Amplifier based on unipolar thin film transistor, chip and electronic equipment
Through the combination of cascron structure, auxiliary amplifier module and capacitor bootstrap technology, the shortcomings of TFT amplifier in terms of gain, noise and output impedance are solved, and the weak signal amplification effect with high gain and low noise is achieved, which is suitable for biomedical signal processing and sensor systems.
Patent Information
- Application Number
- CN202510374769.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-27
- Publication Date
- 2025-07-25
AI Technical Summary
Existing TFT amplifiers have shortcomings in gain, noise and output impedance, which are difficult to meet the needs of biomedical signal processing and sensor systems.
The design is adopted for a combination of cascorder structure, auxiliary amplifier module and capacitor bootstrap technology, including capacitance bootstrap module and auxiliary amplifier module. The output impedance is increased through the cascorder module, the auxiliary amplifier module improves the equivalent impedance of the cascorder level, and the capacitance bootstrap module improves the equivalent impedance of the load.
It significantly improves the gain of the TFT amplifier to 41.2dB, reduces RTI noise to 27.3μVrms, and can effectively amplify weak signals at low voltages, suitable for biomedical signal processing and sensor systems.
Smart Images
Figure CN120377839A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of integrated circuit design, and particularly to an amplifier, a chip and an electronic device based on a unipolar thin film transistor. Background Art
[0002] As an important electronic component, the thin film transistor (TFT) has been widely studied and applied in recent years because of its unique advantages (such as low cost, flexibility, ultra-thin form, etc.) in flexible electronic devices, wearable devices and large-area integrated circuits. The structure of the TFT is as Figure 1 shown. As an important part of the TFT circuit, the gain, noise and stability of the TFT amplifier are the key factors determining its performance. In many applications, especially in the fields of sensor systems and biomedical detection, the amplification and processing of weak signals are the core challenges in the design of the TFT amplifier.
[0003] The existing amplifiers using the capacitor bootstrap technology are as Figure 2 shown. However, only using the capacitor bootstrap technology can only achieve a gain of about 20 dB, which cannot meet the application requirements. In order to improve the performance of the TFT amplifier, researchers have tried to improve the gain and output impedance of the amplifier through various technical means. For example, the cascode structure is used to increase the output impedance, and the gain and stability are improved through the auxiliary amplifier (AUX) and capacitor bootstrap (CBS) technologies. Although these methods have been improved to a certain extent, it is often difficult to solve the problems of gain, noise and output impedance simultaneously by using a single technology alone. Summary of the Invention
[0004] To solve at least one of the technical problems existing in the prior art to a certain extent, an object of the present invention is to provide an amplifier, a chip and an electronic device based on a unipolar thin film transistor.
[0005] The first technical solution adopted by the present invention is:
[0006] An amplifier based on a unipolar thin film transistor, which only contains transistors of one polarity, includes:
[0007] A capacitor bootstrap module, composed of a capacitor and a TFT, is used to increase the equivalent impedance of the load;
[0008] An auxiliary amplifier module, realized by a diode-connected TFT load inverter, is used to increase the equivalent impedance of the cascode stage to optimize the gain characteristics of the amplifier;
[0009] A cascode module, used to increase the output impedance of the amplifier and facilitate the embedding of the auxiliary amplifier.
[0010] Further, the cascode module includes transistor M1 and transistor M2. The two transistors together form a cascode structure, and the size of transistor M1 is larger than that of transistor M2.
[0011] Among them, the gate of transistor M1 serves as the input terminal of the amplifier, the source is grounded, and the drain is connected to the source of transistor M2; the drain of transistor M2 serves as the output terminal of the amplifier.
[0012] Further, the capacitive bootstrap module includes transistor M5, transistor M6, capacitor C4, transistor M3, transistor M4, capacitor C3, transistor M10, transistor M11, capacitor C2, transistor M8, transistor M9, and capacitor C1.
[0013] Among them, the source of transistor M3 is connected to the drain of transistor M2, and the gate is connected to the source of transistor M4; the gate and drain of transistor M4 are both connected to the drain of transistor M3; the two ends of capacitor C3 are respectively connected to the gate of transistor M3 and the drain of transistor M2.
[0014] The source of transistor M5 is connected to the drain of transistor M3, the drain is connected to voltage VDD, and the gate is connected to the source of transistor M6; the gate and drain of transistor M6 are both connected to the drain of transistor M5; the two ends of capacitor C4 are respectively connected to the gate of transistor M5 and the drain of transistor M2.
[0015] The source of transistor M8 is connected to the gate of transistor M2, and the gate of transistor M8 is connected to the source of transistor M9; the gate and drain of transistor M9 are both connected to the drain of transistor M8; the two ends of capacitor C1 are respectively connected to the gate of transistor M8 and the gate of transistor M2.
[0016] The source of transistor M10 is connected to the drain of transistor M8, the drain is voltage VDD, and the gate is connected to the source of transistor M11; the gate and drain of transistor M11 are both connected to the drain of transistor M10; the two ends of capacitor C2 are respectively connected to the gate of transistor M10 and the gate of transistor M2.
[0017] Within a preset frequency range, transistor M6 and capacitor C4 form a voltage division structure, feeding back the output voltage Vout of the amplifier to the gate of transistor M5. At this time, the equivalent impedance of transistor M5 is increased, thereby increasing the gain of the circuit.
[0018] Further, the auxiliary amplifier module includes transistor M7, transistor M10, transistor M11, capacitor C2, transistor M8, transistor M9, and capacitor C1.
[0019] Among them, the gate of transistor M7 is connected to the drain of transistor M1, the source is grounded, and the drain is connected to the gate of transistor M2.
[0020] The second technical solution adopted by the present invention is:
[0021] A chip includes the amplifier based on unipolar thin-film transistors as described above.
[0022] The third technical solution adopted by the present invention is:
[0023] An electronic device includes a chip as described above.
[0024] Compared with the prior art, the present invention has at least the following beneficial effects and advantages:
[0025] (1) High gain: By adopting the combined design of a cascode module, an auxiliary amplifier module, and a capacitive bootstrap module, the present invention can significantly improve the gain of the TFT amplifier, achieving a gain level of up to 41.2 dB. Compared with the gain level of traditional TFT amplifiers, it has a significant improvement and can meet the application scenarios with high gain requirements.
[0026] (2) Low noise: The present invention considers noise suppression in the design. Through the optimized combination of the auxiliary amplifier module and the capacitive bootstrap technology, the RTI noise of the amplifier is effectively reduced to 27.3 μVrms, which can improve the signal-to-noise ratio of the signal and is suitable for the detection and processing of weak signals.
[0027] (3) The present invention adopts the combined design of a cascode structure and an auxiliary amplifier module, which can effectively increase the output impedance of the amplifier, enabling it to adapt to high-impedance loads and enhancing the signal amplification effect.
[0028] (4) Suitable for weak signal amplification: Since the present invention combines multiple gain improvement technologies, it can effectively amplify weak signals at low voltages and has important application potential in fields such as biomedical signal processing, sensor systems, and intelligent health monitoring. Description of the Drawings
[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following introduces the accompanying drawings of the relevant technical solutions in the embodiments of the present invention or the prior art. It should be understood that the accompanying drawings in the following introduction are only for conveniently and clearly presenting some embodiments of the technical solutions in the present invention. For those skilled in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0030] Figure 1 It is a schematic structural diagram of MOTFT technology.
[0031] Figure 2 It is a schematic structural diagram of only using a capacitive bootstrap TFT amplifier in the prior art;
[0032] Figure 3 It is a schematic diagram of the auxiliary amplifier and the capacitive self-residence technology in the embodiment of the present invention.
[0033] Figure 4 It is a schematic structural diagram of the TFT amplifier combining the auxiliary amplifier and the capacitive bootstrap technology in the embodiment of the present invention.
[0034] Figure 5 It is a schematic diagram of the gain and phase of the amplifier provided in the embodiment of the present invention.
[0035] Figure 6 It is a schematic diagram of the input-referred noise of the amplifier provided in the embodiment of the present invention.
[0036] Figure 7 It is a schematic circuit diagram of the amplifier used as a piezoelectric sensor in the embodiment of the present invention.
[0037] Figure 8 It is a schematic diagram of the signal collected by the piezoelectric sensor in the embodiment of the present invention. Detailed implementation manners
[0038] The embodiments of the present application will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present application and should not be construed as a limitation of the present application. For the step numbers in the following embodiments, they are only set for the convenience of explanation and no limitation is imposed on the order between the steps. The execution order of each step in the embodiments can be adjusted adaptively according to the understanding of those skilled in the art.
[0039] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the embodiments of the present application. The singular forms of "a", "the" and "said" used in the embodiments of the present application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. In addition, unless otherwise clearly defined, words such as "set", "installed", "connected" should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above words in the present invention in combination with the specific content of the technical solution.
[0040] In the description of the present application, it should be understood that for the orientation descriptions, such as the orientations or positional relationships indicated by up, down, front, back, left, right, etc., they are based on the orientations or positional relationships shown in the drawings. This is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present application.
[0041] In the description of the present application, the meaning of "a number of" is one or more, the meaning of "a plurality of" is two or more. Understandings such as "greater than", "less than", "exceeding", etc. do not include the recited number, and understandings such as "above", "below", "within", etc. include the recited number. If there is a description of "first" and "second", it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.
[0042] In the description of the present application, "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. These three situations. The character " / " generally represents an "or" relationship between the front and back associated objects.
[0043] Aiming at the problems of low gain, low output impedance and relatively high noise existing in the existing TFT amplifiers, the present invention proposes an integrated amplifier design combining a cascode structure, an auxiliary amplifier module and a capacitive bootstrap technique, aiming to achieve high gain, low noise and excellent output impedance characteristics through effective technical combination to meet the requirements of applications such as weak signal detection and biomedical signal processing.
[0044] As Figure 4 shown, the present embodiment provides an amplifier based on a unipolar thin film transistor, including:
[0045] A capacitive bootstrap module, composed of a capacitor and a TFT, is used to increase the equivalent impedance of the load;
[0046] An auxiliary amplifier module, implemented by a diode-connected TFT load inverter, is used to increase the equivalent impedance of the cascode stage to optimize the gain characteristics of the amplifier;
[0047] A cascode module is used to increase the output impedance of the amplifier and facilitate the embedding of the auxiliary amplifier.
[0048] In this embodiment, the auxiliary amplifier module is implemented by an inverter of a transistor. The auxiliary amplifier can increase the equivalent output impedance of the cascode stage. At the same time, the auxiliary amplifier can also cooperate with the capacitor bootstrap module to make the gain of the auxiliary amplifier more significant. By effectively combining the above modules, this amplifier design achieves high gain, low noise, and good operating stability, and is suitable for amplifying weak signals at low voltages. When the auxiliary amplifier is used in cooperation with the capacitor bootstrap module, it can improve the gain of the auxiliary amplifier itself and further enhance the improvement of the output impedance. Optionally, the structure of the TFT used in the amplifier is as Figure 1 shown.
[0049] As an implementation manner, the cascode module includes transistor M1 and transistor M2. The two transistors together form a cascode structure, and the size of transistor M1 is larger than that of transistor M2;
[0050] wherein, the gate of transistor M1 serves as the input terminal of the amplifier, the source is grounded, and the drain is connected to the source of transistor M2; the drain of transistor M2 serves as the output terminal of the amplifier.
[0051] As an implementation manner, the capacitor bootstrap module includes transistor M5, transistor M6, capacitor C4, transistor M3, transistor M4, capacitor C3, transistor M10, transistor M11, capacitor C2, transistor M8, transistor M9, and capacitor C1;
[0052] wherein, the source of transistor M3 is connected to the drain of transistor M2, and the gate is connected to the source of transistor M4; the gate and drain of transistor M4 are both connected to the drain of transistor M3; both ends of capacitor C3 are respectively connected to the gate of transistor M3 and the drain of transistor M2;
[0053] the source of transistor M5 is connected to the drain of transistor M3, the drain is connected to voltage VDD, and the gate is connected to the source of transistor M6; the gate and drain of transistor M6 are both connected to the drain of transistor M5; both ends of capacitor C4 are respectively connected to the gate of transistor M5 and the drain of transistor M2;
[0054] the source of transistor M8 is connected to the gate of transistor M2, and the gate of transistor M8 is connected to the source of transistor M9; the gate and drain of transistor M9 are both connected to the drain of transistor M8; both ends of capacitor C1 are respectively connected to the gate of transistor M8 and the gate of transistor M2;
[0055] the source of transistor M10 is connected to the drain of transistor M8, the drain is voltage VDD, and the gate is connected to the source of transistor M11; the gate and drain of transistor M11 are both connected to the drain of transistor M10; both ends of capacitor C2 are respectively connected to the gate of transistor M10 and the gate of transistor M2;
[0056] Within a preset frequency range, the transistor M6 and the capacitor C4 form a voltage dividing structure, feeding back the output voltage Vout of the amplifier to the gate of the transistor M5. At this time, the equivalent impedance of the transistor M5 is increased, thereby increasing the gain of the circuit.
[0057] As an implementation, the auxiliary amplifier module includes a transistor M7, a transistor M10, a transistor M11, a capacitor C2, a transistor M8, a transistor M9, and a capacitor C1;
[0058] Among them, the gate of the transistor M7 is connected to the drain of the transistor M1, the source is grounded, and the drain is connected to the gate of the transistor M2.
[0059] The basic structure of the auxiliary amplifier module is an inverter with two transistors. By changing its load transistor to a two-stage capacitive bootstrap structure, the auxiliary amplifier is realized. The input of the auxiliary amplifier is the drain of the transistor M1, and the output is connected to the gate of the transistor M2. When the gate voltage of the transistor M7 increases, the gate voltage of the transistor M2 decreases, resulting in a decrease in the gate voltage of the transistor M7, that is, the auxiliary amplifier can more effectively control the currents of the transistor M1 and the transistor M2, increase its output impedance, thereby increasing the gain. The capacitive bootstrap structure is added to the auxiliary amplifier, making the gain of the auxiliary amplifier effectively increased. Its current control effect on the transistors M1 and M2 is more obvious, and the gain of the amplifier is more effectively increased. A high gain can obtain lower input equivalent noise.
[0060] The above amplifier will be introduced in detail below in combination with the accompanying drawings and specific implementation manners.
[0061] The cascode module is mainly used to increase the output impedance of the amplifier and facilitate the embedding of the auxiliary amplifier. Through the design of the cascode structure, the gain and stability of the amplifier are significantly improved. Assume that the auxiliary amplifier (AUX) is connected to a cascode stage, as shown in Figure 3 (a) therein. To calculate its output resistance (Rout), the equivalent circuit diagram is as shown in Figure 3 (b) therein. I x is the total current of r o2 and g m2 . Therefore, R out can be calculated as follows:
[0062]
[0063] If there is no auxiliary amplifier (AUX), the output resistance (R out ) of the cascode stage should be g m1 r o2 r o1 . After adding AUX, Rout increases significantly. When the voltage at point P increases, AUX reduces the gate voltage of transistor M2, thereby reducing the voltage at point P. In other words, AUX mitigates the change in the output current I x and ultimately increases R out .
[0064] The capacitive bootstrap module consists of a capacitor and a transistor (TFT) and can achieve positive feedback within a specific frequency range. This feedback mechanism increases the equivalent impedance of the load transistor, thereby enhancing the gain and frequency response performance of the amplifier. In Figure 3 (a) of, Vout is connected to an ideal current source I s , and its impedance was ignored in the previous analysis. However, it is challenging to implement a stable current source in a TFT, and its impedance cannot be ignored. The non-ideal current source significantly limits the output resistance (R out ). Capacitive bootstrap technology (CBS) is used to solve this problem. As shown in Figure 3 (c) and (d) of, the voltage divider formed by transistor M2 and capacitor C provides positive feedback to transistor M1. By appropriately setting the value of capacitor C, CBS will operate within the desired frequency range. The feedback coefficient (A f ) of CBS is close to 1, thereby effectively increasing the impedance of transistor M1. Therefore, the output resistance (R out ) of CBS should be:
[0065]
[0066] Obviously, transistor M2 is in a zero-bias state. Generally, the resistance of a TFT at zero bias is 10^12 ohms. When the capacitance is 10 pF and CBS operates at a frequency of around 1 Hz, the feedback coefficient (A f ) can be close to 1. The output resistance (R out ) of CBS is close to r o1 , while without CBS, its output resistance is 1 / g m1 . Therefore, CBS can effectively increase the impedance of the load transistor.
[0067] The auxiliary amplifier module is implemented by an inverter with a diode-connected TFT load. Its main function is to increase the equivalent impedance of the cascode stage and further optimize the gain characteristics of the amplifier. When the auxiliary amplifier is used in conjunction with the capacitive bootstrap module, it can enhance the gain of the auxiliary amplifier itself and further strengthen the improvement of the output impedance.
[0068] The performance of the amplifier in this embodiment will be described below in combination with test examples.
[0069] The output waveforms of the amplifier are collected under inputs of the same amplitude at different frequencies to obtain its gain and phase, as Figure 5 shown. The output is connected to the AC ground, and the spectrum analysis of the output waveform is performed to obtain the waveform as Figure 6 shown, which is its input reference noise. Specifically, the gain of this amplifier is 42.7 dB, the bandwidth is 5.96 KHz, and the input equivalent noise from 1 to 200 Hz is 27.3 μV rms . This amplifier is applied in a piezoelectric sensor and can effectively detect pressure signals.
[0070] The amplifier is connected to a TFT piezoelectric sensor. PVDF and dual-gate TFT are common TFT piezoelectric sensors, and their schematic diagram is as Figure 7 shown. Pressure is applied to the PVDF, generating a current on the dual-gate TFT M2. The transistor M2 and M1 form a current-to-voltage converter to convert the current into a voltage, which is amplified by the amplifier. The PVDF is attached to the knee, and the movement of lifting the leg is performed to collect the waveform, obtaining the waveform as Figure 8 shown.
[0071] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.
[0072] The above embodiments are only for illustrating the technical concept and characteristics of the present invention, and their purpose is to enable those of ordinary skill in the art to understand the content of the present invention and implement it accordingly, and cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the essence of the content of the present invention should be covered within the protection scope of the present invention.
Claims
1. An amplifier based on a unipolar thin film transistor, characterized in that, Comprising: A capacitor bootstrap module, composed of a capacitor and a TFT, for increasing the equivalent impedance of the load; An auxiliary amplifier module, implemented by a diode-connected TFT load inverter, for increasing the equivalent impedance of the cascode stage to optimize the gain characteristic of the amplifier; A cascode module, for increasing the output impedance of the amplifier and facilitating the embedding of the auxiliary amplifier.
2. The amplifier based on a unipolar thin-film transistor according to claim 1, wherein The cascode module includes transistor M1 and transistor M2, and the two transistors together form a cascode structure, and the size of transistor M1 is larger than that of transistor M2; Among them, the gate of transistor M1 serves as the input terminal of the amplifier, the source is grounded, and the drain is connected to the source of transistor M2; The drain of transistor M2 serves as the output terminal of the amplifier.
3. The amplifier based on a unipolar thin film transistor according to claim 2, characterized in that, The capacitor bootstrap module includes transistor M5, transistor M6, capacitor C4, transistor M3, transistor M4, capacitor C3, transistor M10, transistor M11, capacitor C2, transistor M8, transistor M9, and capacitor C1; Among them, the source of transistor M3 is connected to the drain of transistor M2, and the gate is connected to the source of transistor M4; the gate and drain of transistor M4 are both connected to the drain of transistor M3; both ends of capacitor C3 are respectively connected to the gate of transistor M3 and the drain of transistor M2; The source of transistor M5 is connected to the drain of transistor M3, the drain is connected to voltage VDD, and the gate is connected to the source of transistor M6; the gate and drain of transistor M6 are both connected to the drain of transistor M5; both ends of capacitor C4 are respectively connected to the gate of transistor M5 and the drain of transistor M2; The source of transistor M8 is connected to the gate of transistor M2, and the gate of transistor M8 is connected to the source of transistor M9; the gate and drain of transistor M9 are both connected to the drain of transistor M8; both ends of capacitor C1 are respectively connected to the gate of transistor M8 and the gate of transistor M2; The source of transistor M10 is connected to the drain of transistor M8, the drain is voltage VDD, and the gate is connected to the source of transistor M11; the gate and drain of transistor M11 are both connected to the drain of transistor M10; both ends of capacitor C2 are respectively connected to the gate of transistor M10 and the gate of transistor M2; Within a preset frequency range, transistor M6 and capacitor C4 form a voltage division structure, feeding back the output voltage Vout of the amplifier to the gate of transistor M5. At this time, the equivalent impedance of transistor M5 is increased, thereby increasing the gain of the circuit.
4. The amplifier based on a unipolar thin film transistor according to claim 3, wherein The auxiliary amplifier module includes transistor M7, transistor M10, transistor M11, capacitor C2, transistor M8, transistor M9, and capacitor C1; Among them, the gate of transistor M7 is connected to the drain of transistor M1, the source is grounded, and the drain is connected to the gate of transistor M2.
5. A chip, characterized in that, Including the amplifier based on unipolar thin film transistors according to any one of claims 1-4.
6. An electronic device, characterized in that, Including the chip according to claim 5.