Automatic gain control circuit and satellite navigation signal forwarding equipment

Abstract

The utility model discloses an automatic gain control circuit and satellite navigation signal forwarding equipment. The automatic gain control circuit comprises two voltage-controlled attenuation circuits, two radio frequency amplification circuits, a filter, a coupling circuit and an operational amplifier circuit, the first voltage-controlled attenuation circuit is connected with the input end of the first radio frequency amplification circuit; the input end of the second voltage-controlled attenuation circuit is connected with the output end of the first radio frequency amplification circuit, and the output end is connected with the input end of the filter; the input end of the second radio frequency amplification circuit is connected with the output end of the filter, and the output end is connected with the coupling circuit; the input end of the detection circuit is connected with the output end of the coupling circuit, the output end is connected with the input end of the operational amplifier circuit, and the output end of the operational amplifier circuit is connected with the control ends of the first voltage-controlled attenuation circuit and the second voltage-controlled attenuation circuit. According to the invention, the two-stage amplifier and the two-stage voltage-controlled attenuator are adopted to regulate and control the input signal, so that the signal power regulation range is widened.

Description

Technical Field

[0001] The present invention belongs to the field of electronic technology, and particularly relates to an automatic gain control circuit and a satellite navigation signal forwarding device. Background Art

[0002] Automatic gain control is an automatic control method that enables the gain of an amplifier circuit to automatically adjust with the signal strength. The circuit that realizes the above function is abbreviated as an AGC loop. The AGC loop is a closed-loop electronic circuit and a negative feedback system. It can be divided into two parts: a gain-controlled amplifier circuit and a control voltage formation circuit. The gain-controlled amplifier circuit is located in the forward amplification path, and its gain changes with the control voltage. The basic components of the control voltage formation circuit are an AGC detector and a low-pass smoothing filter, and sometimes also include components such as a gate circuit and a DC amplifier. The output signal U0 of the amplifier circuit is detected and filtered by the filter to remove the low-frequency modulation component and noise, and then a voltage Uc for controlling the gain-controlled amplifier is generated. When the input signal Ui increases, U0 and Uc also increase. The increase in Uc causes the gain of the amplifier circuit to decrease, so that the change amount of the output signal is significantly smaller than the change amount of the input signal, achieving the purpose of automatic gain control.

[0003] The traditional automatic gain control circuit is usually composed of only one-stage voltage-controlled attenuator and one-stage radio frequency amplifier. However, the one-stage voltage-controlled attenuator and one-stage radio frequency amplifier have a small signal adjustment range, a long response time, and when the signal is a high-power signal, they cannot quickly adjust the signal, resulting in the drawback of burning out the subsequent circuit. Summary of the Invention

[0004] To solve the above problems existing in the prior art, the present invention designs an automatic gain control circuit, which includes: two voltage-controlled attenuation circuits, two radio frequency amplifier circuits, a filter, a coupling circuit, and an operational amplifier circuit; the input end of the first voltage-controlled attenuation circuit is connected to the input signal, and the output end is connected to the input end of the first radio frequency amplifier circuit; the output end of the first radio frequency amplifier circuit is connected to the input end of the second voltage-controlled attenuation circuit; the output end of the second voltage-controlled attenuation circuit is connected to the input end of the filter; the output end of the filter is connected to the input end of the second radio frequency amplifier circuit; the output end of the second radio frequency amplifier circuit is connected to the coupling circuit, the output end of the coupling circuit is connected to the detection circuit, the output end of the detection circuit is connected to the input end of the operational amplifier circuit, and the output end of the operational amplifier circuit is respectively connected to the control ends of the first voltage-controlled attenuation circuit and the second voltage-controlled attenuation circuit, and the output end of the second radio frequency amplifier circuit is used as the output end of the automatic gain control circuit.

[0005] Preferably, the first voltage-controlled attenuation circuit includes: a first voltage-controlled attenuator and five capacitors. The positive voltage input terminal of the first voltage-controlled attenuator is respectively connected to capacitors C1 and C2, and the other ends of capacitors C1 and C2 are grounded, such that capacitors C1 and C2 are in parallel; the negative voltage input terminal of the first voltage-controlled attenuator is connected to capacitor C3, and the other end of capacitor C3 is grounded; the signal input terminal of the first voltage-controlled attenuator is connected to capacitor C4, and the signal output terminal of the first voltage-controlled attenuator is connected to capacitor C5.

[0006] Further, the capacitance value of capacitor C3 is equal to the capacitance value of capacitor C4.

[0007] Preferably, the structure of the second voltage-controlled attenuation circuit is the same as that of the first voltage-controlled attenuation circuit.

[0008] Preferably, the structure of the first radio frequency amplification circuit includes a radio frequency amplifier, resistor R54, resistor R51, capacitor C70, capacitor C76, capacitor C87, and inductor L17; the input terminal of the radio frequency amplifier is connected to resistor R54, and the other end of resistor R54 is respectively connected to the power supply terminal and resistor R51. The other end of resistor R51 is respectively connected to the positive electrode of capacitor C70, the positive electrode of capacitor C76, and inductor L17; the negative electrodes of capacitors C70 and C76 are both grounded, and the other end of inductor L17 is respectively connected to the output terminal of the radio frequency amplifier and capacitor C87; the other terminals of the radio frequency amplifier are grounded.

[0009] Preferably, the coupling circuit includes a coupler, three capacitors, and three resistors; the signal input terminal of the coupler is connected to capacitor C7, the output terminal is connected to capacitor C8, and the signal control terminal is connected to one end of capacitor C9; the other end of capacitor C9 is respectively connected to one end of resistor R1 and resistor R2. The other end of resistor R1 is grounded, and the other end of resistor R2 is connected to resistor R3, and the other end of resistor R3 is grounded.

[0010] Preferably, the detection circuit includes a detector, four capacitors, and two resistors; wherein the power supply input terminal of the detector is externally connected to the power supply and then respectively connected to capacitors C20 and C21. The other ends of capacitors C20 and C21 are respectively grounded, such that capacitors C20 and C21 are in parallel; the signal input terminal of the detector is respectively connected to resistor R5 and capacitor C22, and the other end of resistor R5 is grounded; the signal output terminal of the detector is connected to resistor R4, and the other end of resistor R4 is respectively connected to the input terminal of the operational amplifier circuit and one end of capacitor C23, and the other end of capacitor C23 is grounded.

[0011] Preferably, the operational amplifier circuit includes an amplifier, four capacitors, and an inductor; the input terminal of the amplifier is connected to capacitor C14, and the power input terminal is connected to a voltage source and then connected to capacitor c13, capacitor c16, and inductor L1 respectively; the other ends of capacitor c13 and capacitor c16 are grounded; the other end of inductor L1 is connected to the output terminal of the amplifier and capacitor c15 respectively.

[0012] A satellite navigation signal forwarding device, which includes an outdoor antenna, an indoor antenna, an indoor host, and a radio frequency connection cable. The outdoor antenna is connected to the indoor antenna, and the indoor antenna is connected to the indoor host through the radio frequency connection cable; an automatic gain control circuit is provided in the indoor antenna.

[0013] Advantages of the present invention:

[0014] The present invention uses two-stage amplifiers and two-stage voltage-controlled attenuators to regulate the input signal, so as to have a larger signal power adjustment range; the present invention regulates the signal through two-stage voltage-controlled attenuators, making the power of the signal output more constant and the signal quality better; the present invention uses a logarithmic detector and a high-rate amplifier to regulate the input signal, improving the corresponding rate of the circuit. Description of the drawings

[0015] Figure 1 It is the structure diagram of the automatic gain control circuit of the present invention;

[0016] Figure 2 It is the structure diagram of the voltage-controlled attenuation circuit of the present invention;

[0017] Figure 3 It is the structure diagram of the coupling circuit of the present invention;

[0018] Figure 4 It is the structure diagram of the detection circuit of the present invention;

[0019] Figure 5 It is the structure diagram of the operational amplifier circuit of the present invention;

[0020] Figure 6 It is the structure diagram of the implementation manner circuit of another automatic gain control circuit of the present invention. Detailed implementation manners

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0022] An automatic gain control circuit, as Figure 1As shown in the figure, the circuit includes: two voltage-controlled attenuation circuits, two RF amplification circuits, a filter, a coupling circuit, and an operational amplifier circuit; the input end of the first voltage-controlled attenuation circuit is connected to the input signal, and the output end is connected to the input end of the first RF amplification circuit; the output end of the first RF amplification circuit is connected to the input end of the second voltage-controlled attenuation circuit; the output end of the second voltage-controlled attenuation circuit is connected to the input end of the filter; the output end of the filter is connected to the input end of the second RF amplification circuit; the output end of the second RF amplification circuit is connected to the coupling circuit, the output end of the coupling circuit is connected to the detection circuit, the output end of the detection circuit is connected to the input end of the operational amplifier circuit, and the output end of the operational amplifier circuit is respectively connected to the control ends of the first voltage-controlled attenuation circuit and the second voltage-controlled attenuation circuit, and the output end of the second RF amplification circuit is used as the output end of the automatic gain control circuit.

[0023] In this embodiment, as Figure 2 shown, the first voltage-controlled attenuation circuit includes: a first voltage-controlled attenuator and five capacitors. The positive voltage input end of the first voltage-controlled attenuator is respectively connected to capacitors C1 and C2, and the other ends of capacitors C1 and C2 are grounded, so that capacitors C1 and C2 are in parallel; the negative voltage input end of the first voltage-controlled attenuator is connected to capacitor C3, and the other end of capacitor C3 is grounded; the signal input end of the first voltage-controlled attenuator is connected to capacitor C4, and the signal output end of the first voltage-controlled attenuator is connected to capacitor C5. Among them, the capacitance value of capacitor C3 is equal to the capacitance value of capacitor C4.

[0024] In this embodiment, the structure of the second voltage-controlled attenuation circuit is the same as that of the first voltage-controlled attenuation circuit, but the parameters of the components are different, so that the circuit can have a larger signal power adjustment range.

[0025] In this embodiment, the structure of the first RF amplification circuit includes an RF amplifier, resistor R54, resistor R51, capacitor C70, capacitor C76, capacitor C87, and inductor L17; the input end of the RF amplifier is connected to resistor R54, and the other end of resistor R54 is respectively connected to the power supply end and resistor R51. The other end of resistor R51 is respectively connected to the positive poles of capacitor C70, capacitor C76, and inductor L17; the negative poles of capacitor C70 and capacitor C76 are both grounded, and the other end of inductor L17 is respectively connected to the output end of the RF amplifier and the terminal of capacitor C87; the other ends of the RF amplifier are grounded.

[0026] As Figure 3As shown in the figure, the coupling circuit includes: a coupler, three capacitors, and three resistors; the signal input terminal of the coupler is connected to capacitor C7, the output terminal is connected to capacitor C8, and one end of capacitor C9 connected to the signal control terminal; the other end of capacitor C9 is respectively connected to one end of resistor R1 and resistor R2, the other end of resistor R1 is grounded, the other end of resistor R2 is connected to resistor R3, and the other end of resistor R3 is grounded. The coupler is used to extract a small part of the signal from the RF signal backbone channel.

[0027] As Figure 6 shown, in another embodiment of the present invention, the coupling circuit includes a coupler, resistor R58, resistor R59, resistor R62, and capacitor C77; the input terminal of the coupler is connected to the output terminal of the second RF amplifier circuit, the output terminal is connected to capacitor C77, the adjustment terminal is respectively connected to resistor R58 and resistor R59, and the remaining ports are grounded; the other end of resistor R58 is grounded, the other end of resistor R59 is respectively connected to resistor R62 and the detection circuit; the other end of resistor R62 is grounded.

[0028] As Figure 4 shown, the detection circuit includes: a detector, four capacitors, and two resistors; the power input terminal of the detector is externally connected to a power supply and then respectively connected to capacitor C20 and capacitor C21, the other ends of capacitor C20 and capacitor C21 are respectively grounded, so that capacitor C20 and capacitor C21 are in parallel; the signal input terminal of the detector is respectively connected to resistor R5 and capacitor C22, the other end of resistor R5 is grounded; the signal output terminal of the detector is connected to resistor R4, the other end of resistor R4 is respectively connected to the input terminal of the operational amplifier circuit and one end of capacitor C23, and the other end of capacitor C23 is grounded. The function of the detector is to convert a rapidly changing voltage signal into a slowly changing DC voltage signal. The magnitude of this DC voltage should be proportional to the magnitude of the input signal. It has a wide dynamic range (detection range of 0 to -45 dBm).

[0029] In this embodiment, as Figure 5 shown, the circuit includes: the operational amplifier circuit includes an amplifier, four capacitors, and an inductor; the input terminal of the amplifier is connected to capacitor C14, the power input terminal is connected to a voltage source and then respectively connected to capacitor C13, capacitor C16, and inductor L1; the other ends of capacitor C13 and capacitor C16 are grounded; the other end of inductor L1 is respectively connected to the output terminal of the amplifier and capacitor C15.

[0030] In another embodiment, as Figure 6As shown, the operational amplifier circuit includes an amplifier, six resistors, and five capacitors; one end of resistor R70 is connected to the detection circuit, and the other end is connected to the negative input terminal of the amplifier; capacitor C96 is in parallel with resistor R60 and then in series with capacitor C104. The parallel port of capacitor C96 and resistor R60 is connected to the negative terminal of the amplifier, and the other end of capacitor C104 is respectively connected to the output terminal of the amplifier and resistor R110; the negative terminal of capacitor C115 is grounded, and the positive terminal is respectively connected to the positive input terminal of the amplifier, resistor R78, and resistor R79; the other end of resistor R78 is grounded, and the other end of resistor R79 is respectively connected to the input voltage, the positive terminal of capacitor C118 at the voltage input terminal of the amplifier, and the negative terminal of capacitor C118 is grounded; the positive terminal of the voltage input terminal of the amplifier is connected to the voltage source, and the negative terminal is grounded; the other end of resistor R110 is respectively connected to the positive terminal of capacitor C113, resistor R75, and the first voltage-controlled attenuation circuit; the negative terminal of capacitor C113 and the other end of resistor R75 are both grounded.

[0031] The function of the automatic gain control circuit designed by the present invention is: when the input radio frequency changes greatly, keep the output voltage constant or basically unchanged. In the signal relay system, when the L signal to be relayed is far from the indoor antenna, that is, the indoor input signal is very weak at this time, the link gain is made larger through the automatic gain control circuit; when the L signal to be relayed is very close to the indoor antenna, the gain of the receiver is made smaller. In this way, it is ensured that the signal at the output end of the signal repeater is basically unchanged or remains constant, and the outdoor antenna will not be unable to work properly due to too small an input signal, nor will it be damaged due to too large an input signal.

[0032] When the automatic gain control circuit is working, the input signal is attenuated and controlled by the first-stage voltage-controlled attenuator, then amplified in gain by the first-stage radio frequency amplifier, then attenuated and controlled by the second-stage voltage-controlled attenuator again, the signal is filtered by the filter, and after being amplified and output by the second-stage radio frequency amplifier, the output signal power is coupled to the detector through the coupler, the detector outputs the detection voltage, and through the operational amplifier circuit, the first and second stage voltage-controlled attenuators are attenuated and controlled.

[0033] A satellite navigation signal relay device, which includes an outdoor antenna, an indoor antenna, an indoor host, and a radio frequency connection cable. The outdoor antenna is connected to the indoor antenna, and the indoor antenna is connected to the indoor host through the radio frequency connection cable; among them, the indoor antenna is provided with the above-mentioned automatic gain control circuit.

[0034] The above-described embodiments have further elaborated on the object, technical solution, and advantages of the present invention. It should be understood that the above-described embodiments are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made to the present invention within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An automatic gain control circuit, characterized in that, The circuit includes: two voltage-controlled attenuation circuits, two RF amplification circuits, a filter, a coupling circuit, and an operational amplifier circuit; the input end of the first voltage-controlled attenuation circuit is connected to an input signal, and the output end is connected to the input end of the first RF amplification circuit; the output end of the first RF amplification circuit is connected to the input end of the second voltage-controlled attenuation circuit; the output end of the second voltage-controlled attenuation circuit is connected to the input end of the filter; the output end of the filter is connected to the input end of the second RF amplification circuit; the output end of the second RF amplification circuit is connected to the coupling circuit, the output end of the coupling circuit is connected to the detection circuit, the output end of the detection circuit is connected to the input end of the operational amplifier circuit, and the output end of the operational amplifier circuit is respectively connected to the control ends of the first voltage-controlled attenuation circuit and the second voltage-controlled attenuation circuit, and the output end of the second RF amplification circuit is used as the output end of the automatic gain control circuit.

2. The automatic gain control circuit according to claim 1, wherein The first voltage-controlled attenuation circuit includes: a first voltage-controlled attenuator and five capacitors. The positive voltage input end of the first voltage-controlled attenuator is respectively connected to capacitors C1 and C2, and the other ends of capacitors C1 and C2 are grounded, so that capacitors C1 and C2 are in parallel; the negative voltage input end of the first voltage-controlled attenuator is connected to capacitor C3, and the other end of capacitor C3 is grounded; the signal input end of the first voltage-controlled attenuator is connected to capacitor C4, and the signal output end of the first voltage-controlled attenuator is connected to capacitor C5.

3. An automatic gain control circuit according to claim 2, characterized in that, The capacitance value of capacitor C3 is equal to the capacitance value of capacitor C4.

4. An automatic gain control circuit according to claim 1, wherein The structure of the second voltage-controlled attenuation circuit is the same as that of the first voltage-controlled attenuation circuit.

5. An automatic gain control circuit according to claim 1, characterized in that, The structure of the first RF amplification circuit includes an RF amplifier, resistor R54, resistor R51, capacitor C70, capacitor C76, capacitor C87, and inductor L17; the input end of the RF amplifier is connected to resistor R54, and the other end of resistor R54 is respectively connected to the power supply end and resistor R51, and the other end of resistor R51 is respectively connected to the positive poles of capacitor C70, capacitor C76, and inductor L17; the negative poles of capacitor C70 and capacitor C76 are both grounded, and the other end of inductor L17 is respectively connected to the output end of the RF amplifier and the end of capacitor C87; the other ends of the RF amplifier are grounded.

6. An automatic gain control circuit according to claim 1, characterized in that, The coupling circuit includes a coupler, three capacitors, and three resistors; the signal input end of the coupler is connected to capacitor C7, the output end is connected to capacitor C8, and the signal control end is connected to one end of capacitor C9; the other end of capacitor C9 is respectively connected to one ends of resistor R1 and resistor R2, the other end of resistor R1 is grounded, and the other end of resistor R2 is connected to resistor R3, and the other end of resistor R3 is grounded.

7. An automatic gain control circuit according to claim 1, characterized in that, The detection circuit includes: a detector, four capacitors, and two resistors; the power supply input end of the detector is externally connected to a power supply and then respectively connected to capacitors C20 and C21, and the other ends of capacitors C20 and C21 are respectively grounded, so that capacitors C20 and C21 are in parallel; the signal input end of the detector is respectively connected to resistor R5 and capacitor C22, and the other end of resistor R5 is grounded; the signal output end of the detector is connected to resistor R4, and the other end of resistor R4 is respectively connected to the input end of the operational amplifier circuit and one end of capacitor C23, and the other end of capacitor C23 is grounded.

8. An automatic gain control circuit according to claim 1, characterized in that, The operational amplifier circuit includes an amplifier, four capacitors, and an inductor; the input terminal of the amplifier is connected to capacitor C14, and the power input terminal is connected to a voltage source and then connected to capacitor c13, capacitor c16, and inductor L1 respectively; the other ends of capacitor c13 and capacitor c16 are grounded; the other end of inductor L1 is connected to the output terminal of the amplifier and capacitor c15 respectively.

9. A satellite navigation signal retransmission device, characterized in that, The device includes: an outdoor antenna, an indoor antenna, an indoor host, and a radio frequency connection cable. The outdoor antenna is connected to the indoor antenna, and the indoor antenna is connected to the indoor host through the radio frequency connection cable; wherein the indoor antenna is provided with the automatic gain control circuit described in any one of claims 1 to 7.

Images