CN118100814A - Variable gain amplifier and communication device - Google Patents
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- CN118100814A CN118100814A CN202410227297.9A CN202410227297A CN118100814A CN 118100814 A CN118100814 A CN 118100814A CN 202410227297 A CN202410227297 A CN 202410227297A CN 118100814 A CN118100814 A CN 118100814A
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Abstract
The application provides a variable gain amplifier and communication equipment, wherein the variable gain amplifier comprises a first gain output unit, a second gain output unit, a first input unit, a second input unit, a first isolation unit, a second isolation unit, a connection unit, a current source unit, a voltage output unit and a feedback unit, wherein the first end of the connection unit is respectively and electrically connected with the first input unit and the first isolation unit, the second end of the connection unit is respectively and electrically connected with the second input unit and the second isolation unit, the current source unit is respectively and electrically connected with the first isolation unit, the second isolation unit and the feedback unit, and the voltage output unit is respectively and electrically connected with the first gain output unit, the second gain output unit, the feedback unit and a power supply. The direct-current voltage at the output end of the variable gain amplifier is not influenced by external factors, and the performance of the VGA circuit is improved.
Description
Technical Field
The application belongs to the technical field of variable gain amplifiers, and particularly relates to a variable gain amplifier and communication equipment.
Background
A Variable gain amplifier (Variable GAIN AMPLIFIER, VGA) is an amplifier whose gain multiple depends on the voltage of a regulation signal, and can amplify the waveform of an input signal, and is widely used in communication devices. In the existing VGA structure, the direct-current voltage of an output end is not changed along with the gain of a VGA circuit theoretically. However, in practical applications, the accuracy and temperature characteristics of the reference current source, and the accuracy and temperature characteristics of the resistor affect the dc voltage at the output end of the VGA circuit, resulting in poor performance of the VGA circuit itself and deterioration of the operation state of the post-stage circuit.
Disclosure of Invention
The embodiment of the application provides a variable gain amplifier and communication equipment, which can solve the problem that the performance of a VGA circuit is poor due to the fact that the direct current voltage of the output end of the existing VGA circuit is influenced by external factors.
In a first aspect, an embodiment of the present application provides a variable gain amplifier, including a first gain output unit, a second gain output unit, a first input unit, a second input unit, a first isolation unit, a second isolation unit, a connection unit, a current source unit, a voltage output unit, and a feedback unit, where the first gain output unit, the first input unit, and the first isolation unit are sequentially electrically connected, the second gain output unit, the second input unit, and the second isolation unit are sequentially electrically connected, a first end of the connection unit is electrically connected with the first input unit and the first isolation unit, a second end of the connection unit is electrically connected with the second input unit and the second isolation unit, the current source unit is electrically connected with the first isolation unit, the second isolation unit, and the feedback unit, and the voltage output unit is electrically connected with the first gain output unit, the second gain output unit, the feedback unit, and a power supply unit, and the first gain output unit and the second gain output unit are electrically connected with the power supply unit;
The first input unit is used for modulating the input current of the first gain output unit according to a received first input signal, the first gain output unit is used for adjusting and distributing the output current of the first input unit according to a received first bias voltage and a received second bias voltage and outputting a first gain voltage, and the first isolation unit is used for isolating the first input unit and the current source unit;
The second input unit is used for modulating the input current of the second gain output unit according to a received second input signal, the second gain output unit is used for adjusting and distributing the output current of the second input unit according to the received first bias voltage and the second bias voltage and outputting a second gain voltage, and the second isolation unit is used for isolating the second input unit and the current source unit;
The connecting unit is used for communicating the first input unit and the second input unit; the voltage output unit is used for outputting a first voltage according to the power supply, and the feedback unit is used for outputting a feedback voltage signal according to the first voltage and the reference voltage.
In a possible implementation manner of the first aspect, the first isolation unit includes a first resistor, a first end of the first resistor is electrically connected to the first input unit and a first end of the connection unit, and a second end of the first resistor is electrically connected to the current source unit and the second isolation unit, respectively;
The second isolation unit comprises a second resistor, wherein the first end of the second resistor is electrically connected with the second input unit and the second end of the connection unit respectively, and the second end of the second resistor is electrically connected with the current source unit and the first isolation unit respectively.
In a possible implementation manner of the first aspect, the voltage output unit includes a third resistor, a fourth resistor and a first capacitor, a first end of the third resistor is electrically connected to the first gain output unit, a second end of the third resistor is electrically connected to the first end of the fourth resistor, a second end of the first capacitor and the feedback unit, a second end of the fourth resistor is electrically connected to the second gain output unit, and a first end of the first capacitor is electrically connected to the power supply, the first gain output unit and the second gain output unit, respectively.
In a possible implementation manner of the first aspect, the feedback unit includes an amplifier, a non-inverting input terminal of the amplifier is electrically connected to the voltage output unit, an inverting input terminal of the amplifier is configured to receive the reference voltage, and an output terminal of the amplifier is electrically connected to the current source unit.
In a possible implementation manner of the first aspect, the first gain output unit includes a first triode, a second triode, and a fifth resistor; the first end of the fifth resistor is used for being electrically connected with the power supply, the second end of the fifth resistor is used as an output end of the first gain output unit and is respectively and electrically connected with a collector electrode of the first triode, the voltage output unit and the second gain output unit, a base electrode of the second triode is used for receiving the first bias voltage, the collector electrode of the second triode is electrically connected with the second gain output unit, an emitter electrode of the second triode is respectively and electrically connected with an emitter electrode of the first triode and the first input unit, and a base electrode of the first triode is used for receiving the second bias voltage;
The second gain output unit comprises a third triode, a fourth triode and a sixth resistor; the first end of the sixth resistor is used for being electrically connected with the power supply, the second end of the sixth resistor is used as an output end of the second gain output unit and is respectively and electrically connected with the collector electrode of the fourth triode, the voltage output unit and the first gain output unit, the base electrode of the third triode is used for receiving the first bias voltage, the collector electrode of the third triode is electrically connected with the first gain output unit, the emitter electrode of the third triode is respectively and electrically connected with the emitter electrode of the fourth triode and the second input unit, and the base electrode of the fourth triode is used for receiving the second bias voltage.
In a possible implementation manner of the first aspect, the first input unit includes a fifth triode, a base electrode of the fifth triode is used for receiving the first input signal, a collector electrode of the fifth triode is electrically connected with the first gain output unit, and an emitter electrode of the fifth triode is electrically connected with the first isolation unit and the first end of the connection unit respectively;
the second input unit comprises a sixth triode, the base electrode of the sixth triode is used for receiving the second input signal, the collector electrode of the sixth triode is electrically connected with the second gain output unit, and the emitter electrode of the sixth triode is respectively and electrically connected with the second isolation unit and the second end of the connection unit.
In a possible implementation manner of the first aspect, the connection unit includes a second capacitor, a first end of the second capacitor is electrically connected to the first input unit and the first isolation unit, and a second end of the second capacitor is electrically connected to the second input unit and the second isolation unit, respectively.
In a possible implementation manner of the first aspect, the current source unit includes a first current source, a first end of the first current source is electrically connected to the first isolation unit and the second isolation unit, and a second end of the first current source is grounded.
In a possible implementation manner of the first aspect, the variable gain amplifier further includes a third capacitor, a first end of the third capacitor is electrically connected to the first isolation unit and the second isolation unit, and a second end of the third capacitor is grounded.
In a second aspect, an embodiment of the present application provides a communication device comprising a variable gain amplifier according to any one of the first aspects.
Compared with the prior art, the embodiment of the application has the beneficial effects that:
The variable gain amplifier provided by the embodiment of the application comprises a first gain output unit, a second gain output unit, a first input unit, a second input unit, a first isolation unit, a second isolation unit, a connecting unit, a current source unit, a voltage output unit and a feedback unit, wherein the first gain output unit, the first input unit and the first isolation unit are sequentially and electrically connected, the second gain output unit, the second input unit and the second isolation unit are sequentially and electrically connected, the first end of the connecting unit is respectively and electrically connected with the first input unit and the first isolation unit, the second end of the connecting unit is respectively and electrically connected with the second input unit and the second isolation unit, the current source unit is respectively and electrically connected with the first isolation unit, the second isolation unit and the feedback unit, the voltage output unit is respectively and electrically connected with the first gain output unit, the second gain output unit, the feedback unit and the power supply, and the first gain output unit and the second gain output unit are both used for being electrically connected with the power supply.
Compared with the prior variable gain amplifier, the variable gain amplifier provided by the embodiment of the application is provided with the first isolation unit and the second isolation unit, the first isolation unit is used for isolating the first input unit from the current source unit, and the second isolation unit is used for isolating the second input unit from the current source unit, so that the current source unit is not directly connected with the first input unit and the second input unit, and the first isolation unit is connected with the second isolation unit, thereby reducing the influence of parasitic capacitance of the current source unit on the adjustable range of the AC response of the VGA. In addition, the voltage output unit and the feedback unit are additionally arranged in the variable gain amplifier provided by the embodiment of the application, the feedback unit outputs a feedback voltage signal according to the received reference voltage and the first voltage output by the voltage output unit, and the current source unit adjusts the direct current voltage of the output end of the VGA circuit according to the feedback voltage signal, so that the direct current voltage of the output end of the VGA circuit is stabilized at the set value of the reference voltage, the direct current voltage of the output end of the VGA circuit is effectively prevented from being influenced by external factors such as manufacturing process, temperature and the like, and the performance of the VGA circuit is improved.
It will be appreciated that the advantages of the second aspect may be found in the relevant description of the first aspect, and will not be described in detail herein.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic diagram of the circuit connections of a prior art variable gain amplifier;
Fig. 2 is a functional block diagram of a variable gain amplifier provided in accordance with an embodiment of the present application;
fig. 3 is a schematic circuit connection diagram of a variable gain amplifier according to an embodiment of the present application.
In the figure: 10. a variable gain amplifier; 101. a first gain output unit; 102. a second gain output unit; 103. a first input unit; 104. a second input unit; 105. a first isolation unit; 106. a second isolation unit; 107. a connection unit; 108. a current source unit; 109. a voltage output unit; 110. and a feedback unit.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth such as the particular system architecture, techniques, etc., in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.
It should be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
As used in the present description and the appended claims, the term "if" may be interpreted in context as "when …" or "once" or "in response to a determination" or "in response to detection. Similarly, the phrase "if a determination" or "if a [ described condition or event ] is detected" may be interpreted in the context of meaning "upon determination" or "in response to determination" or "upon detection of a [ described condition or event ]" or "in response to detection of a [ described condition or event ]".
Furthermore, the terms "first," "second," "third," and the like in the description of the present specification and in the appended claims, are used for distinguishing between descriptions and not necessarily for indicating or implying a relative importance.
Reference in the specification to "one embodiment" or "some embodiments" or the like means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the application. Thus, appearances of the phrases "in one embodiment," "in some embodiments," "in other embodiments," and the like in the specification are not necessarily all referring to the same embodiment, but mean "one or more but not all embodiments" unless expressly specified otherwise. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless expressly specified otherwise.
As shown in fig. 1, the conventional variable gain amplifier mainly includes a first resistor R1, a second resistor R2, a third resistor R3, a first transistor T1, a second transistor T2, a third transistor T3, a fourth transistor T4, a fifth transistor T5, a sixth transistor T6, a first capacitor C1, a first current source Isource1, and a second current source Isource2. The maximum capacitance value and the minimum capacitance value of the emitter of the fifth triode T5 determine the adjusting range of the AC response of the VGA, the first capacitor C1 and the first current source Isource1 are both connected to the emitter of the fifth triode T5, the parasitic capacitance of the current sources Isource1 and Isource2 can influence the adjusting range of the AC response of the VGA, and the existing VGA structure can reduce the adjusting range of the AC response of the VGA due to the parasitic capacitance of the current sources under the condition that the total capacitance (the first capacitor C1 and the parasitic capacitance) is unchanged; and the drain voltage of the first current source Isource1 and the second current source Isource2 have a large range of variation, and especially when the common mode level of the base inputs of the fifth triode T5 and the sixth triode T6 is lower, the stability and the accuracy of the current sources are poor. Meanwhile, in the existing VGA structure, the direct-current voltage of an output end is not changed along with the gain of a VGA circuit theoretically. However, in practical applications, the accuracy and temperature characteristics of the reference current sources (Isource 1 and Isource 2), and the accuracy and temperature characteristics of the resistors (R1 and R2) are affected by external factors such as the manufacturing process, and thus the dc voltage at the output end of the VGA circuit is affected, resulting in poor performance of the VGA circuit.
Based on the above-mentioned problems, the variable gain amplifier provided by the embodiment of the application comprises a first gain output unit, a second gain output unit, a first input unit, a second input unit, a first isolation unit, a second isolation unit, a connecting unit, a current source unit, a voltage output unit and a feedback unit, wherein the first gain output unit, the first input unit and the first isolation unit are sequentially and electrically connected, the second gain output unit, the second input unit and the second isolation unit are sequentially and electrically connected, a first end of the connecting unit is respectively and electrically connected with the first input unit and the first isolation unit, a second end of the connecting unit is respectively and electrically connected with the second input unit and the second isolation unit, the current source unit is respectively and electrically connected with the first isolation unit, the second isolation unit and the feedback unit, the voltage output unit is respectively and electrically connected with the first gain output unit, the second gain output unit, the feedback unit and the power supply, and the first gain output unit and the second gain output unit are both used for being electrically connected with the power supply.
Compared with the prior variable gain amplifier, the variable gain amplifier provided by the embodiment of the application is provided with the first isolation unit and the second isolation unit, the first isolation unit is used for isolating the first input unit from the current source unit, and the second isolation unit is used for isolating the second input unit from the current source unit, so that the current source unit is not directly connected with the first input unit and the second input unit, and the first isolation unit is connected with the second isolation unit, thereby reducing the influence of parasitic capacitance of the current source unit on the adjustable range of the AC response of the VGA. In addition, the voltage output unit and the feedback unit are additionally arranged in the variable gain amplifier provided by the embodiment of the application, the feedback unit outputs a feedback voltage signal according to the received reference voltage and the first voltage output by the voltage output unit, and the current source unit adjusts the direct current voltage of the output end of the VGA circuit according to the feedback voltage signal, so that the direct current voltage of the output end of the VGA circuit is stabilized at the set value of the reference voltage, the direct current voltage of the output end of the VGA circuit is effectively prevented from being influenced by external factors such as manufacturing process, temperature and the like, and the performance of the VGA circuit is improved.
In order to illustrate the technical scheme of the application, the following description is made by specific examples.
Fig. 2 shows a functional block diagram of a variable gain amplifier 10 provided in accordance with an embodiment of the present application. Referring to fig. 2, the variable gain amplifier 10 includes a first gain output unit 101, a second gain output unit 102, a first input unit 103, a second input unit 104, a first isolation unit 105, a second isolation unit 106, a connection unit 107, a current source unit 108, a voltage output unit 109, and a feedback unit 110, the first gain output unit 101, the first input unit 103, and the first isolation unit 105 are electrically connected in sequence, the second gain output unit 102, the second input unit 104, and the second isolation unit 106 are electrically connected in sequence, a first end of the connection unit 107 is electrically connected with the first input unit 103 and the first isolation unit 105, respectively, a second end of the connection unit 107 is electrically connected with the second input unit 104 and the second isolation unit 106, respectively, the current source unit 108 is electrically connected with the first isolation unit 105, the second isolation unit 106, and the feedback unit 110, the voltage output unit 109 is electrically connected with the first gain output unit 101, the second gain output unit 102, the feedback unit 110, and the power supply VDD, respectively, and the first gain output unit 101 and the second gain output unit 102 are all used for electrically connecting with the power supply VDD.
Specifically, the current source unit 108 is configured to provide a dc bias current, the first input unit 103 is configured to modulate an input current of the first gain output unit 101 according to a received first input signal, the first gain output unit 101 is configured to adjust and distribute an output current of the first input unit 103 according to a received first bias voltage and a received second bias voltage, and output a first gain voltage, and the first isolation unit 105 is configured to isolate the first input unit 103 from the current source unit 108.
The second input unit 104 is configured to modulate an input current of the second gain output unit 102 according to the received second input signal, the second gain output unit 102 is configured to adjust and distribute an output current of the second input unit 104 according to the received first bias voltage and the second bias voltage, and output a second gain voltage, and the second isolation unit 106 is configured to isolate the second input unit 104 from the current source unit 108.
The connection unit 107 is used for communicating the first input unit 103 and the second input unit 104; the voltage output unit 109 is configured to output a first voltage according to the power supply VDD, and the feedback unit 110 is configured to output a feedback voltage signal according to the first voltage and a reference voltage.
Compared with the prior variable gain amplifier, the variable gain amplifier 10 provided by the embodiment of the application is provided with the first isolation unit 105 and the second isolation unit 106, wherein the first isolation unit 105 is used for isolating the first input unit 103 from the current source unit 108, and the second isolation unit 106 is used for isolating the second input unit 104 from the current source unit 108, so that the current source unit 108 is not directly connected with the first input unit 103 and the second input unit 104, and the first isolation unit 105 is connected with the second isolation unit 106, thereby reducing the influence of parasitic capacitance of the current source unit 108 on the adjustable range of the AC response of the VGA. In addition, the voltage output unit 109 and the feedback unit 110 are further added in the variable gain amplifier 10 provided in the embodiment of the present application, the feedback unit 110 outputs a feedback voltage signal according to the received reference voltage and the first voltage output by the voltage output unit 109, and the current source unit 108 adjusts the dc voltage of the output end of the VGA circuit according to the feedback voltage signal, so that the dc voltage of the output end of the VGA circuit is stabilized at the set value of the reference voltage, thereby effectively avoiding the dc voltage of the output end of the VGA circuit from being affected by external factors such as the manufacturing process, the temperature, and the like, and improving the performance of the VGA circuit.
The first gain output unit 101, the first input unit 103, and the first isolation unit 105 constitute a first gain amplification module, and the second gain output unit 102, the second input unit 104, and the second isolation unit 106 constitute a second gain amplification module. The connection unit 107 is connected between the first gain amplification module and the second gain amplification module.
In one embodiment of the present application, as shown in fig. 3, the first isolation unit 105 includes a first resistor R1, a first end of the first resistor R1 is electrically connected to the first input unit 103 and a first end of the connection unit 107, and a second end of the first resistor R1 is electrically connected to the current source unit 108 and the second isolation unit 106, respectively.
The second isolation unit 106 includes a second resistor R2, a first end of the second resistor R2 is electrically connected to the second input unit 104 and a second end of the connection unit 107, respectively, and a second end of the second resistor R2 is electrically connected to the current source unit 108 and the first isolation unit 105, respectively.
Specifically, the first resistor R1 is configured to isolate the first input unit 103 from the current source unit 108, so as to ensure that the first input unit 103 and the current source unit 108 are not directly connected, reduce an influence of parasitic capacitance of the current source unit 108 on an adjustable range of an AC response of the VGA, and avoid an influence of variation of the first input signal INA on the current source unit 108, so as to ensure stability of the current source unit 108. The second resistor R2 is used for isolating the second input unit 104 from the current source unit 108, so as to ensure that the second input unit 104 and the current source unit 108 are not directly connected, reduce the influence of the parasitic capacitance of the current source unit 108 on the adjustable range of the AC response of the VGA, avoid the influence of the second input signal INB on the current source unit 108, and ensure the stability of the current source unit 108. Meanwhile, the second terminal of the first resistor R1 and the second terminal of the second resistor R2 are electrically connected, and at this time, the parasitic capacitance of the current source unit 108 is substantially invisible to the input units (the first input unit 103 and the second input unit 104) and the parasitic capacitance of the current source unit 108 can be ignored.
The first resistor R1 and the second resistor R2 cooperate with the first input unit 103, the second input unit 104, and the connection unit 107 to modulate the output current of the first input unit 103 and the output current of the second input unit 104 according to the input signal.
For example, the resistance of the first resistor R1 and the resistance of the second resistor R2 may be set to be the same, and half the resistance of the third resistor R3 in the conventional variable gain amplifier structure.
It should be noted that, in the variable gain amplifier 10 provided in the embodiment of the present application, since the VS voltage has small symmetrical variation when the VS terminal is in normal operation, the stability of the current source can be realized.
In one embodiment of the present application, as shown in fig. 3, the voltage output unit 109 includes a third resistor R3, a fourth resistor R4, and a first capacitor C1, where a first end of the third resistor R3 is electrically connected to the first gain output unit 101, a second end of the third resistor R3 is electrically connected to a first end of the fourth resistor R4, a second end of the first capacitor C1, and the feedback unit 110, and a second end of the fourth resistor R4 is electrically connected to the second gain output unit 102, and a first end of the first capacitor C1 is electrically connected to the power supply VDD, the first gain output unit 101, and the second gain output unit 102, respectively.
Specifically, the third resistor R3 and the fourth resistor R4 are used for current limiting and voltage dividing, and a common connection terminal of the third resistor R3 and the fourth resistor R4 is used as an output terminal of the voltage output unit 109 to provide the first voltage (OUT-CM) to the feedback unit 110. The first capacitor C1 is used for filtering, and can filter out high-frequency noise in the first gain voltage signal of the first gain output unit 101 and the second gain voltage signal of the second gain output unit 102, so as to prevent the high-frequency noise signal from affecting the VGA circuit.
It should be noted that, the VGA circuit of the present application monitors the change of the first voltage in real time by setting the third resistor R3 and the fourth resistor R4, and feeds back the change of the first voltage through the feedback unit 110, so that the direct current voltage at the output end of the VGA circuit will not change along with the change of the gain of the VGA circuit, and the performance of the VGA circuit is improved.
For example, the resistance value of the third resistor R3 and the resistance value of the fourth resistor R4 may be set to be the same, and at this time, the first voltage is equal to half of the sum of the first gain voltage of the first gain output unit 101 and the second gain voltage of the second gain output unit 102.
In one embodiment of the present application, as shown in fig. 3, the feedback unit 110 includes an amplifier U1, a non-inverting input terminal of the amplifier U1 is electrically connected to the voltage output unit 109, an inverting input terminal of the amplifier U1 is used for receiving the reference voltage, and an output terminal of the amplifier U1 is electrically connected to the current source unit 108.
Specifically, the amplifier U1 outputs a feedback voltage signal VCTRL for controlling the current source unit 108 according to the received reference voltage and the first voltage. The current source unit 108 adjusts the direct current bias current according to the feedback voltage signal VCTRL, so that the direct current voltage at the output end of the VGA circuit is stabilized at the set value of the reference voltage, thereby effectively avoiding the influence of external factors such as manufacturing process, temperature and the like on the direct current voltage at the output end of the VGA circuit and improving the performance of the VGA circuit.
In one embodiment of the present application, as shown in fig. 3, the first gain output unit 101 includes a first triode T1, a second triode T2, and a fifth resistor R5, where a first end of the fifth resistor R5 is electrically connected to the power supply VDD, a second end of the fifth resistor R5 is used as an output end OUTB of the first gain output unit 101, and is electrically connected to a collector of the first triode T1, the voltage output unit 109, and the second gain output unit 102, respectively, a base of the second triode T2 is used to receive the first bias voltage Vbias1, a collector of the second triode T2 is electrically connected to the second gain output unit 102, an emitter of the second triode T2 is electrically connected to an emitter of the first triode T1 and the first input unit 103, respectively, and a base of the first triode T1 is used to receive the second bias voltage Vbias2.
The second gain output unit 102 includes a third triode T3, a fourth triode T4, and a sixth resistor R6, where a first end of the sixth resistor R6 is electrically connected to the power supply VDD, a second end of the sixth resistor R6 is used as an output end OUTA of the second gain output unit 102, and is electrically connected to a collector of the fourth triode T4, the voltage output unit 109, and the first gain output unit 101, respectively, a base of the third triode T3 is used to receive the first bias voltage Vbias1, a collector of the third triode T3 is electrically connected to the first gain output unit 101, an emitter of the third triode T3 is electrically connected to an emitter of the fourth triode T4 and the second input unit 104, and a base of the fourth triode T4 is used to receive the second bias voltage Vbias2.
Specifically, the first bias voltage Vbias1 and the second bias voltage Vbias2 are used for controlling the amplification gains of the first gain output unit 101 and the second gain output unit 102. The emitter of the first triode T1 and the emitter of the second triode T2 serve as receiving ends of the first gain output unit 101, and are used for receiving the output current of the first input unit 103, adjusting the output current of the first input unit 103 according to the first bias voltage Vbias1 and the second bias voltage Vbias2, generating a first gain voltage on the fifth resistor R5, and outputting through the output end OUTB of the first gain output unit 101 to achieve gain control. The relationship among the first gain voltage, the fifth resistor R5 and the power supply VDD is: v OUTB＝VDD-IR5 R5. Wherein V OUTB is the first gain voltage, I R5 is the current flowing through the fifth resistor R5, and R5 is the resistance of the fifth resistor R5.
The emitter of the third triode T3 and the emitter of the fourth triode T4 serve as receiving ends of the second gain output unit 102, and are used for receiving the output current of the second input unit 104, adjusting the output current of the second input unit 104 according to the first bias voltage Vbias1 and the second bias voltage Vbias2, generating a second gain voltage on the sixth resistor R6, and outputting through the output end OUTA of the second gain output unit 102 to achieve gain control. The relationship among the second gain voltage, the sixth resistor R6 and the power supply VDD is: v OUTA＝VDD-IR6 R6. Wherein V OUTA is the second gain voltage, I R6 is the current flowing through the sixth resistor R6, and R6 is the resistance of the sixth resistor R6.
For example, the types of the first transistor T1, the second transistor T2, the third transistor T3, and the fourth transistor T4 may be NPN transistors, PNP transistors, or MOS transistors.
The fifth resistor R5 and the sixth resistor R6 are susceptible to temperature, and thus affect the dc voltage at the output terminal of the VGA circuit. According to the application, the voltage output unit 109 and the feedback unit 110 are arranged, the feedback unit 110 outputs a feedback voltage signal according to the received reference voltage and the first voltage output by the voltage output unit 109, and the current source unit 108 adjusts the direct current voltage of the output end of the VGA circuit according to the feedback voltage signal, so that the direct current voltage of the output end of the VGA circuit is stabilized at the set value of the reference voltage, the direct current voltage of the output end of the VGA circuit is effectively prevented from being influenced by external factors such as manufacturing process, temperature and the like, and the performance of the VGA circuit is improved.
In one embodiment of the present application, as shown in fig. 3, the first input unit 103 includes a fifth triode T5, a base electrode of the fifth triode T5 is configured to receive the first input signal INA, a collector electrode of the fifth triode T5 is electrically connected to the first gain output unit 101, and an emitter electrode of the fifth triode T5 is electrically connected to the first isolation unit 105 and the first end of the connection unit 107, respectively.
The second input unit 104 includes a sixth triode T6, a base electrode of the sixth triode T6 is configured to receive the second input signal INB, a collector electrode of the sixth triode T6 is electrically connected to the second gain output unit 102, and an emitter electrode of the sixth triode T6 is electrically connected to the second isolation unit 106 and the second end of the connection unit 107, respectively.
Specifically, the base of the fifth transistor T5 is configured to receive the first input signal INA, and adjust the on current according to the first input signal INA, so that the input signal INA is converted into a current to be loaded on the output bias dc of the current source unit 108, and the input current is provided to the first gain output unit 101, and the first gain output unit 101 can adjust the input current of the first gain output unit 101. The base of the sixth triode T6 is configured to receive the second input signal INB, and adjust the on current according to the second input signal INB, so that the input signal INB is converted into a current to be loaded on the output bias dc of the current source unit 108, and the input current is provided to the second gain output unit 102, and the second gain output unit 102 can adjust the input current of the second gain output unit 102.
For example, the fifth transistor T5 and the sixth transistor T6 may be NPN transistors, PNP transistors, or MOS transistors.
In one embodiment of the present application, as shown in fig. 3, the connection unit 107 includes a second capacitor C2, wherein a first end of the second capacitor C2 is electrically connected to the first input unit 103 and the first isolation unit 105, and a second end of the second capacitor C2 is electrically connected to the second input unit 104 and the second isolation unit 106, respectively.
Specifically, the second capacitor C2 is configured to add a negative feedback to the input ends of the first gain amplifying module and the second gain amplifying module, so that the high-frequency gain can be effectively improved, the high-frequency input impedance can be reduced, and the bandwidth of the whole circuit can be expanded.
It should be noted that the second capacitor C2 may be a capacitor with adjustable capacitance, and the adjustable range of the AC response of the structure of the variable gain amplifier 10 provided in the embodiment of the present application is only determined by the maximum value and the minimum value of the second capacitor C2.
In one embodiment of the present application, as shown in fig. 3, the current source unit 108 includes a first current source Isource1, and a first end of the first current source Isource1 is electrically connected to the first isolation unit 105 and the second isolation unit 106, respectively, and a second end of the first current source Isource1 is grounded.
Specifically, the first current source Isource1 is configured to provide a constant first dc bias current, and provide appropriate working states for the first gain amplification module and the second gain amplification module.
It should be noted that, the first current source Isource1 in the current source unit 108 may be replaced by a MOS transistor, that is, a drain electrode of the MOS transistor is connected to the second end of the first resistor R1 and the second end of the second resistor R2, a source electrode of the MOS transistor is grounded, and a gate electrode of the MOS transistor is connected to the output end of the feedback unit 110.
For example, the MOS transistor may be an N-type MOS transistor.
In one embodiment of the present application, as shown in fig. 3, the variable gain amplifier 10 further includes a third capacitor C3, where a first end of the third capacitor C3 is electrically connected to the first isolation unit 105 and the second isolation unit 106, and a second end of the third capacitor C3 is grounded.
Specifically, the third capacitor C3 is used for voltage stabilization, and can be used for smoothing voltage fluctuation in the circuit, so as to improve the reliability of the VGA circuit. The third capacitor C3 may be omitted for cost reduction or circuit board volume.
In the present application, it should be noted that, in some special application scenarios or under the condition of relatively low supply voltage, the input common-mode voltage of the VGA needs to be as low as possible, so that enough working voltage space is left for other circuits to make the whole circuit work in a proper state.
The application also discloses a communication device which comprises the variable gain amplifier 10, and the communication device can solve the problem that the adjustable range of the AC response of the VGA is reduced due to the parasitic capacitance of the current source by adopting the variable gain amplifier 10, and the adjustable range of the AC response of the VGA is enlarged. By reducing the minimum reasonable working voltage of the current source, the minimum value of the input common mode level is reduced, the variation range of the input common mode level is increased, and the VGA circuit can be suitable for more scenes. In addition, the direct current voltage at the output end of the VGA circuit can be effectively prevented from being influenced by external factors such as manufacturing process, temperature and the like, so that the direct current voltage at the output end of the VGA circuit is stabilized at the set value of the reference voltage, and the performance of the VGA circuit is improved.
Since the processing and functions implemented by the communication device in this embodiment basically correspond to the embodiments, principles and examples of the variable gain amplifier, the description of this embodiment is not exhaustive, and reference may be made to the related descriptions in the foregoing embodiments, which are not repeated herein.
The above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application, and are intended to be included in the scope of the present application.
Claims (10)
1. The variable gain amplifier is characterized by comprising a first gain output unit, a second gain output unit, a first input unit, a second input unit, a first isolation unit, a second isolation unit, a connecting unit, a current source unit, a voltage output unit and a feedback unit, wherein the first gain output unit, the first input unit and the first isolation unit are sequentially and electrically connected, the second gain output unit, the second input unit and the second isolation unit are sequentially and electrically connected, a first end of the connecting unit is respectively and electrically connected with the first input unit and the first isolation unit, a second end of the connecting unit is respectively and electrically connected with the second input unit and the second isolation unit, the current source unit is respectively and electrically connected with the first isolation unit, the second isolation unit and the feedback unit, the voltage output unit is respectively and electrically connected with the first gain output unit, the second gain output unit, the feedback unit and a power supply, and the first gain output unit and the second output unit are respectively and electrically connected with the power supply;
The first input unit is used for modulating the input current of the first gain output unit according to a received first input signal, the first gain output unit is used for adjusting and distributing the output current of the first input unit according to a received first bias voltage and a received second bias voltage and outputting a first gain voltage, and the first isolation unit is used for isolating the first input unit and the current source unit;
The second input unit is used for modulating the input current of the second gain output unit according to a received second input signal, the second gain output unit is used for adjusting and distributing the output current of the second input unit according to the received first bias voltage and the second bias voltage and outputting a second gain voltage, and the second isolation unit is used for isolating the second input unit and the current source unit;
The connecting unit is used for communicating the first input unit and the second input unit; the voltage output unit is used for outputting a first voltage according to the power supply, and the feedback unit is used for outputting a feedback voltage signal according to the first voltage and the reference voltage.
2. The variable gain amplifier of claim 1 wherein the first isolation unit comprises a first resistor having a first end electrically connected to the first input unit and the first end of the connection unit, respectively, and a second end electrically connected to the current source unit and the second isolation unit, respectively;
The second isolation unit comprises a second resistor, wherein the first end of the second resistor is electrically connected with the second input unit and the second end of the connection unit respectively, and the second end of the second resistor is electrically connected with the current source unit and the first isolation unit respectively.
3. The variable gain amplifier of claim 1 wherein the voltage output unit comprises a third resistor, a fourth resistor, and a first capacitor, the first end of the third resistor being electrically connected to the first gain output unit, the second end of the third resistor being electrically connected to the first end of the fourth resistor, the second end of the first capacitor, and the feedback unit, respectively, the second end of the fourth resistor being electrically connected to the second gain output unit, the first end of the first capacitor being for electrically connecting to the power supply, the first gain output unit, and the second gain output unit, respectively.
4. The variable gain amplifier of claim 1, wherein the feedback unit comprises an amplifier having a non-inverting input electrically coupled to the voltage output unit, an inverting input for receiving the reference voltage, and an output electrically coupled to the current source unit.
5. The variable gain amplifier of claim 1 wherein the first gain output unit comprises a first transistor, a second transistor, and a fifth resistor; the first end of the fifth resistor is used for being electrically connected with the power supply, the second end of the fifth resistor is used as an output end of the first gain output unit and is respectively and electrically connected with a collector electrode of the first triode, the voltage output unit and the second gain output unit, a base electrode of the second triode is used for receiving the first bias voltage, the collector electrode of the second triode is electrically connected with the second gain output unit, an emitter electrode of the second triode is respectively and electrically connected with an emitter electrode of the first triode and the first input unit, and a base electrode of the first triode is used for receiving the second bias voltage;
The second gain output unit comprises a third triode, a fourth triode and a sixth resistor; the first end of the sixth resistor is used for being electrically connected with the power supply, the second end of the sixth resistor is used as an output end of the second gain output unit and is respectively and electrically connected with the collector electrode of the fourth triode, the voltage output unit and the first gain output unit, the base electrode of the third triode is used for receiving the first bias voltage, the collector electrode of the third triode is electrically connected with the first gain output unit, the emitter electrode of the third triode is respectively and electrically connected with the emitter electrode of the fourth triode and the second input unit, and the base electrode of the fourth triode is used for receiving the second bias voltage.
6. The variable gain amplifier of claim 1 wherein the first input unit comprises a fifth transistor having a base for receiving the first input signal, a collector electrically connected to the first gain output unit, and an emitter electrically connected to the first isolation unit and the first end of the connection unit, respectively;
the second input unit comprises a sixth triode, the base electrode of the sixth triode is used for receiving the second input signal, the collector electrode of the sixth triode is electrically connected with the second gain output unit, and the emitter electrode of the sixth triode is respectively and electrically connected with the second isolation unit and the second end of the connection unit.
7. The variable gain amplifier of claim 1 wherein the connection unit comprises a second capacitor having a first end electrically connected to the first input unit and the first isolation unit, respectively, and a second end electrically connected to the second input unit and the second isolation unit, respectively.
8. The variable gain amplifier of claim 1 wherein the current source unit comprises a first current source having a first end electrically connected to the first isolation unit and the second isolation unit, respectively, and a second end of the first current source being grounded.
9. The variable gain amplifier of any of claims 1-8 further comprising a third capacitor, a first end of the third capacitor being electrically connected to the first isolation element and the second isolation element, respectively, and a second end of the third capacitor being grounded.
10. A communication device comprising a variable gain amplifier as claimed in any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410227297.9A CN118100814A (en) | 2024-02-29 | 2024-02-29 | Variable gain amplifier and communication device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410227297.9A CN118100814A (en) | 2024-02-29 | 2024-02-29 | Variable gain amplifier and communication device |
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| CN118100814A true CN118100814A (en) | 2024-05-28 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202410227297.9A Pending CN118100814A (en) | 2024-02-29 | 2024-02-29 | Variable gain amplifier and communication device |
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| CN (1) | CN118100814A (en) |
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- 2024-02-29 CN CN202410227297.9A patent/CN118100814A/en active Pending
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