Low-phase-noise-width tuning voltage-controlled oscillator

Abstract

The invention discloses a low-phase-noise wide-tuning voltage-controlled oscillator, which comprises an oscillation module, a bias module and an output buffer module, and is characterized in that the oscillation module is used for generating a high-frequency oscillation signal and realizing a wide frequency tuning range and low-phase noise of the voltage-controlled oscillator; the bias module is used for providing stable bias current so as to ensure that the oscillation module operates at an optimal working point; and the output buffer module is used for realizing frequency tuning range expansion for the high-frequency oscillation signal generated by the oscillation module. The wide frequency tuning range of an existing voltage-controlled oscillator can be expanded, and low phase noise is achieved.

Description

Technical Field

[0001] The present application relates to an oscillator, and in particular to a low phase noise wide-tuned voltage-controlled oscillator. Background Art

[0002] In recent years, the rapid development of wireless communication systems has stimulated the research and design of low-cost, high-performance, and miniaturized RF integrated circuits. Due to the current shortage of spectrum resources in wireless communication systems, in contrast, the spectrum resources in the millimeter wave band are abundant and have higher anti-interference capabilities. At present, the voltage-controlled oscillator (VCO) is developing towards high frequency, wide tuning, and low phase noise.

[0003] High operating frequency and wide tuning range have become the most mainstream research directions of voltage-controlled oscillators, but it is difficult for voltage-controlled oscillators with a wide tuning range to achieve low phase noise, especially the phase noise performance at high frequencies, which has a great impact on the overall performance of the voltage-controlled oscillator. The output frequency tuning range of traditional voltage-controlled oscillators in the high frequency band is about 10%, so it is necessary to design a voltage-controlled oscillator with low phase noise and a wide frequency tuning range. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the main purpose of the present application is to provide a low phase noise wide tuning voltage controlled oscillator, aiming to overcome the problem of limited output frequency tuning range of the existing voltage controlled oscillator in the high frequency band.

[0005] To achieve the above objectives, this application provides the following technical solutions:

[0006] A low phase noise wide tuning voltage controlled oscillator, the voltage controlled oscillator comprising: an oscillation module, a bias module and an output buffer module, wherein the oscillation module is used to generate a high frequency oscillation signal and to achieve a wide frequency tuning range and low phase noise of the voltage controlled oscillator; the bias module is used to provide a stable bias current to ensure that the oscillation module operates at an optimal operating point; the output buffer module is used to achieve frequency tuning range expansion for the high frequency oscillation signal generated by the oscillation module.

[0007] Optionally, the oscillation module includes: an oscillation branch, a bias current supply branch, a frequency tuning branch and an output coupling and buffer branch, wherein the oscillation branch is used to generate a high-frequency oscillation signal; the bias current supply branch is used to provide a stable bias current for the oscillation branch; the frequency tuning branch is used to adjust the oscillation frequency of the oscillation branch by changing the tuning voltage to achieve a frequency tuning function; the output coupling and buffer branch is used to transmit the high-frequency oscillation signal generated by the oscillation branch to the output buffer module.

[0008] Optionally, the oscillation branch includes: a first HBT transistor, a seventh inductor, a third inductor and a first capacitor, wherein the base of the first HBT transistor is connected to the first end of the seventh inductor to form a first node, the collector of the first HBT transistor is connected to the output buffer module, the emitter of the first HBT transistor is connected to the first end of the third inductor to form a second node, the first end of the first capacitor is connected to the first node, and the second end of the first capacitor is connected to the second node.

[0009] Optionally, the bias current supply branch includes: a fifth inductor and a fourth inductor, wherein the first end of the fourth inductor is connected to the second end of the third inductor to form a fifth node, the first end of the fifth inductor is connected to the second end of the sixth inductor to form a sixth node, and the second end of the fifth inductor is connected to the second end of the fourth inductor and is also connected to the bias module.

[0010] Optionally, the frequency tuning branch includes: a first varactor and a second varactor, wherein the first end of the first varactor is connected to the fifth node, the first end of the second varactor is connected to the sixth node, and the second end of the first varactor is connected to the second end of the second varactor and is simultaneously connected to the first input port.

[0011] Optionally, the output coupling and buffer branch includes: a fourth HBT transistor, a second capacitor, an eighth inductor and a sixth inductor, wherein the base of the fourth HBT transistor is connected to the first end of the eighth inductor to form a third node, the second end of the eighth inductor is connected to the second end of the seventh inductor and is simultaneously connected to a third input port, the collector of the fourth HBT transistor is connected to the output buffer module, the emitter of the fourth HBT transistor is connected to the first end of the sixth inductor to form a fourth node, the first end of the second capacitor is connected to the third node, and the second end of the second capacitor is connected to the fourth node.

[0012] Optionally, the bias module includes: a current source branch, a bias voltage adjustment branch and a stable operating point setting branch, wherein the current source branch is used to provide a stable DC bias current; the bias voltage adjustment branch is used to adjust and provide a suitable bias current to the oscillation module; and the stable operating point setting branch is used to provide stable DC working conditions for the bias voltage adjustment branch.

[0013] Optionally, the current source branch includes a seventh HBT transistor and a second resistor, wherein the emitter of the seventh HBT transistor is connected to the first end of the second resistor, the second end of the second resistor is connected to the second ground terminal, the base of the seventh HBT transistor T7 is connected to the stable operating point setting branch, and the collector of the seventh HBT transistor is connected to the connection between the second end of the fifth inductor and the second end of the fourth inductor.

[0014] Optionally, the bias voltage adjustment branch includes a fifth HBT transistor, the collector of the fifth HBT transistor is connected to the oscillation module, the emitter of the fifth HBT transistor is connected to the stable operating point setting branch, and the collector and base of the fifth HBT transistor are simultaneously connected to the bias voltage through a fourth input port.

[0015] Optionally, the stable operating point setting branch includes a sixth HBT transistor and a first resistor, wherein the emitter of the sixth HBT transistor is connected to the first end of the first resistor, the second end of the first resistor is connected to the first ground terminal, the collector of the sixth HBT transistor is connected to the emitter of the fifth HBT transistor, and the collector of the sixth HBT transistor is also connected to its base.

[0016] Optionally, the output buffer module includes: a first inductor, a second inductor, a second HBT transistor and a third HBT transistor, wherein the collector of the second HBT transistor is connected to the first end of the first inductor and is connected to the first output port at the same time, the second end of the first inductor is connected to a DC voltage through a fifth input port, and the emitter of the second HBT transistor is connected to the collector of the first HBT transistor; the collector of the third HBT transistor is connected to the first end of the second inductor and is connected to the second output port at the same time, the second end of the second inductor is connected to a DC voltage through the fifth input port, the emitter of the third HBT transistor is connected to the collector of the fourth HBT transistor, the base of the third HBT transistor is connected to the base of the second HBT transistor and is connected to a tuning voltage through the second input port at the same time.

[0017] The present application can bring the following beneficial effects: The present application achieves a wide frequency tuning range and low phase noise performance by optimizing the design of the oscillation branch, bias module and output buffer module. Stable DC operating point setting and efficient impedance matching ensure high stability and reliability of the system, while flexible tuning voltage control further enhances the flexibility of frequency tuning. The overall design is compact and cost-effective, suitable for millimeter wave band applications in high-performance communication systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1This is a schematic diagram of the circuit structure of a low phase noise wide tuned voltage controlled oscillator provided by an embodiment of the present application;

[0019] Figure 2 It is a schematic diagram of a half-side equivalent circuit structure of a low phase noise wide tuned voltage controlled oscillator provided by another embodiment of the present application;

[0020] Figure 3 yes Figure 1 A schematic diagram of test results showing that the frequency of the output signal of the voltage-controlled oscillator varies with the tuning voltage;

[0021] Figure 4 yes Figure 1 The diagram is a test result diagram of the phase noise of the output signal of the voltage-controlled oscillator varying with frequency. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0024] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0026] Figure 1 FIG. 1 is a schematic diagram of a circuit structure of a low phase noise wide tuned voltage controlled oscillator according to an embodiment of the present application. Figure 1 As shown, the voltage-controlled oscillator includes: an oscillation module 100, a bias module 200 and an output buffer module 300, wherein the oscillation module 100 is used to generate a high-frequency oscillation signal and to achieve a wide frequency tuning range and low phase noise of the voltage-controlled oscillator; the bias module 200 is used to provide a stable bias current to ensure that the oscillation module operates at an optimal operating point; and the output buffer module 300 is used to achieve a frequency tuning range extension for the high-frequency oscillation signal generated by the oscillation module.

[0027] The voltage-controlled oscillator proposed in the present application can operate in a wider frequency range while maintaining a lower phase noise level through the close cooperation of the oscillation module 100, the bias module 200 and the output buffer module 300. The voltage-controlled oscillator proposed in the present application is particularly suitable for millimeter-wave frequency band applications in high-performance communication systems, and can meet the requirements of modern wireless communication systems for high operating frequency, wide tuning range and low phase noise performance.

[0028] In another exemplary embodiment, the oscillation module 100 includes: an oscillation branch 101, a bias current supply branch 102, a frequency tuning branch 103 and an output coupling and buffer branch 104, wherein the oscillation branch 101 is used to generate a high-frequency oscillation signal; the bias current supply branch 102 is used to provide a stable bias current for the oscillation branch 101; the frequency tuning branch 103 is used to adjust the oscillation frequency of the oscillation branch 101 by changing the tuning voltage to achieve a frequency tuning function; the output coupling and buffer branch 104 is used to transmit the high-frequency oscillation signal generated by the oscillation branch 101 to the output buffer module 300.

[0029] In another exemplary embodiment, the oscillation branch 101 includes a first HBT transistor T1, a seventh inductor L B1 , the third inductor L E1 , the first capacitor C F1 , wherein the base of the first HBT transistor T1 and the seventh inductor L B1 The first end of the first HBT transistor T1 is connected to form a first node N1, the collector of the first HBT transistor T1 is connected to the output buffer module 300, and the emitter of the first HBT transistor T1 is connected to the third inductor L E1 The first end of the first capacitor C is connected to form a second node N2. F1 The first end of the first capacitor C F1 The second end of is connected to the second node N2.

[0030] In this embodiment, the first capacitor C F1 A coupling path is provided between the first node N1 and the second node N2, so that the AC signal from the base to the emitter of the first HBT transistor T1 can flow smoothly while blocking the DC component. F1 With the seventh inductor L B1 And the third inductor L E1 Together they form an LC resonant circuit, which plays a key role in determining the oscillation frequency. When the power is turned on, due to the existence of the bias condition, the first HBT transistor T1 starts to work. At this time, in the LC resonant circuit, if the Barkhausen criterion is met (i.e., the loop gain is greater than or equal to 1 and the phase difference is 0 degrees or an integer multiple of 360 degrees), oscillation will occur spontaneously at a certain frequency. The oscillation branch 101 utilizes the characteristics of the LC resonant circuit and the HBT transistor to achieve stable high-frequency oscillation, and controls the oscillation frequency through external adjustable parameters such as the tuning voltage VT1 and the common base voltage VT2, ensuring low phase noise performance within a wide tuning range.

[0031] In another exemplary embodiment, the bias current supply branch 102 includes a fifth inductor L E3 and the fourth inductor L E2 , wherein the fourth inductor L E2 The first end of the third inductor L E1 The second end of the fifth inductor L is connected to form a fifth node N5. E3 The first end of the sixth inductor L E4 The second end of the fifth inductor L is connected to form a sixth node N6. E3 The second end of the fourth inductor L E2 The second end is connected to the bias module 200 at the same time.

[0032] In this embodiment, the fifth inductor L E3 The second end of the fourth inductor L E2 The second end of the fifth inductor L is connected to the bias module 200 at the same time. This connection allows the bias current to flow from the bias module 200 into and through the fifth inductor L E3 The second end of the fourth inductor L E2 is transmitted to the oscillation branch 101. E3 With the fourth inductor L E2 The fifth inductor L has low impedance characteristics for DC components, so they will not hinder the flow of bias current; and for AC signals (i.e. oscillating signals), the fifth inductor L E3 The second end of the fourth inductor L E2 A high impedance is provided, thereby effectively isolating the bias module 200 from the oscillation module 100 and preventing the bias current from interfering with the oscillation frequency.

[0033] In another exemplary embodiment, the frequency tuning branch 103 includes a first varactor C VAR1 and the second varactor C VAR2 , wherein the first varactor C VAR1 The first end of the second variable capacitance tube C VAR2 The first end of the first variable capacitance tube C VAR1 The second end of the second varactor C VAR2 The second end is connected to and simultaneously connected to the first input port V T1 .

[0034] In this embodiment, in the oscillation circuit, the first varactor C VAR1 and the second varactor C VAR2 Together with the inductor, an LC resonant circuit is formed. Since the capacitance of the varactor changes with the change of the tuning voltage VT1, the total capacitance of the oscillation circuit can be dynamically adjusted by changing the tuning voltage VT1, thereby changing the LC resonant frequency. This feature allows the user to control the output frequency of the VCO by adjusting the external tuning voltage VT1, thereby achieving a frequency tuning function in a wide range. In the frequency tuning branch 103, the first varactor C VAR1 and the second varactor C VAR2 The capacitance value of the oscillation circuit is adjusted according to the change of the tuning voltage VT1, so that the high-frequency oscillation frequency generated by the oscillation branch 101 can be accurately controlled.

[0035] In another exemplary embodiment, the output coupling and buffer branch 104 includes a fourth HBT transistor T4, a second capacitor CF2 、The eighth inductor L B2 and the sixth inductor L E4 , wherein the base of the fourth HBT transistor T4 and the eighth inductor L B2 The first end of the eighth inductor L is connected to form a third node N3. B2 The second end of the seventh inductor L B1 The second end is connected to and simultaneously connected to the third input port V B1 The collector of the fourth HBT transistor T4 is connected to the output buffer module 300, and the emitter of the fourth HBT transistor T4 is connected to the sixth inductor L E4 The first end of the second capacitor C F2 The first end of the second capacitor C F2 The second end of is connected to the fourth node N4.

[0036] In this embodiment, the eighth inductor L B2 The second end of the seventh inductor L B1 The second end is connected to the third input port V B1 This design allows the bias voltage V B1 Through the eighth inductor L B2 The second end of the seventh inductor L B1 Provide a DC bias condition for the fourth HBT transistor T4 to ensure that it works in a suitable state. For AC signals, the eighth inductor L B2 The second end of the seventh inductor L B1 The output coupling and buffering branch 104 presents high impedance to the high frequency oscillation signal, and can effectively isolate the DC bias path and the AC oscillation path, thereby preventing the bias current from interfering with the oscillation frequency. F2 、The eighth inductor L B 2 and the sixth inductor L E4 The coordinated work of the second capacitor C realizes the effective transmission and amplification of the oscillation signal and provides the necessary impedance matching. F2 The fourth HBT transistor T4 is used as a buffer amplifier to enhance the signal strength and can control the output frequency by adjusting the common base voltage VT2. E4 The overall design not only expands the frequency tuning range, but also improves the stability and reliability of the system, ensuring high performance output with low phase noise.

[0037] In summary, in the oscillation module 100, the first HBT transistor T1 and the fourth HBT transistor T4 form an oscillation circuit with a plurality of inductors and capacitors to generate a high-frequency signal. T1 The tuning voltage can change the first varactor C VAR1 and the second varactor C VAR2 The capacitance value of the first varactor C VAR1 and the second varactor C VAR2 The change of the capacitance value will affect the equivalent capacitance of the oscillation circuit, thereby adjusting the oscillation frequency. In addition, by adjusting the second input port V T2 The common base voltage can change the working state of the first HBT transistor T1 and the fourth HBT transistor T4, so that the first HBT transistor T1 and the fourth HBT transistor T4 gradually transition from the forward amplification region to the saturation region, wherein in the forward amplification region, the parasitic capacitance of the first HBT transistor T1 and the fourth HBT transistor T4 is large, limiting the frequency tuning range; while in the saturation region, the parasitic capacitance of the first HBT transistor T1 and the fourth HBT transistor T4 is reduced, thereby expanding the frequency tuning range.

[0038] In another exemplary embodiment, the bias module 200 includes: a current source branch 201, a bias voltage adjustment branch 202 and a stable operating point setting branch 203, wherein the current source branch 201 is used to provide a stable DC bias current; the bias voltage adjustment branch 202 is used to adjust and provide a suitable bias current to the oscillation module 100; and the stable operating point setting branch 203 is used to provide a stable DC working condition for the bias voltage adjustment branch 202.

[0039] In another exemplary embodiment, the current source branch 201 includes a seventh HBT transistor T7 and a second resistor R2, wherein the emitter of the seventh HBT transistor T7 is connected to the first end of the second resistor R2, the second end of the second resistor R2 is connected to the second ground terminal GND2, the base of the seventh HBT transistor T7 is connected to the stable operating point setting branch 203, and the collector of the seventh HBT transistor T7 is connected to the fifth inductor L E3 The second end of the fourth inductor L E2 The second end of the connection is connected.

[0040] In this embodiment, the emitter of the seventh HBT transistor T7 is grounded through the second resistor R2, so that the seventh HBT transistor T7 can provide a relatively constant current output. When the base-emitter voltage (VBE) of the seventh HBT transistor T7 remains unchanged, the current flowing through the seventh HBT transistor T7 hardly changes with the change of the power supply voltage or temperature, thereby forming a stable current source. In addition, the base of the seventh HBT transistor T7 is connected to the stable operating point setting branch 203, and the control signal provided by the branch can accurately adjust the working state of the seventh HBT transistor T7. The stable operating point setting branch 203 ensures that the seventh HBT transistor T7 can operate at the optimal operating point, and can maintain a stable current output even in the face of temperature fluctuations or other environmental factors. It is worth noting that the second resistor R2 not only provides an emitter grounding path for the seventh HBT transistor T7, but also participates in a simple negative feedback mechanism. When the collector current of the seventh HBT transistor T7 attempts to increase, the voltage drop across the second resistor R2 will also increase, which in turn will reduce the base-emitter voltage of the seventh HBT transistor T7 and inhibit the increase of current. On the contrary, if the current attempts to decrease, the voltage drop across the second resistor R2 decreases, VBE increases, thereby compensating for the decrease in current. This feedback mechanism helps to maintain the stability of the current.

[0041] In another exemplary embodiment, the bias voltage adjustment branch 202 includes a fifth HBT transistor T5, the collector of the fifth HBT transistor T5 is connected to the oscillation module 100, the emitter of the fifth HBT transistor T5 is connected to the stable operating point setting branch 203, and the collector and base of the fifth HBT transistor T5 are simultaneously connected through the fourth input port V B2 Apply bias voltage.

[0042] In this embodiment, the bias voltage connected through the fourth input port VB2 is directly applied to the base and collector of the fifth HBT transistor T5. This bias voltage determines the working state (such as the degree of conduction) of the fifth HBT transistor T5, thereby affecting the bias current provided by it. By changing the voltage value of VB2, the bias condition of the fifth HBT transistor T5 can be dynamically adjusted, thereby optimizing the working performance of the oscillation module 100. In addition, the collector of the fifth HBT transistor T5 is connected to the oscillation module 100, and the stable bias current provided by the current source branch 201 is passed to the key components in the oscillation module. In this way, the bias voltage adjustment branch 202 not only provides the necessary DC bias conditions for the oscillation module 100, but also ensures that these conditions can be flexibly adjusted as needed to adapt to different operating requirements or environmental changes.

[0043] In another exemplary embodiment, the stable operating point setting branch 203 includes a sixth HBT transistor T6 and a first resistor R1, wherein the emitter of the sixth HBT transistor T6 is connected to the first end of the first resistor R1, the second end of the first resistor R1 is connected to the first ground terminal GND1, the collector of the sixth HBT transistor T6 is connected to the emitter of the fifth HBT transistor T5, and the collector of the sixth HBT transistor T6 is also connected to its base.

[0044] In this embodiment, the base and collector of the sixth HBT transistor T6 are connected to form a diode connection mode. Under this configuration, the sixth HBT transistor T6 can always be in a saturated state, that is, the voltage difference (VCE) between its collector and emitter is very small. This state ensures that the sixth HBT transistor T6 can provide a relatively constant voltage drop without being affected by temperature or power supply voltage changes. In addition, the emitter of the sixth HBT transistor T6 is grounded through the first resistor R1. The function of the first resistor R1 is to provide a fixed current path for the sixth HBT transistor T6, thereby determining the emitter voltage of the sixth HBT transistor T6. Since the sixth HBT transistor T6 is in a saturated state, this emitter voltage will remain relatively stable, thereby providing a stable bias condition for the fifth HBT transistor T5. It should be noted that the first resistor R1 not only provides an emitter grounding path for the sixth HBT transistor T6, but also participates in a simple negative feedback mechanism. If the collector current of the sixth HBT transistor T6 attempts to increase, the voltage drop across the first resistor R1 will also increase, which in turn will reduce the emitter voltage of the sixth HBT transistor T6 and suppress the increase of current. On the contrary, if the current attempts to decrease, the voltage drop across the first resistor R1 decreases, and the emitter voltage increases, thereby compensating for the decrease in current. This feedback mechanism helps to maintain the stability of the current, thereby further enhancing the stability of the working point of the fifth HBT transistor T5.

[0045] In the above-mentioned bias module 200, the emitter of the seventh HBT transistor T7 is connected to the first ground terminal GND1 through the second resistor R2, the base is connected to the base of the sixth HBT transistor T6, and the collector is connected to the fifth inductor L E3 and the fourth inductor L E2The common terminal of the seventh HBT transistor T7 is designed so that the seventh HBT transistor T7 can be used as a current source to provide a stable current for the voltage-controlled oscillator, thereby helping to improve the stability of the oscillator and reduce phase noise. The emitter of the sixth HBT transistor T6 is connected to the second terminal GND2 through the first resistor R1, and the collector is connected to the emitter of the fifth HBT transistor T5. At the same time, the base and collector of the sixth HBT transistor T6 are connected to form a diode connection mode. This connection mode can ensure that the sixth HBT transistor T6 is in a saturated state, thereby stabilizing the operating point of the fifth HBT transistor T5. The base and collector of the fifth HBT transistor T5 are simultaneously connected through the fourth input port V B2 By connecting the bias voltage, it can be ensured that the fifth HBT transistor T5 can work under appropriate bias conditions, thereby providing the necessary bias current for the voltage-controlled oscillator to ensure the normal operation of the voltage-controlled oscillator. Therefore, the bias module with the above structure can not only provide a stable bias condition for the voltage-controlled oscillator, but also effectively improve the performance indicators of the oscillator, such as frequency stability, phase noise, etc., so as to meet the needs of modern communication systems for high-performance oscillators.

[0046] In another exemplary embodiment, the output buffer module 300 includes: a first inductor L C1 , the second inductor L C2 , a second HBT transistor T2 and a third HBT transistor T3, wherein the collector of the second HBT transistor T2 is connected to the first inductor L C1 The first end is connected to and simultaneously connected to the first output port V + , the first inductor L C1 The second end passes through the fifth input port V DD The DC voltage is connected, the emitter of the second HBT transistor T2 is connected to the collector of the first HBT transistor T1; the collector of the third HBT transistor T3 is connected to the second inductor L C2 The first end of the second inductor L is connected to the second output port V- at the same time. C2 The second end passes through the fifth input port V DD The DC voltage is connected, the emitter of the third HBT transistor T3 is connected to the collector of the fourth HBT transistor T4, the base of the third HBT transistor T3 is connected to the base of the second HBT transistor T2 and at the same time through the second input port V T2 Connect the tuning voltage.

[0047] In this embodiment, the collector of the second HBT transistor T2 and the first inductor L C1 At the same time, connect to the first output port V +, and the collector of the third HBT transistor T3 and the second inductor L C2 At the same time, the second output port V- is connected, wherein the first inductor L C1 and the second inductor L C2 The function of the first inductor L is to provide the necessary impedance matching in the output path to help effectively transfer the high-frequency signal generated by the voltage-controlled oscillator to the external load. C1 and the second inductor L C2 The second end is connected to the fifth input port V DD , which can provide the necessary DC bias voltage for the second HBT transistor T2 and the third HBT transistor T3 to ensure that the second HBT transistor T2 and the third HBT transistor T3 can operate in a correct bias state. The present invention uses such a DC bias design to ensure that the second HBT transistor T2 and the third HBT transistor T3 can remain stable during high-frequency signal transmission and are not affected by changes in external loads.

[0048] In addition, the bases of the second HBT transistor T2 and the third HBT transistor T3 are connected through the second input port V T2 By connecting the tuning voltage, the change of the tuning voltage can affect the working state of the second HBT transistor T2 and the third HBT transistor T3, and further affect the frequency and amplitude of the output signal. This design allows the user to control the output frequency of the oscillator by adjusting the tuning voltage, thereby realizing the frequency tuning function.

[0049] The output buffer module 300 significantly improves the output driving capability and signal transmission efficiency of the voltage-controlled oscillator by adding an additional amplifier stage and impedance matching design, and controls the working state of the output stage transistor by tuning the voltage, thereby achieving wide-range frequency tuning, so that the voltage-controlled oscillator can work in a wider frequency tuning range to meet the needs of different application scenarios. At the same time, the presence of the output buffer module can isolate the oscillator core from the external load, and can effectively reduce the impact of external load changes on the internal working state of the oscillator, thereby improving the stability and reliability of the system, while maintaining low phase noise, and is suitable for high-performance communication systems.

[0050] Below, this application Figure 2 Taking the half-edge equivalent circuit shown as an example, the working principle of the voltage-controlled oscillator described in this application is described in detail.

[0051] In such Figure 2 In the equivalent circuit shown in FIG. 1 , the oscillation frequency is determined by the equivalent capacitance (C EQ ) and the equivalent inductance (L EQ). According to the Barkhausen criterion, the resonant frequency expression is:

[0052]

[0053] The traditional method of adjusting the oscillation frequency is to change the first variable capacitance tube C VAR1 and the second varactor C VAR2 The first input port V T1 This method is simple, but it will greatly limit the frequency tuning range of the first variable capacitance tube C. VAR1 and the second varactor C VAR2 The present application uses the HBT parasitic tuning technology, that is, by adjusting the second input port V T2 The common base voltage of the second input port V T2 When the common base voltage decreases, the working states of the first HBT transistor T1 and the fourth HBT transistor T4 change, gradually entering the saturation region from the forward amplification region. In the forward amplification region, the parasitic capacitance of the HBT transistor is large, which limits the frequency tuning range. In the saturation region, the parasitic capacitance of the HBT transistor is reduced, so that the frequency tuning range can be expanded. In addition, the parasitic capacitance and parasitic inductance of the HBT transistor exhibit different characteristics under different working conditions. By adjusting the common base voltage, these parasitic parameters can be effectively controlled, thereby optimizing the frequency tuning performance of the oscillator. Especially in the high frequency band, the parasitic effect of the HBT transistor should have a greater impact on the phase noise. The parasitic tuning technology can reduce these parasitic effects and improve the phase noise performance.

[0054] Figure 3 FIG. 1 is a schematic diagram of the test results of the frequency of the output signal of the voltage-controlled oscillator proposed in this application changing with the tuning voltage. Figure 3 As shown, the voltage controlled oscillator provided by the present application has a tuning voltage V T1When changing from -0.5V to 3.5V, the first HBT transistor T1 and the fourth HBT transistor T4 in the oscillation loop transition from the forward amplification region to the saturation region. In the forward amplification region, the frequency tuning range is limited due to the larger parasitic capacitance; in the saturation region, the smaller parasitic capacitance allows a wider frequency tuning. This transition of working state not only broadens the tuning range, but also optimizes the frequency response. In addition, the output frequency of the voltage-controlled oscillator can cover a range from 32.0GHz to 39.9GHz, which shows that the design is particularly suitable for application scenarios that require high-frequency operation, such as millimeter-wave communication systems. And the frequency tuning range of 22.0% far exceeds the tuning range of about 10% of the traditional VCO, greatly improving the flexibility and adaptability of the system.

[0055] Figure 4 FIG. 1 is a schematic diagram showing the test results of the phase noise of the output signal of the voltage-controlled oscillator proposed in this application changing with frequency. Figure 4 As shown, the output frequency range of the voltage-controlled oscillator proposed in the present application is between 32.0 GHz and 39.9 GHz, and the phase noise is maintained at a level lower than -91dBc / Hz@1MHz, indicating that the voltage-controlled oscillator proposed in the present application can provide a wide frequency tuning capability without sacrificing signal purity.

[0056] In summary, the voltage-controlled oscillator presented in this application not only achieves a significantly increased frequency tuning range, but also maintains excellent phase noise characteristics throughout the entire tuning range, which is an important advancement for modern high-performance communication systems. This design provides an ideal solution for applications in the millimeter wave band, while meeting the requirements for high operating frequency, wide tuning range, and low phase noise performance.

[0057] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A low phase noise wide tuned voltage controlled oscillator, characterized in that: The voltage controlled oscillator comprises: An oscillation module (100), a bias module (200) and an output buffer module (300), wherein: The oscillation module (100) is used to generate a high-frequency oscillation signal and to achieve a wide frequency tuning range and low phase noise of a voltage-controlled oscillator; The bias module (200) is used to provide a stable bias current to ensure that the oscillation module (100) operates at an optimal operating point; The output buffer module (300) is used to expand the frequency tuning range of the high-frequency oscillation signal generated by the oscillation module (100).

2. A low phase noise wide tuned voltage controlled oscillator according to claim 1, characterized in that: The oscillation module (100) comprises: Oscillation branch, bias current supply branch, frequency tuning branch and output coupling and buffer branch, wherein, The oscillation branch is used to generate a high-frequency oscillation signal; The bias current supply branch is used to provide a stable bias current for the oscillation branch; The frequency tuning branch is used to adjust the oscillation frequency of the oscillation branch by changing the tuning voltage to achieve a frequency tuning function; The output coupling and buffer branch is used to transmit the high-frequency oscillation signal generated by the oscillation branch to the output buffer module (300).

3. A low phase noise wide tuned voltage controlled oscillator according to claim 2, characterized in that: The oscillation branch comprises: a first HBT transistor, a seventh inductor, a third inductor and a first capacitor, wherein: The base of the first HBT transistor is connected to the first end of the seventh inductor to form a first node, the collector of the first HBT transistor is connected to the output buffer module, the emitter of the first HBT transistor is connected to the first end of the third inductor to form a second node, the first end of the first capacitor is connected to the first node, and the second end of the first capacitor is connected to the second node.

4. A low phase noise wide tuned voltage controlled oscillator according to claim 3, characterized in that: The bias current supply branch comprises: The fifth inductor and the fourth inductor, wherein, The first end of the fourth inductor is connected to the second end of the third inductor to form a fifth node, the first end of the fifth inductor is connected to the second end of the sixth inductor to form a sixth node, and the second end of the fifth inductor is connected to the second end of the fourth inductor and is also connected to the bias module (200).

5. A low phase noise wide tuned voltage controlled oscillator according to claim 4, characterized in that: The frequency tuning branch comprises: A first varactor and a second varactor, wherein The first end of the first varactor is connected to the fifth node, the first end of the second varactor is connected to the sixth node, and the second end of the first varactor is connected to the second end of the second varactor and is connected to the first input port at the same time.

6. A low phase noise wide tuned voltage controlled oscillator according to claim 2, characterized in that: The output coupling and buffer branch comprises: a fourth HBT transistor, a second capacitor, an eighth inductor and a sixth inductor, wherein: The base of the fourth HBT transistor is connected to the first end of the eighth inductor to form a third node, the second end of the eighth inductor is connected to the second end of the seventh inductor and is connected to the third input port at the same time, the collector of the fourth HBT transistor is connected to the output buffer module, the emitter of the fourth HBT transistor is connected to the first end of the sixth inductor to form a fourth node, the first end of the second capacitor is connected to the third node, and the second end of the second capacitor is connected to the fourth node.

7. The low phase noise wide tuned voltage controlled oscillator according to claim 1, characterized in that: The bias module (200) comprises: Current source branch, bias voltage adjustment branch and stable operating point setting branch, where: The current source branch is used to provide a stable DC bias current; The bias voltage adjustment branch is used to adjust and provide a suitable bias current to the oscillation module; The stable operating point setting branch is used to provide a stable DC operating condition for the bias voltage adjustment branch.

8. The low phase noise wide tuned voltage controlled oscillator according to claim 7, characterized in that: The current source branch comprises: The seventh HBT transistor and the second resistor, wherein The emitter of the seventh HBT transistor is connected to the first end of the second resistor, the second end of the second resistor is connected to the second ground terminal, the base of the seventh HBT transistor is connected to the stable operating point setting branch, and the collector of the seventh HBT transistor is connected to the connection between the second end of the fifth inductor and the second end of the fourth inductor.

9. The low phase noise wide tuned voltage controlled oscillator according to claim 7, characterized in that: The bias voltage adjustment branch comprises: A fifth HBT transistor, wherein the collector of the fifth HBT transistor is connected to the oscillation module, the emitter of the fifth HBT transistor is connected to the stable operating point setting branch, and the collector and base of the fifth HBT transistor are simultaneously connected to the bias voltage through the fourth input port.

10. The low phase noise wide tuned voltage controlled oscillator according to claim 7, characterized in that: The stable operating point setting branch includes: a sixth HBT transistor and a first resistor, wherein The emitter of the sixth HBT transistor is connected to the first end of the first resistor, the second end of the first resistor is connected to the first ground terminal, the collector of the sixth HBT transistor is connected to the emitter of the fifth HBT transistor, and the collector of the sixth HBT transistor is also connected to its base.

11. The low phase noise wide tuned voltage controlled oscillator according to claim 1, characterized in that: The output buffer module (300) comprises: A first inductor, a second inductor, a second HBT transistor and a third HBT transistor, wherein: The collector of the second HBT transistor is connected to the first end of the first inductor and is connected to the first output port at the same time, the second end of the first inductor is connected to the DC voltage through the fifth input port, and the emitter of the second HBT transistor is connected to the collector of the first HBT transistor; the collector of the third HBT transistor is connected to the first end of the second inductor and is connected to the second output port at the same time, the second end of the second inductor is connected to the DC voltage through the fifth input port, the emitter of the third HBT transistor is connected to the collector of the fourth HBT transistor, the base of the third HBT transistor is connected to the base of the second HBT transistor and is connected to the tuning voltage through the second input port at the same time.

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