Temperature variable oscillator circuit

Abstract

The invention provides a temperature-variable oscillator circuit, which belongs to the technical field of electronic control, and is characterized in that a first output end of a current mirror module is connected to an input end of a charging and discharging module; the output end of the charging and discharging module is connected to the inverted input end of the comparator, and the charging and discharging module is used for generating a voltage signal related to the temperature in the charging and discharging process. The first switch module is used for controlling switching of charging paths; the first end of the second switch module is connected to the positive input end of the comparator, and the second switch module is used for controlling switching of discharge paths; the comparator is used for generating a clock signal; the clock signal is used for controlling the on-off states of the first switch module and the second switch module so as to achieve dynamic switching of a charging path and a discharging path and adjust the output frequency of the oscillation signal. By integrating voltage and current conversion, current mirror distribution, dynamic path switching and comparison control, temperature signals are converted into oscillation signals with high precision and stable output is realized under the condition of low power consumption.

Description

Technical Field

[0001] The present invention relates to the field of electronic control technology, and particularly to a temperature-variable oscillator circuit. Background Art

[0002] With the rapid development of sensor technology, temperature monitoring has been widely demanded in industrial automation, environmental monitoring, and Internet of Things applications. However, due to the extremely strict power consumption requirements for sensor nodes in many application scenarios (such as self-powered wireless sensor networks, which have very weak energy from the environment, so the power consumption requirements for wireless sensor nodes are very harsh, for example, less than 1 mW), traditional temperature signal processing methods face major challenges.

[0003] The prior art usually adopts the following process: First, the temperature change is converted into a voltage signal by a temperature sensor, then the voltage signal is converted into a digital signal by an analog-to-digital converter (ADC), and finally the digital signal is processed by a microcontroller (MCU) to generate an output signal for communication. However, due to multiple signal conversions involved in this method, as well as the high power consumption characteristics of the ADC and MCU, the overall energy consumption of the system is relatively high, which cannot meet the requirements of low-power application scenarios. In addition, the oscillator circuits in the prior art usually adopt a fixed capacitor design, and the oscillation frequency is dynamically adjusted through an external circuit to achieve signal modulation. This design not only increases the complexity of the circuit, but also has a certain impact on the conversion accuracy of temperature signals. Especially in temperature monitoring applications that require high sensitivity, it is difficult for the existing designs to balance the requirements of high precision and low power consumption.

[0004] Therefore, how to improve the accuracy of converting temperature signals into oscillation signals and the stability of output under low-power conditions has become a technical problem to be urgently solved. Summary of the Invention

[0005] The present invention provides a temperature-variable oscillator circuit to solve the defects in the prior art, and realizes converting temperature signals into oscillation signals with high precision and achieving stable output under low-power conditions.

[0006] The present invention provides a temperature-variable oscillator circuit, including: a voltage-current conversion module, a current mirror module, a charge-discharge module, a first switch module, a second switch module, and a comparator; The input end of the voltage-current conversion module is connected to a first reference voltage, and the output end of the voltage-current conversion module is connected to the input end of the current mirror module, and is used for converting the first reference voltage into a constant current; The first output end of the current mirror module is connected to the input end of the charge-discharge module, and is used for providing a charging current for the charge-discharge module; The output terminal of the charge and discharge module is connected to the inverting input terminal of the comparator, and is used to generate a temperature-related voltage signal during the charge and discharge process; The first terminal of the first switch module is connected to the inverting input terminal of the comparator, the second terminal of the first switch module is connected to the second output terminal of the current mirror module, and the third terminal of the first switch module is connected to the third output terminal of the current mirror module, and is used to control the switching of the charging path; The first terminal of the second switch module is connected to the non-inverting input terminal of the comparator, the second terminal of the second switch module is connected to the second reference voltage, and the third terminal of the second switch module is connected to the third reference voltage, and is used to control the switching of the discharging path; The comparator is used to compare the voltage signal with the second reference voltage or the third reference voltage to generate a clock signal; Wherein, the clock signal is used to control the switching states of the first switch module and the second switch module to realize the dynamic switching of the charging path and the discharging path, and adjust the output frequency of the oscillation signal.

[0007] According to the temperature-variable oscillator circuit provided by the present invention, the voltage-current conversion module includes an operational amplifier, a resistor, and a first transistor; The non-inverting input terminal of the operational amplifier is connected to the first reference voltage, the output terminal of the operational amplifier is connected to the gate of the first transistor, and the output terminal of the operational amplifier is feedback-connected to the inverting input terminal through the first transistor; The first terminal of the resistor is connected to the source of the first transistor, and the second terminal of the resistor is grounded.

[0008] According to the temperature-variable oscillator circuit provided by the present invention, the current mirror module includes a first current mirror unit and a second current mirror unit; The input terminal of the first current mirror unit is connected to the drain of the first transistor, the first output terminal of the first current mirror unit is connected to the input terminal of the second current mirror unit, and the second output terminal of the first current mirror unit is connected to the second terminal of the first switch module; The first output terminal of the second current mirror unit is connected to the input terminal of the charge and discharge module, and the second output terminal of the second current mirror unit is connected to the third terminal of the first switch module, and is used to provide a charging current for the charge and discharge module.

[0009] According to the temperature-variable oscillator circuit provided by the present invention, the first current mirror unit includes a second transistor, a third transistor, and a fourth transistor; The sources of the second transistor, the third transistor, and the fourth transistor are all connected to the power supply voltage; The gates of the second transistor, the third transistor, and the fourth transistor are interconnected and serve as an input terminal; The drain of the second transistor is connected to the drain of the first transistor.

[0010] According to the temperature-variable oscillator circuit provided by the present invention, the second current mirror unit includes a fifth transistor and a sixth transistor; The sources of the fifth transistor and the sixth transistor are both grounded; The gates of the fifth transistor and the sixth transistor are interconnected and serve as an input terminal; The drain of the fifth transistor is connected to the first output terminal of the first current mirror unit.

[0011] According to the temperature-variable oscillator circuit provided by the present invention, the charge and discharge module includes a plurality of variable capacitance units; each variable capacitance unit includes a capacitor and a switch, and the capacitor and the switch are connected in series; The capacitors of all the variable capacitance units are connected in parallel; the switch in each variable capacitance unit is used to control whether its corresponding capacitor is connected to the charge and discharge loop.

[0012] According to the temperature-variable oscillator circuit provided by the present invention, the first switch module includes a transmission gate composed of a seventh transistor and an eighth transistor and an inverter composed of a ninth transistor and a tenth transistor; Among them, the seventh transistor and the ninth transistor are both P-channel transistors, and the eighth transistor and the tenth transistor are both N-channel transistors.

[0013] According to the temperature-variable oscillator circuit provided by the present invention, the resistor is a thermistor.

[0014] According to the temperature-variable oscillator circuit provided by the present invention, the second transistor, the third transistor, and the fourth transistor are all P-channel transistors.

[0015] According to the temperature-variable oscillator circuit provided by the present invention, the first transistor, the fifth transistor, and the sixth transistor are all N-channel transistors.

[0016] The present invention also provides a temperature signal frequency conversion method, and the method includes: Converting a first reference voltage into a constant control current through a voltage-current conversion module; Receiving the constant control current through a current mirror module, and by controlling the conduction state of the first switch module, distributing the constant control current as a charging current for the charge and discharge module; Store the charging current in the charge and discharge module to form a voltage signal, and input the voltage signal into a comparator, where the voltage signal is related to a temperature signal; Input a second reference voltage or a third reference voltage into the comparator by controlling the conduction state of a second switch module; Compare the voltage signal with the second reference voltage or the third reference voltage through the comparator to obtain a comparison result; Generate a clock signal according to the comparison result, where the clock signal is used to reflect the charge and discharge cycle of the charge and discharge module; Obtain the output frequency of an oscillation signal according to the charge and discharge cycle.

[0017] In summary, one or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages: By providing a voltage-current conversion module, a first reference voltage is input into the circuit, and a voltage signal is converted into a constant control current through a thermistor. Since the resistance value of the thermistor changes with temperature, this control current is directly related to temperature, providing a stable and temperature-related input signal for subsequent modules in the circuit. Secondly, a current mirror module receives the output current of the voltage-current conversion module and copies and distributes the input current to different paths through its symmetric structure. By dynamically adjusting the conduction state of a first switch module, the current mirror module can stably provide a constant charging current for the charge and discharge module, thereby forming a charge accumulation and release process related to temperature in the charge and discharge module. The design of the charge and discharge module further optimizes the charge storage efficiency by dynamically adjusting the capacitance value, enabling the generated voltage signal to accurately reflect the change in temperature. Then, through the function of the comparator, the output voltage signal of the charge and discharge module is compared with the second reference voltage or the third reference voltage to generate a clock signal. The clock signal reflects the charge and discharge cycle of the charge and discharge module and directly controls the switching states of the first switch module and the second switch module. The first switch module is used to switch the charging path to ensure the stability of the charging process; the second switch module is used to switch the discharging path and selectively connect different reference voltages to achieve precise control of the discharging process. Finally, through the clock signal generated by the comparator, the switching of the charging path and the discharging path is dynamically controlled, enabling the output frequency of the oscillator to reflect the change in the temperature signal in real time. Thus, the entire circuit realizes a highly sensitive conversion of the temperature signal, and the frequency of the output signal corresponds one-to-one with the temperature. Through the above solution, this temperature-variable oscillator circuit can achieve high-precision temperature signal detection and frequency output under low-power conditions. Description of the Drawings

[0018] To more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 It is a schematic structural diagram of the temperature-variable oscillator circuit provided by the present invention.

[0020] Figure 2 It is a schematic circuit diagram of the temperature-variable oscillator provided by the present invention.

[0021] Figure 3 It is a schematic circuit diagram of the charge-discharge module provided by the present invention.

[0022] Figure 4 It is a schematic diagram of frequency band division provided by the present invention.

[0023] Figure 5 It is a schematic flow diagram of a temperature signal frequency conversion method provided by the present invention. Detailed implementation manners

[0024] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the present invention in conjunction with the drawings in the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0025] It should be noted that in the description of the present invention, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. The terms "include", "comprise", "have" and their variants all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0026] In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "electrically connected", "electrically connected" or "communicatively electrically connected" should be understood in a broad sense. For example, "electrically connected", "electrically connected" or "communicatively electrically connected" can refer to not only physical electrical connection, but also electrical connection or signal electrical connection. For example, it can be a direct electrical connection, that is, a physical electrical connection, or can be indirectly electrically connected through at least one intermediate element, as long as the circuit is connected. It can also be the connection inside two elements; signal electrical connection can refer to signal electrical connection through a medium in addition to signal electrical connection through a circuit. For example, radio waves. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0027] The following will describe the temperature-variable oscillator circuit provided by the present invention in conjunction with Figures 1-5 Describe the temperature-variable oscillator circuit provided by the present invention.

[0028] Figure 1 is a schematic structural diagram of the temperature-variable oscillator circuit provided by the present invention. As Figure 1 shown, the temperature-variable oscillator circuit includes: a voltage-current conversion module, a current mirror module, a charge-discharge module, a first switch module, a second switch module, and a comparator; The input end of the voltage-current conversion module is connected to the first reference voltage, and the output end of the voltage-current conversion module is connected to the input end of the current mirror module, and is used to convert the first reference voltage into a constant current; The first output end of the current mirror module is connected to the input end of the charge-discharge module, and is used to provide a charging current for the charge-discharge module; The output end of the charge-discharge module is connected to the inverting input end of the comparator, and is used to generate a temperature-related voltage signal during the charge-discharge process; The first end of the first switch module is connected to the inverting input end of the comparator, the second end of the first switch module is connected to the second output end of the current mirror module, and the third end of the first switch module is connected to the third output end of the current mirror module, and is used to control the switching of the charging path; The first end of the second switch module is connected to the non-inverting input end of the comparator, the second end of the second switch module is connected to the second reference voltage, and the third end of the second switch module is connected to the third reference voltage, and is used to control the switching of the discharging path; The comparator is used to compare the voltage signal with the second reference voltage or the third reference voltage to generate a clock signal; Among them, the clock signal is used to control the switching states of the first switch module and the second switch module to realize the dynamic switching of the charging path and the discharging path, and adjust the output frequency of the oscillation signal.

[0029] The temperature-variable oscillator circuit is designed to accurately convert the temperature signal into an oscillation frequency signal under low-power conditions and improve the system's response efficiency and working stability through dynamic path switching.

[0030] In this embodiment, the input terminal of the voltage-current conversion module is connected to the first reference voltage. Since the resistance value of the thermistor changes with temperature, the voltage-current conversion module utilizes the feedback characteristic of the operational amplifier to generate a temperature-related current signal by applying the first reference voltage to the thermistor. To ensure the stability of the output current, the operational amplifier achieves precise control of the current through the feedback connection with the N-channel transistor, thereby converting the first reference voltage into a constant control current, which is directly related to temperature.

[0031] Subsequently, this constant control current passes through the current mirror module connected to the output terminal of the voltage-current conversion module. To achieve precise current replication and distribution, the current mirror module consists of a first current mirror unit and a second current mirror unit. The first current mirror unit replicates and distributes the constant current to the second current mirror unit using a P-channel transistor structure, and the second current mirror unit provides a stable charging current through an N-channel transistor and transmits it to the input terminal of the charge-discharge module, thus providing sufficient energy support for the core function of the circuit.

[0032] The charge-discharge module is responsible for converting the input constant charging current into a voltage signal on the capacitor. To achieve this function, the charge-discharge module adopts a parallel design of multiple variable capacitor units, and each variable capacitor unit consists of a capacitor and a switch in series. By dynamically adjusting the switch state, different capacitors can be selectively connected to the charge-discharge circuit, thereby realizing the adjustment of the capacitance value. The capacitor accumulates or releases charges during the charge-discharge process, thus generating a dynamic voltage signal related to temperature changes.

[0033] This dynamic voltage signal is transmitted from the output terminal of the charge-discharge module to the inverting input terminal of the comparator. At the same time, the second switch module is connected to the non-inverting input terminal of the comparator through its first end and selectively inputs the second reference voltage or the third reference voltage to the comparator. The comparator generates a clock signal that controls the overall operation of the circuit by comparing the output voltage signal of the charge-discharge module with the reference voltage.

[0034] The function of the clock signal is reflected in controlling the dynamic switching states of the first switch module and the second switch module. The first switch module is connected to the inverting input terminal of the comparator, the second output terminal, and the third output terminal of the current mirror module, and is used to dynamically switch the charging path according to the clock signal, thereby optimizing the charging process of the circuit. The second switch module controls the discharging path of the capacitor by selectively connecting the second reference voltage and the third reference voltage, further improving the accuracy and stability of the entire charge-discharge process.

[0035] With this design, the temperature-variable oscillator circuit of this embodiment can efficiently convert the temperature signal into a corresponding oscillation signal, control the output frequency of the oscillation signal, and ensure low-power operation. By using dynamic path switching, the circuit can adapt to various working conditions, improve the system response speed and the accuracy of signal transmission, so as to accurately convert the temperature signal into an oscillation signal and achieve stable output under low-power conditions.

[0036] In a possible implementation manner, the voltage-current conversion module includes an operational amplifier, a resistor, and a first transistor; The positive input terminal of the operational amplifier is connected to the first reference voltage, the output terminal of the operational amplifier is connected to the gate of the first transistor, and the output terminal of the operational amplifier is feedback-connected to the negative input terminal through the first transistor; The first end of the resistor is connected to the source of the first transistor, and the second end of the resistor is grounded. Among them, the resistor is a thermistor, and the first transistor is an N-channel transistor.

[0037] To better understand the solution of this embodiment, reference can be made to Figure 2 , Figure 2 which is a schematic diagram of the temperature-variable oscillator circuit provided by the present invention. As shown in Figure 2 , the voltage-current conversion module includes an operational amplifier (denoted by the letter AMP in Figure 2 ), a resistor (denoted by the letter R in Figure 2 ), and a first transistor (denoted by the letter NM1 in Figure 2 ). Its design aims to achieve a sensitive response to temperature changes and efficiently convert the first reference voltage into a constant control current related to temperature, providing a stable input signal for subsequent circuit modules.

[0038] The positive input terminal of the operational amplifier is connected to the first reference voltage, providing a stable reference voltage as the input signal source. To ensure the precise control of the output current, the output terminal of the operational amplifier is connected to the gate of the first transistor and is feedback-connected to the negative input terminal through the first transistor, forming a closed-loop control structure. This feedback design makes the source voltage of the first transistor always clamped to a value close to the first reference voltage, thereby achieving stable regulation of the working state of the first transistor.

[0039] The source of the first transistor is connected to the first end of the resistor, and the second end of the resistor is grounded. The resistor is a thermistor, and its resistance value is dynamically adjusted according to the ambient temperature. This characteristic enables the magnitude of the current passing through the thermistor to be directly affected by temperature changes, and this current change will be further converted into a corresponding current signal output through the amplification of the first transistor. Since the closed-loop structure of the operational amplifier can adjust the gate voltage of the first transistor in real time, thereby stabilizing the output current. Even in the case of rapid temperature changes, the output current can always be inversely proportional to the resistance value of the thermistor, maintaining good linear response characteristics.

[0040] Through this design, the voltage-current conversion module can generate a constant current directly related to temperature changes, providing accurate input signals for subsequent modules such as the current mirror module and the charge and discharge module. Compared with the traditional method of directly using voltage signals to represent temperature in circuits, this design avoids complex signal conversion processes and reduces error accumulation caused by multi-stage processing. In addition, this structure relies on the high-sensitivity characteristics of the thermistor and the precise control of the operational amplifier, significantly improving the temperature response accuracy and stability of the circuit, while maintaining low-power consumption characteristics, which is particularly suitable for application scenarios such as self-powered wireless sensor networks.

[0041] In a possible implementation manner, the current mirror module includes a first current mirror unit and a second current mirror unit; The input end of the first current mirror unit is connected to the drain of the first transistor. The first output end of the first current mirror unit is connected to the input end of the second current mirror unit, and the second output end of the first current mirror unit is connected to the second end of the first switch module; The first output end of the second current mirror unit is connected to the input end of the charge and discharge module, and the second output end of the second current mirror unit is connected to the third end of the first switch module, for providing a charging current for the charge and discharge module.

[0042] In this embodiment, the current mirror module includes a first current mirror unit and a second current mirror unit. Its design purpose is to copy and distribute the constant control current output by the voltage-current conversion module, providing stable and controllable current signals for the charge and discharge module and other functional modules, while ensuring the low-power consumption characteristics and high-efficiency operation of the entire circuit.

[0043] The input terminal of the first current mirror unit is connected to the drain of the first transistor in the voltage-current conversion module. As the input terminal for controlling the current, this connection can directly receive a constant current signal related to temperature. The first current mirror unit realizes the accurate replication of the input current through the symmetrical structure of P-channel transistors, ensuring the stability of the output current. The first output terminal of the first current mirror unit is connected to the input terminal of the second current mirror unit, transmitting the replicated current to the second current mirror unit for further distribution to the charge-discharge module. At the same time, the second output terminal of the first current mirror unit is connected to the second terminal of the first switch module, providing a control current for the dynamic path switching of the switch module.

[0044] The second current mirror unit receives the input current from the first current mirror unit and provides a constant charging current for the charge-discharge module through its first output terminal to ensure the normal operation of the charge-discharge module. This current mirror unit adopts the design of N-channel transistors, which can efficiently amplify the input current under low-power conditions and at the same time achieve precise control of the output current. In addition, the second output terminal of the second current mirror unit is connected to the third terminal of the first switch module, providing the necessary current support for the path selection function of the switch module.

[0045] Through the design of this two-stage current mirror structure, the current mirror module can efficiently transfer the constant control current generated by the voltage-current conversion module to the charge-discharge module and provide the required current support for dynamic path switching. This design not only improves the stability and current utilization efficiency of the circuit, but also avoids the problem of unstable operation of the charge-discharge module caused by uneven current distribution through the accurate replication ability of the current mirror. At the same time, the hierarchical design of the two-stage current mirror module makes the circuit more flexible, capable of dynamically adjusting the current path according to different working states, providing a reliable basic support for the frequency adjustment and signal output of the oscillator.

[0046] The design of this embodiment makes full use of the high efficiency and low power consumption characteristics of the current mirror, ensuring both the accurate distribution of current and reducing the energy consumption of the entire system, providing strong support for high-precision and low-power temperature signal conversion.

[0047] In a possible implementation manner, the first current mirror unit includes a second transistor, a third transistor, and a fourth transistor; The sources of the second transistor, the third transistor, and the fourth transistor are all connected to the power supply voltage; The gates of the second transistor, the third transistor, and the fourth transistor are connected to each other and used as the input terminal; The drain of the second transistor is connected to the drain of the first transistor; Among them, the second transistor, the third transistor, and the fourth transistor are all P-channel transistors.

[0048] In this embodiment, as Figure 2 shown, the first current mirror unit includes a second transistor (denoted by the letter PM1 in Figure 2 ), a third transistor (denoted by the letter PM2 in Figure 2 ), and a fourth transistor (denoted by the letter PM3 in Figure 2 ). Its design aims to distribute and amplify the input current from the first transistor through the efficient current replication characteristics of P-channel transistors, providing precise and stable current source support for subsequent modules, thereby ensuring the overall performance and reliability of the circuit.

[0049] The sources of the second, third, and fourth transistors are all connected to the power supply voltage, giving them the same power supply reference and ensuring consistent current characteristics at each output during the current replication process. The gates of the three transistors are interconnected and used as the input terminal. Through this symmetric design, the input signal can act on the second, third, and fourth transistors simultaneously, ensuring the efficient distribution of the input current and the precise control of the output current.

[0050] The drain of the second transistor is directly connected to the drain of the first transistor to receive the constant control current signal from the first transistor. Through the series structure of the first and second transistors, the input current is transmitted to the gate of the first current mirror unit, thereby realizing the feedback control of the input current. At the same time, the drains of the third and fourth transistors serve as the first output terminal and the second output terminal of the first current mirror unit respectively, for transmitting the replicated current to subsequent modules, such as the second current mirror unit and the first switch module.

[0051] This design realizes the efficient replication and stable output of the input current by utilizing the symmetry and high gain characteristics of P-channel transistors, thus ensuring the overall stability of the circuit. The symmetric structure of the three transistors can not only reduce the error in the current distribution process but also provide multi-path current support through multiple output terminals, making the circuit more flexible and adaptable.

[0052] Through this transistor combination design, the first current mirror unit can stably distribute the control current from the first transistor to subsequent modules, providing basic support for the overall operation of the current mirror module. This design scheme effectively reduces the loss in the current distribution process, improves the efficiency of current transmission, and at the same time, through the precise current replication ability, avoids the unstable phenomena that may occur during the circuit operation. Finally, this design ensures that the circuit can always maintain an efficient and stable operating state under different temperature and load conditions.

[0053] In a possible implementation manner, the second current mirror unit includes a fifth transistor and a sixth transistor; The sources of the fifth and sixth transistors are both grounded; The gates of the fifth transistor and the sixth transistor are interconnected and serve as the input terminal; The drain of the fifth transistor is connected to the first output terminal of the first current mirror unit; Wherein, both the fifth transistor and the sixth transistor are N-channel transistors.

[0054] In this embodiment, as Figure 2 shown, the second current mirror unit includes a fifth transistor (denoted by the letter NM2 in Figure 2 ) and a sixth transistor (denoted by the letter NM3 in Figure 2 ), which is designed to further copy and transfer the current signal provided by the first current mirror unit, ensuring the stability and consistency of the output current, and at the same time providing precise charging current support for the charge and discharge module.

[0055] The sources of the fifth transistor and the sixth transistor are both connected to the ground potential. This design ensures that the transistors have a unified reference potential during operation, avoiding instability caused by potential differences during current transmission. At the same time, the gates of the fifth transistor and the sixth transistor are interconnected and serve as the input terminal. Through this symmetric design, the input signal can act on the two transistors evenly, thus ensuring the efficiency and consistency of the current copying process.

[0056] The drain of the fifth transistor is connected to the first output terminal of the first current mirror unit for receiving the current signal from the first current mirror unit. The input current of the fifth transistor is copied and output to the output terminal of the second current mirror unit through the drain of the sixth transistor, thereby providing stable charging current support for the subsequent charge and discharge module. Through this dual-transistor mirror structure design, the second current mirror unit can accurately copy and amplify the input current, enabling the output current to meet the working requirements of the charge and discharge module.

[0057] In this design, both the fifth transistor and the sixth transistor are N-channel transistors. Their conduction characteristics and high current transmission capabilities ensure the low-power consumption and high-efficiency characteristics of the circuit. The selection of N-channel transistors can not only achieve efficient operation at a relatively low drive voltage but also further improve the current stability through their good current gain characteristics.

[0058] Through the design of the second current mirror unit, the current mirror module can efficiently transfer the input current from the first current mirror unit to the charge and discharge module and ensure the stability of the output current. This design greatly improves the working efficiency of the charge and discharge module, and at the same time effectively reduces the losses and errors in the current distribution process through the dual-transistor mirror structure.

[0059] In a possible implementation, the charge and discharge module includes a plurality of variable capacitance units; each variable capacitance unit includes a capacitor and a switch, and the capacitor and the switch are connected in series; The capacitors of all variable capacitance units are connected in parallel; the switch in each variable capacitance unit is used to control whether its corresponding capacitor is connected to the charge and discharge circuit.

[0060] In this embodiment, as Figure 2 shown, each variable capacitance unit in the charge and discharge module (denoted by the letter C in Figure 2 ) consists of a capacitor and a switch, and the capacitor and the switch are connected in series. With this design, the state of each capacitor can be individually controlled by turning the switch on or off. When the switch is turned on, the capacitor is connected to the charge and discharge circuit and participates in the storage or release of charge; when the switch is turned off, the capacitor is isolated and does not affect the working state of the circuit. The capacitors of all variable capacitance units are connected to the charge and discharge circuit in parallel, and this parallel structure can dynamically change the total capacitance value of the charge and discharge circuit by adjusting the number of capacitors connected.

[0061] In a specific implementation, referring to Figure 3 , Figure 3 is a schematic circuit diagram of the charge and discharge module provided by the present invention, Figure 3 showing the specific circuit structure for implementing this function: a plurality of capacitors C01, C02, …, C0n control their connection states through switches T01, T02, …, T0n. Among them, the i-th capacitor C0i and the i-th switch T0i form the i-th variable capacitance unit, where i ∈ [1, n].

[0062] In this design, the total capacitance value of the capacitance unit can be achieved through dynamic combination: When all switches are turned on, all capacitors are connected to the circuit, and the total capacitance is C = C01 + C02 + … + C0n; when some switches are turned off, only some capacitors are connected to the circuit, and the total capacitance value decreases accordingly.

[0063] This dynamically adjustable capacitance design can adjust the equivalent capacitance value of the charge and discharge module according to the change of the external temperature signal during the operation of the oscillator, thereby affecting the charge and discharge cycle of the oscillator, and finally changing the frequency of the output oscillation signal, realizing the accurate conversion of the temperature signal to the frequency signal.

[0064] In a possible implementation, the first switch module includes a transmission gate composed of a seventh transistor and an eighth transistor and an inverter composed of a ninth transistor and a tenth transistor; Among them, the seventh transistor and the ninth transistor are both P-channel transistors, and the eighth transistor and the tenth transistor are both N-channel transistors.

[0065] Specifically, the transmission gate is composed of a seventh transistor (P-channel transistor) and an eighth transistor (N-channel transistor) in parallel. Its two ends serve as the input terminal and output terminal of the first switch module respectively, and are responsible for signal transmission. The transmission gate can, under the action of a control signal, achieve reliable conduction or disconnection of the signal: When the control signal is at a low level, the seventh transistor conducts while the eighth transistor cuts off, and the signal is transmitted through the P-channel transistor.

[0066] When the control signal is at a high level, the eighth transistor conducts while the seventh transistor cuts off, and the signal is transmitted through the N-channel transistor.

[0067] This complementary design ensures that the transmission gate can maintain a low impedance state under any control signal, thereby avoiding signal distortion and ensuring the switching efficiency of the current path.

[0068] The inverter is composed of a ninth transistor (P-channel transistor) and a tenth transistor (N-channel transistor) in series. Its input terminal receives the control signal, and its output terminal is connected to the other control terminal of the transmission gate. The function of the inverter is to generate a logic signal opposite to the input control signal to achieve complementary control of the two transistors in the transmission gate. When the control signal changes, the inverter automatically generates a reverse signal, enabling the seventh transistor and the eighth transistor to synchronously switch between the conducting and cutoff states.

[0069] In practical applications, as Figure 2 shown, the clock signal generated by the comparator (denoted by the letter CK in Figure 2 ) serves as the control signal of the first switch module, acts on the control terminal of the transmission gate through the inverter, and is used to dynamically switch the charging path. The first terminal of the first switch module is connected to the output terminal of the charge and discharge module, the second terminal is connected to the second output terminal of the current mirror module, and the third terminal is connected to the third output terminal of the current mirror module. Through the action of the control signal, the first switch module switches between different charging paths: When the clock signal is at a high level, the transmission gate conducts, and the charge and discharge module obtains the charging current through the second output terminal of the current mirror module.

[0070] When the clock signal is at a low level, the transmission gate switches to the off state, blocking the charging path.

[0071] Through this dynamic switching, the first switch module can effectively control the accumulation process of charge in the charge and discharge module, thereby generating a voltage signal related to temperature.

[0072] Furthermore, combining Figure 2 and all the above embodiments to give an overall description of this solution: Ideally, the voltage at the upper end of the resistor R is stably clamped to the first reference voltage V REF, ensure that the current I passing through the resistor R REF is inversely proportional to the resistance value of R, that is, I REF =V REF / R. When R is a thermistor, its resistance value will be dynamically adjusted with the change of temperature, so that I REF reflects the current temperature information. This constant current is accurately transmitted to the charge and discharge module through the P-type current mirror structure composed of the second transistor (PM1), the third transistor (PM2) and the fourth transistor (PM3), and the N-type current mirror structure composed of the fifth transistor (NM2) and the sixth transistor (NM3) (in Figure 2 represented by the letter C), to provide a charging current for it.

[0073] The core operation of the oscillator is completed by a comparator (represented by the letter COMP in Figure 2 ). The clock signal CK output by the comparator serves as both the clock output signal of the oscillator and the charge and discharge control signal of the charge and discharge module. When CK is at a high level (i.e., CK+), the positive input terminal of the comparator is connected to the second reference voltage (represented by the letter V Figure 2 in H ), the charging branch of the charge and discharge module is closed, the discharging branch is disconnected, and the capacitor starts to accumulate charge, and the voltage signal V C rises with time. When V C exceeds V H , the clock signal CK jumps to a low level (i.e., CK−). At this time, the positive input terminal of the comparator is connected to the third reference voltage (represented by the letter V Figure 2 in L ), V L , the charging branch of the charge and discharge module is disconnected, the discharging branch is closed, the capacitor starts to release charge, and the voltage signal V C drops with time. When V C is lower than V L , the clock signal CK jumps to a high level again, and so on, forming a stable square wave clock signal at the output terminal of the comparator.

[0074] According to the working principle of the oscillator, the charge and discharge cycle T of the charge and discharge module can be expressed as T = 2C(V H −V L ) / I C . And the output frequency freq = 1 / T is directly related to the current I C and the parameters of the charge and discharge module. From the formula I C =m⋅I REF =m⋅V REF / R, the expression of the output frequency of the oscillator can be obtained: freq = m⋅V REF / [2R⋅C⋅(V H−V L )]; where the second reference voltage V H and the third reference voltage V L are from a reference power supply and do not change with temperature. It can be seen from the above formula that the output frequency freq of the oscillator is inversely proportional to the resistance value of the resistor R, and R is a thermistor whose resistance value changes dynamically with temperature. Therefore, by selecting a suitable resistor and the combination of each capacitor in the charge and discharge module, different temperature ranges can be mapped to different oscillation frequency ranges. In this embodiment, the dynamic capacitance selection technology is introduced to meet the requirements of multiple frequency bands. Referring to Figure 4 , Figure 4 which is a schematic diagram of the frequency band division provided by the present invention, Figure 4 showing a scheme for dynamic adjustment through multiple capacitor units, where C1 > C2 > ⋯ > Cm is monotonically decreasing, and each capacitor corresponds to a working frequency band TX_Fj, where j ∈ [1, m]. When a certain frequency band is selected, the change of the thermistor will further adjust the frequency to realize the real-time acquisition and conversion of temperature.

[0075] Through this design, the oscillator of this embodiment can not only accurately convert the temperature signal into a frequency signal, but also improve the adaptability through dynamic frequency band selection, and can adapt to the requirements of different sensor nodes. At the same time, the power consumption of the entire circuit is effectively controlled, which is particularly suitable for low-power application scenarios such as self-powered wireless sensor networks.

[0076] This application embodiment also provides a method, which is applied to the circuit in any of the above embodiments. Referring to Figure 5 , which shows a schematic flowchart of a temperature signal frequency conversion method provided by the present invention. The method includes steps 1-7: Step 1: Convert the first reference voltage into a constant control current through a voltage-current conversion module.

[0077] Step 2: Receive the constant control current through a current mirror module, and distribute the constant control current as a charging current for the charge and discharge module by controlling the conduction state of the first switch module.

[0078] Step 3: Store the charging current in the charge and discharge module to form a voltage signal, and input the voltage signal to a comparator. The voltage signal is related to the temperature signal.

[0079] Step 4: Input the second reference voltage or the third reference voltage to the comparator by controlling the conduction state of the second switch module.

[0080] Step 5: Compare the voltage signal with the second reference voltage or the third reference voltage through the comparator to obtain a comparison result.

[0081] Step 6: Generate a clock signal according to the comparison result, and the clock signal is used to reflect the charge and discharge cycle of the charge and discharge module.

[0082] Step 7: Obtain the output frequency of the oscillation signal according to the charge and discharge cycle.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A temperature variable oscillator circuit, characterized in that: It includes a voltage-current conversion module, a current mirror module, a charge-discharge module, a first switch module, a second switch module and a comparator; The input end of the voltage-to-current conversion module is connected to a first reference voltage, and the output end of the voltage-to-current conversion module is connected to the input end of the current mirror module, for converting the first reference voltage into a constant current; The first output end of the current mirror module is connected to the input end of the charge and discharge module, and is used to provide a charging current for the charge and discharge module; The output end of the charging and discharging module is connected to the inverting input end of the comparator, and is used to generate a voltage signal related to temperature during the charging and discharging process; The first end of the first switch module is connected to the inverting input end of the comparator, the second end of the first switch module is connected to the second output end of the current mirror module, and the third end of the first switch module is connected to the third output end of the current mirror module, for controlling the switching of the charging path; The first end of the second switch module is connected to the positive input end of the comparator, the second end of the second switch module is connected to the second reference voltage, and the third end of the second switch module is connected to the third reference voltage, which is used to control the switching of the discharge path; The comparator is used for comparing the voltage signal with the second reference voltage or the third reference voltage to generate a clock signal; The clock signal is used to control the switching states of the first switch module and the second switch module to achieve dynamic switching of the charging path and the discharging path and adjust the output frequency of the oscillation signal.

2. The temperature variable oscillator circuit according to claim 1, characterized in that: The voltage-current conversion module includes an operational amplifier, a resistor and a first transistor; The positive input terminal of the operational amplifier is connected to the first reference voltage, the output terminal of the operational amplifier is connected to the gate of the first transistor, and the output terminal of the operational amplifier is feedback-connected to the negative input terminal through the first transistor; A first end of the resistor is connected to a source of the first transistor, and a second end of the resistor is grounded.

3. The temperature variable oscillator circuit according to claim 2, characterized in that: The current mirror module includes a first current mirror unit and a second current mirror unit; The input end of the first current mirror unit is connected to the drain of the first transistor, the first output end of the first current mirror unit is connected to the input end of the second current mirror unit, and the second output end of the first current mirror unit is connected to the second end of the first switch module; The first output end of the second current mirror unit is connected to the input end of the charge and discharge module, and the second output end of the second current mirror unit is connected to the third end of the first switch module, for providing charging current for the charge and discharge module.

4. The temperature variable oscillator circuit according to claim 3, characterized in that: The first current mirror unit includes a second transistor, a third transistor and a fourth transistor; The sources of the second transistor, the third transistor and the fourth transistor are all connected to a power supply voltage; The gates of the second transistor, the third transistor and the fourth transistor are connected to each other and serve as input terminals; The drain of the second transistor is connected to the drain of the first transistor.

5. The temperature variable oscillator circuit according to claim 3, characterized in that: The second current mirror unit includes a fifth transistor and a sixth transistor; Sources of the fifth transistor and the sixth transistor are both grounded; The gates of the fifth transistor and the sixth transistor are connected to each other and serve as input terminals; A drain of the fifth transistor is connected to the first output terminal of the first current mirror unit.

6. The temperature variable oscillator circuit according to claim 1, characterized in that: The charging and discharging module includes a plurality of variable capacitance units; each of the variable capacitance units includes a capacitor and a switch, and the capacitor and the switch are connected in series; The capacitors of all the variable capacitance units are connected in parallel; the switch in each variable capacitance unit is used to control whether the corresponding capacitor is connected to the charging and discharging circuit.

7. The temperature variable oscillator circuit according to claim 1, characterized in that: The first switch module includes a transmission gate composed of a seventh transistor and an eighth transistor and an inverter composed of a ninth transistor and a tenth transistor; The seventh transistor and the ninth transistor are both P-channel transistors, and the eighth transistor and the tenth transistor are both N-channel transistors.

8. The temperature variable oscillator circuit according to claim 2, characterized in that: The resistor is a thermistor.

9. The temperature variable oscillator circuit according to claim 4, characterized in that: The second transistor, the third transistor and the fourth transistor are all P-channel transistors.

10. The temperature variable oscillator circuit according to claim 5, characterized in that: The first transistor, the fifth transistor and the sixth transistor are all N-channel transistors.

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