Adjustment-free dual-channel isolation amplification conversion distribution circuit and system
By designing a dual-channel isolation amplifier conversion and distribution circuit that does not require adjustment, the problem of limited signal isolation and conversion functions in existing technologies is solved. This enables flexible and diverse signal conversion, improves signal bandwidth and anti-interference capabilities, simplifies system design, and reduces cost and size.
Patent Information
- Application Number
- CN202510947601.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-10
- Publication Date
- 2025-10-31
AI Technical Summary
Existing signal isolation and conversion circuits have limited functionality, typically only able to process single-channel signals, and cannot achieve signal isolation, amplification, conversion, and distribution. They are particularly complex and difficult to debug when processing DC positive and negative bidirectional signals and AC signals, and are not suitable for strong magnetic field environments.
A dual-channel isolation amplifier conversion and distribution circuit without adjustment is designed, which includes a dual-channel input module, an isolation amplification processing module, an isolation power supply module, a bias adjustment module, and an output module. It adopts a capacitive isolation circuit and a full-bridge topology isolation regulated power supply circuit, supports positive and negative bidirectional linear input voltage and high common-mode rejection ratio, realizes multi-level conditioning and isolation amplification of signals, and supports both voltage and current output modes.
It achieves flexibility and versatility in signal isolation conversion, improves signal bandwidth and conversion rate, enhances anti-interference capability, simplifies user system design, reduces cost and size, is suitable for strong magnetic field environments, and supports isolation, amplification, conversion, and distribution of voltage and current signals.
Smart Images
Figure CN120880425A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of analog signal isolation, conversion, and distribution technology, specifically to a dual-channel isolation amplifier, conversion, and distribution circuit and system that does not require adjustment. Background Technology
[0002] In industrial production, various automated instruments, control systems, and actuators are needed for monitoring and control. Different signal transmission devices have different signal types and magnitudes. When they are combined into a system, signal transmission between instruments and equipment often becomes mismatched and interferes with each other. Therefore, it is necessary to isolate, amplify, convert, and distribute different signals.
[0003] Traditional signal isolation conversion circuits employ two isolation methods. One is magnetic coupling isolation using a transformer. This method first loads the signal onto a carrier wave and then couples it to the transformer's secondary winding via an isolation transformer. However, due to the size limitations of the transformer's coil and core, it's difficult to create a small package. Manually wound coils suffer from uneven enameled wire arrangement and air gaps, affecting accuracy. Furthermore, the transformer's magnetic coupling generates magnetic radiation, making it susceptible to strong magnetic field interference and unsuitable for use in strong magnetic field environments. The other method is optocoupler isolation. However, reducing the size of optocouplers is very difficult, and the isolation voltage is limited by the optocoupler's withstand voltage. The product also needs to address the issue of isolated power supply. Furthermore, optocouplers themselves have poor temperature stability, leading to light decay and affecting accuracy. Isolating DC analog signals through optocouplers is also costly. Additionally, due to the unidirectional conductivity of photodiodes, processing both DC and AC signals is difficult, requiring a differential configuration with dual optocouplers. This results in complex circuitry, high requirements for component matching and consistency, and challenging debugging. It is difficult to process both DC and AC signals effectively, and the complex circuitry and debugging make it unsuitable for practical applications. In order to effectively suppress common-mode noise and common ground between control and execution devices... Interference typically requires effective signal isolation and conversion into voltage and current signals of the desired polarity for acquisition and control. Signal and impedance matching between the control device interface and the execution device interface is also crucial. Currently, magneto-electric coupling isolation amplifiers and opto-coupled isolation amplifiers are commonly used for signal isolation and conversion. These amplifiers are not only large and expensive, but also have limited conversion functions, making it difficult to achieve small-volume, multi-channel signal isolation, amplification, conversion, and distribution. Optocoupler isolation, a traditional physical isolation method, suffers from short lifespan, high supply current, large size, low data transmission rate, low CMTI, and long transmission delay. Magneto-electric isolation offers some improvements over optocoupler isolation, including... While magnetically isolated amplifiers offer advantages such as long lifespan, low supply current, high data transmission rate, high CMTI (Common Criteria and Transmission Time), and low transmission delay, they also suffer from strong emission and low immunity to interference. Furthermore, they are not flexible enough to adapt to the diverse signal isolation and conversion requirements of industrial environments, and their customization costs are high. Although some major domestic and international manufacturers have introduced capacitively isolated amplifier ICs, their functions are limited, only able to isolate minute voltage signals with a gain of 1 millivolt. This single function presents significant limitations, as they lack signal conversion and amplification capabilities. To achieve the diverse signal isolation and conversion requirements of industrial environments, complex external conversion circuits are needed. Moreover, the amplifier itself does not have an isolated power supply; power supply isolation must be addressed to achieve signal isolation.
[0004] However, existing isolation conversion circuits have relatively simple conversion functions and limited number of channels. They can usually only process single-channel signals and can only achieve isolation, amplification, and conversion of a certain type of signal without signal distribution function. Therefore, there is an urgent need for a dual-channel isolation amplification conversion and distribution circuit that can isolate, amplify, convert, and distribute different signals. Summary of the Invention
[0005] In view of the aforementioned existing problems, the present invention is proposed.
[0006] Therefore, the purpose of this invention is to provide an adjustment-free dual-channel isolation amplification conversion and distribution circuit and system, which solves the problem of analog signal isolation conversion and distribution.
[0007] To achieve the above objectives, the present invention provides the following technical solution:
[0008] A dual-channel isolation amplifier-conversion-distribution circuit and system without adjustment, comprising the following:
[0009] S001, Dual-channel input module: includes a first input channel (Sin1) and a second input channel (Sin2). Each channel is independently configured with a current sampling circuit and a voltage divider circuit for initial acquisition and voltage division processing of the input signal.
[0010] S002, Isolation Amplification Processing Module: The first-stage filter circuit, gain amplifier circuit, second-stage filter circuit, impedance transformation circuit, capacitive isolation circuit, differential amplifier circuit, second-order low-pass filter circuit and voltage amplification output circuit are connected in series to form a multi-stage conditioning and isolation amplification link for the signal.
[0011] S003, Isolated Power Supply Module: Includes DC-DC isolated power supply circuit and multiple sets of isolated voltage regulator circuits (Circuit 1 to Circuit 4), providing independent isolated power supply for dual-channel and signal processing modules;
[0012] S004, Bias Adjustment Module: Includes a subtraction bias circuit and an addition bias circuit, used for DC bias adjustment of the signal;
[0013] S005, Output Module: Provides dual-channel voltage output (Vo1, Vo2) and unidirectional bidirectional voltage-controlled constant current source output (Io1, Io2), supporting both voltage and current output modes;
[0014] S006. The first input channel (Sin1) is connected in series with a current sampling circuit and a voltage divider circuit. The second input channel (Sin2) is independently configured with the same current sampling circuit and voltage divider circuit. The outputs of the two input channels are respectively connected to the inputs of the first-stage filter circuit, forming the initial signal processing path. The output of the first-stage filter circuit is connected in series with a gain amplifier circuit, and the output of the gain amplifier circuit is connected in series with a second-stage filter circuit, forming a signal preprocessing link. The output of the second-stage filter circuit is connected to the input of an impedance transformation circuit. The output of the impedance transformation circuit is electrically isolated through a capacitive coupling isolation circuit. The isolated signal is output to the input of a differential amplifier circuit. The output of the differential amplifier circuit is connected in series with a second-order low-pass filter circuit. The output of the second-order low-pass filter circuit is connected in parallel with a voltage amplifier output circuit and a third-stage filter circuit. The output of the voltage amplifier output circuit is directly connected to the voltage output ports (Vo1, Vo2). The output of the third-stage filter circuit is connected to the input of a unidirectional voltage-controlled constant current source circuit, and the output of the unidirectional voltage-controlled constant current source circuit is connected to the current output port (Io). 1. Io2), the current output mode is configured via a digital selector. Circuit 2's regulated isolation power supply circuit 2 supplies power to the second input channel (Sin2) and the corresponding first-stage filter circuit, gain amplifier circuit, and second-stage filter circuit. Circuit 4 supplies power to the second-order low-pass filter circuit, voltage amplifier output circuit, and third-stage filter circuit. The output terminal of the voltage reference circuit is connected to the reference voltage input terminal of the subtraction bias circuit and the addition bias circuit. The subtraction bias circuit is connected in series between the voltage divider circuit and the first-stage filter circuit to eliminate the potential difference between the signal ground and the power supply ground. The addition bias circuit is connected in series between the second-order low-pass filter circuit and the voltage amplifier output circuit to adjust the DC bias of the output signal. The input signals Sin1 / Sin2 are sampled by current and divided by voltage, and then pass through the first-stage filter, gain amplifier, second-stage filter, impedance transformation, capacitive isolation, differential amplifier, and second-order low-pass filter in sequence. Then one path is output through voltage amplification, and finally the voltage signal is output by Vo1 / Vo2. The other path is converted into the Io1 / Io2 current signal through the third-stage filter circuit and the unidirectional and bidirectional voltage-controlled constant current source circuit.
[0015] Furthermore, the capacitive isolation circuit adopts double-sided high-voltage isolation capacitor technology, supports positive and negative bidirectional linear input voltage, isolation voltage ≥3KVDC, common-mode rejection ratio (CMTI) >150kV / μs, and signal bandwidth ≥100kHz.
[0016] Furthermore, the isolated voltage regulator circuit adopts a full-bridge topology, with an output power ≥5W, efficiency ≥85%, and output ripple ≤10mVpp, meeting the power supply requirements for multi-level circuit isolation.
[0017] Furthermore, the unidirectional and bidirectional voltage-controlled constant current source circuit supports 0-20mA / 4-20mA programmable current output, has a load capacity of ≥500Ω, an output accuracy of ≤0.2%, and the output mode can be configured via a digital selector.
[0018] Furthermore, the gain amplifier circuit adopts a fixed gain resistor network with a gain error ≤0.1%, the isolation power supply circuit has a built-in automatic voltage regulation feedback loop with an output voltage fluctuation ≤0.5%, the bias adjustment module has preset default parameters, and can automatically match the input signal range without manual intervention after power-on. The circuit supports one signal input and multiple signal outputs, and signal distribution is achieved through parallel or series connection of the input terminals, meeting the isolation amplification conversion and distribution requirements of one input and two outputs, one input and four outputs, or two inputs and two outputs. Moreover, the input and output signal types can be freely combined into voltage / current signals or single-ended / differential signals, providing flexible signal interface configuration.
[0019] A system for a non-adjustable dual-channel isolation amplifier-converter-distributor circuit includes the following:
[0020] S1. After the operating system starts, it first performs a hardware self-test, including checking the working status of the dual-channel input module, filtering and gain module, isolation and differential module, secondary filtering and output module, power supply module, bias adjustment module, and constant current source module; it then supplies power to each module through a DC-DC isolated power supply circuit and verifies the stability of the isolated power supply, ensuring that the output voltage is within the rated range and the ripple is ≤10mVpp; at the same time, it calibrates the voltage reference circuit to ensure that the bias voltage accuracy is ≤1mV.
[0021] S2. When a signal input is detected in the first signal input channel (Sin1) and / or the second signal input channel (Sin2), the operating system starts the signal acquisition process; the current sampling circuit samples the input signal and converts it into a voltage signal; the voltage divider circuit divides the high voltage signal to adapt to the input range of subsequent circuits; the first-stage filter circuit performs preliminary filtering on the sampled signal to remove high-frequency noise.
[0022] S3. The filtered signal enters the gain amplifier circuit and is amplified according to the preset gain parameters (achieved through a fixed gain resistor network, with a gain error ≤0.1%). The amplified signal then passes through a two-stage filtering circuit to further remove noise and interference. The impedance transformation circuit adjusts the signal impedance to match the input requirements of the capacitive isolation circuit. The capacitive isolation circuit uses double-sided high-voltage isolation capacitor technology to electrically isolate the signal, with an isolation voltage ≥3KVDC and a common-mode rejection ratio (CMTI) >150kV / μs, ensuring lossless signal transmission to the differential amplifier circuit. The differential amplifier circuit differentially amplifies the isolated signal to improve its anti-interference capability.
[0023] S4. The differentially amplified signal enters a second-order low-pass filter circuit to further filter out high-frequency noise and ensure signal quality. The filtered signal passes through a voltage amplification output circuit, where it undergoes final voltage amplification according to output requirements (voltage or current mode). If current output is required, the signal enters a bidirectional voltage-controlled constant current source circuit, which converts it into a programmable current signal of 0-20mA / 4-20mA with a load capacity ≥500Ω and an output accuracy ≤0.2%.
[0024] S5. During system operation, the microprocessor or FPGA monitors the working status of each module in real time, including parameters such as temperature, voltage, and current; it communicates with the host computer through the SPI / I2C interface to realize remote parameter configuration (such as gain adjustment, bias calibration, output mode selection, etc.), status query, and fault diagnosis; when a fault or abnormal state is detected, the system automatically triggers the protection mechanism, such as shutting down the output and cutting off the power supply, and sends alarm information to the host computer through the communication interface.
[0025] S6. When the operating system receives a shutdown command or no signal input is detected for a long time, the system enters power saving mode; it shuts down the power of non-essential modules to reduce system power consumption; at the same time, it maintains the power supply of critical modules (such as microprocessors, communication interfaces, etc.) so as to respond to external commands or perform status monitoring at any time.
[0026] The technical effects and advantages provided by the present invention in the above technical solution are as follows:
[0027] 1. The circuit of the present invention enables flexible and versatile signal isolation conversion, meets various signal isolation conversion functions, and has the characteristics of strong versatility; it also improves signal bandwidth and conversion rate, enhances product reliability and temperature stability, and improves signal isolation conversion accuracy and anti-interference capability.
[0028] 2. This invention, through its design, enables the conversion circuit to achieve complete electrical isolation between dual analog signal inputs, outputs, operating power supplies, and each signal channel with only one power supply. It is suitable for eliminating ground loop interference, suppressing common-mode noise, isolating high-voltage surges, and other harsh environments, ensuring the reliability of signal transmission and the safety of equipment operation.
[0029] 3. The circuit of this invention supports the isolation, amplification, conversion and distribution of voltage and current signals, as well as the isolation and transmission functions of analog single-ended input to positive and negative signals and positive and negative signals to single-ended signals. The whole circuit does not require external potentiometers and other electronic components, and eliminates the need for zero-point and gain adjustment, thus greatly simplifying the user's system design and field usage costs.
[0030] 4. This invention employs a single power supply for the auxiliary power supply and features a 3KVDC six-isolation design between the auxiliary power supply and the signal input, output, and channels. This allows users to utilize a single or multiple power supplies when using multiple modules simultaneously, effectively reducing the design cost and size of the control system. Fewer circuit components are required, debugging is simple and convenient, product costs are reduced, product size is minimized, and product integration is facilitated. Attached Figure Description
[0031] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.
[0032] Figure 1 This is a schematic diagram illustrating the composition principle of the present invention;
[0033] Figure 2 This is the intended implementation principle of the present invention;
[0034] Figure 3 This is a schematic diagram of the isolated power supply circuit of the present invention. Detailed Implementation
[0035] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.
[0036] This invention discloses a dual-channel isolation amplifier conversion and distribution circuit and system that does not require adjustment.
[0037] This invention provides, for example Figure 1-3 The adjustable dual-channel isolation amplifier-conversion-distribution circuit shown includes the following:
[0038] S001, Dual-channel input module: includes a first input channel (Sin1) and a second input channel (Si n2). Each channel is independently configured with a current sampling circuit and a voltage divider circuit for initial acquisition and voltage division processing of the input signal.
[0039] S002, Isolation Amplification Processing Module: The first-stage filter circuit, gain amplifier circuit, second-stage filter circuit, impedance transformation circuit, capacitive isolation circuit, differential amplifier circuit, second-order low-pass filter circuit and voltage amplification output circuit are connected in series to form a multi-stage conditioning and isolation amplification link for the signal.
[0040] S003, Isolated Power Supply Module: Includes DC-DC isolated power supply circuit and multiple sets of isolated voltage regulator circuits (Circuit 1 to Circuit 4), providing independent isolated power supply for dual-channel and signal processing modules;
[0041] S004, Bias Adjustment Module: Includes a subtraction bias circuit and an addition bias circuit, used for DC bias adjustment of the signal;
[0042] S005, Output Module: Provides dual-channel voltage output (Vo1, Vo2) and unidirectional bidirectional voltage-controlled constant current source output (Io1, Io2), supporting both voltage and current output modes;
[0043] S006. The first input channel (Sin1) is connected in series with a current sampling circuit and a voltage divider circuit. The second input channel (Sin2) is independently configured with the same current sampling circuit and voltage divider circuit. The outputs of the two input channels are respectively connected to the inputs of the first-stage filter circuit, forming the initial signal processing path. The output of the first-stage filter circuit is connected in series with a gain amplifier circuit, and the output of the gain amplifier circuit is connected in series with a second-stage filter circuit, forming a signal preprocessing link. The output of the second-stage filter circuit is connected to the input of an impedance transformation circuit. The output of the impedance transformation circuit is electrically isolated through a capacitive coupling isolation circuit. The isolated signal is output to the input of a differential amplifier circuit, and the output of the differential amplifier circuit is connected in series with a second-order low-pass filter circuit. The output terminals of the circuit are connected in parallel with a voltage amplifier output circuit and a three-stage filter circuit. The output terminal of the voltage amplifier output circuit is directly connected to the voltage output ports (Vo1, Vo2). The output terminal of the three-stage filter circuit is connected to the input terminal of the unidirectional voltage-controlled constant current source circuit. The output terminal of the unidirectional voltage-controlled constant current source circuit is connected to the current output ports (Io1, Io2). The current output mode is configured via a digital selector. The voltage regulation isolation power supply circuit 2 of circuit 2 supplies power to the second input channel (Sin2) and the corresponding first-stage filter circuit, gain amplifier circuit, and second-stage filter circuit. Circuit 4 supplies power to the second-order low-pass filter circuit, voltage amplifier output circuit, and third-stage filter circuit. The output terminal of the voltage reference circuit is connected to the subtraction bias circuit. The reference voltage input terminal of the addition bias circuit, the subtraction bias circuit connected in series between the voltage divider circuit and the first-stage filter circuit to eliminate the potential difference between the signal ground and the power supply ground, and the addition bias circuit connected in series between the second-order low-pass filter circuit and the voltage amplifier output circuit to adjust the DC bias of the output signal. The input signals Sin1 / Sin2 are sampled by current and divided by voltage, and then pass through the first-stage filter, gain amplification, second-stage filter, impedance transformation, capacitive isolation, differential amplification, and second-order low-pass filter in sequence. Then one path is passed through the voltage amplifier output, and finally the voltage signal is output by Vo1 / Vo2. The other path passes through the third-stage filter circuit and the unidirectional and bidirectional voltage-controlled constant current source circuit to be converted into the Io1 / Io2 current signal, using a dual-pass filter. The symmetrical architecture features independent pre-amplifier and demodulator circuits for each channel. It employs integrated precision operational amplifiers, high-precision low-drift reference sources, and high-precision non-standard matching resistors to ensure consistent circuit parameters. The isolation circuit utilizes intelligent voltage divider technology within a capacitive isolation chip for adaptive adjustment, guaranteeing 1:1 lossless isolation transmission of the input signal to the output. This keeps transmission and nonlinearity errors within ±0.2%, eliminating the need for manual intervention and preventing fluctuations caused by environmental changes or usage frequency. This ensures continuous and reliable operation, simplifies structural design, reduces failure rates, minimizes daily debugging needs, and balances ease of installation with long-term maintenance efficiency, significantly saving manpower and time costs.
[0044] The capacitive isolation circuit employs double-sided high-voltage isolation capacitor technology, supporting positive and negative bidirectional linear input voltages. It features an isolation voltage ≥3KVDC, a common-mode rejection ratio (CMTI) >150kV / μs, and a signal bandwidth ≥100kHz. Integrating a DC-DC isolation power supply circuit, the conversion circuit requires only a single power supply to achieve complete 3KVDC electrical isolation between dual analog signal inputs, outputs, operating power supplies, and each signal channel. It also fulfills the isolation and transmission functions of converting dual analog single-ended inputs to positive and negative signals and vice versa. The entire circuit requires no external potentiometers or other electronic components, eliminating the need for zero-point and gain adjustments. The capacitive isolation technology overcomes the shortcomings of existing optocoupler and magnetocoupler isolation technologies. Furthermore, through high-precision, multi-functional, high-bandwidth, and high-conversion-rate isolation conversion technology with signal and power supply isolation, it establishes a unified design standard for signal isolation conversion technology. This addresses the current limitations of this technology in terms of versatility and enhances the circuit's flexibility and versatility in signal isolation conversion. The circuit simultaneously supports the acquisition of AC and DC voltage and current signals and has a combined voltage and current output function.
[0045] The isolated voltage regulator circuit adopts a full-bridge topology, with an output power ≥5W, efficiency ≥85%, and output ripple ≤10mVpp, meeting the power supply requirements for multi-level circuit isolation. The circuit uses a small SIP16Pin package to integrate the isolated power supply and dual signal isolation channels, reducing the size by 60% compared to traditional DIN rail-mounted modules and lowering the complexity of multi-component matching. The circuit gain and input offset voltage can be adjusted via external resistors. This circuit has few external components and is easy to use. Each isolation amplifier can form a unity-gain buffer, with the gain achieved through a preamplifier or input signal voltage divider. It features low cost, deep electrical isolation, wide frequency response, and high reliability.
[0046] The unidirectional and bidirectional voltage-controlled constant current source circuit supports 0-20mA / 4-20mA programmable current output, has a load capacity of ≥500Ω, and an output accuracy of ≤0.2%. The output mode can be configured via a digital selector.
[0047] The gain amplifier circuit employs a fixed-gain resistor network with a gain error ≤0.1%. The isolation power supply circuit features a built-in automatic voltage regulation feedback loop, ensuring output voltage fluctuation ≤0.5%. The bias adjustment module has preset default parameters and automatically matches the input signal range without manual intervention after power-on. The circuit supports one signal input and multiple signal outputs, achieving signal distribution through parallel or series connection of input terminals. This meets the isolation amplification conversion and distribution requirements of one-input-two-output, one-input-four-output, or two-input-two-output configurations. Furthermore, the input and output signal types can be freely combined into voltage / current signals or single-ended / differential signals, providing flexible signal interface configuration. The integrated design of dual-channel signal transmission directly reduces on-site installation costs and space occupation. The two input and two output channels are independently isolated, and the two signals are transmitted in parallel, avoiding signal channel interference. It features one-in-two-out, one-in-four-out, and two-in-two-out isolation amplification, conversion, and distribution functions, effectively reducing system complexity and cost. It also supports independent and flexible matching of different analog signals across dual channels. The input and output signal types of the dual channels can be selected to be the same or different and can be freely combined, allowing users to choose according to site requirements. The input signal processing unit converts AC / DC unipolar and bipolar voltage / current input signals (current input can be converted to voltage signals through sampling resistor R1) into voltage signals of the required polarity. When the input signal is unipolar and needs to be converted to bipolar output, or bipolar input and needs to be converted to unipolar output, or when zero-point bias is required for input and output, the conversion and offset can be performed through the bias circuit and addition / subtraction circuit at the input terminal, greatly facilitating the flexibility of analog signal isolation and conversion. The isolation circuit uses a capacitive isolation voltage sampling chip for isolation. The chip employs adaptive coding technology, resulting in low EMI radiation, low bit error rate, and effectively improved common-mode noise immunity (CMTI) of the isolation device. In practice, it can support an insulation voltage of 5kV / μs, a CMTI greater than 150kV / μs, and a signal bandwidth of up to 100KHz. This chip innovates with double-sided high-voltage isolation capacitor technology, supporting positive and negative bidirectional linear input voltages. The series isolation capacitors and SiO2 isolation dielectric achieve enhanced insulation, providing a wide temperature range and long lifespan, ensuring higher reliability for the entire circuit. At the same time, its adaptive coding technology can support higher switching frequencies and short delay differences. Combined with differential transmission and various low-pass filter designs, it can effectively improve common-mode rejection capability.
[0048] S1. After the operating system starts, it first performs a hardware self-test, including checking the working status of the dual-channel input module, filtering and gain module, isolation and differential module, secondary filtering and output module, power supply module, bias adjustment module, and constant current source module; it then supplies power to each module through a DC-DC isolated power supply circuit and verifies the stability of the isolated power supply, ensuring that the output voltage is within the rated range and the ripple is ≤10mVpp; at the same time, it calibrates the voltage reference circuit to ensure that the bias voltage accuracy is ≤1mV.
[0049] S2. When a signal input is detected in the first signal input channel (Sin1) and / or the second signal input channel (Sin2), the operating system starts the signal acquisition process; the current sampling circuit samples the input signal and converts it into a voltage signal; the voltage divider circuit divides the high voltage signal to adapt to the input range of subsequent circuits; the first-stage filter circuit performs preliminary filtering on the sampled signal to remove high-frequency noise.
[0050] S3. The filtered signal enters the gain amplifier circuit and is amplified according to the preset gain parameters (achieved through a fixed gain resistor network, with a gain error ≤0.1%). The amplified signal then passes through a two-stage filtering circuit to further remove noise and interference. The impedance transformation circuit adjusts the signal impedance to match the input requirements of the capacitive isolation circuit. The capacitive isolation circuit uses double-sided high-voltage isolation capacitor technology to electrically isolate the signal, with an isolation voltage ≥3KVDC and a common-mode rejection ratio (CMTI) >150kV / μs, ensuring lossless signal transmission to the differential amplifier circuit. The differential amplifier circuit differentially amplifies the isolated signal to improve its anti-interference capability.
[0051] S4. The differentially amplified signal enters a second-order low-pass filter circuit to further filter out high-frequency noise and ensure signal quality. The filtered signal passes through a voltage amplification output circuit, where it undergoes final voltage amplification according to output requirements (voltage or current mode). If current output is required, the signal enters a bidirectional voltage-controlled constant current source circuit, which converts it into a programmable current signal of 0-20mA / 4-20mA with a load capacity ≥500Ω and an output accuracy ≤0.2%.
[0052] S5. During system operation, the microprocessor or FPGA monitors the working status of each module in real time, including parameters such as temperature, voltage, and current; it communicates with the host computer through the SPI / I2C interface to realize remote parameter configuration (such as gain adjustment, bias calibration, output mode selection, etc.), status query, and fault diagnosis; when a fault or abnormal state is detected, the system automatically triggers the protection mechanism, such as shutting down the output and cutting off the power supply, and sends alarm information to the host computer through the communication interface.
[0053] S6. When the operating system receives a shutdown command or no signal input is detected for an extended period, the system enters power-saving mode; it shuts down the power to unnecessary modules to reduce system power consumption; simultaneously, it maintains power supply to critical modules (such as microprocessors and communication interfaces) to respond to external commands or perform status monitoring. The input analog voltage signal is connected to the input terminal of the input signal processing unit. When the input signal voltage is too high, a voltage divider circuit is used to achieve large signal acquisition; when the input is a current signal, it is converted into a voltage signal by a sampling resistor through a current sampling circuit; the first-stage filter circuit filters and purifies the input signal; when the input is a small millivolt signal, the gain amplifier circuit first amplifies the small input signal; the precision voltage reference circuit and bias addition / subtraction circuit perform signal bias and addition / subtraction operations, converting positive and negative bipolar signals into unipolar signals, or vice versa. The signal bias addition / subtraction circuit can also perform zero-point biasing and linear offset correction of the input signal. The second-stage filter circuit further filters the processed signal to remove noise, glitches, and interference signals, ensuring signal accuracy and stability. The output of the impedance transformation circuit is connected to the input of the capacitive isolation circuit; the output of the capacitive isolation circuit is connected to the differential amplifier circuit, realizing the function of converting the differential signal output of the isolation circuit to single-ended restoration, which helps to improve the circuit accuracy and stability, reduce noise interference, and enhance the circuit's anti-interference capability; the three-stage filter circuit filters and purifies the signal again to ensure a pure and high-precision output; the filter circuit is connected to the voltage amplifier circuit, which amplifies the signal to the required voltage value for output; the voltage signal amplifier circuit is connected to the VI conversion bidirectional voltage-controlled constant current source circuit to achieve bidirectional voltage-controlled constant current output.
[0054] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.
Claims
1. A dual-channel isolation amplifier-conversion-distribution circuit without adjustment, characterized in that, Includes the following: S001, Dual-channel input module: includes a first input channel (Sin1) and a second input channel (Sin2). Each channel is independently configured with a current sampling circuit and a voltage divider circuit for initial acquisition and voltage division processing of the input signal. S002, Isolation Amplification Processing Module: The first-stage filter circuit, gain amplifier circuit, second-stage filter circuit, impedance transformation circuit, capacitive isolation circuit, differential amplifier circuit, second-order low-pass filter circuit and voltage amplification output circuit are connected in series to form a multi-stage conditioning and isolation amplification link for the signal. S003, Isolated Power Supply Module: Includes DC-DC isolated power supply circuit and multiple sets of isolated voltage regulator circuits (Circuit 1 to Circuit 4), providing independent isolated power supply for dual-channel and signal processing modules; S004, Bias Adjustment Module: Includes a subtraction bias circuit and an addition bias circuit, used for DC bias adjustment of the signal; S005, Output Module: Provides dual-channel voltage output (Vo1, Vo2) and unidirectional bidirectional voltage-controlled constant current source output (Io1, Io2), supporting both voltage and current output modes; S006. The first input channel (Sin1) is connected in series with a current sampling circuit and a voltage divider circuit. The second input channel (Sin2) is independently configured with the same current sampling circuit and voltage divider circuit. The outputs of the two input channels are respectively connected to the inputs of the first-stage filter circuit, forming the initial signal processing path. The output of the first-stage filter circuit is connected in series with a gain amplifier circuit, and the output of the gain amplifier circuit is connected in series with a second-stage filter circuit, forming a signal preprocessing link. The output of the second-stage filter circuit is connected to the input of an impedance transformation circuit. The output of the impedance transformation circuit is electrically isolated through a capacitive coupling isolation circuit. The isolated signal is output to the input of a differential amplifier circuit. The output of the differential amplifier circuit is connected in series with a second-order low-pass filter circuit. The output of the second-order low-pass filter circuit is connected in parallel with a voltage amplifier output circuit and a third-stage filter circuit. The output of the voltage amplifier output circuit is directly connected to the voltage output ports (Vo1, Vo2). The output of the third-stage filter circuit is connected to the input of a unidirectional voltage-controlled constant current source circuit, and the output of the unidirectional voltage-controlled constant current source circuit is connected to the current output port (Io).
1. Io2), the current output mode is configured via a digital selector. Circuit 2's regulated isolation power supply circuit 2 supplies power to the second input channel (Sin2) and the corresponding first-stage filter circuit, gain amplifier circuit, and second-stage filter circuit. Circuit 4 supplies power to the second-order low-pass filter circuit, voltage amplifier output circuit, and third-stage filter circuit. The output terminal of the voltage reference circuit is connected to the reference voltage input terminal of the subtraction bias circuit and the addition bias circuit. The subtraction bias circuit is connected in series between the voltage divider circuit and the first-stage filter circuit to eliminate the potential difference between the signal ground and the power supply ground. The addition bias circuit is connected in series between the second-order low-pass filter circuit and the voltage amplifier output circuit to adjust the DC bias of the output signal. The input signals Sin1 / Sin2 are sampled by current and divided by voltage, and then pass through the first-stage filter, gain amplifier, second-stage filter, impedance transformation, capacitive isolation, differential amplifier, and second-order low-pass filter in sequence. Then one path is output through voltage amplification, and finally the voltage signal is output by Vo1 / Vo2. The other path is converted into the Io1 / Io2 current signal through the third-stage filter circuit and the unidirectional and bidirectional voltage-controlled constant current source circuit.
2. The adjustment-free dual-channel isolation amplification conversion and distribution circuit and system according to claim 1, characterized in that, The capacitive isolation circuit adopts double-sided high-voltage isolation capacitor technology, supports positive and negative bidirectional linear input voltage, isolation voltage ≥3KVDC, common-mode rejection ratio (CMTI) >150kV / μs, signal bandwidth ≥100kHz, the circuit supports one signal input and multiple signal outputs, and the signal distribution is achieved by parallel or series connection of the input terminals, which can meet the isolation amplification conversion and distribution requirements of one input and two outputs, one input and four outputs or two inputs and two outputs, and the input and output signal types can be freely combined into voltage / current signals or single-ended / differential signals, providing flexible signal interface configuration.
3. The adjustment-free dual-channel isolation amplification conversion and distribution circuit and system according to claim 2, characterized in that, The isolated voltage regulator circuit adopts a full-bridge topology, with an output power of ≥5W, efficiency of ≥85%, and output ripple of ≤10mVpp, meeting the power supply requirements for multi-level circuit isolation.
4. The adjustment-free dual-channel isolation amplification conversion and distribution circuit and system according to claim 3, characterized in that, The unidirectional and bidirectional voltage-controlled constant current source circuit supports 0-20mA / 4-20mA programmable current output, load capacity ≥500Ω, output accuracy ≤0.2%, and the output mode can be configured via a digital selector.
5. The adjustment-free dual-channel isolation amplification conversion and distribution circuit and system according to claim 4, characterized in that, The gain amplifier circuit uses a fixed gain resistor network with a gain error of ≤0.1%. The isolation power supply circuit has a built-in automatic voltage regulation feedback loop with an output voltage fluctuation of ≤0.5%. The bias adjustment module has preset default parameters and can automatically match the input signal range without manual intervention after power-on.
6. A system for an adjustment-free dual-channel isolation amplification-conversion-distribution circuit, implemented in claim 5, characterized in that, This includes the following: S1. After the operating system starts, it first performs a hardware self-test, including checking the working status of the dual-channel input module, filtering and gain module, isolation and differential module, secondary filtering and output module, power supply module, bias adjustment module and constant current source module. Each module is powered by a DC-DC isolated power supply circuit, and the stability of the isolated power supply is verified to ensure that the output voltage is within the rated range and the ripple is ≤10mVpp; at the same time, the voltage reference circuit is calibrated to ensure that the bias voltage accuracy is ≤1mV. S2. When a signal input is detected in the first signal input channel (Sin1) and / or the second signal input channel (Sin2), the operating system starts the signal acquisition process. The current sampling circuit samples the input signal and converts it into a voltage signal; the voltage divider circuit divides the high-voltage signal to adapt to the input range of subsequent circuits; the first-stage filter circuit performs preliminary filtering on the sampled signal to remove high-frequency noise. S3. The filtered signal enters the gain amplifier circuit and is amplified according to the preset gain parameters (achieved through a fixed gain resistor network, with a gain error ≤0.1%). The amplified signal then passes through a two-stage filtering circuit to further remove noise and interference. The impedance transformation circuit adjusts the signal impedance to match the input requirements of the capacitive isolation circuit. The capacitive isolation circuit uses double-sided high-voltage isolation capacitor technology to electrically isolate the signal, with an isolation voltage ≥3KVDC and a common-mode rejection ratio (CMTI) >150kV / μs, ensuring lossless signal transmission to the differential amplifier circuit. The differential amplifier circuit differentially amplifies the isolated signal to improve its anti-interference capability. S4. The differentially amplified signal enters a second-order low-pass filter circuit to further filter out high-frequency noise and ensure signal quality. The filtered signal passes through a voltage amplification output circuit for final voltage amplification according to output requirements. If current output is required, the signal enters a bidirectional voltage-controlled constant current source circuit to convert it into a 0-20mA / 4-20mA programmable current signal with a load capacity ≥500Ω and an output accuracy ≤0.2%. S5. During system operation, the microprocessor or FPGA monitors the working status of each module in real time, including temperature, voltage, and current parameters; it communicates with the host computer through the SPI / I2C interface to realize remote parameter configuration, status query, and fault diagnosis; when a fault or abnormal state is detected, the system automatically triggers the protection mechanism, such as shutting down the output, cutting off the power supply, and sending alarm information to the host computer through the communication interface. S6. When the operating system receives a shutdown command or no signal input is detected for a long time, the system enters power saving mode; it shuts down the power supply of non-essential modules to reduce system power consumption; at the same time, it maintains the power supply of critical modules so as to respond to external commands or perform status monitoring at any time.