CN219227560U - Self-bias negative feedback circuit - Google Patents
Self-bias negative feedback circuit Download PDFInfo
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- CN219227560U CN219227560U CN202223517966.1U CN202223517966U CN219227560U CN 219227560 U CN219227560 U CN 219227560U CN 202223517966 U CN202223517966 U CN 202223517966U CN 219227560 U CN219227560 U CN 219227560U
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Abstract
The utility model relates to a self-bias negative feedback circuit, which relates to the technical field of radio frequency electronics and comprises a first-stage circuit and a second-stage circuit, wherein the first-stage circuit is a self-bias circuit, and the second-stage circuit is a voltage division type bias circuit; the output end of the noise matching circuit is connected with the input end of the self-bias circuit, the bias circuit is connected with the voltage division type bias circuit in parallel, and the output end of the voltage division type bias circuit is connected with the input end of the power matching circuit. The utility model can realize large signal amplitude limiting protection and low noise amplification of 4000W of the peak power of the receiving channel. The device overcomes the defects of the prior art, and the limiter is started at a high speed through bias feedback, so that the device is prevented from being burnt out instantly with high power, electromagnetic explosion and electromagnetic surge can be prevented, a receiver is protected, and meanwhile, in order to better match a front-stage circuit and a rear-stage circuit, a matching circuit is designed at an input end and an output end.
Description
Technical Field
The utility model relates to the technical field of radio frequency electronics, in particular to a self-bias negative feedback circuit.
Background
Along with the development of communication technology, the power of a power module is larger and larger, the power requirement of a circulator shared by receiving and transmitting is higher and the power bearing capacity of the circulator is higher and higher, so that corresponding signal transmitting and receiving components have an increasingly important role in the communication field, in particular to the high-frequency receiving field, such as an X-band product, how to provide a flexible and reliable high-frequency receiving component has an important significance on the receiving and transmitting operation of signals, and the self-bias negative feedback analysis in low-noise amplification is also important to consider.
Disclosure of Invention
The utility model aims to overcome the defects of the prior art, provides a self-bias negative feedback circuit, overcomes the defects of the prior art, and solves the problem that a limiter is started at a high speed through bias feedback so as to avoid instant high-power burning of devices.
The aim of the utility model is achieved by the following technical scheme: the self-bias negative feedback circuit comprises a first-stage circuit and a second-stage circuit, wherein the first-stage circuit is a self-bias circuit, and the second-stage circuit is a voltage-division type bias circuit; the output end of the noise matching circuit is connected with the input end of the self-bias circuit, the bias circuit is connected with the voltage division type bias circuit in parallel, and the output end of the voltage division type bias circuit is connected with the input end of the power matching circuit.
The self-bias circuit includes a transistor M 1 Resistance R 1 Resistance R F And resistance R L1 Constructing; the output end of the noise matching circuit is connected with the transistor M 1 Base connection of transistor M 1 The emitter of (2) is grounded; the resistor R 1 And resistance R F Series connected resistors R F And transistor M 1 Collector connection of resistor R 1 Grounding; the resistor R L1 Is connected to one end of the transistor M 1 The other end is connected with the voltage division type bias circuit。
The voltage division type bias circuit comprises a transistor M 2 Resistance R E Capacitance C E And resistance R L2 Constructing; the transistor M 2 Base of (d) and said transistor M 1 Collector connection of said resistor R E And capacitor C E One end connected in parallel with the transistor M 2 The other end is grounded; the resistor R L2 Is connected to one end of the transistor M 2 Is connected with the collector of the resistor R at the other end L1 Connecting; the transistor M 2 The collector of which is connected to the input of the power matching circuit.
The self-bias negative feedback circuit also comprises an inductive load inductance L 1 The inductive load inductance L 1 And the resistance R L2 And a connection for canceling the influence of the parasitic capacitance on the impedance, thereby improving the matching of the circuit.
The input matching circuit is connected with the input end of the self-bias negative feedback circuit, and the output end of the self-bias negative feedback circuit is connected with the output matching circuit so as to better match the front-stage circuit and the rear-stage circuit; the input matching circuit is a noise matching circuit, and the output matching circuit is a power matching circuit.
The utility model has the following advantages: a self-bias negative feedback circuit can realize large-signal amplitude limiting protection and low-noise amplification of 4000W of peak power of a receiving channel. The device overcomes the defects of the prior art, and the limiter is started at a high speed through bias feedback, so that the device is prevented from being burnt out instantly with high power, electromagnetic explosion and electromagnetic surge can be prevented, a receiver is protected, and meanwhile, in order to better match a front-stage circuit and a rear-stage circuit, a matching circuit is designed at an input end and an output end.
Drawings
FIG. 1 is a schematic circuit diagram of the present utility model;
FIG. 2 is a circuit diagram of a small signal model of a self-biasing negative feedback circuit;
FIG. 3 is a circuit diagram of a high frequency small signal model of the first stage circuit;
FIG. 4 is a circuit diagram of a high frequency small signal model of the second stage circuit;
FIG. 5 is a diagram of a small signal circuit after the miller equivalent of the first stage circuit;
FIG. 6 is a diagram of a small signal circuit after Miller equivalence of the second stage circuit;
FIG. 7 is a graph I of the impedance change of the circuit in the Simth circle;
FIG. 8 is a second graph of the impedance change of the circuit in the Simth circle;
FIG. 9 is a third graph of the impedance change of the circuit in the Simth circle graph;
FIG. 10 is an input matching circuit;
fig. 11 is an output matching circuit.
Detailed Description
For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, which are generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Accordingly, the following detailed description of the embodiments of the present application, provided in connection with the accompanying drawings, is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present application without making any inventive effort, are intended to be within the scope of the present application. The utility model is further described below with reference to the accompanying drawings.
As shown in fig. 1, the present utility model specifically relates to a self-bias negative feedback circuit, which comprises a first stage circuit and a second stage circuit, wherein the first stage circuit is a self-bias circuit, and the second stage circuit is a voltage division type bias circuit; the output end of the noise matching circuit is connected with the input end of the self-bias circuit, the bias circuit is connected with the voltage division type bias circuit in parallel, and the output end of the voltage division type bias circuit is connected with the input end of the power matching circuit.
The self-bias circuit includes a transistor M 1 Resistance R 1 Resistance R F And resistance R L1 Constructing; the output end of the noise matching circuit is connected with the transistor M 1 Base connection of transistor M 1 The emitter of (2) is grounded; the resistor R 1 And resistance R F Series connected resistors R F And transistor M 1 Collector connection of resistor R 1 Grounding; the resistor R L1 Is connected to one end of the transistor M 1 The other end of the voltage division type bias circuit is connected with the collector electrode of the voltage division type bias circuit.
The voltage division type bias circuit comprises a transistor M 2 Resistance R E Capacitance C E And resistance R L2 Constructing; the transistor M 2 Base of (d) and said transistor M 1 Collector connection of said resistor R E And capacitor C E One end connected in parallel with the transistor M 2 The other end is grounded; the resistor R L2 Is connected to one end of the transistor M 2 Is connected with the collector of the resistor R at the other end L1 Connecting; the transistor M 2 The collector of which is connected to the input of the power matching circuit.
In which transistor M 1 The source-drain voltages of (2) are:
V DS1 ＝V DD -I DS1 R L1 (1)
transistor M 1 The gate voltage of (2) is:
transistor M 2 The gate voltage of (2) is:
V GS2 ＝V DS1 ＝V DD -I DS1 R L1 (3)
transistor M 2 The source-drain voltages of (2) are:
V DS2 ＝V DD -I DS2 (R L2 +R E ) (4)
as can be seen from the formulas (1), (2), (3) and (4), the resistance R is adjusted F Resistance R L1 And resistance R 1 Is of a size such that transistor M 1 Work in a required working state. Similarly, the transistor M2 is operated by the resistor R 1 、R F 、R L1 、R E 、R L2 And (5) determining.
As shown in fig. 2, to further analyze the reactance characteristics of the self-biasing negative feedback circuit, a low frequency small signal model of the circuit is analyzed;
wherein D is 1 The KCL equation for a point is:
the above formula can be obtained:
and:
from (6) and (7), the equivalent input impedance R of the self-biased negative feedback circuit can be obtained in The method comprises the following steps:
while the low frequency output impedance R of the circuit out The method comprises the following steps:
R out ＝R L2 +R E (9)
as can be seen from equation (8), the equivalent input impedance of the circuit is equal to that of transistor M alone, regardless of parasitic effects 1 G of (2) m Resistance R 1 Resistance R F Resistance R L1 In relation, so that the input impedance of the circuit at low frequencies can be made close to 50 ohms by selecting appropriate parameters; from equation (9), the equivalent output impedance and resistance R of the circuit L2 And resistance R E In relation, selecting the appropriate parametersThe output impedance of the circuit at low frequencies can be made close to 50 ohms.
However, the above analysis is only directed to the case of lower frequencies, and as the frequencies increase, the parasitic effects of the transistors become more and more obvious, and in order to analyze the influence of these parasitic effects on the circuit impedance, a high-frequency small-signal model is built for the first stage circuit and the second stage circuit, as shown in fig. 3 and fig. 4, respectively.
The equivalent input impedance of the first stage circuit is as follows:
the equivalent output impedance of the second stage is:
z in (11) L The method comprises the following steps:
it can be seen that, because of the parasitic capacitance relationship, the input impedance and the output impedance are both related to the frequency, and as the frequency increases, the input impedance and the output impedance both show capacitive properties, and in order to more intuitively represent the characteristics of the input impedance and the output impedance, the miller equivalent is performed on fig. 3 and fig. 4, and the equivalent small signal circuit diagrams are shown in fig. 5 and fig. 6:
c 'in FIG. 5' gd1 、C" gd1 、R′ F 、R" F Capacitance and resistance after miller equivalence; c 'in FIG. 6' gd2 And C' gd2 Is the capacitance after miller equivalence. It can be seen from fig. 5 that the input impedance can be equivalently in the form of a resistive shunt capacitance, and from fig. 6 that the output impedance can likewise be equivalently in the form of a reactive element shunt capacitance. Thus, the impedance of the self-biasing negative feedback circuit exhibits capacitance at high frequencies.
When the capacitor C E ＝6pFWhen the input impedance and the output impedance of the circuit are simulated, the simulation results are shown in fig. 7, the input matching and the output matching of the self-bias negative feedback circuit do not meet the design index, the low-frequency input impedance of the circuit is lower, and the impedance of the circuit presents capacitance along with the increase of frequency because of high-frequency parasitism. In order to increase the low frequency input impedance of the circuit, the resistance R is increased by the proper increase 1 And R is F And properly adjust the resistance R L1 Thereby changing the impedance of the self-biasing negative feedback circuit, and finally obtaining the impedance simulation result of the circuit as shown in fig. 8. .
As can be seen from the simulation results of FIG. 8, the low-frequency input impedance and the output impedance of the self-bias negative feedback circuit are very close to 50Ω, but the influence of frequency on the impedance is great, and in order to reduce the influence of frequency on the impedance, an inductive load inductance L is added into the self-bias negative feedback circuit 1 The inductance L 1 The influence of parasitic capacitance on impedance can be counteracted to a certain extent, so that the matching of the circuit is improved. Adding a suitable inductance L 1 The simulation results of (2) are shown in fig. 9.
As can be seen from the simulation result of FIG. 9, the impedance influence of the frequency in the bandwidth on the self-bias negative feedback circuit is reduced, but the high-frequency impedance matching of the self-bias negative feedback circuit is still poor, so that the matching circuit is added at the input end and the output end of the self-bias negative feedback circuit, thereby optimizing the high-frequency impedance matching of the broadband low-noise amplifier.
As shown in fig. 10, the input matching circuit is composed of a capacitor CM1 and an inductor LM1, and forms a low-pass filter structure with the input equivalent capacitance of the amplifier. An LC filter equivalent to a termination resistor, with impedance matching the input in the passband, and the stopband reflects the signal back to the input. The input good matching can be obtained only by including the working bandwidth of the amplifier in the pass band of the filter, wherein the input impedance and the output impedance of the filter are respectively the input impedance (50Ω) of the amplifier and the equivalent input resistance of the amplifier.
As shown in fig. 11, the output matching circuit is similar to the input matching except that the input impedance of the filter is different, the input impedance of the output matching circuit is the amplifier output impedance, and the output impedance of the matching circuit is the amplifier output impedance (50Ω). The input capacitance and the output capacitance are only used for preventing the direct current of the input and output ports from affecting the working point of the amplifier, and do not participate in impedance matching.
The foregoing is merely a preferred embodiment of the utility model, and it is to be understood that the utility model is not limited to the form disclosed herein but is not to be construed as excluding other embodiments, but is capable of numerous other combinations, modifications and environments and is capable of modifications within the scope of the inventive concept, either as taught or as a matter of routine skill or knowledge in the relevant art. And that modifications and variations which do not depart from the spirit and scope of the utility model are intended to be within the scope of the appended claims.
Claims (5)
1. A self-biasing negative feedback circuit, characterized by: the circuit comprises a first-stage circuit and a second-stage circuit, wherein the first-stage circuit is a self-biasing circuit, and the second-stage circuit is a voltage-dividing biasing circuit; the output end of the noise matching circuit is connected with the input end of the self-bias circuit, the bias circuit is connected with the voltage division type bias circuit in parallel, and the output end of the voltage division type bias circuit is connected with the input end of the power matching circuit.
2. A self-biasing negative feedback circuit as defined in claim 1, wherein: the self-bias circuit includes a transistor
Resistance->
Resistance->
And resistance->
Constructing; the output of the noise matching circuit is connected with the transistor +.>
Base connection of transistor->
The emitter of (2) is grounded; said resistance->
And resistance->
Series, resistance after series->
Transistor->
Collector connection, resistance->
Grounding; said resistance->
Said transistor->
The other end of the voltage division type bias circuit is connected with the collector electrode of the voltage division type bias circuit.
3. A self-biasing negative feedback circuit as defined in claim 2, wherein: the voltage division type bias circuit comprises a transistor
Resistance->
Capacitance->
And resistance->
Constructing; said transistor->
Is +.>
Is connected to the collector of the resistor +.>
And capacitance->
One end connected in parallel with the transistor +.>
The other end is grounded; said resistance->
Is +.>
The other end is connected to the collector of the resistor +.>
Connecting; said transistor->
The collector of which is connected to the input of the power matching circuit.
4. A self-biasing negative feedback circuit as defined in claim 3, wherein: the self-bias negative feedback circuit also comprises an inductive load inductance
Said inductive load inductance->
Is +_with the resistance>
And a connection for canceling the influence of the parasitic capacitance on the impedance, thereby improving the matching of the circuit.
5. A self-biasing negative feedback circuit as claimed in any one of claims 1-4, wherein: the input matching circuit is connected with the input end of the self-bias negative feedback circuit, and the output end of the self-bias negative feedback circuit is connected with the output matching circuit so as to better match the front-stage circuit and the rear-stage circuit; the input matching circuit is a noise matching circuit, and the output matching circuit is a power matching circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202223517966.1U CN219227560U (en) | 2022-12-28 | 2022-12-28 | Self-bias negative feedback circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202223517966.1U CN219227560U (en) | 2022-12-28 | 2022-12-28 | Self-bias negative feedback circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN219227560U true CN219227560U (en) | 2023-06-20 |
Family
ID=86748901
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202223517966.1U Active CN219227560U (en) | 2022-12-28 | 2022-12-28 | Self-bias negative feedback circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN219227560U (en) |
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2022
- 2022-12-28 CN CN202223517966.1U patent/CN219227560U/en active Active
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