An Asymmetric Nonlinear Temperature Compensated Attenuator and Its Design Method

Abstract

This invention discloses an asymmetric nonlinear temperature-compensated attenuator and its design method, belonging to the field of electronic circuit technology. Specifically, it is based on a T-type or π-type two-port attenuation network design. The series and parallel arms are selected from parallel or series equivalent resistance units, and the series and parallel arms of the same type of two-port attenuation network are different. The parallel equivalent resistance unit consists of a first PTC thermistor, a first NTC thermistor, and a first fixed resistor connected in parallel. The series equivalent resistance unit consists of a second PTC thermistor, a second NTC thermistor, and a second fixed resistor. The second NTC thermistor is connected in parallel with the second fixed resistor, and then connected in series with the second PTC thermistor. This invention achieves accurate mirror fitting of non-monotonic temperature characteristics in a passive network by constructing equivalent resistance units with extreme points, flexibly adapting to various asymmetric nonlinear curves.

Description

Technical Field

[0001] This invention belongs to the field of electronic circuit technology, specifically relating to an asymmetric nonlinear temperature-compensated attenuator and its design method. Background Technology

[0002] As electronic devices become smaller, denser, and more multifunctional, the problem of significant gain variations in RF / microwave amplifiers (such as GaAs field-effect transistors and high electron mobility transistors) with temperature is becoming increasingly prominent. To compensate for this temperature drift, temperature-compensated attenuators have become the preferred solution for RF engineers, offering advantages such as simple design, low cost, high reliability, fast response, and no frequency distortion.

[0003] Existing passive temperature-compensated attenuators are typically based on a T-type or π-type two-port network design consisting of PTC (positive temperature coefficient) thermistors and NTC (negative temperature coefficient) thermistors. The thermistors in the series and parallel arms have resistance temperature coefficients with opposite signs, which makes the attenuation change almost linearly with temperature at a specific slope, while keeping the characteristic impedance basically unchanged.

[0004] However, existing passive temperature-compensated attenuators have the following shortcomings:

[0005] First, the gain-temperature characteristics of semiconductor devices (especially complex cascaded RF front-ends) are often not linear. Actual operating environments typically cover a wide temperature range of -55°C to 85°C, which is not symmetrical relative to room temperature (25°C). For some devices, the gain / loss fluctuations at high and low temperatures are relatively small, while the fluctuations between room and low temperatures are much larger.

[0006] Meanwhile, when the performance of multiple devices with different characteristics is superimposed, the overall link may exhibit various asymmetric temperature characteristics, such as the highest gain at room temperature (i.e., the gain at both low and high temperatures is lower than at room temperature) or the lowest gain at room temperature (i.e., the gain at both low and high temperatures is higher than at room temperature). Existing linear temperature-compensated attenuators cannot meet such nonlinear compensation requirements.

[0007] Secondly, when nonlinear temperature compensation is required, existing technologies typically employ a digital solution consisting of a temperature sensor, an analog-to-digital converter (ADC), an FPGA (Field-Programmable Gate Array), and a digitally controlled attenuator. While this solution offers flexible compensation, it has significant drawbacks in high-reliability applications such as aerospace, nuclear industry, and medical equipment: the digital circuitry requires radiation hardening, which is extremely costly; furthermore, aerospace products have radiation resistance requirements for digital circuitry, making the introduction of complex digital circuitry solely for temperature compensation often counterproductive; additionally, the digital solution requires power supply and control circuitry, increasing system power consumption and size, which contradicts the aerospace product requirements for low power consumption and miniaturization.

[0008] Third, some existing technologies attempt to achieve temperature compensation through combinations of thermistors, but their compensation curves are still limited to linear or simple monotonic changes, and cannot achieve the nonlinear equivalent resistance characteristics of maximum or minimum resistance at room temperature, thus limiting their application in asymmetric temperature compensation scenarios.

[0009] Therefore, there is an urgent need for a pure analog temperature compensation attenuator that can achieve nonlinear temperature compensation characteristics and does not require digital circuit control, in order to meet the asymmetric temperature compensation requirements of high-reliability applications such as aerospace, nuclear industry or medical equipment. Summary of the Invention

[0010] To address the technical problem that existing temperature-compensated attenuators can only achieve linear unipolar temperature compensation and cannot adapt to the requirements of asymmetric nonlinear temperature compensation, this invention provides an asymmetric nonlinear temperature-compensated attenuator and its design method. By constructing an equivalent resistance unit with extreme points, a precise mirror fit of non-monotonic temperature characteristics is achieved in a passive network, filling the gap in the prior art.

[0011] The technical solution adopted in this invention is as follows:

[0012] An asymmetric nonlinear temperature-compensated attenuator is designed based on a T-type or π-type two-port attenuation network. The T-type two-port attenuation network includes two series arms and one parallel arm, while the π-type two-port attenuation network includes one series arm and two parallel arms.

[0013] The thermistor networks of the series arm and parallel arm are selected from parallel equivalent resistance units or series equivalent resistance units, and the thermistor networks of the series arm and parallel arm of the same type of two-port attenuation network are different.

[0014] The parallel equivalent resistance unit is composed of a first PTC thermistor, a first NTC thermistor and a first fixed resistor, which are connected in parallel with each other.

[0015] The series-type equivalent resistance unit consists of a second PTC thermistor, a second NTC thermistor, and a second fixed resistor. The second NTC thermistor is connected in parallel with the second fixed resistor and then connected in series with the second PTC thermistor.

[0016] Furthermore, both the first PTC thermistor and the second PTC thermistor are linear PTC thermistors, meaning that their resistance increases monotonically with temperature within the operating temperature range without any abrupt change.

[0017] Furthermore, the linear PTC thermistor is specifically a silicon-based linear PTC thermistor or a thin-film linear PTC thermistor.

[0018] Furthermore, the operating temperature range of the asymmetric nonlinear temperature compensation attenuator is -55℃ to 85℃.

[0019] Furthermore, the parallel equivalent resistance unit has the largest resistance at room temperature, while the resistance at high temperature and low temperature is smaller than that at room temperature, presenting an arched (∩-shaped) equivalent resistance-temperature curve with a "peak at room temperature and decreasing at both ends".

[0020] Furthermore, the series-type equivalent resistance unit has the lowest resistance at room temperature, while the resistance at high temperature and low temperature is greater than that at room temperature, presenting a bowl-shaped (U-shaped) equivalent resistance-temperature curve with a "valley at room temperature and rising at both ends".

[0021] Furthermore, by configuring different types of equivalent resistance units in the series and parallel arms, the attenuation-temperature curve of the asymmetric nonlinear temperature compensation attenuator is mirrored with the gain-temperature curve of the RF link to be compensated, thus achieving nonlinear temperature compensation.

[0022] Furthermore, the series arm of the T-type two-port attenuation network adopts a parallel equivalent resistance unit, and the parallel arm adopts a series equivalent resistance unit. At this time, the attenuation-temperature curve of the asymmetric nonlinear temperature compensation attenuator is nonlinearly arched.

[0023] Furthermore, the series arm of the T-type two-port attenuation network adopts a series equivalent resistance unit, and the parallel arm adopts a parallel equivalent resistance unit. At this time, the attenuation-temperature curve of the asymmetric nonlinear temperature-compensated attenuator is nonlinear bowl-shaped.

[0024] Furthermore, the series arm of the π-type two-port attenuation network adopts a parallel equivalent resistance unit, and the parallel arm adopts a series equivalent resistance unit. At this time, the attenuation-temperature curve of the asymmetric nonlinear temperature-compensated attenuator is nonlinearly arched.

[0025] Furthermore, the series arm of the π-type two-port attenuation network adopts a series equivalent resistance unit, and the parallel arm adopts a parallel equivalent resistance unit. At this time, the attenuation-temperature curve of the asymmetric nonlinear temperature-compensated attenuator is nonlinear bowl-shaped.

[0026] Furthermore, by changing the room temperature resistance RP and temperature coefficient TCR of the first PTC thermistor and the second PTC thermistor, the room temperature resistance RN and B of the first NTC thermistor and the second NTC thermistor, and the resistance R of the first fixed resistor and the second fixed resistor, the asymmetry, attenuation amount, and compensation amount of the attenuation-temperature curve of the asymmetric nonlinear temperature compensation attenuator can be adjusted.

[0027] Furthermore, by connecting at least one T-type two-port attenuation network and / or at least one π-type two-port attenuation network in series, and superimposing the asymmetric and nonlinear characteristics of the attenuation-temperature curves of different two-port attenuation networks, multi-stage temperature compensation of the asymmetric nonlinear temperature compensation attenuator can be achieved.

[0028] This invention also proposes a design method for an asymmetric nonlinear temperature-compensated attenuator, comprising the following steps:

[0029] Step A1: Based on the gain-temperature curve of the RF link to be compensated, determine the attenuation-temperature curve shape of the asymmetric nonlinear temperature compensation attenuator, and then determine the type of two-port attenuation network to be used, as well as the type of equivalent resistance unit configured for the corresponding series arm and parallel arm.

[0030] Step A2: Based on the attenuation-temperature curve shape, set the target attenuation amount at three temperature points: low temperature end, normal temperature end, and high temperature end. Then, calculate the target resistance value of the series arm and the target resistance value of the parallel arm of the two-port attenuation network used under impedance matching conditions at the three temperature points.

[0031] Step A3: Design the equivalent resistance units configured for the series arm and parallel arm respectively. Specifically, adjust the room temperature resistance RP and temperature coefficient TCR of the first PTC thermistor and the second PTC thermistor, the room temperature resistance RN and B of the first NTC thermistor and the second NTC thermistor, and the resistance R of the first fixed resistor and the second fixed resistor, so that the equivalent resistance of the equivalent resistance units configured for the series arm at the three temperature points meets the target resistance value of the corresponding series arm, and the equivalent resistance of the equivalent resistance units configured for the parallel arm meets the target resistance value of the corresponding parallel arm, thereby completing the design of the asymmetric nonlinear temperature compensation attenuator.

[0032] Furthermore, in the parallel-type equivalent resistance unit, the room-temperature resistance RP of the first PTC thermistor is used to control the magnitude of the equivalent resistance in the low-temperature range. The larger the room-temperature resistance RP, the larger the equivalent resistance in the low-temperature range, and the smaller the decrease in equivalent resistance from room temperature to low temperature. The temperature coefficient TCR of the first PTC thermistor is used to control the magnitude of the decrease in equivalent resistance in the low-temperature range. The larger the temperature coefficient TCR, the more significant the decrease in equivalent resistance from room temperature to low temperature, and the steeper the slope of the equivalent resistance-temperature curve. The room-temperature resistance RN of the first NTC thermistor is used to control the magnitude of the equivalent resistance in the high-temperature range. The larger the room-temperature resistance RN, the larger the equivalent resistance in the high-temperature range, and the smaller the decrease in equivalent resistance from room temperature to high temperature. The B value of the first NTC thermistor is used to control the magnitude of the decrease in equivalent resistance in the high-temperature range. The larger the value, the greater the slope of the equivalent resistance change from room temperature to high temperature. The resistance value R of the first fixed resistor is used to set the peak value of the equivalent resistance at room temperature and adjust the slope of the equivalent resistance-temperature curve throughout the entire temperature range. Increasing the resistance value R can significantly improve the equivalent resistance at room temperature, thereby increasing the decrease in equivalent resistance from room temperature to high temperature and from room temperature to low temperature. Decreasing the resistance value R has the opposite effect, thus achieving nonlinear arched equivalent resistance-temperature curve fitting.

[0033] Furthermore, in the series-type equivalent resistance unit, the room-temperature resistance RP of the second PTC thermistor is used to control the overall magnitude of the equivalent resistance and the slope of the equivalent resistance-temperature curve from room temperature to high temperature. Increasing the room-temperature resistance RP will simultaneously increase the equivalent resistance across the entire temperature range and increase the slope of the equivalent resistance-temperature curve from room temperature to high temperature. Decreasing the room-temperature resistance RP will simultaneously decrease the equivalent resistance across the entire temperature range and decrease the slope of the equivalent resistance-temperature curve from room temperature to high temperature. The temperature coefficient TCR of the second PTC thermistor is used to control the rise in equivalent resistance at high temperatures. The higher the temperature coefficient TCR, the greater the increase in equivalent resistance. The larger the value of the first NTC thermistor, the more significant the increase in equivalent resistance in the high-temperature range, and the steeper the slope of the equivalent resistance-temperature curve. The room-temperature resistance RN of the second NTC thermistor is used to control the increase in equivalent resistance from room temperature to low temperature and the equivalent resistance at low temperature. The larger the room-temperature resistance RN, the steeper the slope of the equivalent resistance-temperature curve from room temperature to low temperature. The B value of the second NTC thermistor is used to control the rate of change of resistance with temperature in the low-temperature range. The larger the B value, the steeper the slope of the equivalent resistance-temperature curve from room temperature to low temperature. The resistance R of the second fixed resistor is used to adjust the slope of the equivalent resistance-temperature curve from room temperature to low temperature.

[0034] Furthermore, in step A3, the relative error between the equivalent resistance of the equivalent resistance unit configured in the series arm and the target resistance value of the corresponding series arm at the three temperature points, as well as the relative error between the equivalent resistance of the equivalent resistance unit configured in the parallel arm and the target resistance value of the corresponding parallel arm, are all controlled within ±15% to ensure that the return loss is higher than 15 dB.

[0035] Furthermore, after step A3, a verification process is also included. Specifically, the equivalent resistance of the series arm configured in step A3 at three temperature points, and the equivalent resistance of the parallel arm configured at three temperature points, are substituted into the adopted two-port attenuation network to calculate the actual attenuation at the three temperature points and compare it with the corresponding target attenuation. If the attenuation error exceeds ±0.5 dB, the process returns to step 3 for fine-tuning.

[0036] For multi-stage temperature compensation, this invention also proposes a design method for an asymmetric nonlinear temperature compensation attenuator, comprising the following steps:

[0037] Step B1: Based on the gain-temperature curve of the RF link to be compensated, determine that the attenuation-temperature curve of the asymmetric nonlinear temperature compensation attenuator is wavy. Then determine that at least one T-type two-port attenuation network or / and at least one π-type two-port attenuation network is used in series. Based on the local characteristics of the attenuation-temperature curve, determine the type of equivalent resistance unit configured for the series arm and parallel arm of different two-port attenuation networks.

[0038] Step B2: Based on the attenuation-temperature curve shape, set the target attenuation amount at three temperature points: low temperature end, normal temperature end, and high temperature end. Then, calculate the target resistance value of the series arm and the target resistance value of the parallel arm of different two-port attenuation networks at the three temperature points under impedance matching conditions.

[0039] Step B3: Design the equivalent resistance units configured for the series and parallel arms of different two-port attenuation networks. Specifically, adjust the room temperature resistance RP and temperature coefficient TCR of the first and second PTC thermistors, the room temperature resistance RN and B of the first and second NTC thermistors, and the resistance R of the first and second fixed resistors. This ensures that the equivalent resistance of the equivalent resistance units configured for the series arms at the three temperature points meets the target resistance value of the corresponding series arm, and the equivalent resistance of the equivalent resistance units configured for the parallel arms meets the target resistance value of the corresponding parallel arm. After superimposing the attenuation-temperature curves of different two-port attenuation networks, multi-level temperature compensation is achieved, completing the design of the asymmetric nonlinear temperature compensation attenuator.

[0040] Compared with existing technologies, the asymmetric nonlinear temperature-compensated attenuator and its design method proposed in this invention have the following advantages:

[0041] 1. Achieving Nonlinear and Asymmetric Temperature Compensation: By combining PTC and NTC thermistors, two types of equivalent resistance units with the largest and smallest resistance values ​​at room temperature are constructed. These units are flexibly configured in π-type or T-type two-port attenuation networks, enabling the attenuator to generate an attenuation-temperature curve that mirrors the gain-temperature curve of the device to be compensated. This fills the gap in existing linear temperature-compensated attenuators that cannot adapt to asymmetric and nonlinear compensation requirements. Compared with existing linear temperature-compensated networks (whose attenuation-temperature curve is a monotonic straight line, which can only solve monotonically changing gain drift), this invention can accurately fit asymmetric and non-monotonic gain-temperature curves (such as an arched curve with the highest gain at room temperature and different rates of gain decrease at both ends, or a bowl-shaped curve with the lowest gain at room temperature and different rates of gain increase at both ends). For the first time, nonlinear compensation for the complex temperature characteristics of multi-stage cascaded RF front-ends is achieved in a purely passive analog circuit.

[0042] 2. Pure analog passive solution to meet the high reliability requirements of aerospace, nuclear industry or medical equipment: This invention completely eliminates the need for digital circuit components such as temperature sensors, ADCs, FPGAs and digitally controlled attenuators, and achieves nonlinear temperature compensation in a pure passive analog manner; this feature gives this invention a significant advantage in high reliability application scenarios such as aerospace, nuclear industry or medical equipment, with no power supply requirements, no risk of radiation soft errors, no introduction of digital noise, simple warranty requirements, and a significant reduction in system cost and design complexity;

[0043] 3. Flexible adaptation to various nonlinear curves: By adjusting the room temperature resistance values ​​of PTC and NTC thermistors, the temperature coefficient (TCR) of PTC, the B value of NTC, the series-parallel combination method, and the resistance value of the fixed resistor, the resistance-temperature curve shape of the equivalent resistance unit can be flexibly adjusted within a wide range. By combining equivalent resistance units with different curve shapes, it can adapt to various complex nonlinear temperature compensation requirements, including but not limited to: the highest gain at room temperature (low at both ends and high in the middle), the lowest gain at room temperature (high at both ends and low in the middle), and the asymmetric curve type. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the circuit structure of the parallel equivalent resistance unit proposed in this invention;

[0045] Figure 2 This is a schematic diagram of the circuit structure of the series-type equivalent resistance unit proposed in this invention;

[0046] Figure 3 This is a schematic diagram of the circuit structure of the asymmetric arched temperature-compensated attenuator based on a π-type two-port attenuation network proposed in Example 1;

[0047] Figure 4The fitted attenuation-temperature curve of the asymmetric arched temperature-compensated attenuator based on the π-type two-port attenuation network proposed in Example 1;

[0048] Figure 5 This is a schematic diagram of the circuit structure of the asymmetric bowl-shaped temperature-compensated attenuator based on a π-type two-port attenuation network proposed in Example 2;

[0049] Figure 6 The fitted attenuation-temperature curve of the asymmetric bowl-shaped temperature-compensated attenuator based on the π-type two-port attenuation network proposed in Example 2;

[0050] Figure 7 This is a schematic diagram of the circuit structure of the asymmetric arched temperature-compensated attenuator based on a T-type two-port attenuation network proposed in Example 3;

[0051] Figure 8 The fitted attenuation-temperature curve of the asymmetric arched temperature-compensated attenuator based on the T-type two-port attenuation network proposed in Example 3;

[0052] Figure 9 This is a schematic diagram of the circuit structure of the asymmetric bowl-shaped temperature-compensated attenuator based on a T-type two-port attenuation network proposed in Example 4;

[0053] Figure 10 The fitted attenuation-temperature curve of the asymmetric bowl-shaped temperature-compensated attenuator based on the T-type two-port attenuation network proposed in Example 4;

[0054] Figure 11 This is a schematic diagram of the circuit structure of the asymmetric wave-shaped temperature-compensated attenuator proposed in Example 5;

[0055] Figure 12 The fitted attenuation-temperature curve of the asymmetric wave-shaped temperature-compensated attenuator proposed in Example 5. Detailed Implementation

[0056] The RF link to be compensated described in this invention consists of two or more cascaded active or passive RF devices. It should be noted that the temperature drift characteristics of each active or passive RF device are often asymmetrical. After cascading, this asymmetrical deviation accumulates stage by stage, resulting in a severe asymmetry in the high-temperature and low-temperature gain deviations of the RF link to be compensated. The cumulative gain-temperature drift effect macroscopically forms a complex gain-temperature drift characteristic, i.e., the gain-temperature curve of the RF link to be compensated. Conventional symmetrical or linear analog temperature-compensated attenuators cannot simultaneously compensate for this asymmetry to a uniform level at both room temperature and high / low temperatures. This invention addresses this problem by combining NTC and PTC thermistors to construct a similarly asymmetrical attenuation-temperature curve, achieving precise matching.

[0057] This invention proposes an asymmetric nonlinear temperature-compensated attenuator based on a T-type or π-type two-port attenuator network design. The T-type two-port attenuator network includes two series arms and one parallel arm, while the π-type two-port attenuator network includes one series arm and two parallel arms. The thermistor networks of the series arms and parallel arms are selected from parallel equivalent resistance units or series equivalent resistance units, and the thermistor networks of the series arms and parallel arms of the same type of two-port attenuator network are different.

[0058] The operating temperature range of the asymmetric nonlinear temperature compensation attenuator is -55℃ to 85℃.

[0059] The circuit structure of the parallel equivalent resistance unit is as follows: Figure 1 As shown, it consists of a first PTC thermistor, a first NTC thermistor, and a first fixed resistor, which are connected in parallel; wherein the first PTC thermistor and the first NTC thermistor are linear PTC thermistors.

[0060] The working principle of the parallel equivalent resistance unit is as follows: At room temperature, both the first PTC thermistor and the first NTC thermistor are at medium resistance values. The equivalent resistance after they are connected in parallel is connected in parallel with the first fixed resistor, maximizing the total resistance. When the temperature rises, the resistance of the first PTC thermistor increases and the resistance of the first NTC thermistor decreases, resulting in a decreasing trend in the equivalent resistance after they are connected in parallel. When the temperature decreases, the resistance of the first PTC thermistor decreases and the resistance of the first NTC thermistor increases, again resulting in a decreasing trend in the equivalent resistance after they are connected in parallel. Therefore, the resistance of the parallel equivalent resistance unit is maximum at room temperature, and is lower than the room temperature resistance at both high and low temperatures, exhibiting an arched (∩-shaped) nonlinear resistance-temperature characteristic with a "peak at room temperature and decreasing at both ends".

[0061] The circuit structure of the series-type equivalent resistance unit is as follows: Figure 2 As shown, it consists of a second PTC thermistor, a second NTC thermistor, and a second fixed resistor. The second NTC thermistor is connected in parallel with the second fixed resistor, and then connected in series with the second PTC thermistor. The second PTC thermistor is a linear PTC thermistor.

[0062] The working principle of the series-type equivalent resistance unit is as follows: the resistance of the second NTC thermistor changes exponentially with temperature, meaning its resistance is extremely high at low temperatures and extremely low at high temperatures. When connected in parallel with the second fixed resistor, the curve of the equivalent resistance of the parallel branch changing with temperature is "flattened": in the low-temperature region, the originally extremely high NTC resistance is reduced by the fixed resistor; in the high-temperature region, the originally extremely low NTC resistance remains at a low level. The equivalent resistance of the parallel branch decreases gradually with increasing temperature, no longer exhibiting a drastic exponential jump. The parallel branch is then connected in series with a linear second PTC thermistor (whose resistance increases linearly with temperature). The equivalent resistance changes at the three temperature points as follows: At room temperature (25℃): the equivalent resistance of the parallel branch is at the middle value, and the resistance of the second PTC thermistor is also at the middle value. The total resistance is the lowest after they are connected in series. At low temperature (-55℃): the equivalent resistance of the parallel branch is not too high because the resistance of the second NTC thermistor is reduced by the second fixed resistor. At the same time, the resistance of the second PTC thermistor drops to the lowest value, but the equivalent resistance of the parallel branch is still significantly higher than the room temperature value. Therefore, the total resistance increases. At high temperature (85℃): the equivalent resistance of the parallel branch decreases further, but the resistance of the second PTC thermistor increases linearly to a higher value. The total resistance also increases after they are superimposed. Furthermore, by adjusting the resistance of the second fixed resistor, the resistance at both the high and low temperature ends can be made basically symmetrical. Therefore, the resistance of the series-type equivalent resistance unit is the smallest at room temperature, and is greater than the room temperature resistance at both high and low temperatures, exhibiting a bowl-shaped (U-shaped) nonlinear resistance-temperature characteristic with a "valley at room temperature and rising at both ends".

[0063] The first and second PTC thermistors used in this invention must be linear PTCs, meaning their resistance increases linearly or nearly linearly with temperature, and their temperature coefficient (TCR) is approximately constant over a wide temperature range. Examples include silicon-based linear PTCs or thin-film linear PTCs. Conventional switching PTCs, such as ceramic or polymer PTCs, are not used because their resistance undergoes abrupt changes (a jump of several orders of magnitude) above the Curie point, making it impossible to superimpose the smooth exponential curve of the NTC thermistor to form the required bowl-shaped or arched resistance-temperature characteristic. The TCR value of the linear PTC is not limited to a specific value; it only needs to increase linearly and stably with temperature within the range of -55°C to 85°C. Accurate mathematical fitting of the parallel or series equivalent resistance units relies on the continuously differentiable characteristics of the linear PTC, which is one of the core prerequisites for achieving asymmetric nonlinear compensation.

[0064] In T-type or π-type two-port attenuation networks, there is a fixed electrical relationship between the attenuation and the arm resistance, providing the core basis for the nonlinear compensation configuration of this invention:

[0065] An increase in the equivalent resistance of the series arm leads to an increase in attenuation; a decrease in the equivalent resistance of the series arm leads to a decrease in attenuation.

[0066] When the equivalent resistance of the parallel arm increases, the attenuation decreases; when the equivalent resistance of the parallel arm decreases, the attenuation increases.

[0067] Simultaneously adjusting the nonlinear equivalent resistance of the series and parallel arms allows the attenuation-temperature curve to be strictly mirrored with the gain-temperature curve of the RF link to be compensated, maintaining characteristic impedance matching and meeting engineering requirements for return loss across the entire temperature range.

[0068] The attenuator configuration method of the present invention is based on the above-mentioned electrical relationship, ensuring the logical uniqueness and feasibility of nonlinear compensation.

[0069] Furthermore, the series arm of the T-type two-port attenuation network adopts a parallel equivalent resistance unit, and the parallel arm adopts a series equivalent resistance unit. At this time, the attenuation-temperature curve of the asymmetric nonlinear temperature compensation attenuator is nonlinearly arched.

[0070] Furthermore, the series arm of the T-type two-port attenuation network adopts a series equivalent resistance unit, and the parallel arm adopts a parallel equivalent resistance unit. At this time, the attenuation-temperature curve of the asymmetric nonlinear temperature-compensated attenuator is nonlinear bowl-shaped.

[0071] Furthermore, the series arm of the π-type two-port attenuation network adopts a parallel equivalent resistance unit, and the parallel arm adopts a series equivalent resistance unit. At this time, the attenuation-temperature curve of the asymmetric nonlinear temperature-compensated attenuator is nonlinearly arched.

[0072] Furthermore, the series arm of the π-type two-port attenuation network adopts a series equivalent resistance unit, and the parallel arm adopts a parallel equivalent resistance unit. At this time, the attenuation-temperature curve of the asymmetric nonlinear temperature-compensated attenuator is nonlinear bowl-shaped.

[0073] Furthermore, by changing the room temperature resistance RP and temperature coefficient TCR of the first PTC thermistor and the second PTC thermistor, the room temperature resistance RN and B of the first NTC thermistor and the second NTC thermistor, and the resistance R of the first fixed resistor and the second fixed resistor, the asymmetry of the attenuation-temperature curve of the asymmetric nonlinear temperature compensation attenuator is adjusted.

[0074] Furthermore, by connecting at least one T-type two-port attenuation network and / or at least one π-type two-port attenuation network in series, and superimposing the asymmetric and nonlinear characteristics of the attenuation-temperature curves of different two-port attenuation networks, multi-stage temperature compensation of the asymmetric nonlinear temperature compensation attenuator can be achieved.

[0075] The relationship between resistance deviation and return loss in this invention:

[0076] For symmetrical π-type or T-type two-port attenuation networks under impedance matching conditions (such as 50 Ω impedance matching), the return loss will decrease when the equivalent resistance of the series arm and the equivalent resistance of the parallel arm deviate from the ideal value at the same time.

[0077] Specifically, when the relative error between the actual equivalent resistance value and the ideal value is controlled within ±15%, the return loss can be maintained above 15 dB (corresponding to a voltage standing wave ratio ≤1.43 and a reflection coefficient ≤0.178). If a return loss ≥20 dB is required, the error needs to be controlled within ±10%.

[0078] This invention sets the design target for the equivalent resistance at each temperature point within ±15% of the ideal value, thus ensuring that the impedance matching of the attenuator meets most engineering requirements across the entire temperature range. For higher requirements, this can be narrowed to ±10%.

[0079] To address the aforementioned relationship, this invention also proposes a design method for an asymmetric nonlinear temperature-compensated attenuator, comprising the following steps:

[0080] Step A1: Based on the gain-temperature curve of the RF link to be compensated, determine the attenuation-temperature curve shape of the asymmetric nonlinear temperature compensation attenuator, and then determine the type of two-port attenuation network to be used, as well as the type of equivalent resistance unit configured for the corresponding series arm and parallel arm. The specific configuration method is shown in Table 1:

[0081] Table 1

[0082]

[0083] Step A2: Based on the attenuation-temperature curve shape, set the target attenuation amount for three temperature points: low temperature endpoint (-55℃), normal temperature endpoint (25℃), and high temperature endpoint (85℃). Then, calculate the target resistance values ​​of the series arm and the parallel arm of the two-port attenuation network used under impedance matching conditions at the three temperature points.

[0084] Step A3: Design the equivalent resistance units configured for the series arm and parallel arm respectively. Specifically, adjust the room temperature resistance RP and temperature coefficient TCR of the first PTC thermistor and the second PTC thermistor, the room temperature resistance RN and B of the first NTC thermistor and the second NTC thermistor, and the resistance R of the first fixed resistor and the second fixed resistor, so that the equivalent resistance of the equivalent resistance units configured for the series arm at the three temperature points meets the target resistance value of the corresponding series arm, and the equivalent resistance of the equivalent resistance units configured for the parallel arm meets the target resistance value of the corresponding parallel arm, thereby completing the design of the asymmetric nonlinear temperature compensation attenuator.

[0085] Furthermore, in the parallel-type equivalent resistance unit, the room-temperature resistance RP of the first PTC thermistor is used to control the magnitude of the equivalent resistance in the low-temperature range. The larger the room-temperature resistance RP, the larger the equivalent resistance in the low-temperature range, and the smaller the decrease in equivalent resistance from room temperature to low temperature. The temperature coefficient TCR of the first PTC thermistor is used to control the magnitude of the decrease in equivalent resistance in the low-temperature range. The larger the temperature coefficient TCR, the more significant the decrease in equivalent resistance from room temperature to low temperature, and the steeper the slope of the equivalent resistance-temperature curve. The room-temperature resistance RN of the first NTC thermistor is used to control the magnitude of the equivalent resistance in the high-temperature range. The larger the room-temperature resistance RN, the larger the equivalent resistance in the high-temperature range, and the smaller the decrease in equivalent resistance from room temperature to high temperature. The B value of the first NTC thermistor is used to control the magnitude of the decrease in equivalent resistance in the high-temperature range. The larger the value, the greater the slope of the equivalent resistance change from room temperature to high temperature. The resistance value R of the first fixed resistor is used to set the peak value of the equivalent resistance at room temperature and adjust the slope of the equivalent resistance-temperature curve throughout the entire temperature range. Increasing the resistance value R can significantly improve the equivalent resistance at room temperature, thereby increasing the decrease in equivalent resistance from room temperature to high temperature and from room temperature to low temperature. Decreasing the resistance value R has the opposite effect, thus achieving nonlinear arched equivalent resistance-temperature curve fitting.

[0086] Furthermore, in the series-type equivalent resistance unit, the room-temperature resistance RP of the second PTC thermistor is used to control the overall magnitude of the equivalent resistance and the slope of the equivalent resistance-temperature curve from room temperature to high temperature. Increasing the room-temperature resistance RP will simultaneously increase the equivalent resistance across the entire temperature range and increase the slope of the equivalent resistance-temperature curve from room temperature to high temperature. Decreasing the room-temperature resistance RP will simultaneously decrease the equivalent resistance across the entire temperature range and decrease the slope of the equivalent resistance-temperature curve from room temperature to high temperature. The temperature coefficient TCR of the second PTC thermistor is used to control the rise in equivalent resistance at high temperatures. The higher the temperature coefficient TCR, the greater the increase in equivalent resistance. The larger the value of the first NTC thermistor, the more significant the increase in equivalent resistance in the high-temperature range, and the steeper the slope of the equivalent resistance-temperature curve. The room-temperature resistance RN of the second NTC thermistor is used to control the increase in equivalent resistance from room temperature to low temperature and the equivalent resistance at low temperature. The larger the room-temperature resistance RN, the steeper the slope of the equivalent resistance-temperature curve from room temperature to low temperature. The B value of the second NTC thermistor is used to control the rate of change of resistance with temperature in the low-temperature range. The larger the B value, the steeper the slope of the equivalent resistance-temperature curve from room temperature to low temperature. The resistance R of the second fixed resistor is used to adjust the slope of the equivalent resistance-temperature curve from room temperature to low temperature.

[0087] Furthermore, in step A3, the relative error between the equivalent resistance of the equivalent resistance unit configured in the series arm and the target resistance value of the corresponding series arm at the three temperature points, as well as the relative error between the equivalent resistance of the equivalent resistance unit configured in the parallel arm and the target resistance value of the corresponding parallel arm, are all controlled within ±15% to ensure that the return loss is higher than 15 dB.

[0088] Furthermore, after step A3, a verification process is also included. Specifically, the equivalent resistance of the series arm configured in step A3 at three temperature points, and the equivalent resistance of the parallel arm configured at three temperature points, are substituted into the adopted two-port attenuation network to calculate the actual attenuation at the three temperature points and compare it with the corresponding target attenuation. If the attenuation error exceeds ±0.5 dB, the process returns to step 3 for fine-tuning.

[0089] For multi-stage temperature compensation, this invention also proposes a design method for an asymmetric nonlinear temperature compensation attenuator, comprising the following steps:

[0090] Step B1: Based on the gain-temperature curve of the RF link to be compensated, determine that the attenuation-temperature curve of the asymmetric nonlinear temperature compensation attenuator is wavy. Then determine that at least one T-type two-port attenuation network or / and at least one π-type two-port attenuation network is used in series. Based on the local characteristics of the attenuation-temperature curve, determine the type of equivalent resistance unit configured for the series arm and parallel arm of different two-port attenuation networks.

[0091] Step B2: Based on the attenuation-temperature curve shape, set the target attenuation amount at three temperature points: low temperature end, normal temperature end, and high temperature end. Then, calculate the target resistance value of the series arm and the target resistance value of the parallel arm of different two-port attenuation networks at the three temperature points under impedance matching conditions.

[0092] Step B3: Design the equivalent resistance units configured for the series and parallel arms of different two-port attenuation networks. Specifically, adjust the room temperature resistance RP and temperature coefficient TCR of the first and second PTC thermistors, the room temperature resistance RN and B of the first and second NTC thermistors, and the resistance R of the first and second fixed resistors. This ensures that the equivalent resistance of the equivalent resistance units configured for the series arms at the three temperature points meets the target resistance value of the corresponding series arm, and the equivalent resistance of the equivalent resistance units configured for the parallel arms meets the target resistance value of the corresponding parallel arm. After superimposing the attenuation-temperature curves of different two-port attenuation networks, multi-level temperature compensation is achieved, completing the design of the asymmetric nonlinear temperature compensation attenuator.

[0093] In this invention, the room temperature resistance values ​​of the first NTC thermistor and the second NTC thermistor can be selected in the range of 1 Ω to 1000 Ω, and their B value can be selected in the range of 2000 K to 6000 K; the room temperature resistance values ​​of the first PTC thermistor and the second PTC thermistor can be selected in the range of 1 Ω to 1000 Ω, and their temperature coefficient TCR can be selected in the range of 150 ppm / ℃ to 7000 ppm / ℃.

[0094] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0095] In the following embodiments, the subscript "s" in the parameter symbol indicates the parameter corresponding to the series arm of the π-type or T-type two-port attenuation network, and the subscript "p" indicates the parameter corresponding to the parallel arm of the π-type or T-type two-port attenuation network. The subscripts "s" and "p" do not directly indicate the parameters of the parallel equivalent resistance unit and the series equivalent resistance unit.

[0096] Example 1

[0097] Based on a π-type two-port attenuation network, this embodiment proposes an asymmetric nonlinear temperature-compensated attenuator, the design method of which specifically includes the following steps:

[0098] Step C1: Based on the gain-temperature curve of the RF link to be compensated, which shows "highest gain at room temperature and decreased gain at high and low temperatures," determine the attenuation-temperature curve shape of the asymmetric nonlinear temperature-compensated attenuator. Its attenuation is greatest near room temperature (25℃) and decreases at both low (-55℃) and high (85℃) temperatures. Therefore, the specific asymmetric nonlinear temperature-compensated attenuator to be designed is an asymmetric arched temperature-compensated attenuator based on a π-type two-port attenuation network, with the structure as follows... Figure 3 As shown, the π-type two-port attenuation network includes one series arm and two parallel arms; wherein, the thermistor network of the series arm is a parallel equivalent resistance unit, and the thermistor network of the parallel arm is a series equivalent resistance unit.

[0099] Step C2: Based on the attenuation-temperature curve shape, set the target attenuation at three temperature points: low temperature endpoint (-55℃), normal temperature endpoint (25℃), and high temperature endpoint (85℃). Then, calculate the target resistance values ​​of the series arm and parallel arm of the π-type two-port attenuation network at the three temperature points under the condition of 50 Ω impedance matching.

[0100] Step C3: In a 50 Ω impedance-matched system, design the equivalent resistance units configured for the series arm and parallel arm respectively. Specifically, adjust the room temperature resistance RP and temperature coefficient TCR of the first PTC thermistor and the second PTC thermistor, the room temperature resistance RN and B of the first NTC thermistor and the second NTC thermistor, and the resistance R of the first fixed resistor and the second fixed resistor, so that the equivalent resistance of the equivalent resistance units configured for the series arm at the three temperature points meets the target resistance value of the corresponding series arm, and the equivalent resistance of the equivalent resistance units configured for the parallel arm meets the target resistance value of the corresponding parallel arm, thereby completing the design of the asymmetric nonlinear temperature compensation attenuator.

[0101] In this embodiment, the attenuation value of the asymmetric nonlinear temperature-compensated attenuator in a 50 Ω impedance system is... The calculation formula is:

[0102] ;

[0103] ;

[0104] ;

[0105] In the formula, Indicates the current temperature; This indicates a standard impedance of 50Ω. The equivalent resistance represents the parallel-type equivalent resistance unit, which is the equivalent resistance of the series arm of the π-type two-port attenuation network in this embodiment. The equivalent resistance represents the series-type equivalent resistance unit, which is the equivalent resistance of the parallel arm of the π-type two-port attenuation network in this embodiment. This indicates the resistance value of the first PTC thermistor in the series arm at room temperature (25℃); This represents the temperature coefficient of the first PTC thermistor in the series arm; This indicates the resistance value of the first NTC thermistor in the series arm at room temperature (25℃); This indicates the B value of the first NTC thermistor in the series arm; This indicates the resistance value of the first fixed resistor in the series arm; This indicates the resistance value of the second PTC thermistor in the parallel arm at room temperature (25℃); This indicates the temperature coefficient of the second PTC thermistor in the parallel arm; This indicates the resistance value of the second NTC thermistor in the parallel arm at room temperature (25°C); This indicates the B value of the second NTC thermistor in the parallel arm; This indicates the resistance value of the second fixed resistor in the parallel arm.

[0106] By adjusting , , , , , , , , and These 10 parameters can adjust the attenuation. It exhibits the desired arched (maximum at room temperature) nonlinear curve within the range of -55℃ to 85℃.

[0107] In this embodiment, the specific design parameters of the equivalent resistance units configured in the series arm and the parallel arm are shown in Table 2:

[0108] Table 2

[0109]

[0110] Based on the above design parameters, the equivalent resistance of the series and parallel arms configured within the temperature range of -55℃ to 85℃, as well as the attenuation value and return loss value of the attenuator, are calculated, as shown in Table 3 below:

[0111] Table 3

[0112]

[0113] The calculation results show that the return loss of the π-type two-port attenuation network is above 28 dB, ensuring good matching. The attenuation is 4.5 dB at 25℃, and approximately 3 dB at both 85℃ and -55℃. The corresponding fitted attenuation-temperature curves are shown below. Figure 4 As shown, this demonstrates the design of an asymmetric nonlinear temperature-compensated attenuator.

[0114] Example 2

[0115] Based on a π-type two-port attenuation network, this embodiment proposes an asymmetric nonlinear temperature-compensated attenuator, the design method of which specifically includes the following steps:

[0116] Step D1: Based on the gain-temperature curve of the RF link to be compensated, which shows "lowest gain at room temperature and increased gain at high and low temperatures," determine the attenuation-temperature curve shape of the asymmetric nonlinear temperature-compensated attenuator. Its attenuation is minimum near room temperature (25℃) and increases at both low temperatures (-55℃) and high temperatures (85℃). Therefore, the specific asymmetric nonlinear temperature-compensated attenuator to be designed is an asymmetric bowl-shaped temperature-compensated attenuator based on a π-type two-port attenuation network, with the structure as follows... Figure 5 As shown, the π-type two-port attenuation network includes one series arm and two parallel arms; wherein, the thermistor network of the series arm is a series equivalent resistance unit, and the thermistor network of the parallel arm is a parallel equivalent resistance unit.

[0117] Step D2: Based on the attenuation-temperature curve shape, set the target attenuation at three temperature points: low temperature endpoint (-55℃), normal temperature endpoint (25℃), and high temperature endpoint (85℃). Then, calculate the target resistance values ​​of the series arm and parallel arm of the π-type two-port attenuation network at the three temperature points under the condition of 50 Ω impedance matching.

[0118] Step D3: In a 50 Ω impedance-matched system, design the equivalent resistance units configured for the series arm and parallel arm respectively. Specifically, adjust the room temperature resistance RP and temperature coefficient TCR of the first PTC thermistor and the second PTC thermistor, the room temperature resistance RN and B of the first NTC thermistor and the second NTC thermistor, and the resistance R of the first fixed resistor and the second fixed resistor, so that the equivalent resistance of the equivalent resistance units configured for the series arm at the three temperature points meets the target resistance value of the corresponding series arm, and the equivalent resistance of the equivalent resistance units configured for the parallel arm meets the target resistance value of the corresponding parallel arm, thereby completing the design of the asymmetric nonlinear temperature compensation attenuator.

[0119] In this embodiment, the attenuation value of the asymmetric nonlinear temperature-compensated attenuator in a system with a 50 Ω impedance is... The calculation formula is:

[0120] ;

[0121] ;

[0122] ;

[0123] In the formula, This indicates a standard impedance of 50 Ω. The equivalent resistance of the series-type equivalent resistance unit is the equivalent resistance of the series arm of the π-type two-port attenuation network in this embodiment. This represents the equivalent impedance of the parallel-type equivalent resistance unit, which is the equivalent resistance of the parallel arm of the π-type two-port attenuation network in this embodiment. This indicates the resistance value of the second PTC thermistor in the series arm at room temperature (25℃); This represents the temperature coefficient of the second PTC thermistor in the series arm; This indicates the resistance value of the second NTC thermistor in the series arm at room temperature (25℃); This indicates the B value of the second NTC thermistor in the series arm; This indicates the resistance value of the second fixed resistor in the series arm; This indicates the resistance value of the first PTC thermistor in the parallel arm at room temperature (25℃); This indicates the temperature coefficient of the first PTC thermistor in the parallel arm; This indicates the resistance value of the first NTC thermistor in the parallel arm at room temperature (25°C); This indicates the B value of the first NTC thermistor in the parallel arm; This indicates the resistance value of the first fixed resistor in the parallel arm.

[0124] By adjusting , , , , , , , , and These 10 parameters can adjust the attenuation. It exhibits the desired bowl-shaped (minimum at room temperature) nonlinear curve within the range of -55℃ to 85℃.

[0125] In this embodiment, the specific design parameters of the equivalent resistance units configured in the series arm and the parallel arm are shown in Table 4:

[0126] Table 4

[0127]

[0128] Based on the above design parameters, the equivalent resistance of the series and parallel arms configured within the temperature range of -55℃ to 85℃, as well as the attenuation value and return loss value of the attenuator, are calculated, as shown in Table 5 below:

[0129] Table 5

[0130]

[0131] The calculation results show that the return loss of the π-type two-port attenuation network is above 25 dB, ensuring good matching. The attenuation is 3.6 dB at 25℃, and approximately 5.2 dB at both 85℃ and -55℃. The corresponding fitted attenuation-temperature curves are shown below. Figure 6 As shown, this demonstrates the design of an asymmetric nonlinear temperature-compensated attenuator.

[0132] Example 3

[0133] Based on a T-type two-port attenuation network, this embodiment proposes an asymmetric nonlinear temperature-compensated attenuator, the design method of which specifically includes the following steps:

[0134] Step E1: Based on the gain-temperature curve of the RF link to be compensated, which shows "highest gain at room temperature and decreased gain at high and low temperatures," determine the attenuation-temperature curve shape of the asymmetric nonlinear temperature-compensated attenuator. Its attenuation is greatest near room temperature (25℃) and decreases at both low (-55℃) and high (85℃) temperatures. Therefore, the specific asymmetric nonlinear temperature-compensated attenuator to be designed is an asymmetric arched temperature-compensated attenuator based on a T-type two-port attenuation network, with the structure as follows... Figure 7 As shown, the T-type two-port attenuation network includes two series arms and one parallel arm; wherein, the thermistor network of the series arm is a parallel equivalent resistance unit, and the thermistor network of the parallel arm is a series equivalent resistance unit.

[0135] Step E2: Based on the attenuation-temperature curve shape, set the target attenuation at three temperature points: low temperature endpoint (-55℃), normal temperature endpoint (25℃), and high temperature endpoint (85℃). Then, calculate the target resistance values ​​of the series arm and parallel arm of the T-type two-port attenuation network at the three temperature points under the condition of 50 Ω impedance matching.

[0136] Step E3: In a 50 Ω impedance-matched system, design the equivalent resistance units configured for the series arm and parallel arm respectively. Specifically, adjust the room temperature resistance RP and temperature coefficient TCR of the first PTC thermistor and the second PTC thermistor, the room temperature resistance RN and B of the first NTC thermistor and the second NTC thermistor, and the resistance R of the first fixed resistor and the second fixed resistor, so that the equivalent resistance of the equivalent resistance units configured for the series arm at the three temperature points meets the target resistance value of the corresponding series arm, and the equivalent resistance of the equivalent resistance units configured for the parallel arm meets the target resistance value of the corresponding parallel arm, thereby completing the design of the asymmetric nonlinear temperature compensation attenuator.

[0137] In this embodiment, the attenuation value of the asymmetric nonlinear temperature-compensated attenuator in a system with a 50Ω impedance is... The calculation formula is:

[0138] ;

[0139] ;

[0140] ;

[0141] In the formula, This indicates a standard impedance of 50 Ω. The equivalent resistance of the parallel-type equivalent resistance unit is the equivalent resistance of the series arm of the T-type two-port attenuation network in this embodiment. The equivalent resistance represents the series-type equivalent resistance unit, which is the equivalent resistance of the parallel arm of the T-type two-port attenuation network in this embodiment. This indicates the resistance value of the first PTC thermistor in the series arm at room temperature (25℃); This represents the temperature coefficient of the first PTC thermistor in the series arm; This indicates the resistance value of the first NTC thermistor in the series arm at room temperature (25℃); This indicates the B value of the first NTC thermistor in the series arm; This indicates the resistance value of the first fixed resistor in the series arm; This indicates the resistance value of the second PTC thermistor in the parallel arm at room temperature (25℃); This indicates the temperature coefficient of the second PTC thermistor in the parallel arm; This indicates the resistance value of the second NTC thermistor in the parallel arm at room temperature (25°C); This indicates the B value of the second NTC thermistor in the parallel arm; This indicates the resistance value of the second fixed resistor in the parallel arm.

[0142] By adjusting , , , , , , , , and These 10 parameters can adjust the attenuation. It exhibits the desired arched (maximum at room temperature) nonlinear curve within the range of -55℃ to 85℃.

[0143] In this embodiment, the specific design parameters of the equivalent resistance units configured in the series arm and the parallel arm are shown in Table 6:

[0144] Table 6

[0145]

[0146] Based on the above design parameters, the equivalent resistance of the series and parallel arms configured within the temperature range of -55℃ to 85℃, as well as the attenuation value and return loss value of the attenuator, are calculated, as shown in Table 7 below:

[0147] Table 7

[0148]

[0149] The calculation results show that the return loss of the T-type two-port attenuation network is above 25 dB, ensuring good matching. The attenuation is 6.5 dB at 25℃, and approximately 4 dB at both 85℃ and -55℃. The corresponding fitted attenuation-temperature curves are shown below. Figure 8 As shown, this demonstrates the design of an asymmetric nonlinear temperature-compensated attenuator.

[0150] Example 4

[0151] Based on a T-type two-port attenuation network, this embodiment proposes an asymmetric nonlinear temperature-compensated attenuator, the design method of which specifically includes the following steps:

[0152] Step F1: Based on the gain-temperature curve of the RF link to be compensated, which shows "lowest gain at room temperature and increased gain at high and low temperatures," determine the attenuation-temperature curve shape of the asymmetric nonlinear temperature-compensated attenuator. Its attenuation is minimum near room temperature (25℃) and increases at both low temperatures (-55℃) and high temperatures (85℃). Therefore, the specific asymmetric nonlinear temperature-compensated attenuator to be designed is an asymmetric bowl-shaped temperature-compensated attenuator based on a T-type two-port attenuation network, with the structure as follows... Figure 9 As shown, the T-type two-port attenuation network includes two series arms and one parallel arm; wherein, the thermistor network of the series arm is a series equivalent resistance unit, and the thermistor network of the parallel arm is a parallel equivalent resistance unit.

[0153] Step F2: Based on the attenuation-temperature curve shape, set the target attenuation values ​​for three temperature points: the low temperature endpoint (-55℃), the normal temperature endpoint (25℃), and the high temperature endpoint (85℃). Then, calculate the target resistance values ​​of the series arm and the parallel arm of the T-type two-port attenuation network at the three temperature points under the condition of 50 Ω impedance matching.

[0154] Step F3: Under a 50 Ω impedance-matched system, design the equivalent resistance units configured for the series arm and parallel arm respectively. Specifically, adjust the room temperature resistance RP and temperature coefficient TCR of the first PTC thermistor and the second PTC thermistor, the room temperature resistance RN and B of the first NTC thermistor and the second NTC thermistor, and the resistance R of the first fixed resistor and the second fixed resistor, so that the equivalent resistance of the equivalent resistance units configured for the series arm at the three temperature points meets the target resistance value of the corresponding series arm, and the equivalent resistance of the equivalent resistance units configured for the parallel arm meets the target resistance value of the corresponding parallel arm, thereby completing the design of the asymmetric nonlinear temperature compensation attenuator.

[0155] In this embodiment, the attenuation value of the asymmetric nonlinear temperature-compensated attenuator in a system with a standard impedance of 50Ω is... The calculation formula is:

[0156] ;

[0157] ;

[0158] ;

[0159] In the formula, This indicates a standard impedance of 50 Ω. The equivalent resistance of the series-type equivalent resistance unit is the equivalent resistance of the series arm of the T-type two-port attenuation network in this embodiment. The equivalent resistance represents the parallel-type equivalent resistance unit, that is, the equivalent resistance of the parallel arm of the T-type two-port attenuation network in this embodiment; This indicates the resistance value of the second PTC thermistor in the series arm at room temperature (25℃); This represents the temperature coefficient of the second PTC thermistor in the series arm; This indicates the resistance value of the second NTC thermistor in the series arm at room temperature (25℃); This indicates the B value of the second NTC thermistor in the series arm; This indicates the resistance value of the second fixed resistor in the series arm; This indicates the resistance value of the first PTC thermistor in the parallel arm at room temperature (25℃); This indicates the temperature coefficient of the first PTC thermistor in the parallel arm; This indicates the resistance value of the first NTC thermistor in the parallel arm at room temperature (25°C); This indicates the B value of the first NTC thermistor in the parallel arm; This indicates the resistance value of the first fixed resistor in the parallel arm.

[0160] By adjusting , , , , , , , , and These 10 parameters can adjust the attenuation. It exhibits the desired bowl-shaped (minimum at room temperature) nonlinear curve within the range of -55℃ to 85℃.

[0161] In this embodiment, the specific design parameters of the equivalent resistance units configured in the series arm and the parallel arm are shown in Table 8:

[0162] Table 8

[0163]

[0164] Based on the above design parameters, the equivalent resistance of the series and parallel arms configured within the temperature range of -55℃ to 85℃, as well as the attenuation value and return loss value of the attenuator, are calculated, as shown in Table 9 below:

[0165] Table 9

[0166]

[0167] The calculation results show that the return loss of the T-type two-port attenuation network is above 28 dB, ensuring good matching. The attenuation is 7.5 dB at 25℃, and approximately 10.6 dB at both 85℃ and -55℃. The corresponding fitted attenuation-temperature curves are shown below. Figure 10As shown, this demonstrates the design of an asymmetric nonlinear temperature-compensated attenuator.

[0168] Example 5

[0169] This embodiment proposes an asymmetric wave-shaped temperature-compensated attenuator, the design method of which specifically includes the following steps:

[0170] Step G1: Based on the wavy gain-temperature curve of the RF link to be compensated, determine the attenuation-temperature curve shape of the asymmetric wavy temperature compensation attenuator. Its attenuation generally presents a bowl-shaped trend, and it has an arched compensation characteristic with a local temperature range near room temperature, as well as multiple characteristics such as more attenuation at low temperature than at high temperature. It can adapt to more complex temperature compensation requirements, namely, the composite asymmetric curve shape of "overall bowl shape, local compensation".

[0171] For the complex asymmetric curve shape, the required asymmetric wavy temperature-compensated attenuator is determined to consist of a π-type two-port attenuation network and a T-type two-port attenuation network connected in series, as shown in the structure below. Figure 11 As shown; among them, the T-type two-port attenuation network is used to provide the basic bowl-shaped curve (large attenuation in the low temperature and high temperature ranges, and small attenuation in the room temperature range), including two series arms and one parallel arm. The thermistor network of the series arm is a series equivalent resistance unit, and the thermistor network of the parallel arm is a parallel equivalent resistance unit. The π-type two-port attenuation network is used to superimpose a positive peak value near room temperature (an arch-shaped curve with larger attenuation near room temperature), including one series arm and two parallel arms. The thermistor network of the series arm is a parallel equivalent resistance unit, and the thermistor network of the parallel arm is a series equivalent resistance unit. After the π-type two-port attenuation network and the T-type two-port attenuation network are connected in series, the overall attenuation curve presents a wave-shaped shape of "an arch in a bowl".

[0172] Step G2: Based on the shape of the composite asymmetric curve, set the target attenuation at three temperature points: the low temperature endpoint (-55℃), the normal temperature endpoint (25℃), and the high temperature endpoint (85℃). Calculate the target resistance values ​​of the series arm and the parallel arm of the π-type two-port attenuation network and the T-type two-port attenuation network at the three temperature points under the condition of 50 Ω impedance matching.

[0173] Step G3: Under a 50 Ω impedance-matched system, design the equivalent resistance units configured for the series and parallel arms of the π-type two-port attenuation network and the T-type two-port attenuation network, respectively. Specifically, adjust the room temperature resistance RP and temperature coefficient TCR of the first PTC thermistor and the second PTC thermistor, the room temperature resistance RN and B of the first NTC thermistor and the second NTC thermistor, and the resistance R of the first fixed resistor and the second fixed resistor, so that the equivalent resistance of the equivalent resistance units configured for the series arm at the three temperature points meets the target resistance value of the corresponding series arm, and the equivalent resistance of the equivalent resistance units configured for the parallel arm meets the target resistance value of the corresponding parallel arm, thereby completing the design of the asymmetric nonlinear temperature-compensated attenuator.

[0174] In this embodiment, the specific design parameters of the equivalent resistance units configured for the series and parallel arms of the π-type two-port attenuation network are shown in Table 10:

[0175] Table 10

[0176]

[0177] The specific design parameters of the equivalent resistance units configured for the series and parallel arms of the T-type two-port attenuation network are shown in Table 11:

[0178] Table 11

[0179]

[0180] Based on the above design parameters, the attenuation values ​​and return loss values ​​of the π-type two-port attenuation network and the T-type two-port attenuation network in the range of -55℃ to 85℃, as well as the overall composite attenuation value of the asymmetric corrugated temperature-compensated attenuator, are calculated, as shown in Table 12 below:

[0181] Table 12

[0182]

[0183] The calculation results show that the return loss of both the π-type two-port attenuation network and the T-type two-port attenuation network is above 18 dB, ensuring good matching. They also exhibit a wavy compensation curve resembling an arch within a bowl. Figure 12 As shown, this demonstrates the successful design of an asymmetric wave-shaped temperature-compensated attenuator.

[0184] It should be noted that this is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An asymmetric nonlinear temperature-compensated attenuator, designed based on a T-type two-port attenuator network or a π-type two-port attenuator network, wherein the T-type two-port attenuator network includes two series arms and one parallel arm, and the π-type two-port attenuator network includes one series arm and two parallel arms. Its features are, The thermistor networks of the series arm and parallel arm are selected from parallel equivalent resistance units or series equivalent resistance units, and the thermistor networks of the series arm and parallel arm of the same type of two-port attenuation network are different. The parallel equivalent resistance unit is composed of a first PTC thermistor, a first NTC thermistor and a first fixed resistor, which are connected in parallel with each other. The series-type equivalent resistance unit consists of a second PTC thermistor, a second NTC thermistor, and a second fixed resistor. The second NTC thermistor is connected in parallel with the second fixed resistor and then connected in series with the second PTC thermistor. Both the first PTC thermistor and the second PTC thermistor are linear PTC thermistors.

2. The asymmetric nonlinear temperature-compensated attenuator according to claim 1, characterized in that, The first PTC thermistor and the second PTC thermistor are silicon-based linear PTC thermistors or thin-film linear PTC thermistors.

3. The asymmetric nonlinear temperature-compensated attenuator according to claim 2, characterized in that, The operating temperature range of the asymmetric nonlinear temperature compensation attenuator is -55℃ to 85℃.

4. The asymmetric nonlinear temperature-compensated attenuator according to claim 3, characterized in that, By configuring different types of equivalent resistance units in the series and parallel arms, the attenuation-temperature curve of the asymmetric nonlinear temperature compensation attenuator is mirrored with the gain-temperature curve of the RF link to be compensated, thus achieving nonlinear temperature compensation.

5. The asymmetric nonlinear temperature-compensated attenuator according to claim 4, characterized in that, The series arm of the T-type two-port attenuation network adopts a parallel equivalent resistance unit, and the parallel arm adopts a series equivalent resistance unit. At this time, the attenuation-temperature curve of the asymmetric nonlinear temperature compensation attenuator is nonlinear arched. The series arm of the T-type two-port attenuation network adopts a series equivalent resistance unit, and the parallel arm adopts a parallel equivalent resistance unit. At this time, the attenuation-temperature curve of the asymmetric nonlinear temperature compensation attenuator is nonlinear bowl-shaped. The series arm of the π-type two-port attenuation network adopts a parallel equivalent resistance unit, and the parallel arm adopts a series equivalent resistance unit. At this time, the attenuation-temperature curve of the asymmetric nonlinear temperature compensation attenuator is nonlinear arched. The series arm of the π-type two-port attenuation network adopts a series equivalent resistance unit, and the parallel arm adopts a parallel equivalent resistance unit. At this time, the attenuation-temperature curve of the asymmetric nonlinear temperature-compensated attenuator is nonlinear bowl-shaped.

6. The asymmetric nonlinear temperature-compensated attenuator according to claim 3, characterized in that, By changing the room temperature resistance RP and temperature coefficient TCR of the first PTC thermistor and the second PTC thermistor, the room temperature resistance RN and B of the first NTC thermistor and the second NTC thermistor, and the resistance R of the first fixed resistor and the second fixed resistor, the asymmetry, attenuation amount, and compensation amount of the attenuation-temperature curve of the asymmetric nonlinear temperature compensation attenuator can be adjusted.

7. The asymmetric nonlinear temperature-compensated attenuator according to claim 3, characterized in that, By connecting at least one T-type two-port attenuation network and at least one π-type two-port attenuation network in series, and superimposing the asymmetric and nonlinear characteristics of the attenuation-temperature curves of different two-port attenuation networks, multi-stage temperature compensation of the asymmetric nonlinear temperature compensation attenuator can be achieved.

8. A design method for an asymmetric nonlinear temperature-compensated attenuator, characterized in that, Includes the following steps: Step A1: Based on the gain-temperature curve of the RF link to be compensated, determine the attenuation-temperature curve shape of the asymmetric nonlinear temperature compensation attenuator, and then determine the type of two-port attenuation network to be used, as well as the type of equivalent resistance unit configured for the corresponding series arm and parallel arm. Step A2: Based on the attenuation-temperature curve shape, set the target attenuation amount at three temperature points: low temperature end, normal temperature end, and high temperature end. Then, calculate the target resistance value of the series arm and the target resistance value of the parallel arm of the two-port attenuation network used under impedance matching conditions at the three temperature points. Step A3: Design the equivalent resistance units configured for the series arm and the parallel arm respectively. Specifically, adjust the room temperature resistance RP and temperature coefficient TCR of the first PTC thermistor and the second PTC thermistor, the room temperature resistance RN and B of the first NTC thermistor and the second NTC thermistor, and the resistance R of the first fixed resistor and the second fixed resistor, so that the equivalent resistance of the equivalent resistance units configured for the series arm at the three temperature points meets the target resistance value of the corresponding series arm, and the equivalent resistance of the equivalent resistance units configured for the parallel arm meets the target resistance value of the corresponding parallel arm, thereby completing the design of the asymmetric nonlinear temperature compensation attenuator as described in any one of claims 1 to 6.

9. The design method of the asymmetric nonlinear temperature-compensated attenuator according to claim 8, characterized in that, In step A3, the relative error between the equivalent resistance of the equivalent resistance unit configured in the series arm and the target resistance value of the corresponding series arm at the three temperature points, and the relative error between the equivalent resistance of the equivalent resistance unit configured in the parallel arm and the target resistance value of the corresponding parallel arm, are all controlled within ±15% to ensure that the return loss is higher than 15 dB. The process after step A3 includes a verification process. Specifically, the equivalent resistance of the series arm configured in step A3 at three temperature points, and the equivalent resistance of the parallel arm configured at three temperature points, are substituted into the two-port attenuation network used to calculate the actual attenuation at the three temperature points and compared with the corresponding target attenuation. If the attenuation error exceeds ±0.5 dB, the process returns to step A3 for fine-tuning.

10. A design method for an asymmetric nonlinear temperature-compensated attenuator, characterized in that, Includes the following steps: Step B1: Based on the gain-temperature curve of the RF link to be compensated, determine that the attenuation-temperature curve of the asymmetric nonlinear temperature compensation attenuator is wavy. Then determine that at least one T-type two-port attenuation network and at least one π-type two-port attenuation network are used in series. Based on the local characteristics of the attenuation-temperature curve, determine the type of equivalent resistance unit configured for the series arm and parallel arm of different two-port attenuation networks. Step B2: Based on the attenuation-temperature curve shape, set the target attenuation amount at three temperature points: low temperature end, normal temperature end, and high temperature end. Then, calculate the target resistance value of the series arm and the target resistance value of the parallel arm of different two-port attenuation networks at the three temperature points under impedance matching conditions. Step B3: Design the equivalent resistance units configured for the series and parallel arms of different two-port attenuation networks respectively. Specifically, adjust the room temperature resistance RP and temperature coefficient TCR of the first PTC thermistor and the second PTC thermistor, the room temperature resistance RN and B of the first NTC thermistor and the second NTC thermistor, and the resistance R of the first fixed resistor and the second fixed resistor, so that the equivalent resistance of the equivalent resistance units configured for the series arm at the three temperature points meets the target resistance value of the corresponding series arm, and the equivalent resistance of the equivalent resistance units configured for the parallel arm meets the target resistance value of the corresponding parallel arm. After superimposing the attenuation-temperature curves of different two-port attenuation networks, multi-level temperature compensation is achieved, and the design of the asymmetric nonlinear temperature compensation attenuator as described in claim 7 is completed.

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