Bipolar attenuator adopting specially packaged PIN diode

Abstract

The utility model discloses a bipolar attenuator adopting a specifically packaged PIN diode, relates to the technical field of attenuators, and solves the technical problem that a traditional attenuator is difficult to consider both the size and the performance at the same time. The circuit comprises a positive-phase attenuation circuit and a negative-phase attenuation circuit which are vertically symmetrical, the input ends of the positive-phase attenuation circuit and the negative-phase attenuation circuit are electrically connected with a radio-frequency signal input end through a balun, and the output ends of the positive-phase attenuation circuit and the negative-phase attenuation circuit are electrically connected with a radio-frequency signal output end. The positive-phase attenuation circuit is electrically connected with a positive-phase control voltage, the negative-phase attenuation circuit is electrically connected with a negative-phase control voltage, and only one of the positive-phase attenuation circuit and the negative-phase attenuation circuit is conducted during use; according to the utility model, the performance requirement is met, the miniaturization requirement is also met, the application scene is diversified, and the circuit can be effectively protected.

Description

Technical Field

[0001] This utility model relates to the field of attenuator technology, specifically to a bipolar attenuator using a specially packaged PIN diode. Background Technology

[0002] In radio frequency (RF) receiving systems, attenuators are key components for extending dynamic range and protecting sensitive devices. Electrically adjustable attenuators implemented using PIN diodes are widely used due to their advantages such as fast response, continuous adjustability, flexible control, ease of integration, and stable performance. Traditional solutions often focus on optimizing circuit topology and control logic, but for the PIN diode devices themselves, which form the core of the attenuation network, commercially available packaged products are typically used directly. Furthermore, traditional single-phase attenuators struggle to accommodate a 180° phase difference and lack necessary protection circuitry. This leads to the following problems:

[0003] 1. Size and integration limitations: The long leads and large package size of general-purpose PIN diodes are not conducive to high-density integration of RF circuits.

[0004] 2. Insufficient design flexibility: The pin definitions and parasitic parameters of commercially packaged diodes are fixed. During circuit design, complex impedance matching compensation must be performed on the system-level PCB layout, which increases the difficulty of circuit design and the uncertainty of product performance.

[0005] 3. Increased costs: To meet high performance requirements, expensive special-packaged PIN diodes are often imported, increasing both capital and time costs.

[0006] 4. Functional limitations: If the attenuator is not bipolar and can only perform single-ended input and output, it cannot automatically switch the attenuation circuit. Once damaged, it will cause the entire system to fail. Unipolar attenuators cannot be directly integrated into a balanced architecture and must be connected to external dual-channel devices, which makes the system complex, increases costs significantly, and makes it difficult to guarantee performance consistency. It also cannot achieve integrated control of attenuation adjustment and phase switching (0° / 180°), requiring external switches and phase shifters, increasing the control difficulty.

[0007] 5. Device performance: Traditional attenuators are large in size, have low operating frequency, high insertion loss, small attenuation dynamic range, and low continuously adjustable sensitivity.

[0008] 6. Insufficient circuit protection: When the circuit is on, the radio frequency signal can pass through; when the circuit is off, in traditional designs, the attenuation circuit is not completely isolated from the input and output terminals, which poses a risk of signal leakage or reflection.

[0009] In summary, current technology still lacks a bipolar attenuator that can simultaneously meet both size and performance requirements. Utility Model Content

[0010] In order to solve the problems existing in the prior art, this utility model intends to provide a bipolar attenuator using a specially packaged PIN diode, which aims to solve the technical problem that traditional attenuators cannot simultaneously meet size and performance requirements.

[0011] A bipolar attenuator employing a specifically packaged PIN diode includes a symmetrically arranged positive-phase attenuation circuit and a negative-phase attenuation circuit. The input terminals of the positive-phase attenuation circuit and the negative-phase attenuation circuit are electrically connected to the two radio frequency signal output terminals of the balun, respectively. The output terminals of the positive-phase attenuation circuit and the negative-phase attenuation circuit are electrically connected to the radio frequency signal output terminals, respectively. The positive-phase attenuation circuit is electrically connected to a positive-phase control voltage, and the negative-phase attenuation circuit is electrically connected to a negative-phase control voltage. Only one of the positive-phase attenuation circuit and the negative-phase attenuation circuit needs to be turned on during use.

[0012] Preferably, the positive phase attenuation circuit sequentially includes a first positive phase switching PIN diode, a second positive phase switching PIN diode, a positive phase cascaded attenuation network, and a third positive phase switching PIN diode electrically connected; the negative phase attenuation circuit sequentially includes a first negative phase switching PIN diode, a second negative phase switching PIN diode, a negative phase cascaded attenuation network, and a third negative phase switching PIN diode electrically connected.

[0013] Preferably, the input terminal of the balun receives a single-ended radio frequency signal, and the output terminal of the balun can output two radio frequency signals with a phase difference of 180 degrees and equal amplitude. The radio frequency signals are transmitted to the positive phase attenuation circuit or the negative phase attenuation circuit according to the positive or negative sign of the control voltage.

[0014] Preferably, the positive phase control voltage includes a first positive phase control voltage and a second positive phase control voltage. The first positive phase control voltage is electrically connected to a first positive phase switching PIN diode, a second positive phase switching PIN diode, and a third positive phase switching PIN diode. The second positive phase control voltage is electrically connected to a positive phase cascaded attenuation network. The negative phase control voltage includes a first negative phase control voltage and a second negative phase control voltage. The first negative phase control voltage is electrically connected to a first negative phase switching PIN diode, a second negative phase switching PIN diode, and a third negative phase switching PIN diode. The second negative phase control voltage is electrically connected to a negative phase cascaded attenuation network.

[0015] Preferably, the positive phase cascaded attenuation network includes two sets of positive phase π-type attenuation networks cascaded through capacitors, and the negative phase cascaded attenuation network includes two sets of negative phase π-type attenuation networks cascaded through capacitors.

[0016] Preferably, the positive-phase π-type attenuation network includes two positive-phase PIN diodes connected in series in opposite directions and two positive-phase PIN diodes connected in parallel. The first ports of the two positive-phase PIN diodes connected in series in opposite directions are respectively connected to the first ports of the two positive-phase PIN diodes connected in parallel. The second ports of the two positive-phase PIN diodes connected in series in opposite directions are connected to a second positive-phase control voltage. The second ports of the two positive-phase PIN diodes connected in parallel are respectively connected to an external power supply voltage through a protection resistor.

[0017] Preferably, the negative phase π-type attenuation network includes two negative phase PIN diodes connected in series in opposite directions and two negative phase PIN diodes connected in parallel. The first port of the two negative phase PIN diodes connected in series in opposite directions is connected to a second negative phase control voltage. The second ports of the two negative phase PIN diodes connected in series in opposite directions are respectively connected to the second ports of the two negative phase PIN diodes connected in parallel. The first ports of the two negative phase PIN diodes connected in parallel are respectively connected to an external power supply voltage through a protection resistor.

[0018] Preferably, the PIN diodes are all square flat leadless packages, and the positive electrode width of the substrate is 1.7mm to facilitate impedance matching.

[0019] Preferably, the height to which the encapsulation silver paste of the PIN diode climbs along the side of the bare die is less than 2 / 3 of the height of the bare die side of the PIN diode.

[0020] Preferably, the PIN diode is ball-shaped bonding using a gold wire with a diameter of 25 μm, and the arc height of the gold wire is controlled between 75 μm and 150 μm.

[0021] The beneficial effects of this utility model include:

[0022] 1. In terms of application scenarios, this attenuator, through its bipolar design, can efficiently achieve phase switching between 0° and 180°, significantly reducing the complexity of external control and broadening its applicability in diverse scenarios such as differential signal processing, phase modulation, and interference cancellation.

[0023] 2. In terms of core device performance, it achieves a good combination of low insertion loss (<5dB) and large dynamic attenuation range (over 22dB) in the 100MHz-180MHz operating frequency band, and has the characteristics of continuous adjustability, high sensitivity, compact overall size and excellent comprehensive electrical performance.

[0024] 3. In terms of circuit reliability and signal integrity, a chain structure of "switched PIN diode - two-stage cascaded π-type attenuation network - switched PIN diode" is adopted, which effectively suppresses signal leakage and reflection, and improves the stability and isolation of the system.

[0025] 4. In terms of system integration, the PIN diode package size is only 2mm×2mm×0.8mm, which greatly reduces the PCB layout area, simplifies the impedance matching design process, and successfully achieves the unity of system miniaturization and high performance, making it easy to integrate and apply in modern electronic devices with limited space. Attached Figure Description

[0026] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present invention and form part of this application, do not constitute a limitation on the embodiments of the present invention, wherein:

[0027] Figure 1 This is a circuit diagram of the attenuator involved in an embodiment of this application.

[0028] Figure 2 This is a schematic diagram of the attenuator circuit involved in the embodiments of this application.

[0029] Figure 3 This is a schematic diagram of the substrate frame of the PIN diode involved in the embodiments of this application.

[0030] Figure 4 This is a schematic diagram of the gold wire bonding of the PIN diode involved in the embodiments of this application.

[0031] Figure 5 This is a schematic diagram of the silver paste bonding of the PIN diode involved in the embodiments of this application.

[0032] Figure 6 This is a physical diagram of the attenuator involved in the embodiments of this application.

[0033] Figure reference numerals: 1-positive electrode, 2-negative electrode, 3-gold wire, 4-bare core, 5-silver paste, 6-substrate frame. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0035] The performance specifications of the bipolar attenuator designed in this embodiment are as follows:

[0036] ① Operating frequency: 100MHz~180MHz; ② Insertion loss: ≤5dB; ③ Attenuation dynamics: ≥22dB; ④ In-band flatness: ≤±0.5dB; ⑤ Phase difference: 178°~182° (comparison of signal phase after attenuation by positive and negative phase attenuation circuits); ⑥ Port standing wave ratio: VSWR≤1.5; ⑦ Power supply voltage: +4.8V, -4.8V; ⑧ Control mode: +4V is the first positive phase control voltage, +10V~0V is the second positive phase control voltage (+10V is the insertion loss state); -4V is the first negative phase control voltage, -10V~0V is the second negative phase control voltage (-10V is the insertion loss state); ⑨ Overall attenuator dimensions: 48mm×29.5mm.

[0037] 2. Required electronic components, corresponding Figure 2 As shown:

[0038] (1) PIN diode:

[0039] ① Completely packaged WPX0080H type PIN diodes: a total of 6 (D1, D2, D3, D4, D21, D22);

[0040] ② Completed WPX0077H type PIN diodes: a total of 8 (D5, D7, D9, D11, D13, D15, D17, D19);

[0041] ③ Completed WPX0078H type PIN diodes: a total of 8 (D6, D8, D10, D12, D14, D16, D18, D20).

[0042] (2) Capacitor:

[0043] ④ 1uf capacitors: 6 in total (C1, C2, C19, C20, C21, C22);

[0044] ⑤ 0.01uf capacitors: 17 in total (C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C23).

[0045] (3) Inductance:

[0046] ⑥ 152J inductors: 10 in total (L1, L2, L3, L4, L5, L6, L7, L8, L9, L10);

[0047] ⑦561j inductor: 1 (L11).

[0048] (4) Radio frequency interface: ⑧ There are 2 radio frequency interfaces (P1, P2);

[0049] (5) Resistance:

[0050] ⑨ 100Ω resistors: 4 in total (R1, R2, R23, R24);

[0051] ⑩ 1.5kΩ resistors: 8 in total (R3, R4, R11, R12, R15, R16, R21, R22);

[0052] 7.5kΩ resistors: 8 in total (R5, R6, R7, R8, R17, R18, R19, R20);

[0053] 5.1kΩ resistors: 4 in total (R9, R10, R13, R14).

[0054] (6) TWBL Barron: TWBL Baron 1 (U1).

[0055] like Figure 1 , Figure 2 As shown, a bipolar attenuator employing a specifically packaged PIN diode is described. In this embodiment, the RF signal input is the RF interface port P1. A single-ended RF signal enters the balun U1, and the balun outputs two RF signals with a 180-degree phase difference and equal amplitude. The RF signals are transmitted to either the positive or negative phase attenuation circuit based on the polarity of the control voltage. Pin 1 of the balun is connected to the positive phase attenuation circuit, and pin 3 is connected to the negative phase attenuation circuit. The RF signals pass through the two branches of the positive and negative phase attenuation circuits in a partially symmetrical manner, forming a chain structure of "switching PIN diode – two cascaded π-type attenuation networks – switching PIN diode". The two branches of the positive and negative phase attenuation circuits cannot be simultaneously activated; one branch must be selected to operate based on the actual application scenario. The attenuated RF signal is then output through port P2.

[0056] In the positive phase attenuation circuit, the positive phase switching PIN diodes include a first positive phase switching PIN diode D1, a second positive phase switching PIN diode D3, and a third positive phase switching PIN diode D21. These PIN diodes are controlled by a first positive phase control voltage (+4V) and are used to select the branch. With an external +4V power supply, positive phase switching PIN diodes D3 and D21 conduct, presenting low impedance, while positive phase switching PIN diode D1 is cut off (to prevent signal leakage or reflection). The RF signal can enter the positive phase cascaded attenuation network with low loss. When the +4V power supply switches to -4V, the circuit switches to a negative phase attenuation circuit. Positive phase switching PIN diodes D3 and D21 are cut off, presenting high impedance (nearly open circuit), while positive phase switching PIN diode D1 conducts and is grounded. The RF signal cannot pass through the positive phase cascaded attenuation network, which is completely isolated from the input and output terminals, preventing signal leakage or reflection.

[0057] The cascaded positive-phase attenuation network consists of two identical positive-phase π-type attenuation networks. PIN diodes D5, D6, D9, and D10 form the first stage, and PIN diodes D13, D14, D17, and D18 form the second stage. Each stage of the positive-phase π-type attenuation network includes two parallel positive-phase PIN diodes and two reverse-phase PIN diodes connected in series. In the first stage, the two reverse-phase PIN diodes connected in series are D5 and D9, and the two parallel positive-phase PIN diodes are D6 and D10. These are connected to a +4.8V power supply through protective resistors R5, R7, and R9. In the second stage, the two reverse-phase π-type attenuation networks are D13 and D17 connected in series, and the two parallel positive-phase PIN diodes are D14 and D18. These are connected to a +4.8V power supply through protective resistors R13, R17, and R19. The cascaded attenuation network is continuously regulated by a second positive control voltage (0~+10V). By changing the voltage, the bias resistance of the positive PIN diode connected in series in the opposite direction is changed, thus achieving continuous adjustment of the attenuation.

[0058] In the negative phase attenuation circuit, the negative phase switching PIN diodes include a first negative phase switching PIN diode D2, a second negative phase switching PIN diode D4, and a third negative phase switching PIN diode D22. These PIN diodes are controlled by a first negative phase control voltage (-4V) and are used to select this branch. With an external -4V power supply, negative phase switching PIN diodes D4 and D22 conduct, presenting low impedance, while negative phase switching PIN diode D2 is cut off (to prevent signal leakage or reflection). The RF signal can enter the negative phase cascaded attenuation network with low loss. When the -4V power supply switches to +4V, the circuit switches to a positive phase attenuation circuit. Negative phase switching PIN diodes D4 and D22 are cut off, presenting high impedance (nearly open circuit), while negative phase switching PIN diode D2 conducts and is grounded. The RF signal cannot pass through the negative phase cascaded attenuation network, which is completely isolated from the input and output terminals, preventing signal leakage or reflection.

[0059] The negative-phase cascaded attenuation network consists of two identical negative-phase π-type attenuation networks. PIN diodes D7, D8, D11, and D12 form the first stage, and PIN diodes D15, D16, D19, and D20 form the second stage. Each stage of the negative-phase π-type attenuation network includes two parallel negative-phase PIN diodes and two negative-phase PIN diodes connected in series in the opposite direction. In the first stage, the two negative-phase π-type attenuation networks connected in series in the opposite direction are D8 and D12, and the two negative-phase PIN diodes connected in parallel are D7 and D11. An external -4.8V power supply is connected through protective resistors R6, R8, and R10. In the second stage, the two negative-phase π-type attenuation networks connected in series in the opposite direction are D16 and D20, and the two negative-phase PIN diodes connected in parallel are D15 and D19. An external -4.8V power supply is connected through protective resistors R14, R18, and R20. The cascaded attenuation network is continuously regulated by the second negative phase control voltage (0~-10V). By changing the voltage, the bias resistance of the negative phase PIN diode connected in series in the opposite direction is changed, thus achieving continuous adjustment of the attenuation.

[0060] To ensure effective attenuation, the circuit also includes electronic components such as resistors, inductors, and capacitors, which serve to protect the signal and reduce interference. For example... Figure 2 As shown, specifically:

[0061] There are six 1μF capacitors: C1, C2, C19, C20, C21, and C22. These are used as RF bypass capacitors to directly ground high-frequency noise and coupling noise in the RF path, while simultaneously blocking DC bias from entering the RF input and output ports, preventing damage to subsequent RF chips from DC surges. C1 has one end connected to resistor R1 and the other end grounded. C2 is symmetrically arranged with C1, one end connected to resistor R2 and the other end grounded. C19 has one end connected to resistor R23 and the other end grounded. C20 is connected in parallel with C19, one end also connected to R23 and the other end grounded. This parallel arrangement of two capacitors increases the filtering capacity and enhances high-frequency noise suppression. C21 has one end connected to resistor R24 ​​and the other end grounded. C22 is connected in parallel with C21, one end connected to R24 and the other end grounded, consistent with the arrangement of C19 and C20, achieving enhanced high-frequency noise suppression.

[0062] There are 17 0.01μF capacitors, namely C3~C18 and C23. According to their functions, they can be divided into two categories: RF DC blocking capacitors and bias filter capacitors. Among them, the RF DC blocking capacitors are C3, C4 and C23, which allow the RF signal to pass through with low impedance, while effectively blocking the DC bias, realizing the complete separation of DC and RF signals. One end of C4 is connected to the RF node of inductor L1 and PIN diodes D2 and D4, and the other end is connected to pin 3 of the balun. C3 and C4 are symmetrically arranged. One end of C3 is connected to the RF node of inductor L2 and PIN diodes D1 and D3, and the other end is connected to pin 1 of the balun. The two work together to prevent DC bias from entering the balun and causing the magnetic core to be magnetized, thus ensuring the differential signal conversion performance of the balun.The bias filter capacitors are C5 to C18, totaling 14 capacitors. Their function is to filter out power supply ripple and RF coupling noise in the bias current of the PIN diodes, ensuring the purity of the bias current and preventing noise-induced drift in the RF equivalent resistance of the PIN diodes, thus preventing deviations in circuit attenuation. Specifically, one end of C5 is connected to the common node of the bias nodes of PIN diodes D5 and D6 and resistor R3, and the other end is connected to the common node of D3 and L3. One end of C6 is connected to the common node of the bias nodes of PIN diodes D7 and D8 and resistor R4, and the other end is connected to the common node of D4 and L4. One end of C7 is connected to the common node of the bias nodes of PIN diodes D5 and D6 and resistor R5, and the other end is grounded. C5 works with C11 to achieve dual filtering of the bias currents of D5 and D6; one end of C8 is connected to the common node of the bias nodes of PIN diodes D7 and D8 and resistor R6, and the other end is grounded; one end of C9 is connected to the common node of the bias nodes of PIN diodes D9 and D10 and resistor R7, and the other end is grounded, working with C11 to achieve dual filtering of the bias currents of D9 and D10; one end of C10 is connected to the common node of the bias nodes of PIN diodes D11 and D12 and resistor R8, and the other end is grounded; one end of C11 is connected to the common node of the bias nodes of PIN diodes D13 and D14 and resistor R15, and the other end is connected to the common node of the bias nodes of PIN diodes D9 and D10 and resistor R11. One end of C12 is connected to the common node of the bias nodes of PIN diodes D11 and D12 and resistor R12, and the other end is connected to the common node of the bias nodes of PIN diodes D15 and D16 and resistor R16. Together with C10, this provides dual filtering of the bias currents of D11 and D12. One end of C13 is connected to the common node of the bias nodes of PIN diodes D13 and D14 and resistor R17, and the other end is grounded. Together with C11, this provides dual filtering of the bias currents of D13 and D14. One end of C14 is connected to the common node of the bias nodes of PIN diodes D15 and D16 and resistor R18, and the other end is grounded. One end of C15 is connected to the common node of the bias nodes of PIN diodes D17 and D18 and resistor R16. The common node of L19 is connected to the other end, and the other end is grounded. One end of C16 is connected to the common node of the bias nodes of PIN diodes D19 and D20 and resistor R20, and the other end is grounded. It works with C18 to achieve dual filtering of the bias current of D19 and D20. One end of C17 is connected to the common node of the bias nodes of PIN diodes D17 and D18 and resistor R21, and the other end is connected to the common node of L9 and D21. It works with C15 to achieve dual filtering of the bias current of D17 and D18. One end of C18 is connected to the common node of the bias nodes of PIN diodes D19 and D20 and resistor R22, and the other end is connected to the common node of L10 and D22. It works with C16 to achieve dual filtering of the bias current of D19 and D20.The RF DC blocking capacitor C23 has one end connected to the signal output port P2 and the other end connected to the common node of L11, D21, and D22. It allows the attenuated RF signal to pass through with low impedance, while effectively blocking DC bias, achieving complete separation of DC and RF signals and improving the overall circuit's anti-interference capability.

[0063] All inductors are high-frequency surface-mount RF inductors. There are 10 152J inductors, numbered L1 to L10, and 1 561J inductor, numbered L11. Both types of inductors have the characteristics of passing DC and blocking RF, and respectively undertake the functions of RF choking and RF impedance matching.

[0064] The 152J inductor can be divided into RF chokes and RF matching inductors based on its function. When used as an RF choke, it can effectively block RF signals from entering the DC bias path, prevent RF energy loss in the DC path, and provide a stable DC bias feed for the PIN diode. When used as an RF matching inductor, it can be used with capacitors and resistors to build a 50Ω impedance matching network, reduce RF signal reflection, and improve signal transmission efficiency and VSWR. L1 is connected at one end to resistor R2 and at the other end to the RF nodes of PIN diodes D2 and D4. L2 is symmetrically arranged with L1, with one end connected to resistor R1 and the other end connected to the RF nodes of PIN diodes D1 and D3. Both L2 and L3 act as RF chokes, providing DC power to the preceding PIN diodes and achieving RF isolation. L3 is connected at one end to the bias nodes of PIN diodes D1 and D3 and at the other end to ground. L4 is symmetrically arranged with L3, with one end connected to the bias nodes of PIN diodes D2 and D4 and at the other end to ground. Both L4 and L4 act as RF matching inductors, achieving 50Ω impedance matching for the multi-channel RF input ports and ensuring the consistency of multi-channel signal transmission. L9 is connected at one end to the common node of resistor R23 and capacitor C20 and at the other end to the RF node of PIN diode D21. L10 is symmetrically arranged with L9, with one end connected to resistor R2. L4 connects to the common node of capacitor C21, and the other end connects to the RF node of PIN diode D22. The two act as RF chokes to provide DC power to the output stage PIN diodes and achieve RF isolation. One end of L5 connects to the RF nodes of PIN diodes D8 and D12, and the other end connects to the ±10V second control voltage. L6 is symmetrically arranged with L5, one end of which connects to the RF nodes of PIN diodes D5 and D9, and the other end connects to the ±10V second control voltage. One end of L7 connects to the RF nodes of PIN diodes D16 and D20, and the other end connects to the ±10V second control voltage. L8 is symmetrically arranged with L7, one end of which connects to the RF nodes of PIN diodes D13 and D17, and the other end connects to the ±10V second control voltage. L5~L8 all act as RF chokes to prevent RF signals from leaking from the bias terminals of the PIN diodes and to ensure the purity of the bias current.

[0065] The 561j inductor L11 is used as an RF matching inductor. One end of it is connected to the bias node of capacitor C23 and PIN diodes D21 and D22, and the other end is grounded. It can achieve 50Ω impedance matching of the RF output port and ensure the stability of the RF signal at the output port P2.

[0066] There are four 100Ω resistors: R1, R2, R23, and R24, all used as current-limiting resistors. R1 is connected at one end to the common node of the ±4V first control voltage and capacitor C1, and at the other end to inductor L2. R2 is symmetrically positioned with R1, with one end connected to the common node of the ±4V first control voltage and capacitor C2, and at the other end to inductor L1. R23 is connected at one end to the common node of the ±4V first control voltage and capacitor C19, and at the other end to the common node of inductor L9 and capacitor C20. R24 is symmetrically positioned with R23, with one end connected to the common node of the ±4V first control voltage and capacitor C22, and at the other end to the common node of inductor L10 and capacitor C21.

[0067] There are eight 1.5kΩ resistors: R3, R4, R11, R12, R15, R16, R21, and R22. All serve as 50Ω impedance matching resistors to ensure stable RF signal transmission. One end of R3 is connected to the common node of PIN diodes D5 and D6 and capacitor C5, and the other end is grounded. R4 is symmetrically positioned with one end connected to the common node of PIN diodes D7 and D8 and capacitor C6, and the other end is grounded. One end of R11 is connected to the common node of PIN diodes D9 and D10 and capacitor C11, and the other end is grounded. One end of R12 is connected to PI... The bias nodes of N diodes D11 and D12 are connected to the common node of capacitor C12, and the other end is grounded; one end of R15 is connected to the common node of PIN diodes D13 and D14 and capacitor C11, and the other end is grounded; one end of R16 is connected to the common node of PIN diodes D15 and D16 and capacitor C12, and the other end is grounded; one end of R21 is connected to the common node of PIN diodes D17 and D18 and capacitor C17, and the other end is grounded; one end of R22 is connected to the common node of PIN diodes D19 and D20 and capacitor C18, and the other end is grounded.

[0068] There are eight 7.5kΩ resistors: R5, R6, R7, R8, R17, R18, R19, and R20. These act as current-limiting resistors, working together with the 5.1kΩ resistor to ensure the bias current remains stable in the mA range, preventing the PIN diodes from being damaged. One end of R5 is connected to the common node of PIN diodes D5 and D6 and capacitor C7, and the other end is connected to resistor R9. One end of R6 is connected to the common node of PIN diodes D7 and D8 and capacitor C8, and the other end is connected to resistor R10. One end of R7 is connected to the common node of PIN diodes D9 and D10 and capacitor C9, and the other end is connected to resistor R9. One end of R8 is connected to PIN diode D9... The bias nodes of diodes D11 and D12 are connected to the common node of capacitor C10, and the other end is connected to resistor R10; one end of R17 is connected to the common node of PIN diodes D13 and D14 and capacitor C13, and the other end is connected to resistor R13; one end of R18 is connected to the common node of PIN diodes D15 and D16 and capacitor C14, and the other end is connected to resistor R14; one end of R19 is connected to the common node of PIN diodes D17 and D18 and capacitor C15, and the other end is connected to resistor R13; one end of R20 is connected to the common node of PIN diodes D19 and D20 and capacitor C16, and the other end is connected to resistor R14.

[0069] There are four 5.1kΩ resistors: R9, R10, R13, and R14. These all act as current-limiting resistors, working together with the 7.5kΩ resistor to ensure the bias current remains stable in the mA range, preventing the PIN diode from being damaged and ensuring the switching speed of the attenuation circuit. One end of R9 is connected to the common node of resistors R5 and R7, and the other end is connected to the external +4.8V power supply control signal. One end of R10 is connected to the common node of resistors R6 and R8, and the other end is connected to the external -4.8V power supply control signal. One end of R13 is connected to the common node of resistors R17 and R19, and the other end is connected to the external +4.8V power supply control signal. One end of R14 is connected to the common node of resistors R18 and R20, and the other end is connected to the external -4.8V power supply control signal.

[0070] All the key packaging components of the PIN diodes involved, such as Figure 3 , Figure 4 , Figure 5 As shown in the attached diagram (labels: 1-positive electrode, 2-negative electrode, 3-gold wire, 4-bare core, 5-silver paste, 6-substrate frame), bare core 4 is a planar structure with upper and lower gold Au electrodes, and adopts a square flat no-lead package (i.e., QFN). The specific steps are as follows:

[0071] S1. Design and fabrication of substrate frame 6:

[0072] Based on the size and polarity of the bare core 4 electrode, the substrate frame 6 is designed and fabricated; the width of the positive electrode 1 of the frame is reserved according to the microstrip line characteristic impedance formula of the target operating frequency to ensure that impedance matching is easy to achieve during PCB layout; the negative electrode 2 is designed as a pad area to support the bare core 4 and the silver paste 5.

[0073] S2. Silver paste 5 assembly and bonding: Using sintered silver paste 5, precisely apply it to the specified area of ​​the negative electrode 2 pad on the substrate frame 6; align and press the negative electrode of the bare PIN diode 4 onto the silver paste 5, controlling the pressure so that the height of the silver paste 5 climbing along the side of the bare die 4 is less than 2 / 3 of the height of the side of the bare die 4 to prevent short circuit between the positive and negative electrodes; then bake and cure.

[0074] S3. Gold wire bonding: Gold wire 3 is used for ball bonding to connect the positive electrode of bare core 4 to the positive electrode 1 of substrate frame 6; the bonding arc height is controlled to prevent gold wire 3 from contacting the side of bare core 4 or other parts of substrate frame 6.

[0075] S4. Encapsulation and Cutting: The bonded structure is encapsulated using a low-stress, low-moisture-absorption epoxy encapsulation material, and then cut after curing to obtain the final encapsulated body.

[0076] S5. Engraving and Storage: The model number and polarity markings are laser-engraved on the surface of the package and stored in a specified environment. Finally, the size of all PIN diodes is standardized to 2mm×2mm×0.8mm.

[0077] Taking a domestically produced PIN diode bare die 4 with model number WPX0080H as an example. Typical dimensions of bare die 4 are: ① Negative electrode 450μm × 450μm ② Positive electrode 175μm × 175μm ③ Height 180μm. The positive and negative electrodes are made of gold (Au). The specific steps are as follows:

[0078] (1) Based on the dimensions of the bare core 4 and the electrode polarity, the substrate frame 6 is designed and etched, such as Figure 3 As shown. The entire substrate frame 6 measures 2mm × 2mm. The positive electrode 1 is designed to be 1.7mm × 0.3mm, with a width of 1.7mm to facilitate flexible adjustment of the microstrip line width according to the dielectric constant of the PCB material in the 100MHz-180MHz frequency band, achieving 50Ω impedance matching. The negative electrode 2 pad is the 1.5mm × 0.8mm area in the center of the dashed line.

[0079] (2) The silver paste 5 is a sintered silver paste 5 (503HTC). The silver paste 5 is precisely coated within a specified range of the negative electrode 2 of the substrate frame 6, such as... Figure 3 , Figure 4 , Figure 5As shown, the bare core 4 is picked up with a vacuum pen, accurately placed on the silver paste 5, and appropriate pressure is applied to control the overflow height of the silver paste 5 to be less than 2 / 3 of the height of the sidewall of the bare core 4. Subsequently, the silver paste 5 is cured by baking at 175±5℃ for 90 minutes (30 minutes of heating and 60 minutes of constant temperature).

[0080] (3) Plasma cleaning was performed for 2 minutes under the conditions of compressed air of 0.5 MPa, argon-hydrogen mixed gas of 0.3 MPa and plasma power of 460 W.

[0081] (4) Using a ball-and-wire bonding method, a 25μm diameter gold wire 3 is used for bonding, with the arc height (the upward extension height of the gold wire 3) controlled between 75μm and 150μm, to connect the positive electrode of the bare core 4 to the positive electrode 1 of the substrate frame 6, such as... Figure 3 , Figure 4 , Figure 5 As shown. The first welding pressure is 60gf and the time is 15ms. The second welding pressure is 120gf and the temperature is 200℃.

[0082] (5) Under the conditions of compressed air of 0.5 MPa, argon-hydrogen mixed gas of 0.25 MPa and plasma power of 450 W, plasma cleaning is performed again for 2 minutes.

[0083] (6) Use epoxy molding compound for molding. The molding compound usage time is 0.5h, the temperature is 180±5℃, the mold closing pressure is 75 tons, the injection pressure is 17kg, the injection speed is 1mm / s, the holding pressure time is 90s, and the molding compound warm-up time must be greater than 2 hours. After encapsulation, the length of the device should be controlled within 2mm±0.1mm, the width within 2mm±0.1mm, and the height within 0.8mm±0.1mm.

[0084] (7) Post-curing: The curing temperature is 175℃ and the curing time is 300 minutes.

[0085] (8) Cut and clean the cured chip, and then bake it at 100°C for 10 minutes; after baking, remove the adhesive for 30 seconds.

[0086] (9) Use a laser marking machine to engrave the "80H" model number and positive electrode marking point on the surface of the device. Store the finished product with the marking completed in a well-ventilated warehouse with an ambient temperature of 10°C~30°C and a relative humidity of no more than 60%, free from acid, alkali or other corrosive gases, or in a nitrogen cabinet with constant temperature and humidity. At this point, all packaging processes are complete. The same process was also used to package the bare cores of two PIN diodes, WPX0077H and WPX0078H.

[0087] The final attenuator product diagram involved in this embodiment is as follows: Figure 6As shown, the performance data of the finished product are shown in Tables 1 and 2.

[0088] Table 1. Test data of the positive phase attenuation circuit

[0089]

[0090] Table 2. Test data of negative phase attenuation circuit

[0091]

[0092] From the data in Table 1 and Table 2 and the finished products Figure 6 This attenuator can be summarized as having the following advantages:

[0093] 1. In the actual assembly process, unavoidable operational errors exist, resulting in the positive and negative phase attenuation circuits having essentially the same performance. This indicates that the attenuator involved in this embodiment has good engineering tolerance, can tolerate minor deviations during the production process, and ensures the uniformity and reliability of batch product performance.

[0094] 2. Wide voltage adjustment range for convenient attenuation adjustment. A wider voltage adjustment range usually means more precise attenuation control. This attenuator achieves a good combination of low insertion loss and a wide dynamic attenuation range within the 100MHz-180MHz operating frequency band. Users can achieve wide-range and high-precision attenuation settings through a simple voltage signal, effectively improving the attenuator's integration convenience and control flexibility within the system.

[0095] 3. The phase difference essentially meets 180°. Experimental data confirms that the attenuator involved in this embodiment maintains a stable phase relationship within the operating frequency band. This is crucial for applications requiring signal phase integrity (such as differential signal processing, push-pull circuits, phase-sensitive cancellation, etc.). Not only does it exhibit consistent attenuation, but it also achieves precise constraints on phase characteristics, ensuring signal fidelity and system compatibility in complex RF systems.

[0096] 4. Effective circuit protection: On the one hand, the voltage tolerance range of the system is effectively widened, and the working stability and reliability are significantly enhanced; on the other hand, better impedance matching is achieved in a wide frequency range, and port reflection loss is reduced, thereby ensuring that the continuous adjustability of attenuation is more accurate and stable.

[0097] 5. Suitable size: The overall size of the attenuator is 48mm × 29.5mm, approximately 14.2 square centimeters. This is a compact design within the current technological context, fully considering the rationality of circuit layout, the convenience of component assembly, the compatibility of peripheral circuits, and heat dissipation requirements. Within a practical design size, it combines multiple advantages such as wide-range voltage regulation, phase consistency, and high assembly tolerance, achieving optimized overall performance.

[0098] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

Claims

1. A bipolar attenuator employing a specific packaged PIN diode, characterized by, It includes a symmetrical positive phase attenuation circuit and a negative phase attenuation circuit. The input terminals of the positive phase attenuation circuit and the negative phase attenuation circuit are respectively electrically connected to the two radio frequency signal output terminals of the balun. The output terminals of the positive phase attenuation circuit and the negative phase attenuation circuit are respectively electrically connected to the radio frequency signal output terminals. The positive phase attenuation circuit is electrically connected to the positive phase control voltage, and the negative phase attenuation circuit is electrically connected to the negative phase control voltage. Only one of the positive phase attenuation circuit and the negative phase attenuation circuit needs to be turned on during use.

2. A bipolar attenuator employing a specific packaged PIN diode as claimed in claim 1, wherein, The positive phase attenuation circuit sequentially includes a first positive phase switching PIN diode, a second positive phase switching PIN diode, a positive phase cascaded attenuation network, and a third positive phase switching PIN diode, all electrically connected; the negative phase attenuation circuit sequentially includes a first negative phase switching PIN diode, a second negative phase switching PIN diode, a negative phase cascaded attenuation network, and a third negative phase switching PIN diode, all electrically connected.

3. A bipolar attenuator employing a specific packaged PIN diode as claimed in claim 1, wherein, The balun's input receives a single-ended radio frequency signal, and its output can output two radio frequency signals with a 180-degree phase difference and equal amplitude. The radio frequency signals are transmitted to either a positive-phase attenuation circuit or a negative-phase attenuation circuit according to the positive or negative sign of the control voltage.

4. A bipolar attenuator employing a specifically packaged PIN diode according to claim 1, characterized in that, The positive phase control voltage includes a first positive phase control voltage and a second positive phase control voltage. The first positive phase control voltage is electrically connected to a first positive phase switching PIN diode, a second positive phase switching PIN diode, and a third positive phase switching PIN diode. The second positive phase control voltage is electrically connected to a positive phase cascaded attenuation network. The negative phase control voltage includes a first negative phase control voltage and a second negative phase control voltage. The first negative phase control voltage is electrically connected to a first negative phase switching PIN diode, a second negative phase switching PIN diode, and a third negative phase switching PIN diode. The second negative phase control voltage is electrically connected to a negative phase cascaded attenuation network.

5. A bipolar attenuator employing a specifically packaged PIN diode according to claim 2, characterized in that, The positive phase cascaded attenuation network includes two sets of positive phase π-type attenuation networks cascaded through capacitors, and the negative phase cascaded attenuation network includes two sets of negative phase π-type attenuation networks cascaded through capacitors.

6. A bipolar attenuator employing a specifically packaged PIN diode according to claim 5, characterized in that, The positive-phase π-type attenuation network includes two anti-tandem positive-phase PIN diodes and two parallel positive-phase PIN diodes. The first ports of the two anti-tandem positive-phase PIN diodes are respectively connected to the first ports of the two parallel positive-phase PIN diodes. The second ports of the two anti-tandem positive-phase PIN diodes are connected to a second positive-phase control voltage. The second ports of the two parallel positive-phase PIN diodes are respectively connected to an external power supply voltage through a protection resistor. The negative-phase π-type attenuation network includes two anti-tandem negative-phase PIN diodes and two parallel negative-phase PIN diodes. The first ports of the two anti-tandem negative-phase PIN diodes are connected to a second negative-phase control voltage. The second ports of the two anti-tandem negative-phase PIN diodes are respectively connected to the second ports of the two parallel negative-phase PIN diodes. The first ports of the two parallel negative-phase PIN diodes are respectively connected to an external power supply voltage through a protection resistor.

7. A bipolar attenuator employing a specifically packaged PIN diode according to claim 2 or 6, characterized in that, All PIN diodes are square flat leadless packages, and the positive electrode width of the substrate of each PIN diode is 1.7mm.

8. A bipolar attenuator employing a specifically packaged PIN diode according to claim 2 or 6, characterized in that, The height to which the encapsulation silver paste of the PIN diode climbs along the side of the bare die must be less than 2 / 3 of the height of the bare die side of the PIN diode.

9. A bipolar attenuator employing a specifically packaged PIN diode according to claim 2 or 6, characterized in that, The PIN diode is ball-shaped pressure bonding using a gold wire with a diameter of 25μm, and the arc height of the gold wire is controlled between 75μm and 150μm.

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