Three-dimensional stacked frequency source, manufacturing method and temperature compensation design method thereof

Abstract

This invention provides a three-dimensional stacked frequency source, its fabrication method, and a temperature compensation design method. The frequency source includes: a first ceramic cavity housing a frequency synthesis unit that converts a reference signal into an initial radio frequency (RF) signal, amplifies and temperature-compensates it, and outputs a target RF signal; and a second ceramic cavity stacked on top of and electrically connected to the first cavity, housing a DC-DC converter and a temperature-compensated notch filter unit. The DC-DC converter converts DC voltage into the power supply voltage for the frequency synthesis unit, and the temperature-compensated notch filter unit suppresses the switching frequency generated by the DC-DC converter. This invention employs a stacked dual-cavity structure, resulting in a small size, high integration, low crosstalk, and independent assembly of the upper and lower layers, improving manufacturability. Furthermore, the temperature-compensated notch filter unit passively tracks temperature changes without additional power consumption, effectively suppressing switching frequencies and harmonic interference, and improving spectral purity.

Description

Technical Field

[0001] This invention relates to the fields of microsystem integration and radio frequency microwave technology, and in particular to a three-dimensional stacked frequency source, its fabrication method, and temperature compensation design method. Background Technology

[0002] Frequency sources are core units in radar, communication, and electronic countermeasures systems, and the spectral purity of their output signals directly affects system performance. With the trend towards miniaturization and high integration of equipment, frequency sources are required to be small in size, high in frequency, and low in phase noise. Traditional frequency sources typically consist of phase-locked loops, voltage-controlled oscillators, filters, and DC-DC power conversion chips. Currently, they face two main challenges: first, the switching frequency interference generated by the DC-DC power conversion chip; and second, the difficulty in simultaneously achieving module miniaturization and high integration.

[0003] During operation, DC-DC power converter chips generate periodic ripples characterized by switching frequency and its harmonics. These ripples are conducted through power lines or spatially coupled into devices such as phase-locked loops and voltage-controlled oscillators, causing near-end spurious noise at the frequency source output and deteriorating phase noise. To suppress this interference, existing technologies mainly adopt the following solutions: (1) increasing the capacitance at the output of the DC-DC power converter chip or cascading a low-dropout linear regulator at its output, but this method is bulky and inefficient; (2) connecting a low-pass filter or ferrite bead in series, but the low-pass filter suffers from problems such as temperature drift leading to filter mismatch, inability to track switching frequency jitter, and the need for multiple stages of filtering to suppress multiple harmonics, resulting in increased size. Existing research has proposed using active adjustable filters or switched capacitor arrays to achieve frequency tracking, but this requires complex control circuits and additional power consumption, and introduces new noise. Summary of the Invention

[0004] This invention provides a three-dimensional stacked frequency source, its fabrication method, and a temperature compensation design method to solve the technical problems of existing frequency source designs, such as large size, high loss, poor consistency, strong signal crosstalk, inaccurate circuit testing, and difficult maintenance.

[0005] In a first aspect, the present invention provides a three-dimensional stacked frequency source, comprising: A first ceramic cavity is provided therein, wherein a frequency synthesis unit is configured to convert a reference signal into an initial radio frequency signal, amplify and temperature compensate the initial radio frequency signal, and output a target radio frequency signal. A second ceramic cavity is stacked on the front of the first ceramic cavity and electrically connected to the first ceramic cavity. The second ceramic cavity includes the DC-DC conversion unit and the temperature-compensated notch filter unit. The DC-DC conversion unit is used to convert DC voltage into the power supply voltage of the frequency synthesis unit. The temperature-compensated notch filter unit is used to suppress the switching frequency generated by the DC-DC conversion unit, and the resonant frequency of the temperature-compensated notch filter unit tracks the change of the switching frequency.

[0006] In one embodiment of the present invention, a first air-like coaxial cable and a second air-like coaxial cable are further disposed within the first ceramic cavity; the DC voltage is input from the bottom of the first ceramic cavity and is converted into the supply voltage sequentially via the first air-like coaxial cable, the DC-DC conversion unit, and the temperature-compensated notch filter unit; the supply voltage enters the first ceramic cavity via the second ceramic cavity and is transmitted to the frequency synthesis unit via the second air-like coaxial cable; the frequency synthesis unit, driven by the supply voltage, converts the reference signal into the target radio frequency signal, and the target radio frequency signal is output from the bottom of the first ceramic cavity.

[0007] In one embodiment of the present invention, the first ceramic cavity includes: a first ceramic plate; a first substrate disposed on the front side of the first ceramic plate; a first ceramic vertical wall having an annular structure and integrally formed on the edge of the front side of the first ceramic plate; and a second ceramic plate disposed on the side of the first ceramic vertical wall away from the first ceramic plate; wherein the first ceramic plate, the first ceramic vertical wall, and the second ceramic plate constitute a cavity structure.

[0008] In one embodiment of the present invention, the first air-like coaxial arrangement is disposed between the first ceramic plate and the second ceramic plate, and the second air-like coaxial arrangement is disposed between the first substrate and the second ceramic plate.

[0009] In one embodiment of the present invention, the frequency synthesis unit includes a frequency synthesizer, a loop filter, an amplifier, a temperature-compensated attenuator, and a first integrated sub-unit integrating a first resistor and a first capacitor. The frequency synthesizer, the loop filter, the amplifier, the temperature-compensated attenuator, and the first integrated sub-unit are disposed on the side of the first substrate away from the first ceramic plate. The frequency synthesis unit is electrically connected to the second air-like coaxial plate and the first ceramic plate respectively through the first substrate.

[0010] In one embodiment of the present invention, the second ceramic cavity includes: a third ceramic plate; a second substrate disposed on the front side of the third ceramic plate; a second ceramic vertical wall having an annular structure and integrally formed on the edge of the front side of the third ceramic plate; and a metal cover plate disposed on the side of the second ceramic vertical wall away from the third ceramic plate; wherein the third ceramic plate, the second ceramic vertical wall, and the metal cover plate constitute a cavity structure.

[0011] In one embodiment of the present invention, the second ceramic cavity further includes a second integrated sub-unit integrating a second resistor and a second capacitor. The DC-DC conversion unit, the temperature-compensated notch filter unit, and the second integrated sub-unit are disposed on the side of the second substrate away from the third ceramic plate. The temperature-compensated notch filter unit is electrically connected to the third ceramic plate through the second substrate.

[0012] In one embodiment of the present invention, the temperature-compensated notch filter unit includes a plurality of first notch filter sub-units and a plurality of second notch filter sub-units, wherein the first notch filter sub-units and the second notch filter sub-units are alternately arranged.

[0013] In one embodiment of the present invention, the first notch sub-unit includes a third capacitor, a first inductor, and a third resistor. The first end of the first inductor is connected to the second end of the third resistor via the third capacitor. The first end of the third resistor is grounded. The second end of the first inductor is the positive terminal of the first notch sub-unit, and the first end of the third resistor is the negative terminal of the first notch sub-unit. The second notch sub-unit includes a fourth capacitor, a second inductor, and a fourth resistor. The first end of the second inductor is connected to the first end of the fourth capacitor. The second end of the fourth capacitor is connected to the first end of the fourth resistor. The second end of the second inductor is connected to the second end of the fourth resistor. The first end of the second inductor is the input terminal of the second notch sub-unit, and the second end of the second inductor is the output terminal of the second notch sub-unit. The first notch sub-unit is disposed between the two second notch sub-units.

[0014] In one embodiment of the present invention, the temperature change characteristics of the first inductor are opposite to those of the third capacitor, and the temperature change characteristics of the second inductor are opposite to those of the fourth capacitor.

[0015] Secondly, the present invention also provides a method for fabricating a three-dimensional stacked frequency source, comprising: A first ceramic cavity is prepared, and a frequency synthesis unit is set in the first ceramic cavity; A second ceramic cavity is prepared, and the DC-DC conversion unit and the temperature-compensated notch filter unit are disposed within the second ceramic cavity; The second ceramic cavity is stacked on one side of the first ceramic cavity and fixedly connected to achieve electrical connection between the frequency synthesis unit and the temperature-compensated notch filter unit; The frequency synthesis unit is used to convert the reference signal into an initial radio frequency signal, and amplify and temperature compensate it to output the target radio frequency signal; the DC-DC conversion unit is used to convert the DC voltage into the power supply voltage for the operation of the frequency synthesis unit; the temperature-compensated notch filter unit is used to suppress the switching frequency generated by the DC-DC conversion unit, and the resonant frequency of the temperature-compensated notch filter unit tracks the change of the switching frequency.

[0016] Thirdly, the present invention also provides a temperature compensation design method for a temperature-compensated notch filter element, which is used to design a temperature-compensated notch filter element in the three-dimensional stacked frequency source described above, including: Obtain the first frequency drift of the DC-DC converter unit as a function of temperature; The nominal resonant frequency of the temperature-compensated notch filter unit is determined based on the switching frequency and harmonic order of the DC-DC conversion unit at the reference temperature. Select a target inductor and a target capacitor that satisfy the nominal resonant frequency so that the difference between the second frequency drift and the first frequency drift of the nominal resonant frequency of the temperature-compensated notch filter unit as the nominal resonant frequency changes with temperature does not exceed a preset tracking error threshold.

[0017] The beneficial effects of this invention are as follows: This invention provides a three-dimensional stacked frequency source, its manufacturing method, and a temperature compensation design method. The frequency source includes a first ceramic cavity and a second ceramic cavity. The first ceramic cavity houses a frequency synthesis unit, which is responsible for converting a reference signal into an initial radio frequency signal, amplifying it, and performing temperature compensation to ultimately output the target radio frequency signal. The second ceramic cavity is stacked on the front of the first cavity and electrically connected to it. It houses a DC-DC conversion unit and a temperature-compensated notch filter unit. The DC-DC conversion unit converts DC voltage into the power supply voltage for the frequency synthesis unit, and the temperature-compensated notch filter unit suppresses the switching frequency generated by the DC-DC conversion unit. This invention divides the frequency source into two parts according to functional requirements, each assembled in a different ceramic cavity. The stacked arrangement of the two ceramic cavities improves the product's integration, significantly reduces its size and weight, and meets the module's requirements for miniaturization and lightweight design. The circuits within the upper and lower shells can be independently assembled and tested, improving the module's manufacturability. Separate operation of the radio frequency signal and DC voltage results in low signal crosstalk. In addition, the temperature-compensated notch filter unit achieves passive temperature tracking through the coordinated design of the temperature coefficients of the inductor and capacitor materials, without the need for additional power consumption. It effectively suppresses the switching frequency and harmonic interference generated by the DC-DC converter unit, further improving the spectral purity of the frequency source. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0019] In the attached diagram: Figure 1 This is a cross-sectional schematic diagram of the three-dimensional stacked frequency source provided in an embodiment of the present invention; Figure 2 This is a schematic cross-sectional view of two air-like coaxial elements representing a three-dimensional stacked frequency source provided in an embodiment of the present invention. Figure 3 This is a schematic cross-sectional view of the specific structure of the three-dimensional stacked frequency source provided in the embodiment of the present invention; Figure 4 This is a circuit connection schematic diagram of the three-dimensional stacked frequency source provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the circuit structure of the temperature-compensated notch filter unit provided in an embodiment of the present invention; Figure 6This is a schematic diagram showing the frequency drift comparison curves of the temperature-compensated notch filter unit provided in this embodiment of the invention with those of a conventional notch filter at different temperatures.

[0020] Reference numerals: 110-First ceramic cavity; 120-Second ceramic cavity; 111-Frequency synthesis unit; 1211-DC-DC conversion unit; 1212-Temperature-compensated notch filter unit; 1311-First air-like coaxial; 1312-Second air-like coaxial; 141-First solder ball; 151-Second solder ball; 1101-First ceramic plate; 1102-First substrate; 1103-First ceramic vertical wall; 1104-Second ceramic plate; 1111-Frequency synthesizer; 1112-Loop filter; 1113-Amplifier; 1114-Temperature-compensated attenuator; 1115-First integrated subunit; 1201-Third ceramic plate; 1202-Second substrate; 1203-Second ceramic vertical wall; 1204-Metal cover plate; 1213-Second integrated subunit. Detailed Implementation

[0021] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0022] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0023] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0024] Frequency sources are core units in radar, communication, and electronic countermeasures systems. The spectral purity of their output signals directly determines receiver sensitivity, measurement accuracy, and communication quality. As phased array radar and satellite communication equipment develop towards lightweight and multifunctional designs, frequency source modules face stringent requirements for small size, high frequency, low phase noise, and high consistency.

[0025] Traditional frequency sources typically consist of phase-locked loop (PLL) chips, voltage-controlled oscillators (VCOs), filters, and DC-DC power conversion chips. They face two major technical challenges: interference from the power conversion chip on the output signal and the achievement of module miniaturization and high integration.

[0026] DC-DC power converter chips generate power at a switching frequency f_ during operation. sw Periodic ripple and electromagnetic interference, characterized by harmonics, can enter devices such as phase-locked loops (PLLs) and voltage-controlled oscillators (VCOs) through power line conduction or spatial coupling, leading to near-end spurious emissions and deterioration of phase noise at the frequency source output. To suppress this interference, existing technologies mainly employ the following solutions: First, increasing the capacitance at the output of the DC-DC power converter chip or cascading a low-dropout linear regulator (LDL) at its output. While this method effectively filters out ripple, the LDL requires large capacitors at both the input and output, resulting in a larger footprint. Furthermore, using a LDL significantly reduces power efficiency, especially in high-dropout or high-current scenarios. Second, connecting a low-pass filter or ferrite bead in series at the output of the DC-DC power converter chip. However, low-pass filters suffer from problems such as temperature drift leading to filter mismatch, inability to track switching frequency jitter, and the need for multiple stages of filtering to suppress multiple harmonics, resulting in increased size. Third, using active adjustable filters or switched capacitor arrays to achieve frequency tracking, but this requires complex control circuitry and additional power consumption, and the active devices themselves introduce new noise. Therefore, existing technologies struggle to simultaneously achieve effective suppression of switching ripple and harmonics in DC-DC power conversion chips while maintaining miniaturization, high efficiency, and a wide temperature range.

[0027] To solve the above problems, such as Figure 1 As shown, this application provides a three-dimensional stacked frequency source, including: A first ceramic cavity 110 is provided therein, and a frequency synthesis unit 111 is configured to convert a reference signal into an initial radio frequency signal, amplify and temperature compensate the initial radio frequency signal, and output a target radio frequency signal. The second ceramic cavity 120 is stacked on the front of the first ceramic cavity 110 and electrically connected to the first ceramic cavity 110. The second ceramic cavity 120 is provided with a DC-DC conversion unit 1211 and a temperature-compensated notch filter unit 1212. The DC-DC conversion unit 1211 is used to convert DC voltage into the power supply voltage of the frequency synthesis unit 111. The temperature-compensated notch filter unit 1212 is used to suppress the switching frequency generated by the DC-DC conversion unit 1211, and the resonant frequency of the temperature-compensated notch filter unit 1212 tracks the change of the switching frequency.

[0028] For example, such as Figure 1As shown, the three-dimensional stacked frequency source includes a first ceramic cavity 110 and a second ceramic cavity 120. The second ceramic cavity 120 is stacked on the first ceramic cavity 110. The second ceramic cavity 120 exists independently of the first ceramic cavity 110, but the second ceramic cavity 120 is electrically connected to the first ceramic cavity 110. A frequency synthesis unit 111 is provided in the first ceramic cavity 110. The frequency synthesis unit 111 receives the input reference signal, converts the reference signal into an initial radio frequency signal, and amplifies and performs temperature compensation processing on the initial radio frequency signal. The frequency synthesis unit 111 outputs the target radio frequency signal. The second ceramic cavity 120 houses a DC-DC converter unit 1211 and a temperature-compensated notch filter unit 1212. The DC-DC converter unit 1211 converts the DC voltage VDD into the supply voltage for the frequency synthesis unit 111. The input terminal of the temperature-compensated notch filter unit 1212 is connected to the output terminal of the DC-DC converter unit 1211, and its output terminal is connected to the supply terminal of the frequency synthesis unit 111. The temperature-compensated notch filter unit 1212 suppresses the switching frequency generated by the DC-DC converter unit 1211, and its resonant frequency varies with the switching frequency of the DC-DC converter unit 1211, which in turn varies with temperature. The DC-DC converter unit can be simply referred to as the DC-DC conversion unit.

[0029] It should be noted that the temperature-compensated notch filter unit 1212 includes a series resonant branch composed of an inductor and a capacitor connected in series and a parallel resonant branch composed of an inductor and a capacitor connected in parallel, with a resonant frequency; wherein, the inductor L adopts an inductor element with a temperature coefficient TCL, and the capacitor C adopts a capacitor element with a temperature coefficient TCC.

[0030] Specifically, the first ceramic cavity 110 also includes a first air-type coaxial cable 1311 and a second air-type coaxial cable 1312. The DC voltage VDD is input through the bottom of the first ceramic cavity 110 and sequentially converted into a supply voltage via the first air-type coaxial cable 1311, a DC-DC conversion unit 1211, and a temperature-compensated notch filter unit 1212. The supply voltage enters the first ceramic cavity 110 through the second ceramic cavity 120 and is transmitted to the frequency synthesis unit 111 via the second air-type coaxial cable 1312. Driven by the supply voltage VDD, the frequency synthesis unit converts the reference signal into a target radio frequency signal, which is output through the bottom of the first ceramic cavity 110. Specifically, in... Figure 2In the first ceramic cavity 110, a first air-type coaxial cable 1311 and a second air-type coaxial cable 1312 are also provided. The DC voltage VDD is input from the bottom of the first ceramic cavity and transmitted to the DC-DC conversion unit 1211 through the first air-type coaxial cable 1311 in the first ceramic cavity 110. The DC-DC conversion unit 1211 outputs the initial supply voltage VCC1 and transmits the initial supply voltage VCC1 to the temperature-compensated notch filter unit 1212. The temperature-compensated notch filter unit 1212 outputs multiple supply voltages to drive the frequency synthesis unit 111. The multiple supply voltages are transmitted from the temperature-compensated notch filter unit 1212 in the second ceramic cavity 120 to the first ceramic cavity 110. Finally, the multiple supply voltages are transmitted to the frequency synthesis unit 111 through the second air-type coaxial cable 1312. Driven by the multiple supply voltages, the frequency synthesis unit 111 converts the reference signal into a target radio frequency signal, which is output from the bottom of the first ceramic cavity 110.

[0031] In detail, such as Figure 3 As shown, the first ceramic cavity 110 includes: a first ceramic plate 1101; a first substrate 1102 disposed on the front side of the first ceramic plate 1101; a first ceramic vertical wall 1103 having an annular structure and integrally formed on the edge of the front side of the first ceramic plate 1101; and a second ceramic plate 1104 disposed on the side of the first ceramic vertical wall 1103 away from the first ceramic plate 1101 and in contact with a portion of the first ceramic vertical wall 1103; wherein, the first ceramic plate 1101, the first ceramic vertical wall 1103, and the second ceramic plate 1104 constitute the cavity structure.

[0032] Specifically, the first air-type coaxial 1311 is disposed between the first ceramic plate 1101 and the second ceramic plate 1104; the second air-type coaxial 1312 is disposed between the first substrate 1102 and the second ceramic plate 1104.

[0033] Specifically, such as Figure 3As shown, the first ceramic cavity 110 includes a first ceramic plate 1101, a first substrate 1102, a first ceramic vertical wall 1103, a second ceramic plate 1104, a first air-like coaxial section 1311, and a second air-like coaxial section 1312. The first substrate 1102, the first ceramic vertical wall 1103, and the first air-like coaxial section 1311 are disposed on the front side of the first ceramic plate 1101. The first ceramic vertical wall 1103 has a ring-shaped structure and is integrally formed at the edge of the front side of the first ceramic plate 1101. The first substrate 1102 and the first air-like coaxial section 1311 are disposed in the middle of the first ceramic plate 1101. The height of the first ceramic vertical wall 1103 is greater than the height of the first substrate 1102, and the height of the first ceramic vertical wall 1103 is equal to the height of the first air-like coaxial section 1311. The second air-like coaxial section 1312 is disposed on the first substrate 1102 away from the first ceramic plate 1104. On one side of ceramic plate 1101, a second ceramic plate 1104 is disposed on the side of the first ceramic vertical wall 1103 opposite to the first ceramic plate 1101 and in contact with a portion of the first ceramic vertical wall 1103, a portion of the first air-type coaxial cable 1311, and a portion of the second air-type coaxial cable 1312. The first end of the first air-type coaxial cable 1311 contacts the first ceramic plate 1101, and the second end of the first air-type coaxial cable 1311 contacts the second ceramic plate 1104. The first end of the second air-type coaxial cable 1312 contacts the first substrate 1102, and the second end of the second air-type coaxial cable 1312 contacts the second ceramic plate 1104. The first ceramic plate 1101, the first ceramic vertical wall 1103, and the second ceramic plate 1104 form a first cavity structure. Within this first cavity structure are disposed the first substrate 1102, the first air-type coaxial cable 1311, the second air-type coaxial cable 1312, and a frequency synthesis unit 111. The first substrate 1102 can be welded onto the first ceramic plate 1101 using AuSn alloy (gold-tin alloy) solder eutectic (eutectic temperature 280 degrees Celsius).

[0034] More specifically, the frequency synthesis unit 111 includes a frequency synthesizer 1111, a loop filter 1112, an amplifier 1113, a temperature-compensated attenuator 1114, and a first integrated subunit 1115 integrating a first resistor and a first capacitor. The frequency synthesizer 1111, the loop filter 1112, the amplifier 1113, the temperature-compensated attenuator 1114, and the first integrated subunit 1115 are disposed on the side of the first substrate 1102 facing away from the first ceramic plate 1101. The frequency synthesis unit 111 is electrically connected to the second air-like coaxial 1312 and the first ceramic plate 1101 through the first substrate 1102, respectively.

[0035] Specifically, such as Figure 4As shown, the frequency synthesis unit 111 includes a frequency synthesizer 1111, a loop filter 1112, an amplifier 1113, a temperature-compensated attenuator 1114, and a first integrated subunit 1115 (not shown in the figure) integrating a first resistor and a first capacitor. Reference signals and control signals are input to the frequency synthesizer 1111. Under the control of the control signal, the reference signal is processed by the frequency synthesizer 1111 and the loop filter 1112 to output an initial radio frequency (RF) signal. The initial RF signal is then processed by the amplifier 1113 and the temperature-compensated attenuator 1114 for power adjustment to obtain a target RF signal with the required power. The first capacitor and the first resistor in the first integrated subunit 1115 are used to adjust the RF signal transmitted by the frequency synthesis unit 111. Figure 3 As shown, the frequency synthesizer 1111, loop filter 1112, amplifier 1113, temperature compensation attenuator 1114, and first integrated subunit 1115 are disposed on the side of the first substrate 1102 away from the first ceramic plate 1101. The frequency synthesizer 1111, loop filter 1112, amplifier 1113, temperature compensation attenuator 1114, and first integrated subunit 1115 are soldered onto the first substrate 1102 by reflow soldering or wire bonding. SnAgCu alloy (tin-silver-copper alloy) solder can be used for reflow soldering. The frequency synthesis unit 111 is electrically connected to the second air-like coaxial 1312 and the first ceramic plate 1101 through the first substrate 1102.

[0036] More in detail, such as Figure 3 As shown, a plurality of first solder balls 141 are disposed on the side of the first ceramic plate 1101 opposite to the first substrate 1102. The first ceramic cavity 110 is electrically connected to other circuit boards through the first solder balls 141, thereby realizing the reception of DC voltage VDD, reference signal and control signal, and the output of target radio frequency signal. The solder balls 141 are soldered to the first ceramic cavity 110 and other circuit boards using SnPb solder paste (tin-lead alloy solder).

[0037] More in detail, such as Figure 3 As shown, the first ceramic cavity 110 and the second ceramic cavity 120 are electrically connected by a plurality of second solder balls 151. The DC voltage VDD and the supply voltage are transmitted between the first ceramic cavity 110 and the second ceramic cavity 120 through the plurality of second solder balls 151. The soldering of the second solder balls 151 to the first ceramic cavity 110 and the second ceramic cavity 120 can be performed using SnPb solder paste (tin-lead alloy solder).

[0038] More specifically, the second ceramic cavity 120 includes: a third ceramic plate 1201; a second substrate 1202 disposed on the front side of the third ceramic plate 1201; a second ceramic vertical wall 1203 having an annular structure and integrally formed on the edge of the front side of the third ceramic plate 1201; and a metal cover plate 1204 disposed on the side of the second ceramic vertical wall 1203 away from the third ceramic plate 1201 and in contact with a portion of the second ceramic vertical wall 1203; wherein the third ceramic plate 1201, the second ceramic vertical wall 1203, and the metal cover plate 1204 constitute the cavity structure.

[0039] Specifically, such as Figure 3 As shown, the second ceramic cavity 120 includes a third ceramic plate 1201, a second substrate 1202, a second ceramic vertical wall 1203, and a metal cover plate 1204. The third ceramic plate 1201 is disposed on the side of the second solder ball 151 facing away from the second ceramic plate 1104. The second substrate 1202 and the second ceramic vertical wall 1203 are disposed on the side of the third ceramic plate 1201 facing away from the second solder ball 151. The second ceramic vertical wall 1203 has a ring structure and is integrally formed on the edge of the front side of the third ceramic plate 1201. The second substrate 1202 is disposed in the middle of the third ceramic plate 1201. The height of the second substrate 1202 is small. At the height of the second ceramic vertical wall 1203, a metal cover plate 1204 is disposed on the side of the second ceramic vertical wall 1203 away from the third ceramic plate 1201 and located above the second substrate 1202. The metal cover plate 1204 is in contact with part of the second ceramic vertical wall 1203. The metal cover plate 1204 can be welded to the second ceramic vertical wall 1203 by parallel sealing. The third ceramic plate 1201, the second ceramic vertical wall 1203, and the metal cover plate 1204 form a second cavity structure. The second substrate 1202, a DC-DC conversion unit 1211, and a temperature-compensated notch filter unit 1212 are disposed within the second cavity structure. The second substrate 1202 can be eutecticly welded to the third ceramic plate 1201 using AuSn alloy (gold-tin alloy) solder (eutectic temperature 280 degrees Celsius).

[0040] Specifically, the first substrate 1102 and the second substrate 1202 are single-layer circuit boards or multi-layer circuit boards. That is, the first substrate 1102 and the second substrate 1202 are single-layer circuit boards or multi-layer circuit boards; the second ceramic plate 1104 is made of ceramic material and can be a single-layer or multi-layer circuit board.

[0041] In detail, the second ceramic cavity 120 also includes a second integrated sub-unit 1213 that integrates a second resistor and a second capacitor. The DC-DC conversion unit 1211, the temperature-compensated notch filter unit 1212, and the second integrated sub-unit 1213 are disposed on the side of the second substrate 1202 away from the third ceramic plate 1201. The temperature-compensated notch filter unit 1212 is electrically connected to the third ceramic plate 1201 through the second substrate 1202.

[0042] Specifically, such as Figure 4 As shown, the second ceramic cavity 120 also includes a second integrated subunit 1213 (not shown in the figure) that integrates a second resistor and a second capacitor. The second capacitor and the second resistor in the second integrated subunit 1213 are used to regulate the supply voltage. The DC-DC conversion unit 1211 converts the DC voltage VDD into the initial supply voltage VCC1 that drives the frequency synthesis unit 111. The temperature-compensated notch filter unit 1212 is used to notch filter and suppress the switching frequency and its specified harmonics of the initial supply voltage VCC1, realizing passive temperature tracking suppression of the notch frequency on the switching frequency, and significantly improving the power supply noise suppression capability over a wide temperature range. The temperature-compensated notch filter unit 1212 outputs a first supply voltage VCC1 and a second supply voltage VCC2. The first supply voltage VCC1 is used to power the frequency synthesizer 1111, and the second supply voltage VCC2 is used to power the amplifier 1113. Because the data type of the DC-DC conversion unit 1211 is a data signal, and the data type of the first supply voltage VCC1 and the second supply voltage VCC2 output by the temperature-compensated notch filter unit 1212 is DC voltage, the data type processed in the second ceramic cavity 120 is all data signals. For example... Figure 3 As shown, the DC-DC conversion unit 1211, the temperature-compensated notch filter unit 1212, and the second integrated subunit 1213 are soldered to the side of the second substrate 1202 away from the third ceramic plate 1201 by reflow soldering or gold wire bonding, so that the temperature-compensated notch filter unit 1212 is electrically connected to the third ceramic plate 1201 through the second substrate 1202.

[0043] It should be noted that the number of first resistors and first capacitors in the first integrated subunit 1115 can be one or more, and the number of second resistors and second capacitors in the second integrated subunit 1213 can be one or more, which can be determined according to the actual situation.

[0044] In detail, the temperature-compensated notch filter unit includes multiple first notch filter sub-units and multiple second notch filter sub-units, which are alternately arranged. Specifically, the first and second notch filter sub-units are used to suppress the fundamental frequency f1, second harmonic f2, and third harmonic f3 of the switching frequency in the DC-DC converter unit 1211, respectively. The inductors and capacitors of different first and second notch filter sub-units are matched with devices having the same or different temperature characteristics to match the absolute frequency drift of different harmonic orders.

[0045] More in detail, such as Figure 5As shown, the first notch sub-unit includes a third capacitor, a first inductor, and a third resistor. The first end of the first inductor is connected to the second end of the third resistor via the third capacitor. The first end of the third resistor is grounded. The second end of the first inductor is the positive terminal of the first notch sub-unit, and the first end of the third resistor is the negative terminal of the first notch sub-unit. The second notch sub-unit includes a fourth capacitor, a second inductor, and a fourth resistor. The first end of the second inductor is connected to the first end of the fourth capacitor. The second end of the fourth capacitor is connected to the first end of the fourth resistor. The second end of the second inductor is connected to the second end of the fourth resistor. The first end of the second inductor is the input terminal of the second notch sub-unit, and the second end of the second inductor is the output terminal of the second notch sub-unit. A first notch sub-unit is disposed between the two second notch sub-units.

[0046] Specifically, such as Figure 5 As shown, the temperature-compensated notch filter unit includes m first notch filter sub-units (A1~Am) and n second notch filter sub-units (B1~Bm). The first first notch filter sub-unit A1 includes a third capacitor C31, a first inductor L11, and a third resistor R31. The first end of the first inductor L11 is connected to the second end of the third resistor R31 via the third capacitor C31. The first end of the third resistor R31 is grounded. The second end of the first inductor L11 is the positive terminal of the first first notch filter sub-unit A1, and the first end of the third resistor R31 is the negative terminal of the first first notch filter sub-unit A1. The second first notch filter sub-unit A2 includes a third capacitor C32, a first inductor L12, and a third resistor R32. The first end of the first inductor L12 is connected to the second end of the third resistor R32 via the third capacitor C32. The first end of the third resistor R32 is grounded. The second end of the first inductor L12 is the positive terminal of the second first notch filter sub-unit A2, and the first end of the third resistor R32 is the negative terminal of the second first notch filter sub-unit A2. The m-th first notch sub-unit Am includes a third capacitor C3m, a first inductor L1m, and a third resistor R3m. The first end of the first inductor L1m is connected to the second end of the third resistor R3m via the third capacitor C3m. The first end of the third resistor R3m is grounded. The second end of the first inductor L1m is the positive terminal of the m-th first notch sub-unit Am, and the first end of the third resistor R3m is the negative terminal of the m-th first notch sub-unit Am.

[0047] like Figure 5As shown, the first second notch filter sub-unit B1 includes a fourth capacitor C41, a second inductor L21, and a fourth resistor R41. The first terminal of the second inductor L21 is connected to the first terminal of the fourth capacitor C41, the second terminal of the fourth capacitor C41 is connected to the first terminal of the fourth resistor R41, and the second terminal of the second inductor L21 is connected to the second terminal of the fourth resistor R41. The first terminal of the second inductor L21 is the input terminal of the first second notch filter sub-unit B1, and the second terminal of the second inductor L21 is the output terminal of the first second notch filter sub-unit B1. The second second notch filter sub-unit B2 includes a fourth capacitor C42, a second inductor L22, and a fourth resistor R42. The first terminal of the second inductor L22 is connected to the first terminal of the fourth capacitor C42, the second terminal of the fourth capacitor C42 is connected to the first terminal of the fourth resistor R42, and the second terminal of the second inductor L22 is connected to the second terminal of the fourth resistor R42. The first terminal of the second inductor L22 is the input terminal of the second second notch filter sub-unit B2, and the second terminal of the second inductor L22 is the output terminal of the second second notch filter sub-unit B2. The nth second notch sub-unit Bn includes a fourth capacitor C4n, a second inductor L2n, and a fourth resistor R4n. The first end of the second inductor L2n is connected to the first end of the fourth capacitor C4n, the second end of the fourth capacitor C4n is connected to the first end of the fourth resistor R4n, and the second end of the second inductor L2n is connected to the second end of the fourth resistor R4n. The first end of the second inductor L2n is the input terminal of the nth second notch sub-unit Bn, and the second end of the second inductor L2n is the output terminal of the nth second notch sub-unit Bn.

[0048] like Figure 5 As shown, the output terminal of the first second notch subunit B1 is connected to the input terminal of the second second notch subunit B2. The output terminal of the first second notch subunit B1 is also connected to the positive terminal of the first first notch subunit A1. The first and second notch subunits are alternately arranged. Among them, the third resistor (R31~R3m) and the fourth resistor (R41~R4n) are used to control the quality factor of the temperature-compensated notch unit 1212 and widen the notch bandwidth to adapt to the short-term jitter of the switching frequency of the DC-DC converter unit under transient operating conditions.

[0049] More specifically, the temperature change characteristics of the first inductor L11 are opposite to those of the third capacitor C31, and the temperature change characteristics of the second inductor L21 are opposite to those of the fourth capacitor C41.

[0050] Specifically, the first and second inductors can be composite core inductors, whose core material is composed of two or more magnetic materials with different temperature characteristics mixed in a certain proportion. The inductance is customized by adjusting the mixing ratio so that its inductance value changes with temperature by ΔL. The third and fourth capacitors can be composite dielectric capacitors, and the capacitance is customized by adjusting the volume ratio or electrode area ratio of two or more dielectrics so that its capacitance value changes with temperature by ΔC. This allows the resonant frequency of the temperature-compensated notch filter unit 1212 to change with temperature by ΔC. The switching frequency of the DC-DC converter unit 1211 varies with temperature Δf_ clock The temperature compensation matching conditions are met.

[0051] like Figures 1 to 4 As shown, the working principle of the three-dimensional stacked frequency source provided by this invention is as follows: The DC voltage VDD is received through the first solder ball 141 and transmitted to the second ceramic cavity 120 through the first air-like coaxial cable 1311. The DC-DC conversion unit 1211 converts the DC voltage VDD into an initial supply voltage VCC1. The temperature-compensated notch filter unit 1212 performs notch suppression on the switching frequency of the initial supply voltage VCC1 so that the resonant frequency of the temperature-compensated notch filter unit tracks the change of the switching frequency. The temperature-compensated notch filter unit 1212 outputs a first supply voltage VCC2 and a second supply voltage VCC3. The first supply voltage VCC2 and the second supply voltage VCC3 are transmitted to the second ceramic plate 1104 of the first ceramic cavity 110 through the second solder ball 151 and then to the frequency synthesis unit 111 through the second air-like coaxial cable 1312. The first power supply voltage VCC2 powers the frequency synthesizer 1111. The reference signal and control signal are transmitted to the frequency synthesizer 1111 after passing through the first solder ball 141, the first ceramic plate 1101, and the first substrate 1102. Under the control of the control signal, the frequency synthesizer 1111 controls the reference signal and then filters it through the loop filter 1112 to obtain the initial radio frequency signal. The second power supply voltage VCC3 powers the amplifier 1113. After the initial radio frequency signal is frequency-adjusted by the amplifier 1113 and the temperature compensation attenuator 1114, the target radio frequency signal is obtained. The target radio frequency signal is transmitted to other circuits after passing through the first substrate 1102, the first ceramic plate 1101, and the first solder ball 141.

[0052] like Figure 6As shown, the horizontal axis represents frequency, and the vertical axis represents suppression level, in dB (decibels). At a reference temperature of 25℃, the resonant frequency of a typical notch filter is designed to be 1200kHz, with a suppression level of -45dB. The maximum difference in inductance value of the selected notch filter with temperature varies by ±6%; the maximum difference in capacitance value with temperature varies by ±15%. At an operating temperature of +85℃, the suppression level of the typical notch filter for 1200kHz is -13dB. At an operating temperature of -55℃, the suppression level of the typical notch filter for 1200kHz is -16dB. The temperature-compensated notch filter unit 1212 in this application uses an inductor whose inductance value changes by a maximum of ±3% with temperature, and a capacitor whose capacitance value changes by a maximum of ±5% with temperature. Furthermore, the inductor and capacitor exhibit opposite temperature variations. Therefore, at an operating temperature of +85℃, the temperature-compensated notch filter unit 1212 achieves a 1200kHz suppression level of -33dB. At an operating temperature of -55℃, the suppression level of the temperature-compensated notch filter unit 1212 is -35dB.

[0053] The three-dimensional stacked frequency source provided by this invention is vertically interconnected in the vertical direction and achieves three-dimensional stacking and packaging through two ceramic cavities. Its volume can be reduced by 60% compared with the flat method, and the overall frequency source size can reach 21mm*16mm*6.5mm.

[0054] The three-dimensional stacked frequency source provided by this invention has the following technical effects: 1) Passive temperature tracking with no additional power consumption: Through the coordinated design of the temperature coefficients of inductor and capacitor materials, the temperature coefficient of the resonant frequency of the temperature-compensated notch filter unit 1212 is passively matched with the temperature coefficient of the switching frequency of the DC-DC converter unit 1211, achieving "self-tracking" without consuming any additional power.

[0055] 2) Stable filtering performance over a wide temperature range: Traditional notch filters may deviate from the resonant frequency at the reference temperature by more than 5% due to temperature drift within the range of -55℃ to 85℃. This invention can control the tracking error to within 0.5% and maintain the switching frequency suppression depth at more than 30dB across the entire temperature range.

[0056] 3) Simple structure and easy integration: The temperature-compensated notch filter unit 1212 is composed of only passive components, without the need for active control circuits such as temperature sensors and digital-to-analog converters. It has the advantages of high reliability and low cost, and it is easy to integrate the DC-DC conversion unit 1211 and the temperature-compensated notch filter unit 1212 into the same cavity.

[0057] 4) Simultaneous suppression of multiple harmonics: By cascading multiple first and second notch sub-units designed for different harmonics, the fundamental frequency, second harmonic, and third harmonic can be effectively suppressed simultaneously, thereby obtaining a high-purity power supply voltage.

[0058] 5) Compatible with existing manufacturing processes: Both composite magnetic core inductors and composite dielectric capacitors can be manufactured using existing mature materials and processes without adding extra manufacturing difficulty.

[0059] 6) High integration, small size and light weight: The stacked structure provided in this application allows the circuits in the upper and lower shells to be assembled and tested independently, which improves the manufacturability of the module and significantly reduces the size and weight of the product, fully meeting the needs of module miniaturization and lightweighting.

[0060] This invention also provides a method for fabricating a three-dimensional stacked frequency source, the method comprising: A first ceramic cavity 110 is prepared, and a frequency synthesis unit 111 is provided inside the first ceramic cavity 110; A second ceramic cavity 120 is prepared, and a DC-DC conversion unit 1211 and a temperature-compensated notch filter unit 1212 are provided inside the second ceramic cavity 120; The second ceramic cavity 120 is stacked on one side of the first ceramic cavity 110 and fixedly connected to achieve electrical connection between the frequency synthesis unit 111 and the temperature-compensated notch filter unit 1212. The frequency synthesis unit 111 is used to convert the reference signal into an initial radio frequency signal, and amplify and temperature compensate it to output the target radio frequency signal; the DC-DC conversion unit 1211 is used to convert the DC voltage into the power supply voltage to drive the frequency synthesis unit 111; the temperature-compensated notch filter unit 1212 is used to suppress the switching frequency generated by the DC-DC conversion unit 1211, and the resonant frequency of the temperature-compensated notch filter unit 1212 tracks the change of the switching frequency.

[0061] It should be mentioned that when the first ceramic cavity 110 and the second ceramic cavity 120 are assembled, the third ceramic plate 1201 in the second ceramic cavity 120 needs to be aligned and stacked with the second ceramic plate 1104 in the first ceramic cavity 110 to achieve electrical connection.

[0062] Specifically, the steps for preparing the first ceramic cavity 110 are as follows: sintering the first ceramic vertical wall 1103 onto the front side of the first ceramic plate 1101, sintering the first substrate 1102 onto the front side of the first ceramic plate 1101, integrating a first air-like coaxial 1311 onto the front side of the first ceramic plate 1101, integrating a second air-like coaxial 1312 onto the side of the first substrate 1102 opposite to the first ceramic plate 1101, sintering the frequency synthesis unit 111 onto the first substrate 1102, and sintering the second ceramic plate 1104 onto the first ceramic vertical wall 1103, with its position opposite to the first air-like coaxial 1311 and the second air-like coaxial 1312, to form a sealed cavity. The first air-like coaxial 1311 enables electrical connection between the second ceramic plate 1104 and the first ceramic plate 1101, and the second air-like coaxial 1312 enables electrical connection between the second ceramic plate 1104 and the first substrate 1102, thus completing the preparation of the first ceramic cavity 110.

[0063] The steps for preparing the second ceramic cavity 120 include: first, sintering the second ceramic vertical wall 1203 onto the front side of the third ceramic plate 1201; sintering the second substrate 1202 onto the front side of the third ceramic plate 1201; sintering the DC-DC conversion unit 1211 and the temperature-compensated notch filter unit 1212 onto the side of the second substrate 1202 away from the third ceramic plate 1201; and then sealing the metal cover plate 1204 parallel to the second ceramic vertical wall 1203 to complete the preparation of the second ceramic cavity 120.

[0064] The first ceramic cavity 110 and the second ceramic cavity 120 are stacked and arranged. The second ceramic cavity 120 is soldered to the front side of the first ceramic cavity 110 by multiple second solder balls 151 to obtain a three-dimensional stacked frequency source.

[0065] This invention also provides a temperature compensation design method for a temperature-compensated notch filter element, which is used to design a temperature-compensated notch filter element in a three-dimensional stacked frequency source as described above, including: Obtain the first frequency drift of the DC-DC converter unit as a function of temperature; The nominal resonant frequency of the temperature-compensated notch filter unit is determined based on the switching frequency and harmonic order of the DC-DC converter unit at the reference temperature. Select target inductors and target capacitors that meet the nominal resonant frequency so that the difference between the second frequency drift and the first frequency drift of the temperature-compensated notch filter unit as the nominal resonant frequency changes with temperature does not exceed a preset tracking error threshold.

[0066] Specifically, the first frequency drift Δf_ in the DC-DC converter unit 1211 as a function of temperature is obtained. clockBased on the switching frequency and harmonic order of the DC-DC converter 1211 at the reference temperature T0, the nominal resonant frequency of the temperature-compensated notch filter unit is calculated. The formula for calculating the nominal resonant frequency is: f_ notch_n =n×f_ sw ; where f_ sw f_ is the switching frequency at the reference temperature T0. notch_n Let n be the nominal resonant frequency, and n be the harmonic order of the output switching frequency of the DC-DC converter 1211. At a reference temperature T0, select the capacitance values ​​of the third capacitor, the resistance values ​​of the third resistor, the capacitance values ​​of the fourth capacitor, and the resistance values ​​of the fourth resistor to satisfy the nominal resonant frequency; this results in a second frequency drift Δ of the nominal resonant frequency of the temperature-compensated notch filter 1212 varying with temperature. The first frequency drift Δf_ of the DC-DC converter unit clock The difference between them does not exceed the preset tracking error threshold, that is: |Δ -Δf_clock|≤Δ, where Δ is a preset tracking error threshold. The difference between the resonant frequency of the temperature-compensated notch filter unit 1212 and the switching frequency of the DC-DC converter unit 1211 with temperature is less than the preset threshold, thereby realizing passive temperature tracking of the notch filter frequency to the switching frequency.

[0067] This invention provides a three-dimensional stacked frequency source, its fabrication method, and a temperature compensation design method. The frequency source includes a first ceramic cavity and a second ceramic cavity. The first ceramic cavity houses a frequency synthesis unit responsible for converting a reference signal into an initial radio frequency (RF) signal, amplifying it, and performing temperature compensation to ultimately output the target RF signal. The second ceramic cavity is stacked on the front of the first cavity and electrically connected to it. It houses a DC-DC converter and a temperature-compensated notch filter unit. The DC-DC converter converts DC voltage into the power supply voltage for the frequency synthesis unit, and the temperature-compensated notch filter unit suppresses the switching frequency generated by the DC-DC converter. This invention divides the frequency source into two parts according to functional requirements, each assembled in a different ceramic cavity. The stacked arrangement of the two cavities improves product integration, significantly reduces product size and weight, and meets the module's miniaturization and lightweight requirements. The circuits within the upper and lower housings can be independently assembled and tested, improving module manufacturability. Separate operation of the RF signal and DC voltage results in low signal crosstalk. In addition, the temperature-compensated notch filter unit achieves passive temperature tracking through the coordinated design of the temperature coefficients of the inductor and capacitor materials, without the need for additional power consumption. It effectively suppresses the switching frequency and harmonic interference generated by the DC-DC converter unit, further improving the spectral purity of the frequency source.

[0068] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A three-dimensional stacked frequency source, characterized in that, include: A first ceramic cavity is provided therein, wherein a frequency synthesis unit is configured to convert a reference signal into an initial radio frequency signal, amplify and temperature compensate the initial radio frequency signal, and output a target radio frequency signal. A second ceramic cavity is stacked on the front of the first ceramic cavity and electrically connected to the first ceramic cavity. The second ceramic cavity includes the DC-DC conversion unit and the temperature-compensated notch filter unit. The DC-DC conversion unit is used to convert DC voltage into the power supply voltage of the frequency synthesis unit. The temperature-compensated notch filter unit is used to suppress the switching frequency generated by the DC-DC conversion unit, and the resonant frequency of the temperature-compensated notch filter unit tracks the change of the switching frequency.

2. The three-dimensional stacked frequency source according to claim 1, characterized in that, The first ceramic cavity is also provided with a first air-type coaxial and a second air-type coaxial; The DC voltage is input from the bottom of the first ceramic cavity and is converted into the power supply voltage by the first air-like coaxial converter, the DC-DC converter unit and the temperature-compensated notch filter unit in sequence. The power supply voltage enters the first ceramic cavity through the second ceramic cavity and is transmitted to the frequency synthesis unit via the second air-like coaxial transmission. The frequency synthesis unit, driven by the power supply voltage, converts the reference signal into the target radio frequency signal, which is then output through the bottom of the first ceramic cavity.

3. The three-dimensional stacked frequency source according to claim 2, characterized in that, The first ceramic cavity includes: First ceramic plate; A first substrate is disposed on the front side of the first ceramic plate; The first ceramic vertical wall has a ring structure and is integrally formed on the edge of the front side of the first ceramic plate; The second ceramic plate is disposed on the side of the first ceramic vertical wall away from the first ceramic plate; The first ceramic plate, the first ceramic vertical wall, and the second ceramic plate together form a cavity structure.

4. The three-dimensional stacked frequency source according to claim 3, characterized in that, The first air-type coaxial arrangement is disposed between the first ceramic plate and the second ceramic plate, and the second air-type coaxial arrangement is disposed between the first substrate and the second ceramic plate.

5. The three-dimensional stacked frequency source according to claim 3, characterized in that, The frequency synthesis unit includes a frequency synthesizer, a loop filter, an amplifier, a temperature-compensated attenuator, and a first integrated sub-unit integrating a first resistor and a first capacitor. The frequency synthesizer, the loop filter, the amplifier, the temperature-compensated attenuator, and the first integrated sub-unit are disposed on the side of the first substrate away from the first ceramic plate. The frequency synthesis unit is electrically connected to the second air-like coaxial plate and the first ceramic plate through the first substrate.

6. The three-dimensional stacked frequency source according to claim 3, characterized in that, The second ceramic cavity includes: Third ceramic plate; The second substrate is disposed on the front side of the third ceramic plate; The second ceramic vertical wall has a ring structure and is integrally formed on the edge of the front of the third ceramic plate; A metal cover plate is disposed on the side of the second ceramic vertical wall opposite to the third ceramic plate; The third ceramic plate, the second ceramic vertical wall, and the metal cover plate together form a cavity structure.

7. The three-dimensional stacked frequency source according to claim 6, characterized in that, The second ceramic cavity also includes a second integrated sub-unit that integrates a second resistor and a second capacitor. The DC-DC conversion unit, the temperature-compensated notch filter unit, and the second integrated sub-unit are disposed on the side of the second substrate away from the third ceramic plate. The temperature-compensated notch filter unit is electrically connected to the third ceramic plate through the second substrate.

8. The three-dimensional stacked frequency source according to claim 1, characterized in that, The temperature-compensated notch filter unit includes multiple first notch filter sub-units and multiple second notch filter sub-units, with the first notch filter sub-units and the second notch filter sub-units being alternately arranged.

9. The three-dimensional stacked frequency source according to claim 8, characterized in that, The first notch filter sub-unit includes a third capacitor, a first inductor, and a third resistor. The first end of the first inductor is connected to the second end of the third resistor via the third capacitor. The first end of the third resistor is grounded. The second end of the first inductor is the positive terminal of the first notch filter sub-unit, and the first end of the third resistor is the negative terminal of the first notch filter sub-unit. The second notch filter sub-unit includes a fourth capacitor, a second inductor, and a fourth resistor. The first end of the second inductor is connected to the first end of the fourth capacitor. The second end of the fourth capacitor is connected to the first end of the fourth resistor. The second end of the second inductor is connected to the second end of the fourth resistor. The first end of the second inductor is the input terminal of the second notch filter sub-unit, and the second end of the second inductor is the output terminal of the second notch filter sub-unit. The first notch filter sub-unit is disposed between the two second notch filter sub-units.

10. The three-dimensional stacked frequency source according to claim 8, characterized in that, The temperature change characteristics of the first inductor are opposite to those of the third capacitor, and the temperature change characteristics of the second inductor are opposite to those of the fourth capacitor.

11. A method for fabricating a three-dimensional stacked frequency source, characterized in that, include: A first ceramic cavity is prepared, and a frequency synthesis unit is set in the first ceramic cavity; A second ceramic cavity is prepared, and the DC-DC conversion unit and the temperature-compensated notch filter unit are disposed within the second ceramic cavity; The second ceramic cavity is stacked on one side of the first ceramic cavity and fixedly connected to achieve electrical connection between the frequency synthesis unit and the temperature-compensated notch filter unit; The frequency synthesis unit is used to convert the reference signal into an initial radio frequency signal, and amplify and temperature compensate it to output the target radio frequency signal; the DC-DC conversion unit is used to convert the DC voltage into the power supply voltage for the operation of the frequency synthesis unit; the temperature-compensated notch filter unit is used to suppress the switching frequency generated by the DC-DC conversion unit, and the resonant frequency of the temperature-compensated notch filter unit tracks the change of the switching frequency.

12. A temperature compensation design method for a temperature-compensated notch filter element, characterized in that, Designing a temperature-compensated notch filter element in a three-dimensional stacked frequency source as described in any one of claims 1 to 10, comprising: Obtain the first frequency drift of the DC-DC converter unit as a function of temperature; The nominal resonant frequency of the temperature-compensated notch filter unit is determined based on the switching frequency and harmonic order of the DC-DC conversion unit at the reference temperature. Select a target inductor and a target capacitor that satisfy the nominal resonant frequency so that the difference between the second frequency drift and the first frequency drift of the nominal resonant frequency of the temperature-compensated notch filter unit as the nominal resonant frequency changes with temperature does not exceed a preset tracking error threshold.

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