Wireless low-power energy transmission receiving circuit

Abstract

The utility model relates to a wireless low-power energy transmission receiving circuit, which belongs to the technical field of wireless electric energy transmission, and comprises a rectification module, which is electrically connected with an antenna front end, comprises a positive feedback full-wave rectification circuit and is used for converting a high-frequency radio-frequency signal received by the antenna front end into a direct-current signal; and the voltage regulating module is electrically connected with the load and the rectifying module, and is used for boosting the direct current signal to obtain a boosting signal and outputting the boosting signal to the load when detecting that the boosting signal is smaller than a preset first threshold voltage. According to the utility model, the technical problem of low safety and high efficiency of wireless energy transmission in the prior art is effectively solved.

Description

Technical Field

[0001] This utility model relates to the field of wireless power transmission technology, and in particular to a wireless low-power power transmission and receiving circuit. Background Technology

[0002] With the rapid development of communication and Internet of Things (IoT) technologies, a large number of portable devices such as mobile phones, smart home devices, and various wireless devices have entered daily life, making people's lives more convenient. However, the power supply and charging of mobile electronic devices must be achieved using traditional contact power sources and wired power supply methods, which is inconvenient in many usage scenarios.

[0003] Wireless power transfer technology, as a contactless power transmission method, eliminates the limitations of traditional power transmission lines. It also avoids the potential safety hazards caused by aging power cords, offering greater convenience and eliminating the inconvenience of carrying multiple chargers. This is particularly relevant in the context of a large number of wireless IoT devices, where powering numerous devices is a significant challenge. Therefore, wireless power transfer technology offers a solution to these problems, providing greater convenience and possibilities for powering wireless devices, and has become a hot topic in recent years.

[0004] Wireless power transfer technology eliminates the need for wired connections such as cables, enabling flexible power supply and adapting to diverse environmental needs. This allows devices in complex environments, such as mobile internet devices, drones, and smart homes, to break free from cable constraints, improving ease of use. Wireless power transfer refers to a technology that transmits energy from a power source to a power supply terminal without the aid of transmission lines or spatial media. The main method involves the power source emitting electromagnetic signals, and the receiving end wirelessly receiving the electromagnetic energy from the transmitter and powering the terminal.

[0005] However, since the energy acquired by the receiving device is often weak and unstable, converting the received signal into a stable DC voltage signal is challenging and must be achieved with an energy harvesting and conversion circuit. How to safely and efficiently transmit and convert wireless energy is the key to wireless power transmission and has certain practical value. However, existing wireless power transmission technologies still cannot meet the actual needs of some application scenarios in terms of safety and efficiency. Utility Model Content

[0006] In view of this, it is necessary to provide a wireless low-power energy transmission receiving circuit to solve the technical problem of low security and efficiency of existing wireless energy transmission technologies.

[0007] To address the aforementioned problems, this utility model provides a wireless low-power energy transmission and receiving circuit, comprising:

[0008] The rectifier module, electrically connected to the antenna front end, includes a positive feedback full-wave rectifier circuit for converting the high-frequency radio frequency signal received by the antenna front end into a DC signal;

[0009] The voltage regulation module is electrically connected to the load and the rectifier module. It is used to boost the DC signal to obtain a boost signal, and output the boost signal to the load when the boost signal is detected to be less than a preset threshold voltage.

[0010] In one possible implementation, the positive feedback full-wave rectifier circuit includes: four comparators and four field-effect transistors electrically connected to the four comparators respectively;

[0011] The four comparators form an H-bridge topology;

[0012] The gate of the field-effect transistor is electrically connected to the output terminal of the comparator, the source is electrically connected to the non-inverting terminal of the comparator, and the drain is electrically connected to the inverting terminal of the comparator.

[0013] In one possible implementation, the voltage regulation module includes: an inductor, a diode, a logic AND gate, a first switching transistor, a current closed-loop control circuit, a voltage closed-loop control circuit, and a power supply;

[0014] One end of the inductor is electrically connected to the rectifier module, and the other end is electrically connected to the anode of the diode. The cathode of the diode is electrically connected to the load.

[0015] The input terminal of the current closed-loop control circuit is electrically connected to the power supply and the source of the first switching transistor, respectively, and the output terminal is electrically connected to the input terminal of the logic AND gate. It is used to sample the current on the inductor and set the output terminal to low level when the current is detected to be not less than the control current input by the power supply; otherwise, it sets the output terminal to high level.

[0016] The input terminal of the voltage closed-loop control circuit is electrically connected to the power supply and the cathode of the diode, respectively, and the output terminal is electrically connected to the input terminal of the AND gate. It is used to sample the output voltage of the voltage regulation module and set the output terminal to low level when the output voltage is detected to be not less than the reference voltage of the power supply input; otherwise, the output terminal is set to high level.

[0017] The gate of the first switching transistor is electrically connected to the output of the AND gate, and the drain is electrically connected to the anode of the diode.

[0018] In one possible implementation, the power supply is also electrically connected to the cathode of the diode to absorb and store the electrical energy output by the voltage regulation module in order to maintain the stability of the system voltage.

[0019] In one possible implementation, the current closed-loop control circuit includes:

[0020] First voltage comparator and sampling resistor;

[0021] The power input terminal and the non-inverting terminal of the first voltage comparator are electrically connected to the power supply, and the inverting terminal is electrically connected to one end of the sampling resistor.

[0022] One end of the sampling resistor is electrically connected to the source of the first switching transistor, and the other end is grounded, used to sample the current on the inductor.

[0023] In one possible implementation, the voltage closed-loop control circuit includes:

[0024] Second voltage comparator and voltage divider impedance network;

[0025] The power input terminal and non-inverting terminal of the second voltage comparator are electrically connected to the power supply, and the inverting terminal is electrically connected to the output terminal of the voltage divider impedance network.

[0026] The input terminal of the voltage divider impedance network is electrically connected to the cathode of the diode, and is used to sample the output voltage of the voltage regulation module.

[0027] In one possible implementation, the voltage divider impedance network includes:

[0028] The first voltage divider resistor and the second voltage divider resistor;

[0029] One end of the first voltage divider resistor is electrically connected to the cathode of the diode, and the other end is electrically connected to the inverting input of the second voltage comparator and one end of the second voltage divider resistor, respectively.

[0030] The other end of the second voltage divider resistor is grounded.

[0031] In one possible implementation, the voltage regulating module further includes:

[0032] The voltage monitoring unit and the second transistor have their input terminals electrically connected to the cathode of the diode and their output terminals electrically connected to the gate of the second transistor. They are used to monitor the output voltage of the voltage regulation module and set the output terminal to a low voltage when the output voltage is lower than a preset threshold voltage.

[0033] The drain of the second transistor is electrically connected to the other end of the second voltage divider resistor, and the source is grounded.

[0034] In one possible implementation, the voltage regulating module further includes:

[0035] The oscillator is electrically connected at one end to the power supply and at the other end to the input of the AND gate.

[0036] In one possible implementation, the four field-effect transistors, the first transistor, and the second transistor are all P-channel MOSFETs.

[0037] The beneficial effects of this utility model are as follows: This utility model provides a wireless low-power energy transmission receiving circuit, including a rectifier module and a voltage regulation module. This utility model first converts the high-frequency and unstable radio frequency signal transmitted by the antenna front end into a stable pulsating DC signal through the rectifier module. The positive feedback full-wave rectifier circuit can maintain good performance under high frequency and low input power conditions and can efficiently complete rectification. Then, the rectifier module loads the DC signal to the input terminal of the voltage regulation module. The voltage regulation module first boosts the DC signal to obtain a boosted signal, and then regulates the boosted signal based on a preset threshold voltage to achieve a stable voltage output. This effectively solves the technical problem of low safety and efficiency of wireless energy transmission in the prior art. Attached Figure Description

[0038] Figure 1 A schematic diagram of an embodiment of the wireless low-power energy transmission and receiving circuit provided by this utility model;

[0039] Figure 2 A schematic diagram of the internal structure of the wireless low-power energy transmission and receiving circuit provided by this utility model. Detailed Implementation

[0040] It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0041] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0042] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0043] Furthermore, the use of terms such as "first" and "second" in this utility model is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this utility model.

[0044] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the present invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0045] like Figure 1 As shown, a specific embodiment of this utility model discloses a wireless low-power energy transfer and receiving circuit 10, comprising:

[0046] The rectifier module 110 is electrically connected to the antenna front end 20 and includes a positive feedback full-wave rectifier circuit for converting the high-frequency radio frequency signal received by the antenna front end 20 into a DC signal.

[0047] The voltage regulating module 120 is electrically connected to the load 30 and the rectifier module 110. It is used to boost the DC signal to obtain a boost signal and output the boost signal to the load 30 when the boost signal is detected to be less than a preset threshold voltage.

[0048] It should be noted that the circuit provided by this utility model operates at a frequency between 5MHz and 200MHz. This circuit can conveniently and efficiently convert the received electromagnetic signals into the energy required by the device, and can be widely used in portable electronic products and mobile communication devices, thus having great practical value.

[0049] Compared with the prior art, the present invention provides a wireless low-power energy transmission receiving circuit, including a rectifier module and a voltage regulation module. The present invention first converts the high-frequency and unstable radio frequency signal transmitted by the antenna front end into a stable pulsating DC signal through the rectifier module. The positive feedback full-wave rectifier circuit can maintain good performance under high frequency and low input power conditions and can efficiently complete rectification. Then, the rectifier module loads the DC signal to the input terminal of the voltage regulation module. The voltage regulation module first boosts the DC signal to obtain a boosted signal, and then regulates the boosted signal based on a preset threshold voltage to achieve a stable voltage output. This effectively solves the technical problem of low safety and efficiency of wireless energy transmission in the prior art.

[0050] like Figure 2 In one possible implementation, the positive feedback full-wave rectifier circuit includes: four comparators A1, A2, A3, A4 and four field-effect transistors M1, M2, M3, M4, which are electrically connected to the four comparators respectively;

[0051] The four comparators form an H-bridge topology;

[0052] The gate of the field-effect transistor is electrically connected to the output terminal of the comparator, the source is electrically connected to the non-inverting terminal of the comparator, and the drain is electrically connected to the inverting terminal of the comparator.

[0053] It should be noted that the design of the rectifier module is a crucial part. Its task is to convert AC voltage to DC voltage, and its performance directly affects the functionality and reliability of the entire system. A good rectifier module can greatly improve the reliability and efficiency of the entire energy harvester, and also significantly reduce its cost. In this embodiment, the four comparators and four field-effect transistors can be high-frequency comparators and high-frequency field-effect transistors. High-frequency comparators and high-frequency field-effect transistors maintain good performance even at high frequencies and low input power, further improving the efficiency and quality of rectification.

[0054] Furthermore, the rectifier module 110 operates by converting the received unstable radio frequency (RF) signal into a pulsating DC signal. The rectifier module is designed as a full-wave rectifier bridge circuit, primarily composed of a comparator consisting of four field-effect transistors (FETs) and four high-frequency operational amplifiers. The core function of the rectifier circuit is to convert RF power into DC power. To improve rectification efficiency, impedance matching is required between the antenna front-end and the rectifier circuit. The impedance matching network allows the electromagnetic wave energy received by the antenna to be efficiently delivered to the rectifier module front-end for rectification, thus reducing energy reflection and loss and increasing rectification efficiency. In the RF rectifier circuit, high-frequency FETs and high-frequency comparators are selected as rectifier devices, maintaining good performance under high frequency and low input power conditions. Furthermore, the lower junction capacitance of the high-frequency devices increases the maximum operating frequency of the circuit.

[0055] In one possible implementation, the voltage regulation module includes 120: an inductor L, a diode D, an AND gate 121, a first switching transistor Q1, a current closed-loop control circuit, a voltage closed-loop control circuit, and a power supply 122.

[0056] One end of the inductor L is electrically connected to the rectifier module 110, and the other end is electrically connected to the anode of the diode D. The cathode of the diode D is electrically connected to the load 30.

[0057] The input terminal of the current closed-loop control circuit is electrically connected to the power supply 122 and the source of the first switching transistor Q1, respectively, and the output terminal is electrically connected to the input terminal of the logic AND gate 121. It is used to sample the current on the inductor L and set the output terminal to low level when the detected current is not less than the control current input by the power supply 122; otherwise, it sets the output terminal to high level.

[0058] The input terminal of the voltage closed-loop control circuit is electrically connected to the power supply 122 and the cathode of the diode D, respectively, and the output terminal is electrically connected to the input terminal of the logic AND gate 121. It is used to sample the output voltage of the voltage regulation module 120 and set the output terminal to low level when the output voltage is detected to be not less than the reference voltage input to the power supply 122; otherwise, it sets the output terminal to high level.

[0059] The gate of the first switching transistor Q1 is electrically connected to the output of the logic AND gate 121, and the drain is electrically connected to the anode of the diode D.

[0060] It should be noted that a comparator requires a stable power supply to ensure the normal operation of its internal circuitry. This power supply provides a stable voltage to the comparator, thus ensuring the accuracy of its voltage comparisons. Furthermore, the designed comparator circuit also needs to select an appropriate power supply voltage and consider power consumption optimization.

[0061] In this embodiment, power supply 122 not only provides power to the connected comparator but also provides a stable reference voltage. The feedback loop in the circuit has voltage and current feedback channels, and the reference voltage provides a reference level for the comparator. When the input signal is compared with this reference level, the comparator can determine whether the input signal is higher or lower than the reference level, thereby outputting the corresponding logic level. Furthermore, the regulated reference power supply can stabilize the voltage output, provide an accurate reference voltage, protect the device from overvoltage and undervoltage, and isolate conducted electromagnetic interference. The circuit design of this invention fully considers the performance parameters and application scenarios when selecting and designing the regulated reference power supply to ensure stable voltage output.

[0062] In one possible implementation, the power supply 122 is also electrically connected to the cathode of the diode D to absorb the electrical energy output by the voltage regulation module 120 for energy storage in order to maintain the stability of the system voltage.

[0063] In one possible implementation, the current closed-loop control circuit includes:

[0064] First voltage comparator C1 and sampling resistor R s ;

[0065] The power input terminal and non-inverting terminal of the first voltage comparator C1 are electrically connected to power supply 122, and the inverting terminal is connected to the sampling resistor R. s One end is electrically connected;

[0066] Sampling resistor R s One end is also electrically connected to the source of the first switching transistor Q1, and the other end is grounded, used to sample the current on the inductor L.

[0067] It should be noted that the first voltage comparator C1 and its peripheral circuits adopt a current closed-loop control mode. The comparator acquires the inductor current signal by measuring the voltage across the sampling resistor, forming an inner-loop current control with the current limiting comparator. In the current feedback loop, when the inductor current is compared with the set control current, and the instantaneous current reaches the control current, the comparator output level flips, turning off the switching transistor. The current flows to the load through diode D, forming a BOOST boost control. When the circuit starts, the switching transistor is off, the current sampling signal is low, and it is compared with the feedback error amplifier signal through the comparator. The output signal controls the logic gate circuit, and the output pulse signal turns on the switching transistor. At this time, the sampling current increases, the signal generated across the sampling resistor becomes high, the comparator state flips, and the power switching transistor turns off. The entire current feedback control mode continuously detects the current signal, thus controlling the system output current on each pulse.

[0068] In one possible implementation, the voltage closed-loop control circuit includes:

[0069] The second voltage comparator C2 and the voltage divider impedance network;

[0070] The power input terminal and non-inverting terminal of the second voltage comparator C2 are electrically connected to the power supply 122, and the inverting terminal is electrically connected to the output terminal of the voltage divider impedance network.

[0071] The input terminal of the voltage divider impedance network is electrically connected to the cathode of diode D, and is used to sample the output voltage of voltage regulation module 120.

[0072] Similarly, the second voltage comparator C2 and its peripheral circuits adopt a voltage closed-loop control mode. The outer loop control voltage mode samples the feedback signal from the output terminal to form the voltage outer loop control. When the voltage is higher than the set standard voltage, the switching transistor is turned off.

[0073] In one possible implementation, the voltage divider impedance network includes:

[0074] The first voltage divider resistor R1 and the second voltage divider resistor R2;

[0075] One end of the first voltage divider resistor R1 is electrically connected to the cathode of the diode D, and the other end is electrically connected to the inverting input of the second voltage comparator C2 and one end of the second voltage divider resistor R2.

[0076] The other end of the second voltage divider resistor R2 is grounded.

[0077] In one possible implementation, the voltage regulating module 120 further includes:

[0078] The voltage monitoring unit 123 and the second transistor Q2 have their input terminals electrically connected to the cathode of the diode D and their output terminals electrically connected to the gate of the second transistor Q2. They are used to monitor the output voltage of the voltage regulation module 120 and set the output terminal to a low voltage when the output voltage is lower than the preset second threshold voltage.

[0079] The drain of the second transistor Q2 is electrically connected to the other end of the second voltage divider resistor R2, and the source is grounded.

[0080] In one possible implementation, the voltage regulating module 120 further includes:

[0081] Oscillator 124 is electrically connected at one end to power supply 122 and at the other end to the input of logic AND gate 121.

[0082] It should be noted that an oscillator can generate a stable clock signal through its inherent resonant frequency, providing a time reference for logic and gates, ensuring the consistency of circuit logic output and transmission to ensure synchronous circuit operation, while also improving circuit stability and filtering out noise and jitter.

[0083] Once the oscillator is connected to a power supply, the power supply provides power to the oscillator, ensuring that the oscillator can operate normally and generate oscillation signals automatically without external signal excitation. The operation of the oscillator involves a positive feedback circuit, requiring a stable power supply to maintain its oscillation state. The oscillator power supply plays a crucial role in the oscillator's operation. It not only provides the necessary electrical energy to the oscillator but also maintains its oscillation state and affects the oscillation frequency and stability.

[0084] Furthermore, the oscillation frequency of an oscillator is primarily determined by its internal circuit structure and component parameters. The stability and quality of the power supply also affect the oscillation frequency. A stable power supply ensures the stability of the signal frequency generated by the oscillator, reducing frequency drift and jitter. A high-quality power supply can also reduce noise and interference in the circuit, improving the purity of the oscillation signal. When selecting and designing an oscillator power supply, its stability, quality, and impact on oscillator performance must be fully considered.

[0085] In summary, the wireless low-power energy transmission and receiving circuit provided by this utility model has the following advantages:

[0086] (1) The rectifier module has a good rectification effect, fast response speed, and improves the conversion efficiency of the overall circuit.

[0087] (2) Current limiting and overcurrent protection are realized. The feedback control adopts a dual closed-loop control mode, which can quickly and accurately detect the transient voltage and current of the load and realize real-time detection and protection control.

[0088] (3) The entire system circuit has a fast load response and good stability. The voltage regulation mode achieves voltage boosting and stabilization by adjusting the pulse width. It has a large duty cycle adjustment range, low noise, and high efficiency at full load, ensuring the stability and accuracy of the system output.

[0089] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model should be included within the protection scope of the present utility model.

Claims

1. A wireless low-power energy transfer and receiving circuit, characterized in that, include: The rectifier module, electrically connected to the antenna front end, includes a positive feedback full-wave rectifier circuit for converting the high-frequency radio frequency signal received by the antenna front end into a DC signal; The voltage regulation module is electrically connected to the load and the rectifier module. It is used to boost the DC signal to obtain a boost signal, and output the boost signal to the load when the boost signal is detected to be less than a preset first threshold voltage.

2. The wireless low-power energy transfer and receiving circuit according to claim 1, characterized in that, The positive feedback full-wave rectifier circuit includes: four comparators and four field-effect transistors electrically connected to the four comparators respectively; The four comparators form an H-bridge topology; The gate of the field-effect transistor is electrically connected to the output terminal of the comparator, the source is electrically connected to the non-inverting terminal of the comparator, and the drain is electrically connected to the inverting terminal of the comparator.

3. The wireless low-power energy transfer and receiving circuit according to claim 1, characterized in that, The voltage regulation module includes: an inductor, a diode, a logic AND gate, a first switching transistor, a current closed-loop control circuit, a voltage closed-loop control circuit, and a power supply; One end of the inductor is electrically connected to the rectifier module, and the other end is electrically connected to the anode of the diode. The cathode of the diode is electrically connected to the load. The input terminal of the current closed-loop control circuit is electrically connected to the power supply and the source of the first switching transistor, respectively, and the output terminal is electrically connected to the input terminal of the logic AND gate. It is used to sample the current on the inductor and set the output terminal to low level when the current is detected to be not less than the control current input by the power supply; otherwise, it sets the output terminal to high level. The input terminal of the voltage closed-loop control circuit is electrically connected to the power supply and the cathode of the diode, respectively, and the output terminal is electrically connected to the input terminal of the AND gate. It is used to sample the output voltage of the voltage regulation module and set the output terminal to low level when the output voltage is detected to be not less than the first threshold voltage of the power supply input; otherwise, the output terminal is set to high level. The gate of the first switching transistor is electrically connected to the output of the AND gate, and the drain is electrically connected to the anode of the diode.

4. The wireless low-power energy transfer and receiving circuit according to claim 3, characterized in that, The power supply is also electrically connected to the cathode of the diode to absorb the electrical energy output by the voltage regulation module for energy storage, so as to maintain the stability of the system voltage.

5. The wireless low-power energy transfer and receiving circuit according to claim 3, characterized in that, The current closed-loop control circuit includes: First voltage comparator and sampling resistor; The power input terminal and the non-inverting terminal of the first voltage comparator are electrically connected to the power supply, and the inverting terminal is electrically connected to one end of the sampling resistor. One end of the sampling resistor is electrically connected to the source of the first switching transistor, and the other end is grounded, used to sample the current on the inductor.

6. The wireless low-power energy transfer and receiving circuit according to claim 3, characterized in that, The voltage closed-loop control circuit includes: Second voltage comparator and voltage divider impedance network; The power input terminal and non-inverting terminal of the second voltage comparator are electrically connected to the power supply, and the inverting terminal is electrically connected to the output terminal of the voltage divider impedance network. The input terminal of the voltage divider impedance network is electrically connected to the cathode of the diode, and is used to sample the output voltage of the voltage regulation module.

7. The wireless low-power energy transfer and receiving circuit according to claim 6, characterized in that, The voltage divider impedance network includes: The first voltage divider resistor and the second voltage divider resistor; One end of the first voltage divider resistor is electrically connected to the cathode of the diode, and the other end is electrically connected to the inverting input of the second voltage comparator and one end of the second voltage divider resistor, respectively. The other end of the second voltage divider resistor is grounded.

8. The wireless low-power energy transfer and receiving circuit according to claim 7, characterized in that, The voltage regulating module also includes: The voltage monitoring unit and the second transistor have their input terminals electrically connected to the cathode of the diode and their output terminals electrically connected to the gate of the second transistor. They are used to monitor the output voltage of the voltage regulation module and set the output terminal to a low voltage when the output voltage is lower than a preset second threshold voltage. The drain of the second transistor is electrically connected to the other end of the second voltage divider resistor, and the source is grounded.

9. The wireless low-power energy transfer and receiving circuit according to claim 3, characterized in that, The voltage regulating module also includes: The oscillator is electrically connected at one end to the power supply and at the other end to the input of the AND gate.

10. The wireless low-power energy transfer and receiving circuit according to claim 2 or 8, characterized in that, The four field-effect transistors, the first transistor, and the second transistor are all P-channel MOSFETs.

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