An isolation circuit

Abstract

The present invention provides an isolation circuit, comprising: an input line, an isolator, and an output line; the isolator isolates the power supply and ground of the output line from the power supply and ground of the output circuit; the input line outputs a carrier signal and N modulated signals generated by the carrier signal and the input signal, where N>1; the isolator includes a carrier signal isolator and N modulated signal isolators corresponding to the modulated signals one by one; the carrier signal and each modulated signal are respectively input into the output line to generate N output signals corresponding to the input signal one by one. The above isolation circuit can save area on a multi-channel chip and can maintain good signal transmission without distortion.

Description

Technical Field

[0001] The present invention relates to a power switch tube, and particularly to an isolation circuit. Background Art

[0002] The main function of isolation is to separate one circuit to avoid being interfered by another circuit. For example, an insulator (dielectric) is used to separate these two circuits. It can also be said to isolate two different voltage domains. For example, in a control system, the processor power supply is usually a low voltage of 5V, and the load power supply is usually a high voltage of 220V. If these two voltage domains are not isolated, the operation of the high-voltage domain will cause serious interference to the low-voltage domain, and even cause damage to the devices in the low-voltage domain. Therefore, an insulator is needed to separate the high-voltage domain and the low-voltage domain. However, isolation cannot affect the transmission of digital signals. Digital signals are usually transmitted through high-frequency carriers, and high-frequency carriers can pass through insulators for transmission. Such media that can both isolate different voltage domains and transmit signals include inductors, transformers, optocouplers, capacitors, NVE magnetic switches, GMR giant magnetoresistance, and so on.

[0003] Isolation can be applied to the IGBT gate drive for driving a motor, which will be a floating ground architecture. The power supplies and grounds of the two circuits are inconsistent, and their inconsistency will also change with transient changes, thus generating a so-called Common Mode Transient Immunity (CMTI) performance index. The better this index is, the higher the tolerance to common mode transient interference (CMTI) is, because this high-frequency transient common mode interference will disrupt the information transmission between the isolation dielectrics. Therefore, it is necessary to develop an isolation technology with anti-interference to CMTI.

[0004] Existing methods such as Figure 1 shown, use high-voltage capacitors as insulating dielectrics. Each input corresponds to 2 isolation capacitors, and these 2 isolation capacitors are used to isolate the 2 differential signals of each input. As Figure 1 shown for 2 inputs, 4 isolation capacitors are required. The number of isolation capacitors required for multi-channel isolation drive is 2*N (N is the number of channels). In multi-channel applications, it will consume more area and generate more noise. Summary of the Invention

[0005] The main technical problem to be solved by the present invention is an isolation circuit that can save area on a multi-channel chip and can maintain good signal transmission without distortion.

[0006] To solve the above technical problems, the present invention provides an isolation circuit, including: an input line, an isolator, and an output line; the isolator isolates the power supply and ground of the input line from the power supply and ground of the output line;

[0007] The input line is connected between a first power supply VDD1 and a first ground terminal GND1, and is used to receive an input signal, output a carrier signal and N modulated signals, where the N modulated signals are generated by modulating the carrier signal and the input signal, and N>1;

[0008] The isolator, which includes a carrier signal isolator and N modulated signal isolators corresponding one-to-one to the modulated signals, is used to connect and isolate the input line and the output line;

[0009] The output line is connected between a second power supply VDD2 and a second ground terminal GND2, and is simultaneously connected to the above-mentioned isolator, and is used to receive the modulated signal and the carrier signal processed by the above-mentioned isolator, and demodulate the processed modulated signal and the carrier signal to provide N output signals corresponding one-to-one to the N input signals.

[0010] In a preferred embodiment: The waveform of the output signal is the same as that of the input signal and has a certain delay.

[0011] In a preferred embodiment: The modulated signal is a continuous carrier signal.

[0012] In a preferred embodiment: The output circuit demodulates the modulated signal by using the rising edge and / or falling edge of a single line to lock the data content.

[0013] The present invention also provides an isolation circuit, including: an input line, an isolator and an output line; the power supply and ground of the input line are isolated from the power supply and ground of the output line;

[0014] The input line includes a carrier signal generation part and N modulated signal generation parts; the carrier signal generation part generates a first carrier signal and a second carrier signal; the first carrier signal, the second carrier signal and N input signals are respectively input to the N modulated signal generation parts to generate N modulated signals;

[0015] The isolator includes a carrier signal isolator and N modulated signal isolators corresponding one-to-one to the modulated signals; the input end of the carrier signal isolator is connected to the first carrier signal, and the input ends of the N modulated signal isolators are correspondingly connected to the N modulated signals;

[0016] The output line includes N comparators, and the negative input ends of each comparator are respectively connected to the output end of the carrier signal isolator; the positive input ends of each comparator are respectively correspondingly connected to the output ends of the N modulated signal isolators one-to-one; the output ends of the comparators respectively form N output signals through a level conversion line.

[0017] In a preferred embodiment: The waveform of the output signal is the same as that of the input signal and has a certain delay.

[0018] In a preferred embodiment: The modulation signal is a continuous carrier signal.

[0019] In a preferred embodiment: The output circuit demodulates the modulation signal by using the single rising edge and / or falling edge to lock the data content.

[0020] In a preferred embodiment: The modulation signal generation part is a multiplexer

[0021] In a preferred embodiment: The carrier signal generation part is an oscillator. Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0022] The present invention provides an isolation circuit. For the input lines of the N-channel input signal, only N + 1 isolators are required, while the traditional N-channel isolation drive structure requires 2N isolators. Therefore, the purpose of saving isolators can be achieved, and the cost can be saved. As the number of driven channels increases, the advantages of the present invention become more obvious. Description of the Drawings

[0023] Figure 1 is a framework diagram of the isolation line in the prior art;

[0024] Figure 2 is a framework diagram of the isolation line in the preferred embodiment of the present invention;

[0025] Figure 3 is a structural block diagram of the input line in the preferred embodiment of the present invention;

[0026] Figure 4 is a node waveform diagram of the input line in the preferred embodiment of the present invention;

[0027] Figure 5 is a structural block diagram of the output line in the preferred embodiment of the present invention;

[0028] Figure 6 is a node waveform diagram of the isolation line in the preferred embodiment of the present invention. Detailed Embodiments

[0029] The technical solution of the present invention will be further described below with reference to the drawings and specific embodiments.

[0030] Refer to Figures 1 - 6 , this embodiment provides an isolation circuit, including: an input line, an isolator, and an output line; the isolator isolates the power supply VDD1 and ground GND1 of the output line from the power supply VDD2 and ground GND2 of the output circuit;

[0031] The input line includes a carrier signal generation part and N modulation signal generation parts. In this embodiment, N = 2, and N can also take any other integer, which belongs to a simple replacement of this embodiment. The modulation signal generation part is a multiplexer. The carrier signal generation part is an oscillator.

[0032] The oscillator generates a first carrier signal and a second carrier signal; the carrier signal A, the carrier signal B, and two input signals INPUT1 and INPUT2 are respectively input to the multiplexer 1 and the multiplexer 2 to generate a modulation signal 1 and a modulation signal 2;

[0033] The isolator includes an isolator 1 and isolators 2 and 3 corresponding to the modulation signal 1 and the modulation signal 2 one by one; the input end of the isolator 1 is connected to the carrier signal A, and the input ends of the isolators 2 and 3 are correspondingly connected to the modulation signal 1 and the modulation signal 2;

[0034] The output line includes two comparators. The negative input ends of the comparator 1 and the comparator 2 are respectively connected to the output end of the isolator 1; the positive input ends of the comparator 1 and the comparator 2 are respectively correspondingly connected to the output ends of the isolators 2 and 3 one by one; the output ends of the comparators respectively pass through a level conversion circuit 1 and a level conversion circuit 2 to form output signals OUTPUT1 and OUTPUT2.

[0035] For the above isolation line, each input signal only needs to be isolated by one isolator, plus the isolator 1 for isolating the carrier signal A, only N + 1 isolators are needed, while the traditional N-channel isolation drive structure requires 2N isolators. Therefore, the purpose of saving isolators can be achieved, and the cost can be saved. As the number of driven channels increases, the advantages of this embodiment become more obvious.

[0036] In this embodiment, the waveform of the output signal is the same as the input signal and has a certain delay. The modulation signals 1 and 2 are continuous carrier signals. The output circuit demodulates the modulation signal by using the rising edge and / or falling edge of a single line to lock the data content.

[0037] The modulation and demodulation processes of each signal will be specifically described below:

[0038] As Figure 4As shown, this is the node waveform diagram of the input line. Modulation signal 1(1) is characterized as follows: when the input signal is 1, the multiplexer selects carrier signal A for output; when the input signal is 0, the multiplexer selects carrier signal B for output. Modulation signal 1(2) is characterized as follows: when the input signal is 1, the multiplexer selects carrier signal B for output; when the input signal is 0, the multiplexer selects carrier signal B for output. For specific applications, modulation signal 1(1) or 1(2) can be selected as the specific output, and the magnitude of the carrier signal also depends on the actual application. The characterization methods of modulation signal 2(1) and modulation signal 2(2) are similar to those of modulation signal 1(1) and modulation signal 1(2). In this embodiment, modulation signal 1(1) and modulation signal 2(1) are selected for elaboration. The generated modulation signals enter the isolator after other processing.

[0039] The output line is as Figure 5 shown. The output line includes a comparator and other basic modules. The output line processes the modulation signals and carrier signal A that have passed through the isolator, and uses the comparator and other modules, such as a level conversion module, etc., to restore the modulation signals and carrier signal A that have passed through the isolator to obtain a demodulation signal consistent with the input signal. Among them, comparator 1 compares modulation signal 1 that has passed through isolator 2 and carrier signal A that has passed through isolator 1, and comparator 2 compares modulation signal 2 that has passed through isolator 3 and carrier signal A that has passed through isolator 1. The signals after comparator 1 and comparator 2 are processed by other modules and restored to output signals OUTPUT1 and OUTPUT2 with a certain delay from the input signal. The specific output line structure and the node waveforms of the output line are as Figure 5 and as Figure 6 .

[0040] The above is only a preferred embodiment of the present invention, so the scope of implementation of the present invention cannot be limited thereby. That is, equivalent changes and modifications made according to the scope of the present invention patent and the content of the specification should still fall within the scope covered by the present invention.

Claims

1. An isolation circuit, characterized in that Comprising: An input line, an isolator, and an output line; The isolator isolates the power supply and ground of the input line from the power supply and ground of the output line; The input line is connected between a first power supply VDD1 and a first ground terminal GND1, and is used to receive an input signal, output a carrier signal and N modulated signals, and the N modulated signals are generated by modulating the carrier signal and the input signal, where N > 1; The isolator, which includes a carrier signal isolator and N modulated signal isolators corresponding one-to-one to the modulated signals, is used to connect and isolate the input line and the output line; The output line is connected between a second power supply VDD2 and a second ground terminal GND2, and is simultaneously connected to the above isolator, and is used to receive the modulated signal and the carrier signal processed by the above isolator, and demodulate the processed modulated signal and the carrier signal to provide N output signals corresponding one-to-one to the N input signals; the waveform of the output signal is the same as that of the input signal and has a certain delay; the modulated signal is a continuous carrier signal; the output line demodulates the modulated signal by using the rising edge and / or falling edge of a single line to lock the data content.

2. An isolation circuit, characterized in that Comprising: An input line, an isolator, and an output line; The power supply and ground of the input line are isolated from the power supply and ground of the output line; The input line includes a carrier signal generation part and N modulated signal generation parts; the carrier signal generation part generates a first carrier signal and a second carrier signal; the first carrier signal, the second carrier signal, and N input signals are respectively input to the N modulated signal generation parts to generate N modulated signals; The isolator includes a carrier signal isolator and N modulated signal isolators corresponding one-to-one to the modulated signals; the input end of the carrier signal isolator is connected to the first carrier signal, and the input ends of the N modulated signal isolators are correspondingly connected to the N modulated signals; The output line includes N comparators, and the negative input ends of each comparator are respectively connected to the output end of the carrier signal isolator; the positive input ends of each comparator are respectively correspondingly connected to the output ends of the N modulated signal isolators one-to-one; the output ends of the comparators respectively form N output signals through a level conversion circuit; the waveform of the output signal is the same as that of the input signal and has a certain delay; the modulated signal is a continuous carrier signal; the output line demodulates the modulated signal by using the rising edge and / or falling edge of a single line to lock the data content; The modulated signal generation part is a multiplexer; the carrier signal generation part is an oscillator.

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