CN115425964A - PT (potential Transformer) symmetry principle-based frequency-adjustable non-reciprocal transmission system and detection method thereof - Google Patents

Abstract

The invention discloses a frequency-adjustable non-reciprocal transmission system based on the principle of PT symmetry and a detection method thereof. The circuit system includes: an inductance-capacitance-positive resistance parallel resonance loss resonance module, an adjustable coupling module, and an inductance-capacitance ‑ Gain resonance module with negative resistance connected in parallel; the loss resonance module and the gain resonance module are connected through an adjustable capacitive coupling module to form a PT symmetrical system; the signal transmission from the loss resonance module to the gain resonance module is forward transmission, and vice versa. By changing the adjustable capacitive coupling module, the coupling coefficient between the loss module and the gain module is changed, thereby changing the transmission frequency of the system. The amplitude of the transmission signal is adjusted, and the saturation property of the negative resistance in the gain resonance module is used to realize the difference between the forward transmission coefficient and the reverse transmission coefficient, thereby realizing non-reciprocal transmission. The system has the advantages of high non-reciprocity ratio and low insertion loss.

Description

Frequency adjustable non-reciprocal transmission system and its detection method based on PT symmetry principle

technical field

The invention belongs to the field of two-port transmission systems, and in particular relates to a frequency-adjustable non-reciprocal transmission system based on the principle of PT symmetry and a detection method thereof.

Background technique

Two-port transmission circuits are divided into two types: reciprocal transmission circuits and non-reciprocal transmission circuits. The definition of a reciprocal transmission circuit is that the transmission of the signal between the two ports is the same, so the reciprocal transmission circuit has no directionality and is usually constructed using all passive components. Contrary to reciprocal transmission circuits, the definition of non-reciprocal transmission circuits is that the transmission of signals between two ports is different. Changing the port of the input signal can see different output signal amplitudes at the other port, which has directionality, usually Build using magnetic elements or non-linear active elements. Non-reciprocal transmission of acoustic signals and non-reciprocal transmission of electrical signals can be constructed by using non-reciprocal transmission circuits, which are often used to construct circulators and isolators. The current non-reciprocal transmission system can only achieve non-reciprocal transmission of a single frequency signal. If the signal frequency changes, a non-reciprocal transmission system needs to be re-made, which greatly increases the cost and inconvenience in the application and application, and is not suitable for Variable frequency application environment. Therefore, it is necessary to invent a frequency-tunable non-reciprocal transmission system.

Contents of the invention

The purpose of the present invention is to provide a frequency-adjustable non-reciprocal transmission system and its detection method based on the principle of PT symmetry. The coupling module of the PT symmetry system is constructed with adjustable capacitance to realize the transmission signal frequency of the PT symmetry system in the broken area. Adjustment, using the nonlinearity of the transimpedance amplifier to realize the non-reciprocal transmission of the signal between the two ports, to solve the problem that the current non-reciprocal transmission system can only realize the non-reciprocal transmission of a single frequency signal. If the signal frequency changes, it needs Re-making a non-reciprocal transmission system greatly increases the cost and inconvenience in the application, and is not suitable for the technical problem of the variable frequency application environment.

In order to solve the problems of the technologies described above, the specific technical solutions of the present invention are as follows:

A frequency-tunable non-reciprocal transmission system based on the principle of PT symmetry, which consists of three parts: a loss resonance circuit, a gain resonance circuit, and an adjustable coupling module. The gain resonance circuit is composed of a second inductance, a positive resistance and a negative resistance in parallel. The negative resistance is composed of a transimpedance amplifier; when the transimpedance amplifier works in the linear region, the negative resistance is a fixed value negative resistance that does not change with the input voltage; when the transimpedance amplifier works in the negative saturation region, the negative resistance value is affected by the input Voltage-controlled negative resistance; the loss resonant circuit and the gain resonant circuit are coupled together through an adjustable coupling module, and the coupling coefficient between the loss resonant circuit and the gain resonant circuit is changed by changing the coupling capacitance of the adjustable coupling module, thereby changing the system transmission frequency.

Further, the loss resonant circuit is composed of a first inductor, a first capacitor and a positive resistor connected in parallel.

Further, the transimpedance amplifier includes a first resistor, an operational amplifier, a second resistor, and a third resistor; the first resistor is connected between the same input terminal and the output terminal of the operational amplifier, and the second negative resistor is connected to the reverse direction of the operational amplifier. Between the input end and the output end, one end of the third resistor is grounded and the other end is connected to the second resistor.

Further, the adjustable coupling module is composed of adjustable capacitors.

Further, the first inductance and positive resistance in the loss resonant circuit are respectively equal to the second inductance and negative resistance in the gain resonant circuit.

Further, the resistance value of the positive resistance in the loss resonant circuit is equal to the absolute value of the resistance value of the negative resistance in the gain resonant circuit when it works in the linear region.

A detection method of a frequency-tunable non-reciprocal transmission system based on the principle of PT symmetry, comprising the following steps:

Step 1, adjust the resistance value of the transimpedance amplifier, so that the absolute value of the equivalent negative resistance value in the linear region of the transimpedance amplifier is equal to the absolute value of the positive resistance of the loss resonant circuit, so that the system is in a PT symmetrical state;

Step 2, adjust the capacitance value of the adjustable coupling module so that its value is in

At this time, the system is in the PT symmetry breaking area; where C _L is the capacitance of the loss resonant circuit, _RL is the positive resistance of the loss resonant circuit, and L _L is the inductance of the loss resonant circuit;

Step 3, adjust the amplitude of the input signal, define the signal transmission from the loss resonant circuit to the gain resonant circuit as forward transmission, at this time, the negative resistance works in the linear region, define the signal transmission from the gain resonant circuit to the loss resonant circuit as reverse transmission, At this time, the negative resistance works in the negative saturation region. Since the equivalent negative resistance of the transimpedance amplifier is different during forward transmission and reverse transmission, the system forms non-reciprocal transmission;

之间变化，改变系统信号传输频率，形成传输频率可调谐的非互易传输系统。Step 4, adjust the adjustable capacitance value of the adjustable coupling module to make it

Change between, change the signal transmission frequency of the system, and form a non-reciprocal transmission system with tunable transmission frequency.

The frequency adjustable non-reciprocal transmission system and its detection method based on the principle of PT symmetry of the present invention have the following advantages:

The invention changes the coupling coefficient between the loss module and the gain module by changing the adjustable capacitive coupling module, thereby changing the transmission frequency of the system. The amplitude of the transmission signal is adjusted, and the saturation property of the negative resistance in the gain resonance module is used to realize the difference between the forward transmission coefficient and the reverse transmission coefficient, thereby realizing non-reciprocal transmission. The system has the advantages of high non-reciprocity ratio, low insertion loss and adjustable frequency.

Description of drawings

Fig. 1 is the equivalent circuit diagram of a kind of frequency adjustable non-reciprocal transmission system based on PT symmetry principle of the present invention;

Notes in the figure: 1. Loss resonant circuit; 2. Gain resonant circuit; 3. Adjustable coupling module; 11. First capacitance; 12. Positive resistance; 13. First inductance; 21. Second capacitance; 22. Negative Resistor; 23, second inductance; 221, first resistor; 222, operational amplifier; 223, second resistor; 224, third resistor.

detailed description

In order to better understand the purpose, structure and function of the present invention, a frequency-tunable non-reciprocal transmission system and its detection method based on the principle of PT symmetry of the present invention will be further described in detail in conjunction with the accompanying drawings.

According to the relationship between coupling coefficient and loss factor, the PT symmetry system can be divided into three working areas: PT symmetry area, PT symmetry critical point and PT symmetry breaking area. When the coupling coefficient is greater than the critical coupling coefficient, the system is in the PT symmetry region, and the system resonance frequency in the PT symmetry region is two unequal real numbers. The signal amplitude of the loss resonant circuit is the same as that of the gain resonant circuit, which can be applied to the signal When the coupling coefficient is equal to the critical coupling coefficient, the system is at the critical point of PT symmetry, and the system resonant frequency at the critical point of PT symmetry will merge into a real frequency. When there is a perturbation in the system, the real frequency will split, and the split The frequency difference is very sensitive to perturbation, and is often used in the design of high-sensitivity sensors; when the coupling coefficient is less than the critical coupling coefficient, the system is in the PT symmetry breaking area, and the system resonance frequency in the PT symmetry breaking area is two with the same real part and opposite The complex number of the imaginary part, the signal amplitude of the loss resonant circuit decreases exponentially with time, the signal amplitude of the gain resonant circuit increases exponentially with time, due to the nonlinearity of the negative resistance device, the signal amplitude of the gain resonant circuit enters the transimpedance amplifier The negative saturation region will be amplified nonlinearly, resulting in unequal transmission coefficients in the two transmission directions, which can be used to construct non-reciprocal transmission systems.

As shown in Figure 1, a frequency-tunable non-reciprocal transmission system based on the principle of PT symmetry is composed of a loss resonance circuit 1, a gain resonance circuit 2, and an adjustable coupling module 3. The gain resonance circuit 2 consists of a second inductor 23. The positive resistance 12 and the negative resistance 22 are connected in parallel, wherein the negative resistance 22 is composed of a transimpedance amplifier; when the transimpedance amplifier works in the linear region, the negative resistance 22 is a fixed-value negative resistance that does not change with the input voltage; when the transimpedance amplifier When working in the negative saturation region, the resistance of the negative resistance 22 is a negative resistance controlled by the input voltage; the loss resonant circuit 1 and the gain resonant circuit 2 are coupled together through the adjustable coupling module 3, and by changing the coupling capacitance of the adjustable coupling module 3 To change the coupling coefficient between the loss resonant circuit 1 and the gain resonant circuit 2, thereby changing the transmission frequency of the system.

The loss resonant circuit 1 is composed of a first inductor 13 , a first capacitor 11 and a positive resistor 12 connected in parallel.

The transimpedance amplifier includes a first resistor 221, an operational amplifier 222, a second resistor 223, and a third resistor 224; the first resistor 221 is connected between the same input terminal and the output terminal of the operational amplifier 222, and the second negative resistor 223 is connected between the operational amplifier 222 and the output terminal. Between the inverting input terminal and the output terminal of the amplifier 222 , one end of the third resistor 224 is grounded and the other end is connected to the second resistor 223 .

The adjustable coupling module 3 is composed of adjustable capacitors.

The first inductance 13 and the positive resistance 12 in the loss resonant circuit 1 are respectively equal to the second inductance 23 and the negative resistance 22 in the gain resonant circuit 2 .

The resistance value of the positive resistor 11 in the loss resonance circuit 1 is equal to the absolute value of the resistance value of the negative resistor 21 in the gain resonance circuit when it works in the linear region.

Adjust the first resistor 221, the second resistor 223, and the third resistor 224 to satisfy the formula

Where R ₁ is the first resistor 221 , R ₂ is the second resistor 223 , and R ₃ is the third resistor 224 .

其中C_L是损耗谐振电路电容11，R_L是损耗谐振电路正电阻12，L_L是损耗谐振电路电感13。The symbol that defines the loss factor is γ, and the loss factor satisfies the formula

Where _CL is the lossy resonant circuit capacitance 11 , _RL is the lossy resonant circuit positive resistance 12 , and _LL is the lossy resonant circuit inductance 13 .

设定电容可调耦合模块的电容变化范围满足公式

保证系统工作在PT对称破缺区。调节可调耦合模块(3)电容值然后在跨阻放大器(22)在负饱和区的条件下测量正向传输系数和反向传输系数，可以实现频率可调的非互易传输系统。Define the capacitive coupling coefficient symbol as c, and the capacitive coupling coefficient satisfies the formula

Set the capacitance variation range of the capacitance adjustable coupling module to satisfy the formula

Ensure that the system works in the PT symmetry breaking area. Adjusting the capacitance value of the adjustable coupling module (3) and then measuring the forward transmission coefficient and the reverse transmission coefficient under the condition that the transimpedance amplifier (22) is in the negative saturation region can realize a non-reciprocal transmission system with adjustable frequency.

Its specific working process is:

当信号幅值增加，跨阻放大器会进入饱和区；As shown in Figure 1, the operational amplifier 222, the first resistor 221, the second resistor 223, and the third resistor 224 form a transimpedance amplifier, and the initial state adjusts its resistance in the linear region to satisfy the formula

When the signal amplitude increases, the transimpedance amplifier will enter the saturation region;

Set the value range of the capacitance value of the adjustable coupling module to satisfy

Given a suitable input signal amplitude, the transimpedance amplifier module is in the negative saturation region for reverse transmission, and the forward transmission is in the linear region, and then the forward transmission coefficient and reverse transmission are measured under the condition of changing the signal frequency with a fixed signal amplitude coefficient.

范围内调节可调耦合模块电容值并重复上述步骤，可以得到频率可调的非互易传输测量结果。exist

Adjust the capacitance value of the adjustable coupling module within the range and repeat the above steps to obtain the non-reciprocal transmission measurement results with adjustable frequency.

It can be understood that the present invention is described through some embodiments, and those skilled in the art know that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, the features and examples may be modified to adapt a particular situation and material to the teachings of the invention without departing from the spirit and scope of the invention. Therefore, the present invention is not limited by the specific embodiments disclosed here, and all embodiments falling within the scope of the claims of the present application belong to the protection scope of the present invention.

Claims (7)

1. A frequency-tunable non-reciprocal transmission system based on the principle of PT symmetry, characterized in that it consists of three parts: a loss resonant circuit (1), a gain resonant circuit (2) and an adjustable coupling module (3), and the gain resonant Circuit (2) is made up of second inductance (23), positive resistance (12) and negative resistance (22) in parallel, and wherein negative resistance (22) is made of transimpedance amplifier; When transimpedance amplifier works in linear region, negative resistance (22) is a fixed-value negative resistance that does not vary with the input voltage; when the transimpedance amplifier was operating in the negative saturation region, the resistance of the negative resistance (22) was a negative resistance controlled by the input voltage; loss resonant circuit (1) and gain resonance The circuit (2) is coupled together through the adjustable coupling module (3), and the coupling coefficient between the loss resonant circuit (1) and the gain resonant circuit (2) is changed by changing the coupling capacitance of the adjustable coupling module (3), thereby Change the transmission frequency of the system. 2. The frequency-tunable non-reciprocal transmission system based on the principle of PT symmetry according to claim 1, characterized in that, the loss resonant circuit (1) is composed of a first inductance (13), a first capacitor (11) and a positive Resistors (12) are connected in parallel. 3. the frequency adjustable non-reciprocal transmission system based on PT symmetry principle according to claim 2, is characterized in that, described transimpedance amplifier comprises first resistance (221), operational amplifier (222), second resistance ( 223), the third resistor (224); the first resistor (221) is connected between the same input terminal and the output terminal of the operational amplifier (222), and the second negative resistor (223) is connected to the reverse direction of the operational amplifier (222) Between the input end and the output end, one end of the third resistor (224) is grounded and the other end is connected to the second resistor (223). 4. The frequency-tunable non-reciprocal transmission system based on the principle of PT symmetry according to claim 3, characterized in that, the adjustable coupling module (3) is composed of an adjustable capacitor. 5. The frequency-tunable non-reciprocal transmission system based on the principle of PT symmetry according to claim 4, characterized in that, the first inductance (13) and the positive resistance (12) in the loss resonant circuit (1) are respectively It is equal to the second inductance (23) and the negative resistance (22) in the gain resonance circuit (2). 6. The frequency-tunable non-reciprocal transmission system based on the principle of PT symmetry according to claim 5, characterized in that, the resistance value of the positive resistor (11) in the loss resonant circuit (1) is the same as that in the gain resonant circuit The absolute values of the resistance values of the negative resistance (21) when working in the linear region are equal. 7. the detection method of a kind of frequency adjustable non-reciprocal transmission system based on PT symmetry principle according to claim 6, is characterized in that, comprises the following steps: Step 1, adjusting the resistance value of the transimpedance amplifier, so that the absolute value of the equivalent negative resistance value in the linear region of the transimpedance amplifier is equal to the absolute value of the positive resistance (12) of the loss resonant circuit (1), so that the system is in a PT symmetrical state; Step 2, adjust the capacitance value of the adjustable coupling module (3) so that its value is at

Between, at this time the system is in the PT symmetry breaking area; where C _L is the loss resonant circuit capacitance (11), _RL is the loss resonant circuit positive resistance (12), L _L is the loss resonant circuit inductance (13); Step 3, adjusting the amplitude of the input signal, defining the transmission of the signal from the loss resonant circuit (1) to the gain resonant circuit (2) is positive transmission, at this time the negative resistance (22) works in the linear region, defining the signal from the gain resonant circuit ( 2) The transmission to the loss resonant circuit (1) is reverse transmission. At this time, the negative resistance (22) works in the negative saturation region. Since the equivalent negative resistance of the transimpedance amplifier is different during forward transmission and reverse transmission, the system forms an abnormal reciprocal transmission; Step 4, adjust the adjustable capacitance value of the adjustable coupling module (3), so that it is

Change between, change the signal transmission frequency of the system, and form a non-reciprocal transmission system with tunable transmission frequency.

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