Low-power and high-reliability capacitive digital isolator based on multi-pulse modulation

Abstract

The present invention discloses a low-power and high-reliability capacitive digital isolator based on multi-pulse modulation, comprising a signal transmitting module, a signal receiving module and an isolation capacitor, wherein the signal transmitting module comprises an edge multi-pulse modulation module and a fully differential driving module, modulates a digital signal into a multi-pulse signal and transmits it in the form of a fully differential signal; the signal receiving module comprises a preamplifier, a high-speed comparator, a pulse detection module and an adaptive control module, and the pulse detection module and the adaptive control module communicate with each other to demodulate the signal and control the working state of the adaptive control preamplifier and the high-speed comparator at the same time. The present invention can greatly reduce the power consumption while ensuring the reliability of the transmission signal, save a large amount of static power consumption, extend the standby time, improve the energy efficiency standard, and can greatly increase the application scope of the digital isolator, save the power consumption of the digital isolator and improve the reliability of the digital isolator.

Description

Technical Field

[0001] The invention belongs to the technical field of digital isolation, and in particular relates to a low-power and high-reliability capacitive digital isolator based on multi-pulse modulation. Background Art

[0002] According to the different isolation media, digital isolators can be divided into optocoupler isolators, magnetic coupler isolators and capacitive isolators; 2 The capacitive isolator used as the isolation medium adopts the standard CMOS process and has the advantages of high transmission rate, low delay, long life and high voltage resistance.

[0003] Digital isolators usually include a transmitting module, i.e., a modulation module, a receiving module, i.e., a demodulation module, and an isolation capacitor module. The transmitting end modulates the transmission signal into a signal that can pass through the isolation capacitor, and the receiving end demodulates the signal that has passed through the isolation capacitor and restores it to the transmission signal. The isolation capacitor connects the signal transmitting module and the receiving module. The modulation and demodulation schemes are generally divided into two types: pulse modulation and OOK modulation.

[0004] Isolator chips are often used in low-power scenarios. OOK modulation and demodulation technology has high reliability and stability, and strong anti-disturbance ability, but requires high static power consumption. Pulse modulation has low reliability, but its static power consumption is also much lower than that of pulse modulation solutions. Therefore, high-reliability and low-power digital isolators have become the main research direction.

[0005] For example, the Chinese patent with publication number CN112039517A provides an ultra-low power consumption capacitive digital isolator circuit based on Pulse-Coding, which also adopts a pulse modulation scheme and cooperates with low static current to realize an ultra-low power consumption digital isolator circuit, but the reliability is relatively poor. Another example is the Chinese patent with publication number CN114553209A, which provides a digital isolator and a digital signal transmission method, which uses the same number of pulses with different interval lengths to characterize the rising edge or falling edge of the signal, but does not perform low power consumption processing and has relatively general anti-interference capabilities. Summary of the invention

[0006] In view of the above, the present invention provides a low-power and high-reliability capacitive digital isolator based on multi-pulse modulation, which can greatly increase the application scope of the digital isolator, save the power consumption of the digital isolator and improve the reliability of the digital isolator.

[0007] A low-power, high-reliability capacitive digital isolator based on multi-pulse modulation, comprising a signal transmitting module and a signal receiving module, both of which are connected via an isolation capacitor, and the signal transmitting module modulates the multi-pulse signal into a fully differential signal and then transmits it to the signal receiving module via the isolation capacitor;

[0008] The signal transmission module comprises:

[0009] The edge multi-pulse modulation module is used to perform edge sampling on the input digital signal to obtain the edge signal, and then use the delay method to modulate the edge signal into a multi-pulse signal;

[0010] A fully differential driving module, used for converting the multi-pulse signal into a fully differential signal, and transmitting it to a signal receiving module through an isolation capacitor;

[0011] The signal receiving module comprises:

[0012] A preamplifier, used to amplify the fully differential signal after attenuation through the isolation capacitor transmission;

[0013] A high-speed comparator is used to compare the amplified full differential signal and then restore the output multi-pulse signal;

[0014] A pulse detection module is used to detect the number of pulses of a multi-pulse signal, demodulate the multi-pulse signal into an edge signal according to the number of pulses, and start the adaptive control module at the same time;

[0015] The adaptive control module is used to control the size of the preamplifier working current, and simultaneously control the high-speed comparator working current and the size of the flip threshold.

[0016] Furthermore, the edge multi-pulse modulation module includes a delay method pulse generation circuit. When there is no signal input, the circuit does not generate current consumption; when there is a signal input, the circuit delays and inverts the input signal and then performs AND logic with the original input signal, thereby modulating the edge signal into a pulse signal. Repeating this operation can obtain a multi-pulse signal.

[0017] Furthermore, the control strategy of the adaptive control module is as follows:

[0018] When the signal transmission module has no digital signal input, the preamplifier and the high-speed comparator are in a low operating current state, and the flip threshold of the high-speed comparator is low; when the high-speed comparator outputs the first pulse signal and is detected by the pulse detection module, the adaptive control module controls the operating current of the preamplifier and the high-speed comparator to increase and last for T seconds, and controls the flip threshold of the high-speed comparator to increase and last for T seconds; during the duration, each time the pulse detection module detects a pulse signal, the adaptive control module will increase the operating current of the preamplifier and the high-speed comparator once and extend the duration for T seconds, and increase the flip threshold of the high-speed comparator once and extend the duration for T seconds, where T is the set duration; if the pulse detection module does not detect a pulse signal during the duration, the adaptive control module controls the preamplifier and the high-speed comparator to return to the low operating current state, and restores the flip threshold of the high-speed comparator to a lower level.

[0019] Furthermore, the pulse detection module also has a signal demodulation function, which can demodulate different numbers of pulse signals within a certain time period into rising edges and falling edges. The specific demodulation strategy is as follows:

[0020] For example, the edge multi-pulse modulation module modulates the rising edge of the edge signal into m pulses and the falling edge into n pulses, where m and n are both natural numbers greater than 0;

[0021] Then, within a certain time period, if the number of pulses detected by the pulse detection module is greater than or equal to (m+n) / 2, it is demodulated as a rising edge; if the number of pulses detected is greater than n-(mn) / 2 and less than (m+n) / 2, it is demodulated as a falling edge; if the number of pulses detected is less than or equal to n-(mn) / 2, it is judged as interference and no demodulated signal is output.

[0022] Furthermore, a LEB leading edge blanking circuit is provided between the high-speed comparator and the pulse detection module, and the circuit is used for performing noise shaping on the multi-pulse signal output by the high-speed comparator and then providing it to the pulse detection module.

[0023] Furthermore, the pulse detection module is implemented using a trigger and a counter. The pulse detection module communicates with the adaptive control module through the trigger to control the working state of the preamplifier and the high-speed comparator. Specifically: when the first pulse signal is detected, the pulse detection module controls the adaptive control module to start working for T seconds through the trigger. During the working time, the counter increases by 1 each time the pulse detection module detects a pulse signal, and controls the working time of the adaptive control module to be extended by T seconds; when the pulse detection module detects a total of D pulses, the counter outputs D, and controls the adaptive control module to work for a total of D*T seconds, where T is the set duration and D is a natural number greater than 0; when the adaptive control module finishes working, a signal is sent to reset the trigger. When the trigger is reset, the counter is cleared.

[0024] Furthermore, the adaptive control module includes a capacitor charging and discharging circuit and a current control circuit. When the counter value in the pulse detection module is 1, one capacitor in the capacitor charging and discharging circuit is turned on, and the capacitor is charged through the current control circuit. When the charging lasts for T seconds, the capacitor charging and discharging circuit outputs a high level reset to the trigger in the pulse detection module, and the timer in the pulse detection module is cleared at the same time; when the counter value is D, D capacitors in the capacitor charging and discharging circuit are turned on, and the D capacitors are charged through the current control circuit. When the charging lasts for D*T seconds, the capacitor charging and discharging circuit outputs a high level reset to the trigger in the pulse detection module, and the timer in the pulse detection module is cleared at the same time.

[0025] Furthermore, the working current of the preamplifier and the high-speed comparator and the flip threshold of the high-speed comparator are controlled by an adaptive control module; when the preamplifier and the high-speed comparator are both in a low-current working state, the signal gain is low, and at the same time, the low flip threshold of the high-speed comparator is matched; when the first pulse signal is detected, the preamplifier and the high-speed comparator are converted into a high-current working state, and the signal gain is high, and at the same time, the interference signal will be amplified, thereby causing misjudgment, so at this time, the high flip threshold of the high-speed comparator is matched to avoid misjudgment caused by the high-gain preamplifier.

[0026] The present invention is a low-power and high-reliability capacitive digital isolator based on multi-pulse modulation. Under the premise of ensuring the quality and reliability of signal transmission, the power consumption of the digital isolator, especially the static current, is greatly reduced, and the application requirements of some ultra-low power consumption products can be met. Due to the edge modulation method adopted in the present invention, only a few pulses are generated at the edge of the signal. After the pulse ends, the signal transmission module enters a dormant state in a long-term level signal range, the preamplifier and high-speed comparator in the signal receiving module enter a low-current working state, and the pulse detection module and the adaptive control module in the signal receiving module enter a dormant state, thereby achieving extremely low static current.

[0027] In the present invention, a certain initial flip threshold is set for the comparator to avoid misjudgment when transmitting a full differential level signal; a preamplifier and a high-speed comparator in a low current working state match a lower comparator flip threshold to avoid missing pulse detection; a preamplifier and a high-speed comparator in a high current working state match a higher comparator flip threshold to more quickly and accurately compare pulse signals and avoid misdetecting interference signals as pulses; and then a certain number of pulses within a certain range are demodulated into edge signals, while a lower number of pulses is not demodulated, thereby realizing a high-reliability digital isolator.

[0028] Therefore, the present invention can save power consumption for terminal products, extend standby time, and improve energy efficiency standards, and can greatly increase the application scope of digital isolators, save power consumption of digital isolators, and improve the reliability of digital isolators. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the capacitive digital isolator of the present invention.

[0030] Figure 2 Schematic diagram of waveforms of key node signals in the capacitive digital isolator of the present invention.

[0031] Figure 3 It is a schematic diagram of the structure of the delay method pulse generating circuit in the present invention.

[0032] Figure 4 It is a structural schematic diagram of the receiving module in the present invention. DETAILED DESCRIPTION

[0033] In order to describe the present invention more specifically, the technical solution of the present invention is described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0034] like Figure 1 As shown, the capacitive digital isolator based on multi-pulse modulation of the present invention consists of three parts: a transmitting module 100, an isolation capacitor 110 and a receiving module 120. The transmitting module 100 consists of an edge multi-pulse modulation module 101, a delay method pulse generation module 102 and a fully differential drive module 103, and the receiving module 120 consists of a preamplifier 121, a high-speed comparator 122, a pulse detection module 123 and an adaptive control module 124.

[0035] The edge multi-pulse modulation module 101 receives the VIN signal and detects the edge signal, and modulates the detected edge signal into a certain number of short pulse signals through the delay method pulse generation module 102; in order to directly distinguish the rising edge and the falling edge, in this example, the edge multi-pulse modulation module 101 modulates the rising edge into 6 short pulses and modulates the falling edge into 3 short pulses; the fully differential driving module converts the single-ended multi-pulse signal into a fully differential signal and transmits it to the fully differential isolation capacitor 110.

[0036] The preamplifier module 121 receives the signal from the isolation capacitor 110, and amplifies the fully differential signal that is attenuated after passing through the isolation capacitor 110. The high-speed comparator 122 compares the fully differential signal amplified by the preamplifier 121. The pulse detection module 123 detects the pulse signal transmitted by the high-speed comparator 122, and demodulates the pulse signal into an edge signal and transmits it as a VOUT signal. The adaptive control module 124 and the pulse detection module communicate with each other to control the working status of the preamplifier and the high-speed comparator.

[0037] like Figure 2 As shown, VIN is the input square wave signal, which is output as complementary TX_P and TX_N signals after edge pulse modulation by the transmitting module and sent to the differential dual isolation capacitors. After passing through the isolation capacitors, the signal is greatly attenuated, as shown in Figure 1. Figure 2 As shown in RX_P and RX_N, the differential signal is amplified into AMP_P and AMP_N signals after adjustment by the preamplifier and adaptive control module. The differential signal is restored to a pulse signal after adjustment by the high-speed comparator and adaptive control module. The number of Comp_out within a certain range is detected by the pulse detection module and restored to a square wave signal, as shown in VOUT.

[0038] The transmitting module modulates the rising edge into 6 pulses and the falling edge into 3 pulses; if the receiving module detects that the number of pulses is greater than or equal to 5 within a certain period of time, it is determined to be a rising edge; if the receiving module detects that the number of pulses is greater than 2 and less than 5 within a certain period of time, it is determined to be a falling edge; if the receiving module detects that the number of pulses is less than or equal to 2 within a certain period of time, it is determined to be an interference signal with no demodulated signal output.

[0039] The working state of the preamplifier and the high-speed comparator is controlled by the adaptive control module. After the first pulse appears, the subsequent pulses will obtain a larger gain because the preamplifier and the high-speed comparator enter the high-current working mode.

[0040] like Figure 3 As shown, the delay method pulse generation circuit is composed of a delay inverter 300 and a digital logic AND gate 301, which can simply and reliably convert edge signals into pulse signals. Multiple pulse signal generation can be achieved by repeatedly using this circuit. In addition, this circuit can reduce power consumption to the greatest extent. When an edge signal is input, the delay method pulse generation circuit starts to work. When a level signal is input, the delay method pulse generation circuit does not generate static power consumption.

[0041] Figure 4 The figure shows the specific implementation structure of the receiving module, wherein the preamplifier 427 receives the full differential signal transmitted from the isolation capacitor, amplifies and transmits it to the high-speed comparator 428, and the high-speed comparator compares and restores the full differential signal into a multi-pulse signal and transmits it to the counter 420; when the counter 420 receives the first pulse signal, the trigger 427 is triggered, and at the same time, within a certain time range, the pulse number information detected by the counter is transmitted to the m-bit switch 422, and the m-bit switch 422 is turned on or off according to the number of pulses. When there is 1 pulse, a switch is turned on, and when there are m pulses, the m-bit switch is turned on, thereby determining the number of capacitors connected to the circuit; the constant current source 421 is used to charge the multi-bit capacitor 423 to realize the adaptive timing function. When a capacitor is connected to the circuit, it takes T time to make The output signal is flipped to a high level through inverter 425 and inverter 426, and the trigger 427 is reset. When m capacitors are connected to the circuit, it takes mT time for the output signal to be flipped to a high level through inverter 425 and inverter 426; the high level signal output by inverter 426 resets the trigger 427, turns on the switch tube 424 to change the potential on the capacitor back to a low level, and resets the counter at the same time; when the trigger 427 is triggered to output a high level, the preamplifier 428 and the high-speed comparator 429 change to a high current working state, and the flip threshold of the high-speed comparator 429 is increased. When the trigger 427 is reset to output a low level, the preamplifier 428 and the high-speed comparator 429 change back to a low current working state, and the flip threshold of the high-speed comparator 429 is reduced.

[0042] The high-speed comparator 429 sets a certain initial flip threshold value, and the fixed output will not cause the output flip due to tiny noise when there is no signal input; the preamplifier 428 and the high-speed comparator 429 are in a low working current state, and the flip threshold of the high-speed comparator 429 is low, so the signal can be detected instantly; when the high-speed comparator 429 outputs the first pulse signal and is detected by the counter 420, the trigger 427 is triggered and lasts for T time, the preamplifier 428 and the high-speed comparator 429 enter a high current working state, and the flip threshold of the high-speed comparator 429 is increased and lasts for T time, so that the pulse signal can be compared more quickly and accurately, and the interference signal can be avoided from being mistakenly detected as a pulse, thereby improving the reliability of the isolator.

[0043] The above description of the embodiments is to facilitate the understanding and application of the present invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to the above embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments. Improvements and modifications made by those skilled in the art to the present invention based on the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A low-power and high-reliability capacitive digital isolator based on multi-pulse modulation, characterized in that: It includes a signal transmitting module and a signal receiving module, which are connected via an isolation capacitor. The signal transmitting module modulates the multi-pulse signal into a fully differential signal and then transmits it to the signal receiving module via the isolation capacitor. The signal transmission module comprises: The edge multi-pulse modulation module is used to perform edge sampling on the input digital signal to obtain the edge signal, and then use the delay method to modulate the edge signal into a multi-pulse signal; A fully differential driving module, used for converting the multi-pulse signal into a fully differential signal, and transmitting it to a signal receiving module through an isolation capacitor; The signal receiving module comprises: A preamplifier, used to amplify the fully differential signal after attenuation through the isolation capacitor transmission; A high-speed comparator is used to compare the amplified full differential signal and then restore the output multi-pulse signal; A pulse detection module is used to detect the number of pulses of a multi-pulse signal, demodulate the multi-pulse signal into an edge signal according to the number of pulses, and start the adaptive control module at the same time; The adaptive control module is used to control the size of the preamplifier working current, and at the same time control the high-speed comparator working current and the size of the flip threshold. The specific control strategy is as follows: When the signal transmission module has no digital signal input, the preamplifier and the high-speed comparator are in a low operating current state, and the flip threshold of the high-speed comparator is low; when the high-speed comparator outputs the first pulse signal and is detected by the pulse detection module, the adaptive control module controls the operating current of the preamplifier and the high-speed comparator to increase and last for T seconds, and controls the flip threshold of the high-speed comparator to increase and last for T seconds; during the duration, each time the pulse detection module detects a pulse signal, the adaptive control module will increase the operating current of the preamplifier and the high-speed comparator once and extend the duration for T seconds, and increase the flip threshold of the high-speed comparator once and extend the duration for T seconds, where T is the set duration; if the pulse detection module does not detect a pulse signal during the duration, the adaptive control module controls the preamplifier and the high-speed comparator to return to the low operating current state, and restores the flip threshold of the high-speed comparator to a lower level.

2. The low-power and high-reliability capacitive digital isolator according to claim 1, characterized in that: The edge multi-pulse modulation module includes a delay method pulse generation circuit. When there is no signal input, the circuit does not generate current consumption; when there is a signal input, the circuit delays and inverts the input signal and then performs AND logic with the original input signal, thereby modulating the edge signal into a pulse signal. Repeating this operation can obtain a multi-pulse signal.

3. The low-power and high-reliability capacitive digital isolator according to claim 1, characterized in that: The pulse detection module also has the function of signal demodulation, which can demodulate different numbers of pulse signals within a certain period of time into rising edges and falling edges. The specific demodulation strategy is as follows: For example, the edge multi-pulse modulation module modulates the rising edge of the edge signal into m pulses and the falling edge into n pulses, where m and n are both natural numbers greater than 0; Then, within a certain period of time, if the number of pulses detected by the pulse detection module is greater than or equal to (m+n) / 2, it is demodulated as a rising edge; If the number of pulses detected is greater than n-(mn) / 2 and less than (m+n) / 2, the demodulation is a falling edge; if the number of pulses detected is less than or equal to n-(mn) / 2, it is determined to be interference and no demodulation signal is output.

4. The low-power and high-reliability capacitive digital isolator according to claim 1, characterized in that: An LEB leading edge blanking circuit is provided between the high-speed comparator and the pulse detection module, and the circuit is used for performing noise shaping on the multi-pulse signal output by the high-speed comparator and then providing the signal to the pulse detection module.

5. The low-power and high-reliability capacitive digital isolator according to claim 1, characterized in that: The pulse detection module is implemented by a trigger and a counter. The pulse detection module communicates with the adaptive control module through the trigger to control the working state of the preamplifier and the high-speed comparator. Specifically: when the first pulse signal is detected, the pulse detection module controls the adaptive control module to start working for T seconds through the trigger. During the working time, the pulse detection module increases the counter by 1 each time it detects a pulse signal, and controls the adaptive control module to extend its working time by T seconds; when the pulse detection module detects a total of D pulses, the counter outputs D, and controls the adaptive control module to work for a total of D*T seconds, where T is the set duration and D is a natural number greater than 0; when the adaptive control module finishes working, it sends a signal to reset the trigger, and when the trigger is reset, the counter is cleared.

6. The low-power and high-reliability capacitive digital isolator according to claim 5, characterized in that: The adaptive control module includes a capacitor charging and discharging circuit and a current control circuit. When the counter value in the pulse detection module is 1, one capacitor in the capacitor charging and discharging circuit is turned on, and the capacitor is charged through the current control circuit. When the charging lasts for T seconds, the capacitor charging and discharging circuit outputs a high level reset to the trigger in the pulse detection module, and the timer in the pulse detection module is cleared at the same time; when the counter value is D, D capacitors in the capacitor charging and discharging circuit are turned on, and the D capacitors are charged through the current control circuit. When the charging lasts for D*T seconds, the capacitor charging and discharging circuit outputs a high level reset to the trigger in the pulse detection module, and the timer in the pulse detection module is cleared at the same time.

7. The low-power and high-reliability capacitive digital isolator according to claim 1, characterized in that: The working current of the preamplifier and the high-speed comparator and the flip threshold of the high-speed comparator are controlled by an adaptive control module; when the preamplifier and the high-speed comparator are both in a low-current working state, the signal gain is low, and the low flip threshold of the high-speed comparator is matched; when the first pulse signal is detected, the preamplifier and the high-speed comparator are converted into a high-current working state, the signal gain is high, and the interference signal will be amplified, thereby causing misjudgment, so at this time, the high flip threshold of the high-speed comparator is matched to avoid misjudgment caused by the high-gain preamplifier.

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