmic amplifier inputThe corresponding relation diagram of the output voltage and the input signal power. As shown in fig. 4, the input end of the filter network 21 is the input end of the power detection circuit 2, and the output end of the follower 23 is the output end of the power detection circuit 2.
And after the voltage signal output by the logarithmic amplifier is amplified by the operational amplifier circuit, the controllable gain amplifier is controlled. In the power range of the received signal, when the signal power detected by the logarithmic amplifier is minimum, the operational amplifier acts on the voltage signal output by the logarithmic amplifier to convert the voltage signal into a control voltage corresponding to the maximum gain obtained by the variable gain amplifier; when the signal power detected by the logarithmic amplifier is maximum, the operational amplifier acts on the voltage signal output by the logarithmic amplifier to convert the voltage signal into a control voltage corresponding to the minimum gain obtained by the variable gain amplifier. Suppose that the output voltage signal of the logarithmic amplifier and the control voltage signal of the variable gain amplifier are respectivelyV rAndV cthen, according to the formula:V c =αV r +β，and two groups corresponding to the minimum and maximum signal power received by the logarithmic amplifierV cAndV rby determining the parameters of the formulaαAndβ. The operational amplifier circuit is realized inV rAndV cthe whole control process of automatic gain adjustment is realized after the linear relation is obtained.
Through the control of the automatic gain adjusting circuit, the power signal output to the ADC by the variable gain amplifier in the figure 2 can be ensured to be always within the signal power range accurately processed by the ADC, and the power adjustment with a large dynamic range is realized. In addition, the automatic gain adjusting circuit can output a voltage signal corresponding to the power of the detected signal, so that the circuit structure can indirectly detect the power level of the radio-frequency signal received by the antenna.
The above description is only a preferred embodiment of the present invention, and the scope of the present invention can not be limited thereby, and all the simple changes made in the claims and the description of the present invention should still belong to the protection scope of the present invention.
Claims (2)
1. A large dynamic range automatic gain adjustment circuit, characterized by: the power amplifier comprises a variable gain amplifier (1), a power detection circuit (2) and an operational amplification circuit (3); the input end of the power detection circuit (2) is connected with the output end of the variable gain amplifier (1), and the power detection circuit (2) detects the power level output by the variable gain amplifier (1) and outputs a voltage signal corresponding to the detected signal power; the output end of the power detection circuit (2) is connected with the input end of the operational amplification circuit (3), and the operational amplification circuit (3) amplifies the voltage signal output by the power detection circuit (2); the output end of the operational amplification circuit (3) is connected with the control end of the variable gain amplifier (1).
2. A large dynamic range automatic gain adjustment circuit as claimed in claim 1, wherein: the power detection circuit (2) comprises a filter network (21), a logarithmic amplifier (22) and a follower (23) which are connected in sequence.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011200061191U CN201956980U (en) | 2011-01-11 | 2011-01-11 | Automatic gain adjusting circuit in high dynamic range |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011200061191U CN201956980U (en) | 2011-01-11 | 2011-01-11 | Automatic gain adjusting circuit in high dynamic range |
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| Publication Number | Publication Date |
|---|---|
| CN201956980U true CN201956980U (en) | 2011-08-31 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2011200061191U Expired - Lifetime CN201956980U (en) | 2011-01-11 | 2011-01-11 | Automatic gain adjusting circuit in high dynamic range |
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| CN (1) | CN201956980U (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102255608A (en) * | 2011-01-11 | 2011-11-23 | 苏州英诺迅科技有限公司 | Automatic gain regulating circuit with large dynamic range |
| CN105227196A (en) * | 2015-10-15 | 2016-01-06 | 南京信息工程大学 | Portable sonde receiver radio frequency front-end circuit |
| CN107294505A (en) * | 2017-06-19 | 2017-10-24 | 电信科学技术第研究所 | AGC system and its method of work |
| CN110460317A (en) * | 2019-09-02 | 2019-11-15 | 深圳市强军科技有限公司 | Automatic power control circuit and automatic power controller |
-
2011
- 2011-01-11 CN CN2011200061191U patent/CN201956980U/en not_active Expired - Lifetime
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102255608A (en) * | 2011-01-11 | 2011-11-23 | 苏州英诺迅科技有限公司 | Automatic gain regulating circuit with large dynamic range |
| CN105227196A (en) * | 2015-10-15 | 2016-01-06 | 南京信息工程大学 | Portable sonde receiver radio frequency front-end circuit |
| CN107294505A (en) * | 2017-06-19 | 2017-10-24 | 电信科学技术第研究所 | AGC system and its method of work |
| CN107294505B (en) * | 2017-06-19 | 2020-10-16 | 电信科学技术第一研究所有限公司 | Automatic gain control system and working method thereof |
| CN110460317A (en) * | 2019-09-02 | 2019-11-15 | 深圳市强军科技有限公司 | Automatic power control circuit and automatic power controller |
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| C14 | Grant of patent or utility model | ||
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Granted publication date: 20110831 |