A distributed LC resonant network Ku-band on-chip tunable low-pass filter

Abstract

This invention discloses a distributed LC resonant network Ku-band on-chip tunable low-pass filter. The filter includes an RF signal entering from port 1, flowing sequentially through five high-impedance microstrip lines. These five transmission lines are equivalent to five series inductors at high frequencies. At the nodes of adjacent microstrip lines, four high-impedance microstrip lines and four sets of capacitor switch arrays are connected in parallel. Each high-impedance microstrip line with a series capacitor switch array forms a parallel resonant circuit to ground. Two low-impedance open-circuit microstrip lines are connected in parallel at the input and output ports, respectively. The parasitic capacitance generated at high frequencies is used for impedance matching of the filter. The overall topology is equivalent to an eleventh-order Chebyshev low-pass filter. Compared to existing tunable on-chip low-pass filters, this invention's low-pass filter achieves adjustable cutoff frequency across the entire Ku-band, providing a wide tuning range while ensuring excellent overall performance such as high frequency selectivity, low loss, sufficient out-of-band rejection, and miniaturization.

Description

Technical Field

[0001] This invention relates to the fields of microwave communication and radio frequency integrated circuit technology, and in particular to a distributed LC resonant network Ku-band on-chip tunable low-pass filter. Background Technology

[0002] The Ku band, as the core spectrum window for satellite communication, phased array radar, and airborne data links, places stringent demands on the integration density and dynamic reconfiguration capabilities of the radio frequency front-end. The low-pass filter, located at the end of the receiver link, plays a crucial role in suppressing local oscillator leakage, image noise, and adjacent band interference. The reconfigurability of its cutoff frequency directly determines the system's spectrum adaptability in multi-band and multi-mode scenarios.

[0003] However, most existing Ku-band on-chip tunable low-pass filters are based on varactor diodes for tuning. Due to limitations in Q value and parasitic coupling effects, they generally face problems such as narrow tuning bandwidth, insufficient out-of-band suppression, high loss, and large area. They are difficult to meet the comprehensive requirements of modern wireless communication systems for tunable filters, which require a wide tuning range, small size, low loss, high frequency selectivity, and out-of-band suppression.

[0004] To address the aforementioned shortcomings, this paper proposes an on-chip tunable low-pass filter based on a distributed LC resonant network, providing a high-performance and miniaturized low-pass filtering solution for Ku-band application systems. Summary of the Invention

[0005] The technical problem this invention aims to solve is to provide a distributed LC resonant network Ku-band on-chip tunable low-pass filter that simultaneously possesses characteristics such as wide tuning range, high frequency selectivity, low loss, sufficient out-of-band rejection, and miniaturization. At the same time, this invention is expected to promote the development of Ku-band communication technology and provide a new solution for the design of cutoff frequency tunable low-pass filters in wireless communication systems.

[0006] To address the aforementioned technical problems, this invention discloses a distributed LC resonant network Ku-band on-chip tunable low-pass filter, comprising port 1, port 2, capacitor switch array 1, capacitor switch array 2, capacitor switch array 3, and capacitor switch array 4. The capacitor switch array 1, capacitor switch array 2, capacitor switch array 3, and capacitor switch array 4 are connected through high-impedance microstrip lines, low-impedance microstrip lines, capacitors, switching transistors, and resistors. Port 1 is used to input radio frequency signals; Port 2 is used to output radio frequency signals.

[0007] As an optional implementation, in this embodiment of the invention, the distributed LC resonant network Ku-band on-chip tunable low-pass filter includes nine high-impedance microstrip lines, two low-impedance microstrip lines, twenty-two capacitors, twenty switches, and twenty-four... Resistors and twenty power supply ports; The nine high-impedance microstrip lines include , , , , , , , and ; The two low-impedance microstrip lines include and ; The twenty-two capacitors include , , , , , , , , , , , , , , , , , , , , and ; The twenty switching transistors include , , , , , , , , , , , , , , , , , , and ; The twenty-four The resistors include , , , , , , , , , , , , , , , , , , , , , , and ; The twenty power supply ports include power supply port 1, power supply port 2, power supply port 3, power supply port 4, power supply port 5, power supply port 6, power supply port 7, power supply port 8, power supply port 9, power supply port 10, power supply port 11, power supply port 12, power supply port 13, power supply port 14, power supply port 15, power supply port 16, power supply port 17, power supply port 18, power supply port 19 and power supply port 20.

[0008] As an optional implementation, in this embodiment of the invention, the high-impedance microstrip line , , , , They are connected sequentially along the main road; The high-impedance microstrip line The high-impedance microstrip line is connected to port 1. Connect to port 2; The capacitor Parallel to high impedance microstrip line On both sides of the capacitor Parallel to high impedance microstrip line Both sides; The resistor Parallel to high impedance microstrip line and high impedance microstrip lines The connection point; The resistor Parallel to high impedance microstrip line and high impedance microstrip lines The connection point; The resistor Parallel to high impedance microstrip line and high impedance microstrip lines The connection point; The resistor Parallel to high impedance microstrip line and high impedance microstrip lines The connection point.

[0009] As an optional implementation, in this embodiment of the invention, the high-impedance microstrip line One end is connected in parallel to a high-impedance microstrip line and high impedance microstrip lines At the connection point, the other end is connected to five switching transistors respectively. , , , , The source phases are connected in series; Five switching transistors , , , , The drain of each capacitor is connected in series with five grounding capacitors. , , , , ; The high-impedance microstrip line One end is connected in parallel to a high-impedance microstrip line and high impedance microstrip lines At the connection point, the other end is connected to five switching transistors respectively. , , , , Source-to-line connection; Five switching transistors , , , , The drain of each capacitor is connected in series with five grounding capacitors. , , , , .

[0010] As an optional implementation, in this embodiment of the invention, the high-impedance microstrip line One end is connected in parallel to a high-impedance microstrip line and high impedance microstrip lines At the connection point, the other end is connected to five switching transistors respectively. , , , , The source phases are connected in series; Five switching transistors , , , , The drain of each capacitor is connected in series with five grounding capacitors. , , , , ; High impedance microstrip line One end is connected in parallel to a high-impedance microstrip line and high impedance microstrip lines At the connection point, the other end is connected to five switching transistors respectively. , , , and The source phases are connected in series; Five switching transistors , , , and The drain of each capacitor is connected in series with five grounding capacitors. , , , and .

[0011] As an optional implementation, in this embodiment of the invention, the low-impedance open-circuit transmission line Connected in parallel to port 1 and the high-impedance transmission line The connection point; The low impedance open-circuit transmission line Connected in parallel to port 2 and the high-impedance transmission line The connection point.

[0012] As an optional implementation, in this embodiment of the invention, the switching transistor... , , , , With the capacitor , , , , Forming a capacitor switch array 1; The switching transistor , , , , With the capacitor , , , , Forming a capacitor switch array 2; The switching transistor , , , , With the capacitor , , , , Forming a capacitor switch array 3; The switching transistor , , , and With the capacitor , , , and Form a capacitor switch array 4.

[0013] As an optional implementation, in this embodiment of the invention, the switching transistor... , , , The gates are connected in series with resistors. , , , Then connect to power supply port 1, power supply port 6, power supply port 11, and power supply port 16 respectively; The switching transistor , , , The gates are connected in series with resistors. , , , Then connect to power supply port 2, power supply port 7, power supply port 12, and power supply port 17 respectively.

[0014] As an optional implementation, in this embodiment of the invention, the switching transistor... , , , The gates are connected in series with resistors. , , , Then connect to power supply port 3, power supply port 8, power supply port 13, and power supply port 18 respectively; The switching transistor , , , The gates are connected in series with resistors. , , , Then connect to power supply port 4, power supply port 9, power supply port 14, and power supply port 19 respectively; The switching transistor , , , The gates are connected in series with resistors. , , , Then it is connected to power supply port 5, power supply port 10, power supply port 15 and power supply port 20 respectively.

[0015] As an optional implementation, in this embodiment of the invention, the high-impedance microstrip line When connected in series with capacitor switch array 1 to form an LC resonator, a transmission zero is generated outside the high-frequency band; The high-impedance microstrip line When connected in series with capacitor switch array 2, an LC resonator is formed, generating a transmission zero outside the high-frequency band; The high-impedance microstrip line When connected in series with capacitor switch array 3, an LC resonator is formed, generating a transmission zero outside the high-frequency band; The high-impedance microstrip line When connected in series with capacitor switch array 4, an LC resonator is formed, generating a transmission zero outside the high-frequency band; The capacitor and Connected in parallel to high-impedance microstrip lines and Above, two transmission zeros are generated at high frequencies.

[0016] Compared with the prior art, the embodiments of the present invention have the following beneficial effects: This invention discloses a distributed LC resonant network Ku-band on-chip tunable low-pass filter. Compared with existing tunable on-chip low-pass filters, the low-pass filter obtained by this invention realizes the function of adjustable cutoff frequency throughout the entire Ku-band, with a wide tuning range. At the same time, it ensures that the filter has high frequency selectivity, low loss, sufficient out-of-band rejection and miniaturization, resulting in excellent overall filter performance. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a distributed LC resonant network Ku-band on-chip tunable low-pass filter disclosed in an embodiment of the present invention; Figure 2 This is a schematic diagram of another distributed LC resonant network Ku-band on-chip tunable low-pass filter disclosed in an embodiment of the present invention; Figures 3-18 These are simulation performance diagrams of individual states 1 to 16 of the layout of the Ku-band on-chip tunable low-pass filter based on a distributed LC resonant network disclosed in this embodiment of the invention. Figure 19 This is a simulation diagram of the overall performance of the layout of the Ku-band on-chip tunable low-pass filter based on a distributed LC resonant network disclosed in an embodiment of the present invention. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, apparatus, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0021] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0022] In all embodiments of the present invention, the variables involved in all computational expressions or mathematical functions are dimensionless before calculation. The values ​​of the independent variables in all computational expressions or mathematical functions in these embodiments conform to the reasonable requirements of the input range of the computational expression or mathematical function, ensuring that the computational expression or mathematical function can be calculated smoothly without violating physical laws or mathematical rules.

[0023] This invention discloses a distributed LC resonant network Ku-band on-chip tunable low-pass filter. The filter includes an RF signal entering from port 1, flowing sequentially through five high-impedance microstrip lines. These five transmission lines are equivalent to five series inductors at high frequencies. At the nodes of adjacent microstrip lines, four high-impedance microstrip lines and four sets of capacitor switch arrays are connected in parallel. Each high-impedance microstrip line connected in series with the capacitor switch array forms a parallel resonant circuit to ground. Two low-impedance open-circuit microstrip lines are connected in parallel at the input and output ports, respectively. The parasitic capacitance generated at high frequencies is used for impedance matching of the filter. The overall topology is equivalent to an eleventh-order Chebyshev low-pass filter. Compared to existing tunable on-chip low-pass filters, this invention's low-pass filter achieves adjustable cutoff frequency across the entire Ku-band, providing a wide tuning range while ensuring excellent overall performance such as high frequency selectivity, low loss, sufficient out-of-band rejection, and miniaturization. Detailed descriptions follow.

[0024] Example 1 Please see Figure 1 , Figure 1 This is a schematic diagram of a distributed LC resonant network Ku-band on-chip tunable low-pass filter disclosed in an embodiment of the present invention. Figure 1 The described distributed LC resonant network Ku-band on-chip tunable low-pass filter is applied in microwave communication and radio frequency integrated circuit technology, and the embodiments of this invention are not limited thereto. Figure 1 As shown, the distributed LC resonant network Ku-band on-chip tunable low-pass filter includes port 1, port 2, capacitor switch array 1, capacitor switch array 2, capacitor switch array 3, and capacitor switch array 4. The capacitor switch array 1, capacitor switch array 2, capacitor switch array 3, and capacitor switch array 4 are connected through high-impedance microstrip lines, low-impedance microstrip lines, capacitors, switching transistors, and resistors. Port 1 is used to input radio frequency signals; Port 2 is used to output radio frequency signals.

[0025] Optionally, the distributed LC resonant network Ku-band on-chip tunable low-pass filter includes nine high-impedance microstrip lines, two low-impedance microstrip lines, twenty-two capacitors, twenty switches, and twenty-four... Resistors and twenty power supply ports; The nine high-impedance microstrip lines include , , , , , , , and ; The two low-impedance microstrip lines include and ; The twenty-two capacitors include , , , , , , , , , , , , , , , , , , , , and ; The twenty switching transistors include , , , , , , , , , , , , , , , , , , and ; The twenty-four The resistors include , , , , , , , , , , , , , , , , , , , , , , and ; The twenty power supply ports include power supply port 1, power supply port 2, power supply port 3, power supply port 4, power supply port 5, power supply port 6, power supply port 7, power supply port 8, power supply port 9, power supply port 10, power supply port 11, power supply port 12, power supply port 13, power supply port 14, power supply port 15, power supply port 16, power supply port 17, power supply port 18, power supply port 19 and power supply port 20.

[0026] Optionally, the high-impedance microstrip line , , , , They are connected sequentially along the main road; The high-impedance microstrip line The high-impedance microstrip line is connected to port 1. Connect to port 2; The capacitor Parallel to high impedance microstrip line On both sides of the capacitor Parallel to high impedance microstrip line Both sides; The resistor Parallel to high impedance microstrip line and high impedance microstrip lines The connection point; The resistor Parallel to high impedance microstrip line and high impedance microstrip lines The connection point; The resistor Parallel to high impedance microstrip line and high impedance microstrip lines The connection point; The resistor Parallel to high impedance microstrip line and high impedance microstrip lines The connection point.

[0027] Optionally, the high-impedance microstrip line One end is connected in parallel to a high-impedance microstrip line and high impedance microstrip lines At the connection point, the other end is connected to five switching transistors respectively. , , , , The source phases are connected in series; Five switching transistors , , , , The drain of each capacitor is connected in series with five grounding capacitors. , , , , ; The high-impedance microstrip line One end is connected in parallel to a high-impedance microstrip line and high impedance microstrip lines At the connection point, the other end is connected to five switching transistors respectively. , , , , Source-to-line connection; Five switching transistors , , , , The drain of each capacitor is connected in series with five grounding capacitors. , , , , .

[0028] Optionally, the high-impedance microstrip line One end is connected in parallel to a high-impedance microstrip line and high impedance microstrip lines At the connection point, the other end is connected to five switching transistors respectively. , , , , The source phases are connected in series; Five switching transistors , , , , The drain of each capacitor is connected in series with five grounding capacitors. , , , , ; High impedance microstrip line One end is connected in parallel to a high-impedance microstrip line and high impedance microstrip lines At the connection point, the other end is connected to five switching transistors respectively. , , , and The source phases are connected in series; Five switching transistors , , , and The drain of each capacitor is connected in series with five grounding capacitors. , , , and .

[0029] Optionally, the low-impedance open-circuit transmission line Connected in parallel to port 1 and the high-impedance transmission line The connection point; The low impedance open-circuit transmission line Connected in parallel to port 2 and the high-impedance transmission line The connection point.

[0030] Optionally, the switching transistor , , , , With the capacitor , , , , Forming a capacitor switch array 1; The switching transistor , , , , With the capacitor , , , , Forming a capacitor switch array 2; The switching transistor , , , , With the capacitor , , , , Forming a capacitor switch array 3; The switching transistor , , , and With the capacitor , , , and Form a capacitor switch array 4.

[0031] Optionally, the switching transistor , , , The gates are connected in series with resistors. , , , Then connect to power supply port 1, power supply port 6, power supply port 11, and power supply port 16 respectively; The switching transistor , , , The gates are connected in series with resistors. , , , Then connect to power supply port 2, power supply port 7, power supply port 12, and power supply port 17 respectively.

[0032] Optionally, the switching transistor , , , The gates are connected in series with resistors. , , , Then connect to power supply port 3, power supply port 8, power supply port 13, and power supply port 18 respectively; The switching transistor , , , The gates are connected in series with resistors. , , , Then connect to power supply port 4, power supply port 9, power supply port 14, and power supply port 19 respectively; The switching transistor , , , The gates are connected in series with resistors. , , , Then it is connected to power supply port 5, power supply port 10, power supply port 15 and power supply port 20 respectively.

[0033] Optionally, the high-impedance microstrip line When connected in series with capacitor switch array 1 to form an LC resonator, a transmission zero is generated outside the high-frequency band; The high-impedance microstrip line When connected in series with capacitor switch array 2, an LC resonator is formed, generating a transmission zero outside the high-frequency band; The high-impedance microstrip line When connected in series with capacitor switch array 3, an LC resonator is formed, generating a transmission zero outside the high-frequency band; The high-impedance microstrip line When connected in series with capacitor switch array 4, an LC resonator is formed, generating a transmission zero outside the high-frequency band; The capacitor and Connected in parallel to high-impedance microstrip lines and Above, two transmission zeros are generated at high frequencies.

[0034] Example 2 Please see Figure 2 , Figure 2 This is a schematic diagram of another distributed LC resonant network Ku-band on-chip tunable low-pass filter disclosed in an embodiment of the present invention. Figure 2 The described distributed LC resonant network Ku-band on-chip tunable low-pass filter is applied in microwave communication and radio frequency integrated circuit technology, and the embodiments of this invention are not limited thereto. Figure 2 As shown, it mainly includes two ports (port 1 and port 2), five power supply ports (power supply port 1, power supply port 2, power supply port 3, power supply port 4, and power supply port 5), and nine high-impedance microstrip lines. , , , , , , , , Two low-impedance microstrip lines ( , ), twenty-two capacitors ( , , , , , , , , , , , , , , , , , , , , , ), twenty switching transistors ( , , , , , , , , , , , , , , , , , , , ), twenty-four resistance ( and ).

[0035] High impedance microstrip line , , , , They are connected in series on the main line, and the metal wires are... Connected to port 1, metal wire Connect to port 2. Capacitor. Parallel to microstrip line On both sides of the capacitor Parallel to microstrip line On both sides. Four grounding resistors. Connected in parallel respectively and Connection point and Connection point and Connection point and The connection point.

[0036] High impedance microstrip line One end is connected in parallel to the metal wire and At the connection point, the other end is connected to five switching transistors respectively. , , , , The sources of the five transistors are connected in series, and the drains of the five transistors are connected in series with five grounding capacitors. , , , , Similarly, high-impedance microstrip lines One end is connected in parallel to the metal wire and At the connection point, the other end is connected to five switching transistors respectively. , , , , The sources of the five transistors are connected in series, and the drains of the five transistors are connected in series with five grounding capacitors. , , , , High-impedance microstrip lines One end is connected in parallel to the metal wire and At the connection point, the other end is connected to five switching transistors respectively. , , , , The sources of the five transistors are connected in series, and the drains of the five transistors are connected in series with five grounding capacitors. , , , , High-impedance microstrip lines One end is connected in parallel to the metal wire and At the connection point, the other end is connected to five switching transistors respectively. , , , , The sources of the five transistors are connected in series, and the drains of the five transistors are connected in series with five grounding capacitors. , , , , ).

[0037] Low impedance open circuit transmission line Connected in parallel to port 1 and the high-impedance transmission line At the connection point, low impedance open-circuit transmission line Connected in parallel to port 2 and the high-impedance transmission line The connection point.

[0038] Switching transistor , , , , With capacitor , , , , This forms capacitor switch array 1, with switching transistors... , , , , With capacitor , , , , This forms a capacitor switch array 2, with switching transistors... , , , , With capacitor , , , , This forms a capacitor switch array 3. Switching transistors , , , , With capacitor , , , , This forms a capacitor switch array 4.

[0039] Switching transistor , , , A resistor is connected in series with each gate ( Then connect to power supply port 1, switching transistor , , , A resistor is connected in series with each gate ( Then connect to power supply port 2, switching transistor , , , A resistor is connected in series with each gate ( Then connect to power supply port 3, switching transistor , , , A resistor is connected in series with each gate ( Then connect to power supply port 4, switching transistor , , , A resistor is connected in series with each gate ( Then connect it to power supply port 5. This allows control of twenty switching transistors by directly supplying power to the five power supply ports.

[0040] Port 1 is connected to an external RF input signal, port 2 is connected to an external RF output signal, and power supply ports 1, 2, 3, 4, and 5 are connected to an external DC control voltage.

[0041] This distributed LC resonant network Ku-band on-chip tunable low-pass filter allows RF signals to enter from port 1 and flow sequentially through five high-impedance microstrip lines. , , , , These five transmission lines are equivalent to five series inductors at high frequencies. At the nodes of adjacent microstrip lines, four high-impedance microstrip lines are connected in parallel. , , , ) and four sets of capacitor switch arrays (capacitor switch array 1, capacitor switch array 2, capacitor switch array 3, and capacitor switch array 4), each high-impedance microstrip line connected in series with the capacitor switch array forms a parallel resonant circuit to ground. Simultaneously, two low-impedance open-circuit microstrip lines ( , The components are connected in parallel at the input and output ports, respectively. The parasitic capacitance generated at high frequencies is used to match the impedance of the filter. Therefore, the overall topology is equivalent to an eleventh-order Chebyshev low-pass filter.

[0042] High impedance microstrip line on the branch With switching transistor , , , , With capacitor , , , , The switched capacitor array consists of one phase connected in series, due to the high impedance microstrip line At high frequencies, it is equivalent to an inductor, therefore When connected in series with the capacitor switch array 1, an LC resonator is formed, thereby generating a transmission zero outside the high-frequency band.

[0043] Similarly, high-impedance microstrip lines on the branches The high-impedance microstrip line on the branch is connected in series with the capacitor switch array 2. The high-impedance microstrip line on the branch is connected in series with the capacitor switch array 3. When connected in series with the capacitor switch array 4, they all form LC resonators, and correspondingly generate three transmission zeros outside the high-frequency band.

[0044] In addition, capacitors and For parallel connection to a high impedance microstrip line and Above, two transmission zeros are generated at high frequencies.

[0045] In summary, the proposed low-pass filter has six transmission zeros. Two of these zeros are fixed in position, while the positions of the other four are determined by the overall capacitance values ​​of capacitor switch arrays 1, 2, 3, and 4. Therefore, the transmission zeros can be adjusted using an external DC control voltage connected to the power supply port, thereby controlling the cutoff frequency. Simultaneously, the six transmission zeros are evenly distributed out-of-band, ensuring that the filter maintains high frequency selectivity and sufficient out-of-band rejection while controlling the cutoff frequency.

[0046] The filter's cutoff frequency, frequency selectivity, transmission zero, and out-of-band rejection are mainly controlled by capacitor switch arrays 1, 2, 3, 4, and 5. In-band matching is primarily achieved using high-impedance microstrip lines. , , , , , , , , , and low impedance microstrip lines , To take control.

[0047] Example 3 This embodiment provides a design example of the present invention implemented using Win Semiconductors' GaAs PHEMT technology, and its circuit schematic is shown below. Figure 2 As shown. The simulation software used is Advanced Design System 2021, and its layout simulation results are as follows. Figures 3 to 19 As shown.

[0048] Within the Ku-band, different cutoff frequencies of the filter are achieved by adjusting the DC control voltage at the power supply port, resulting in sixteen different operating states. Detailed performance specifications are as follows: Figures 3-18 As shown. From state 1 to state 16, the corresponding cutoff frequencies are respectively Figure 3-12 0.55GHz, Figure 4-12 .97GHz, Figure 5-13 .39GHz, Figure 6-13 .81GHz, Figure 7-14 .23GHz, Figure 8-14 .65GHz, Figure 9-15 0.07GHz, Figure 10-15 0.49GHz, Figure 11-15 .91GHz, Figure 12-16 .33GHz, Figure 13-16 0.75GHz, Figure 14-17 .17GHz, Figure 15-17 0.59GHz, Figure 16-18 .01GHz, Figure 17-18 0.43GHz, Figure 18-18 0.85GHz. The in-band return loss of states 1-3 is greater than 9dB, the in-band return loss of states 4-12 is approximately 10dB, and the in-band return loss of states 13-16 is greater than 15dB, indicating good overall in-band matching of the filter. The loss at each cutoff frequency in each of the sixteen states is less than 9.0dB, and the loss at 10GHz is generally around 1.2dB, indicating good overall in-band flatness. Meanwhile, all sixteen states exhibit excellent frequency selectivity and sufficient out-of-band suppression. For each of the sixteen states, the out-of-band signal suppression reaches over 45dB in the ranges of 14.5-26GHz, 15.1-26GHz, 15.6-26GHz, 16.1-26GHz, 16.6-26GHz, 17.4-26GHz, 17.8-26GHz, 18.3-26GHz, 18.8-26GHz, 19.1-26GHz, 19.6-26GHz, 20.2-26GHz, 20.7-26GHz, 21.1-26GHz, 21.5-26GHz, and 21.9-26GHz, respectively.

[0049] Figure 19 The effect of combining sixteen different cutoff frequencies is shown, demonstrating that the filter can effectively achieve adjustable cutoff frequencies within the Ku-band. Layout simulation results indicate that the proposed tunable on-chip low-pass filter exhibits excellent overall performance. The physical dimensions of this on-chip filter are 1.6 mm × 0.85 mm.

[0050] Compared to existing tunable on-chip low-pass filters, the low-pass filter obtained by this invention achieves adjustable cutoff frequency across the entire Ku band, with a wide tuning range. At the same time, it ensures that the filter has high frequency selectivity, low loss, sufficient out-of-band rejection, and miniaturization, resulting in excellent overall filter performance.

[0051] The key point of this invention is to utilize the five high-impedance microstrip lines on the main path as equivalent series inductors, and to connect two low-impedance open-circuit microstrip lines and four sets of ground capacitor arrays connected in series with high-impedance microstrip lines in parallel at the nodes to form a distributed LC resonant network. This generates multiple transmission zeros, and the capacitor value is configured in real time by controlling the switching transistors with DC voltage. This enables an on-chip low-pass filter with an adjustable cutoff frequency in the Ku band, while ensuring that the filter has characteristics such as wide tuning range, high frequency selectivity, low loss, sufficient out-of-band rejection, and small size.

[0052] This invention achieves a low-pass filter response with multiple adjustable transmission zeros by connecting five high-impedance microstrip lines in series on the main line, combining four high-impedance transmission lines, four sets of capacitor switch arrays, and two low-impedance open-circuit microstrip lines in parallel on the branch lines. The overall circuit is equivalent to an eleventh-order Chebyshev low-pass filter.

[0053] This invention utilizes the highly distributed parameters of microstrip lines at high frequencies, effectively transforming them into high-Q inductors without requiring lumped inductors, thus reducing losses and area. Furthermore, the self-resonant frequency of the equivalent inductor is far from the operating frequency band, minimizing the impact of parasitic effects at high frequencies.

[0054] This invention utilizes multiple sets of high-impedance microstrip lines on the road ( , , , When the capacitor switch array (capacitor switch array 1, capacitor switch array 2, capacitor switch array 3, capacitor switch array 4) is connected in series, it is equivalent to a series LC resonator. When the frequency reaches its resonant frequency, a notch effect is generated, which generates multiple transmission zeros outside the band, greatly improving the overall out-of-band rejection of the filter.

[0055] The invention relates to a low-impedance open-circuit microstrip line connected in parallel at the input and output ports. , The parasitic capacitance generated at high frequencies is used to adjust the input-output matching of the filter, ensuring that the filter has good impedance matching.

[0056] This invention relates to high-impedance microstrip lines ( , , , ) and low impedance microstrip lines ( , According to the actual equivalent circuit and the overall layout requirements of the chip, various microstrip lines of different shapes can be constructed by autonomous winding, making the layout flexible and changeable, which is conducive to reducing the overall area of ​​the chip and realizing chip miniaturization.

[0057] The four large resistors connected in parallel on the main line of this invention These are used to balance the potential of the switching transistors in the four sets of capacitor switch arrays, so that the potentials at both ends of the switching transistors are zero, ensuring the normal operation of the switching transistors and improving the stability of the filter.

[0058] The device embodiments described above are merely illustrative. The modules described as separate components may or may not be physically separate, and the components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0059] Through the detailed description of the above embodiments, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, including read-only memory (ROM), random access memory (RAM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), one-time programmable read-only memory (OTPROM), electrically-erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disc storage, disk storage, magnetic tape storage, or any other computer-readable medium that can be used to carry or store data.

[0060] Finally, it should be noted that the distributed LC resonant network Ku-band on-chip tunable low-pass filter disclosed in the embodiments of the present invention is only a preferred embodiment of the present invention and is only used to illustrate the technical solutions of the present invention, not to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A distributed LC resonant network Ku-band on-chip tunable low-pass filter, characterized in that, Includes port 1, port 2, capacitor switch array 1, capacitor switch array 2, capacitor switch array 3, and capacitor switch array 4; The capacitor switch array 1, capacitor switch array 2, capacitor switch array 3, and capacitor switch array 4 are connected through high-impedance microstrip lines, low-impedance microstrip lines, capacitors, switching transistors, and resistors. Port 1 is used to input radio frequency signals; Port 2 is used to output radio frequency signals.

2. The distributed LC resonant network Ku-band on-chip tunable low-pass filter according to claim 1, characterized in that, It includes nine high-impedance microstrip lines, two low-impedance microstrip lines, twenty-two capacitors, twenty switching transistors, and twenty-four... Resistors and twenty power supply ports; The nine high-impedance microstrip lines include , , , , , , , and ; The two low-impedance microstrip lines include and ; The twenty-two capacitors include , , , , , , , , , , , , , , , , , , , , and ; The twenty switching transistors include , , , , , , , , , , , , , , , , , , and ; The twenty-four The resistors include , , , , , , , , , , , , , , , , , , , , , , and ; The twenty power supply ports include power supply port 1, power supply port 2, power supply port 3, power supply port 4, power supply port 5, power supply port 6, power supply port 7, power supply port 8, power supply port 9, power supply port 10, power supply port 11, power supply port 12, power supply port 13, power supply port 14, power supply port 15, power supply port 16, power supply port 17, power supply port 18, power supply port 19 and power supply port 20.

3. The distributed LC resonant network Ku-band on-chip tunable low-pass filter according to claim 2, characterized in that, The high-impedance microstrip line , , , , They are connected sequentially along the main road; The high-impedance microstrip line The high-impedance microstrip line is connected to port 1. Connect to port 2; The capacitor Parallel to high impedance microstrip line On both sides of the capacitor Parallel to high impedance microstrip line Both sides; The resistor Parallel to high impedance microstrip line and high impedance microstrip lines The connection point; The resistor Parallel to high impedance microstrip line and high impedance microstrip lines The connection point; The resistor Parallel to high impedance microstrip line and high impedance microstrip lines The connection point; The resistor Parallel to high impedance microstrip line and high impedance microstrip lines The connection point.

4. The distributed LC resonant network Ku-band on-chip tunable low-pass filter according to claim 2, characterized in that, The high-impedance microstrip line One end is connected in parallel to a high-impedance microstrip line and high impedance microstrip lines At the connection point, the other end is connected to five switching transistors respectively. , , , , The source phases are connected in series; Five switching transistors , , , , The drain of each electrode is connected in series with five grounding capacitors. , , , , ; The high-impedance microstrip line One end is connected in parallel to a high-impedance microstrip line and high impedance microstrip lines At the connection point, the other end is connected to five switching transistors respectively. , , , , Source-to-line connection; Five switching transistors , , , , The drain of each electrode is connected in series with five grounding capacitors. , , , , .

5. The distributed LC resonant network Ku-band on-chip tunable low-pass filter according to claim 2, characterized in that, The high-impedance microstrip line One end is connected in parallel to a high-impedance microstrip line and high impedance microstrip lines At the connection point, the other end is connected to five switching transistors respectively. , , , , The source phases are connected in series; Five switching transistors , , , , The drain of each electrode is connected in series with five grounding capacitors. , , , , ; High impedance microstrip line One end is connected in parallel to a high-impedance microstrip line and high impedance microstrip lines At the connection point, the other end is connected to five switching transistors respectively. , , , and The source phases are connected in series; Five switching transistors , , , and The drain of each electrode is connected in series with five grounding capacitors. , , , and .

6. The distributed LC resonant network Ku-band on-chip tunable low-pass filter according to claim 2, characterized in that, The low impedance open-circuit transmission line Connected in parallel to port 1 and the high-impedance transmission line The connection point; The low impedance open-circuit transmission line Connected in parallel to port 2 and the high-impedance transmission line The connection point.

7. The distributed LC resonant network Ku-band on-chip tunable low-pass filter according to claim 2, characterized in that, The switching transistor , , , , With the capacitor , , , , Forming a capacitor switch array 1; The switching transistor , , , , With the capacitor , , , , Forming a capacitor switch array 2; The switching transistor , , , , With the capacitor , , , , Forming a capacitor switch array 3; The switching transistor , , , and With the capacitor , , , and Form a capacitor switch array 4.

8. The distributed LC resonant network Ku-band on-chip tunable low-pass filter according to claim 2, characterized in that, The switching transistor , , , The gates are connected in series with resistors , , , Then connect to power supply port 1, power supply port 6, power supply port 11, and power supply port 16 respectively; The switching transistor , , , The gates are connected in series with resistors , , , Then connect to power supply port 2, power supply port 7, power supply port 12, and power supply port 17 respectively.

9. The distributed LC resonant network Ku-band on-chip tunable low-pass filter according to claim 2, characterized in that, The switching transistor , , , The gates are connected in series with resistors , , , Then connect to power supply port 3, power supply port 8, power supply port 13, and power supply port 18 respectively; The switching transistor , , , The gates are connected in series with resistors , , , Then connect to power supply port 4, power supply port 9, power supply port 14, and power supply port 19 respectively; The switching transistor , , , The gates are connected in series with resistors , , , Then it is connected to power supply port 5, power supply port 10, power supply port 15 and power supply port 20 respectively.

10. The distributed LC resonant network Ku-band on-chip tunable low-pass filter according to claim 2, characterized in that, The high-impedance microstrip line When connected in series with capacitor switch array 1 to form an LC resonator, a transmission zero is generated outside the high-frequency band; The high-impedance microstrip line When connected in series with capacitor switch array 2, an LC resonator is formed, generating a transmission zero outside the high-frequency band; The high-impedance microstrip line When connected in series with capacitor switch array 3, an LC resonator is formed, generating a transmission zero outside the high-frequency band; The high-impedance microstrip line When connected in series with capacitor switch array 4, an LC resonator is formed, generating a transmission zero outside the high-frequency band; The capacitor and Connected in parallel to high-impedance microstrip lines and Above, two transmission zeros are generated at high frequencies.

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