Instrument amplifier system for high-precision signal acquisition
By using an instrumentation amplifier system, including a two-stage amplifier and a folded common-source common-gate amplifier, the difficulty of signal acquisition by biomedical devices in high-noise environments has been solved, achieving accurate amplification and noise suppression of high-precision signals and improving the quality of signal acquisition.
Patent Information
- Application Number
- CN202423062740.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-11
- Publication Date
- 2025-12-09
- Estimated Expiration
- 2034-12-11
AI Technical Summary
Existing biomedical devices struggle to accurately capture microvolt or millivolt signals in high-noise environments. The low input impedance of operational amplifiers leads to signal distortion due to DC offset and noise.
The instrumentation amplifier system, including a two-stage amplifier and a folded cascode amplifier, features high input impedance, low output impedance, high CMRR, low noise, and low offset drift. It amplifies signals through differential input and output and suppresses common-mode noise.
It achieves high-precision signal acquisition, effectively removes sensor noise, extracts minute signals, and improves the accuracy and signal-to-noise ratio of signal acquisition.
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Figure CN223652236U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to amplifier technical field, especially a kind of instrument amplifier system for high-precision signal acquisition. BACKGROUND
[0002] The most commonly used biomedical devices, such as electrocardiogram (ECG), electroencephalogram (EEG) and electromyogram (EMG), will generate microvolt or millivolt signals, which are difficult to be accurately captured in a high-noise environment. In order to suppress noise and amplify differential input, a device with high input impedance, high gain and CMRR is needed. Currently, most devices use operational amplifiers as the main component. For example, in a smoke alarm, the smoke signal is directly captured and amplified by an operational amplifier, and then transmitted into an MCU system, and finally an alarm is given. The main disadvantages of the existing operational amplifier-based biomedical device signal acquisition method are: the input impedance of the operational amplifier is usually only a few milliohms, which is very low and even unmatched; the closed-loop gain of the operational amplifier is controlled by an external resistor connected between its inverting terminal and output terminal; and the operational amplifier will amplify two input signals and any DC signal, as well as the noise associated therewith, so the signal will continue to be obscured by DC offset and noise. SUMMARY
[0003] The utility model discloses a kind of instrument amplifier systems for high-precision signal acquisition, to at least solve one of the technical problems existing in prior art.
[0004] The instrument amplifier system for high-precision signal acquisition according to the utility model embodiment includes: a biomedical device, an instrument amplifier circuit and a master control MCU, the instrument amplifier circuit is used to collect the signal of the biomedical device, and feedback the amplified signal to the master control MCU, and the instrument amplifier circuit includes two-stage amplifier and folded cascode amplifier.
[0005] The instrument amplifier system for high-precision signal acquisition according to the utility model embodiment has at least the following beneficial effects: the instrument amplifier is used to collect and amplify the tiny signal of the biomedical device, the instrument amplifier is a closed-loop gain block, has differential input and output relative to reference voltage measurement, and has particularly high matched input impedance. The instrument amplifier can amplify the difference between input signals while suppressing any common-mode noise. Therefore, the instrument amplifier can be used in precision biomedical devices with high input impedance, low output impedance, high CMRR, low noise and offset drift, especially for removing sensor noise and extracting tiny signals.
[0006] Additional aspects and advantages of the utility model will be partially given in the following description, some will become obvious from the following description, or be understood through the practice of the utility model. BRIEF DESCRIPTION OF DRAWINGS
[0007] The specific embodiments of the present application will be further described in conjunction with the accompanying drawings;
[0008] Figure 1 is the circuit principle diagram of two-stage amplifier;
[0009] Figure 2 is the circuit principle diagram of folded cascode amplifier;
[0010] Figure 3 is the circuit principle diagram of general instrument amplifier. DETAILED DESCRIPTION
[0011] This part will describe the specific embodiments of the present application in detail, the preferred embodiments of the present application are shown in the drawings, the role of the drawings is to supplement the description of the text part with graphics, so that people can intuitively and visually understand each technical feature and the overall technical scheme of the present application, but it cannot be understood as a limitation on the protection scope of the present application.
[0012] In the description of the present application, it is understood that the orientation description, such as up, down, front, back, left, right and other indications of orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and is not intended to indicate or imply that the device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation on the present application.
[0013] In the description of the present application, the meaning of several is one or more, the meaning of multiple is more than two, greater than, less than, more than, etc. are understood as not including the number, above, below, etc. are understood as including the number. If there is a description of the first, second, it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the sequence of indicated technical features.
[0014] Referring to Figure 1 and Figure 2The utility model discloses a kind of instrument amplifier systems for high-precision signal acquisition, comprising: instrument amplifier circuit and main control MCU, the instrument amplifier circuit is used to collect the signal of biomedical equipment, and the signal is amplified and then fed back to main control MCU, the instrument amplifier circuit includes two-stage amplifier, folded cascode amplifier and general instrument amplifier.Main control MCU uses existing main control chip.Using instrument amplifier to collect and amplify the tiny signal of biomedical equipment, instrument amplifier is a closed-loop gain block, with differential input and output relative to reference voltage measurement, it has particularly high matching input impedance.And, the gain of instrument amplifier can also be controlled by input terminal isolated feedback resistor.Instrument amplifier can amplify the difference between input signals while suppressing any common-mode noise.Therefore, instrument amplifier can be used for precision biomedical equipment with high input impedance, low output impedance, high CMRR, low noise and offset drift, especially for removing sensor noise and extracting tiny signal.
[0015] As Figure 1 In some embodiments, the two-stage amplifier includes capacitor Cf, load capacitor Cload, MOS tube M1, MOS tube M2, MOS tube M3, MOS tube M4, MOS tube M5, MOS tube M6, MOS tube M7, MOS tube M8 and current source Idc, the gate of MOS tube M1 and the gate of MOS tube M2 collect the signal of biomedical equipment respectively, the source of MOS tube M1 and the source of MOS tube M2 are electrically connected with the drain of MOS tube M5 respectively, the gate of MOS tube M5, the gate of MOS tube M6 and the drain of MOS tube M6 are electrically connected with the output terminal of current source Idc respectively, the drain of MOS tube M1, the gate of MOS tube M3 and the gate of MOS tube M4 are connected together respectively, the drain of MOS tube M2, the drain of MOS tube M4, the gate of MOS tube M8 and one end of capacitor Cf are connected together respectively, the other end of capacitor Cf, the drain of MOS tube M7, the drain of MOS tube M8 and one end of load capacitor Cload are electrically connected with main control MCU respectively, the source of MOS tube M3, the source of MOS tube M4, the source of MOS tube M8 and the input terminal of current source Idc input voltage VDD respectively, the source of MOS tube M5, the source of MOS tube M6, the source of MOS tube M7 and the other end of load capacitor Cload are grounded respectively.Two-stage operational amplifier provides good gain by isolating two stages and meets the fluctuation requirement, preventing the fluctuation of output voltage from being limited.The first stage is used to provide gain, and the second stage with common-source configuration is used to provide large output voltage fluctuation.In this special design, the first stage adopts a simple differential amplifier, and the second stage adopts a common-source amplifier, and the gain of the first and second stages:
[0016] Therefore, the total voltage gain is:
[0017] Simulation results of two-stage amplifier: The simulation design was performed with Miller capacitance Cf = 0.25 pF and bias current = 5 μA, and a gain of 51 dB, a bandwidth of 154 kHz, and a CMRR of 72.75 dB were obtained.
[0018] As Figure 2In some embodiments, the folded cascode amplifier includes a folded stage input circuit for picking up signals from biomedical devices and a cascode current mirror circuit, an input of the cascode current mirror circuit is electrically connected with the folded stage input circuit, an output of the cascode current mirror circuit is electrically connected with a master control unit and one end of a load capacitor CL respectively, and the other end of the load capacitor CL is grounded. The folded stage input circuit includes a current source Ib, a MOS transistor M1' and a MOS transistor M2', a gate of the MOS transistor M1' and a gate of the MOS transistor M2' pick up signals from biomedical devices respectively, a source of the MOS transistor M1' and a source of the MOS transistor M2' are electrically connected with an output of the current source Ib respectively, a drain of the MOS transistor M2' is electrically connected with the output of the cascode current mirror circuit, and a drain of the MOS transistor M1' is electrically connected with a mirror end of the output of the cascode current mirror circuit. The cascode current mirror circuit includes a MOS transistor M3', a MOS transistor M4', a MOS transistor M5', a MOS transistor M6', a MOS transistor M7', a MOS transistor M8', a MOS transistor M9, a MOS transistor M10 and a MOS transistor M11, a source of the MOS transistor M9, a source of the MOS transistor M10 and an input of the current source Ib input a voltage VDD respectively, a gate of the MOS transistor M9, a gate of the MOS transistor M10, a drain of the MOS transistor M10 and a source of the MOS transistor M8' are connected together respectively, a drain of the MOS transistor M9 is electrically connected with a source of the MOS transistor M7', a gate of the MOS transistor M7', a drain of the MOS transistor M7' and a gate of the MOS transistor M8 are connected together respectively, a drain of the MOS transistor M1' is connected between a drain of the MOS transistor M7' and a drain of the MOS transistor M3', a drain of the MOS transistor M2' and one end of the load capacitor CL are connected between a drain of the MOS transistor M8' and a drain of the MOS transistor M4' respectively, a gate of the MOS transistor M3', a gate of the MOS transistor M4' and a gate of the MOS transistor M11 are connected together respectively, a source of the MOS transistor M3' is electrically connected with a gate of the MOS transistor M5', a source of the MOS transistor M4' is electrically connected with a gate of the MOS transistor M6', a gate of the MOS transistor M5', a gate of the MOS transistor M6', a gate of the MOS transistor M12, a source of the MOS transistor M11 and a drain of the MOS transistor M12 are connected together respectively, a source of the MOS transistor M5', a source of the MOS transistor M6' and a source of the MOS transistor M12 are grounded respectively, and a drain of the MOS transistor M11 is electrically connected with the output of the current source Ib. This amplifier topology consists of multiple stages of transistors carefully arranged to achieve high gain, wide bandwidth, optimized output swing, stability and CMRR enhancement. The cascode transistors in this design increase the output resistance of the circuit, thereby further increasing the small signal gain of the amplifier. The cascode stage circuit provides voltage amplification and isolates the input and output stages. The current mirror configuration is used to provide bias current to the cascode stage. We get the total voltage gain as:
[0019]
[0020] where λ N and λ P are factors related to channel length modulation of NMOS and PMOS devices.
[0021] Simulation results of the folded cascode amplifier: when the analog bias current I b = 5uA, the gain obtained is 52.35dB, the bandwidth is 226.98kHz, and the CMRR is 169dB.
[0022] In some embodiments, the instrumentation amplifier circuit further comprises a general instrumentation amplifier, such as the general INA architecture with 3 operational amplifiers as shown in Figure 3 It is designed using a differential amplifier and two buffer amplifiers. To prevent the load effect on the source, the buffer amplifier is used to isolate the input signal from the load and provide high input impedance. The differential amplifier suppresses common-mode signals while amplifying the voltage difference between the two input signals.
[0023] It is easy for those skilled in the art to understand that the above preferred modes can be freely combined and superimposed without conflict.
[0024] The above is only the preferred embodiment of the utility model, and does not limit the patent range of the utility model, and any equivalent structural transformation made by using the utility model specification and the drawings contents, or directly or indirectly applied in other related technical fields under the utility model concept of the utility model are included in the patent protection range of the utility model.
Claims
1. An instrument amplifier system for high precision signal acquisition, characterized by, The application relates to an instrument amplifier circuit and a master control MCU, wherein the instrument amplifier circuit is used for collecting signals of a biomedical device and feeding back the amplified signals to the master control MCU, and the instrument amplifier circuit comprises two-stage amplifiers and a folded cascode amplifier. The two-stage amplifiers comprise a capacitor Cf, a load capacitor Cload, MOS tubes M1, M2, M3, M4, M5, M6, M7, M8 and a current source Idc, the gates of the MOS tubes M1 and M2 respectively collect signals of a biomedical device, the sources of the MOS tubes M1 and M2 are respectively electrically connected with the drain of the MOS tube M5, the gates of the MOS tubes M5, M6 and the drain of the MOS tube M6 are respectively electrically connected with the output end of the current source Idc, the drains of the MOS tubes M1, M3 and M4 are respectively connected together, the drains of the MOS tubes M2, M4, the gate of the MOS tube M8 and one end of the capacitor Cf are respectively connected together, the other end of the capacitor Cf, the drain of the MOS tube M7, the drain of the MOS tube M8 and one end of the load capacitor Cload are respectively electrically connected with the master control MCU, the sources of the MOS tubes M3, M4, M8 and the input end of the current source Idc are respectively inputted with a voltage VDD, and the sources of the MOS tubes M5, M6, M7 and the other end of the load capacitor Cload are respectively grounded.
2. The instrument amplifier system for high precision signal acquisition of claim 1, wherein: The folded cascode amplifier comprises a folded-stage input circuit, a cascode current mirror circuit and a load capacitor CL, the folded-stage input circuit is used for collecting signals of a biomedical device, the input end of the cascode current mirror circuit is electrically connected with the folded-stage input circuit, the output end of the cascode current mirror circuit is respectively electrically connected with the master control MCU and one end of the load capacitor CL, and the other end of the load capacitor CL is grounded.
3. The instrument amplifier system for high precision signal acquisition of claim 1, wherein: The folded-stage input circuit comprises a current source Ib, MOS tubes M1' and M2', the gates of the MOS tubes M1' and M2' respectively collect signals of a biomedical device, the sources of the MOS tubes M1' and M2' are respectively electrically connected with the output end of the current source Ib, the drain of the MOS tube M2' is electrically connected with the output end of the cascode current mirror circuit, and the drain of the MOS tube M1' is electrically connected with the mirror end of the output end of the cascode current mirror circuit.
4. The instrument amplifier system for high precision signal acquisition of claim 3, wherein: 5. The instrument amplifier system for high precision signal acquisition of claim 4, wherein: The common-source common-gate current mirror circuit comprises MOS transistor M3', MOS transistor M4', MOS transistor M5', MOS transistor M6', MOS transistor M7', MOS transistor M8', MOS transistor M9, MOS transistor M10 and MOS transistor M11, the source of MOS transistor M9, the source of MOS transistor M10 and the input end of current source Ib are input with voltage VDD, the gate of MOS transistor M9, the gate of MOS transistor M10, the drain of MOS transistor M10 and the source of MOS transistor M8' are connected together, the drain of MOS transistor M9 is electrically connected with the source of MOS transistor M7', the gate of MOS transistor M7', the drain of MOS transistor M7' and the gate of MOS transistor M8 are connected together, the drain of MOS transistor M1' is connected between the drain of MOS transistor M7' and the drain of MOS transistor M3', the drain of MOS transistor M2' and one end of load capacitor CL are connected between the drain of MOS transistor M8' and the drain of MOS transistor M4', the gate of MOS transistor M3', the gate of MOS transistor M4' and the gate of MOS transistor M11 are connected together, the source of MOS transistor M3' is electrically connected with the gate of MOS transistor M5', the source of MOS transistor M4' is electrically connected with the gate of MOS transistor M6', the gate of MOS transistor M5', the gate of MOS transistor M6', the gate of MOS transistor M12, the source of MOS transistor M11 and the drain of MOS transistor M12 are connected together, the source of MOS transistor M5', the source of MOS transistor M6' and the source of MOS transistor M12 are grounded, and the drain of MOS transistor M11 is electrically connected with the output end of current source Ib.
6. The instrument amplifier system for high precision signal acquisition of claim 1, wherein: The instrument amplifier circuit further comprises a general instrument amplifier.