Analog light MOS relay

Abstract

The application provides an analog light MOS relay, and belongs to the technical field of integrated circuits, and comprises: a first clamping circuit used for clamping the voltage of an input end; an LC resonant oscillator comprising an active nonlinear load, a transformer and a capacitor circuit; a rectifier circuit connected with the LC resonant oscillator and used for rectifying the alternating current signal output by the LC resonant oscillator into a direct current signal; a voltage boosting module connected with the rectifier circuit and used for boosting the direct current signal; and an output circuit comprising a first power device and a second power device. The first clamping circuit is used to realize the function of an analog diode, the voltage drop of the first clamping circuit is more stable, and the consistency is better; the transformer, the active nonlinear load and the capacitor circuit jointly form the LC resonant oscillator, the LC resonant oscillator can automatically resonate to the resonant frequency, and the circuit has high reliability.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit technology, and in particular to an analog optical MOS relay. Background Technology

[0002] Optical MOS relays are contactless electronic switches that use light as a medium to transmit energy. They are currently the most widely used and important type of solid-state relays, and are widely used in measuring instruments, communication equipment, industrial machinery, medical devices, security systems, home appliances, office automation, monitoring systems and other fields.

[0003] like Figure 1 The diagram shows a traditional optical MOS relay circuit structure. When a positive current signal of a certain magnitude is applied to the input terminal of the optical MOS relay, the photodiode conducts after receiving the optical signal generated by the photodiode. The voltage generated at its output terminal is applied between the gate and source of the first and second power devices. When the voltage output by the photodiode exceeds the device threshold voltage, a conductive channel is formed between the drain and source of the first and second power devices, with very low impedance. The photodiode's triggering function enables the power devices to switch from an off state to an on state (the MOS is off when there is no signal), thus achieving the switching function of controlling a high-power load with a small power input.

[0004] Existing optical MOS relays suffer from low reliability and poor operability. As the device ages, the relay performance also declines. Furthermore, the aging process of optical MOS relays is accelerated when operating in high-temperature environments, shortening the device's lifespan. Summary of the Invention

[0005] To address the above technical problems, this invention provides an analog optical MOS relay.

[0006] The technical problem solved by this invention can be achieved by the following technical solutions:

[0007] An analog optical MOS relay, comprising:

[0008] The first clamping circuit is connected to an input terminal to clamp the voltage at the input terminal.

[0009] An LC resonant oscillator includes: an active nonlinear load, a transformer, and a capacitor circuit connected in series.

[0010] A rectifier circuit, connected to the LC resonant oscillator, is used to rectify the AC signal output by the LC resonant oscillator into a DC signal;

[0011] A boost module, connected to the rectifier circuit, is used to boost the DC signal;

[0012] The output circuit includes a first power device and a second power device. The drain of the first power device is connected to a first output terminal, the source of the first power device is connected to the source of the second power device, and the drain of the second power device is connected to a second output terminal.

[0013] Preferably, it further includes:

[0014] A shutdown control module, wherein the input of the shutdown control module is connected to the boost module, and the output of the shutdown control module is connected to the gates of the first power device and the second power device, for outputting a shutdown control signal when the voltage at the input terminal is lower than a preset threshold.

[0015] The first power device and the second power device are also used to cut off under the action of the shutdown control signal.

[0016] Preferably, it further includes:

[0017] The second clamping circuit is connected between the boost module and the shutdown control module to clamp the gate-source voltages of the first power device and the second power device.

[0018] Preferably, the first clamping circuit includes a diode connected between the positive and negative terminals of the input terminal.

[0019] Preferably, the active nonlinear load includes:

[0020] A first field-effect transistor (FET) has its gate connected to the gate of a second FET and the positive input terminal of the primary side of the transformer, and its drain connected to the drain of the second FET and the negative input terminal of the primary side of the transformer.

[0021] The third field-effect transistor has its gate connected to the gate of a fourth field-effect transistor and the negative input terminal of the primary side of the transformer, and its drain connected to the drain of the fourth field-effect transistor and the positive input terminal of the primary side of the transformer.

[0022] The sources of the first and third field-effect transistors are connected to the positive output terminal of the first clamping circuit, and the sources of the second and fourth field-effect transistors are connected to the negative output terminal of the first clamping circuit.

[0023] Preferably, the boost module includes at least one charge pump unit, which are connected in series.

[0024] Preferably, the LC resonant oscillator automatically resonates to a resonant frequency under the action of the clamping voltage output by the first clamping circuit, and the resonant frequency is:

[0025]

[0026] Among them, L eq C1 represents the resonant inductance of the transformer; C1 represents the resonant capacitance of the capacitor circuit; f0 represents the resonant frequency.

[0027] Preferably, the transformer is integrated on a printed circuit board.

[0028] Preferably, the first clamping circuit and the active nonlinear load are integrated into a first chip.

[0029] Preferably, the transformer, the active nonlinear load, and the capacitor circuit are integrated on different substrates.

[0030] The advantages or beneficial effects of the technical solution of this invention are as follows:

[0031] This invention employs a first clamping circuit to realize the function of an analog diode, compatible with the peripheral circuit of an opto-MOS relay. Compared with traditional light-emitting diodes, its on-state voltage drop is more stable, with a smaller variation range and better consistency. It uses a transformer to transmit energy, which improves the transmission efficiency. Furthermore, the transformer, active nonlinear load, and capacitor circuit together form an LC resonant oscillator, which can automatically resonate to the resonant frequency. At the same time, except for the transformer and the power devices in the output circuit, all other circuits are fabricated using standard CMOS, which improves the reliability of the circuit. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the circuit structure of a traditional optical MOS relay in the existing technology;

[0033] Figure 2 This is a schematic diagram of the structure of an analog optical MOS relay in a preferred embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the structure of a specific embodiment of the analog optical MOS relay in a preferred embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of the structure of a specific embodiment of the LC resonant oscillator in a preferred embodiment of the present invention;

[0036] Figure 5 This is a schematic diagram of the current-voltage characteristics of an active nonlinear load in a preferred embodiment of the present invention.

[0037] Figure 6 This is a schematic diagram of the structure of a specific embodiment of the boost module in a preferred embodiment of the present invention. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0040] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0041] In a preferred embodiment of the present invention, based on the above-mentioned problems existing in the prior art, an analog optical MOS relay is provided, belonging to the field of integrated circuit technology, such as... Figure 2 As shown, it includes:

[0042] The first clamping circuit 1 is connected to an input terminal to clamp the voltage at the input terminal;

[0043] The first clamping circuit 1 includes a diode Dio1, which is connected between the positive terminal ANODE and the negative terminal CATHODE of the input terminal to clamp the voltage at the input terminal at a fixed potential. The diode Dio1 is used to realize the function of an analog diode, so as to achieve compatibility with the peripheral circuit of the optical MOS relay. The forward voltage drop of the diode Dio1 is more stable, has a smaller variation range, and better consistency than that of the light-emitting diode, which makes the clamping current more accurate.

[0044] LC resonant oscillator 2 is connected to the first clamping circuit 1. The LC resonant oscillator includes an active nonlinear load 21, a transformer T1 and a capacitor circuit connected in series. The capacitor circuit includes a capacitor C1, which is connected in parallel with the secondary side of the transformer T1.

[0045] The rectifier circuit 3 is connected to the LC resonant oscillator 2 and is used to rectify the AC signal output by the LC resonant oscillator 2 into a DC signal.

[0046] The boost module 4 is connected to the rectifier circuit 3 and is used to boost the DC signal.

[0047] The output circuit 7 includes a first power device M1 and a second power device M2. The drain of the first power device M1 is connected to a first output terminal 81, the source of the first power device M1 is connected to the source of the second power device M2, and the drain of the second power device M2 is connected to a second output terminal 82.

[0048] Specifically, this invention uses a first clamping circuit 1 to realize the function of an analog diode, compatible with the peripheral circuit of an optical MOS relay. Compared with traditional light-emitting diodes, its on-state voltage drop is more stable, with a smaller variation range and better consistency. The transformer T1 is used to transmit energy, which improves the transmission efficiency. The transformer T1, the active nonlinear load 21, and the capacitor circuit together form an LC resonant oscillator, which can automatically resonate to the resonant frequency, resulting in high transmission efficiency. There is no need to specially design the active nonlinear load 21 to oscillate at the resonant frequency, nor is there a need to set up a matching circuit to match the transformer T1 and the active nonlinear load 21. At the same time, except for the power devices of the transformer T1 and the output circuit 7, all other circuits are fabricated using standard CMOS, which improves the reliability of the circuit.

[0049] In a preferred embodiment, such as Figure 2 As shown, it also includes:

[0050] The shutdown control module 6 has its input connected to the boost module 4 and its output connected to the gates of the first power device M1 and the second power device M2, so as to output a shutdown control signal when the voltage at the input terminal is lower than a preset threshold.

[0051] The first power device M1 and the second power device M2 are also used to cut off under the action of the turn-off control signal.

[0052] Specifically, in this embodiment, the shutdown control module 6 is used to quickly reduce the gate-source voltage of the first power device M1 and the second power device M2 to 0 when there is no signal at the input terminal voltage, thereby achieving the function of quickly shutting down the power devices.

[0053] In a preferred embodiment, such as Figure 2 As shown, it also includes:

[0054] The second clamping circuit 5 is connected between the boost module 4 and the shutdown control module 6 to clamp the gate-source voltage of the first power device M1 and the second power device M2.

[0055] Specifically, in this embodiment, the second clamping circuit 5 is used to control the input voltage of the output circuit 7 within a certain voltage range, so that the impedance output variation range of the power device is small and the consistency is good, avoiding the power device from being too low due to excessively low input voltage or too high due to excessively high input voltage, which would burn out the power device.

[0056] In a preferred embodiment, such as Figure 3 and Figure 4 As shown, the active nonlinear load 21 includes:

[0057] The first field-effect transistor Mp1 has its gate connected to the gate of the second field-effect transistor Mn1 and the positive input terminal of the primary side of the transformer T1, and its drain connected to the drain of the second field-effect transistor Mn1 and the negative input terminal of the primary side of the transformer T1.

[0058] The gate of the third field-effect transistor Mp2 is connected to the gate of the fourth field-effect transistor Mn2 and the negative input terminal of the primary side of the transformer T1, and the drain of the third field-effect transistor Mp2 is connected to the drain of the fourth field-effect transistor Mn2 and the positive input terminal of the primary side of the transformer T1.

[0059] The sources of the first field-effect transistor Mp1 and the third field-effect transistor Mp2 are connected to the positive output terminal of the first clamping circuit 1, and the sources of the second field-effect transistor Mn1 and the fourth field-effect transistor Mn2 are connected to the negative output terminal of the first clamping circuit 1.

[0060] In a preferred embodiment, the LC resonant oscillator 2 automatically resonates to a resonant frequency under the action of the clamping voltage output by the first clamping circuit 1. The resonant frequency is:

[0061]

[0062] Among them, L eq C1 represents the resonant inductance of transformer T1, i.e., the equivalent inductance of transformer T1; C1 represents the resonant capacitance of the capacitor circuit; f0 represents the resonant frequency.

[0063] Furthermore, such as Figure 5 The diagram shows the current-voltage characteristics of an active nonlinear load. The A-A' portion exhibits negative resistance, while the AB and A'-B' portions exhibit positive resistance. The LC resonant oscillator of this invention can start oscillating under negative resistance conditions, stabilize its amplitude under positive resistance conditions, and ultimately achieve oscillation and transfer energy to the secondary side of transformer T1.

[0064] The resonant characteristics of the transformer and capacitor C1 can be observed from the primary side of the transformer. The input impedance can also be observed from the primary side of the transformer as follows:

[0065]

[0066] Where s represents the Laplace transform, s = 2πjf, where j represents the imaginary number and f represents the frequency; L1 represents the primary inductance of transformer T1, i.e., the equivalent inductance of the primary coil of transformer T1; L2 represents the secondary inductance of transformer T1, i.e., the equivalent inductance of the secondary coil of transformer T1; C1 represents the resonant capacitance of the capacitor circuit; k represents the coupling coefficient of transformer T1; Z in This represents the input impedance of the primary side of transformer T1.

[0067] The active nonlinear load 21, transformer T1, and capacitor circuit constitute an LC resonant oscillator 2, whose resonant frequency is:

[0068]

[0069] Where k represents the coupling coefficient; L2 represents the secondary inductance of transformer T1; C1 represents the resonant capacitance of the capacitor circuit; and f0 represents the resonant frequency. eq =(1-k) 2 )*L2.

[0070] After the LC resonant oscillator starts oscillating, a sinusoidal source is used to replace the transformer input. The resonant voltage range across the transformer can reach +VDD to -VDD. The amplification factor of the output voltage amplitude (the load resistance R must be considered when calculating the amplification factor) is:

[0071]

[0072] Where k represents the coupling coefficient; L1 represents the primary inductance; L2 represents the secondary inductance; C1 represents the resonant capacitor; R represents the load resistance; and A represents the amplification factor.

[0073] In the above formula for calculating magnification, This is the gain of transformer T1; Let L2 be the resonant gain of the output inductance (i.e., equivalent inductance L2) and capacitor C1 as seen from the secondary side of the transformer.

[0074] Since the resonant frequency operates precisely near the resonant point of the secondary output inductor and capacitor C1, the output voltage of the LC resonant oscillator can be further amplified through resonance.

[0075] Furthermore, in a preferred embodiment, a low-pass filter LPF is also included, which is connected between the drain of the first field-effect transistor Mp1 and the gate of the third field-effect transistor Mp2, and between the gate of the first field-effect transistor Mp1 and the drain of the third field-effect transistor Mp2.

[0076] Specifically, due to the parasitic capacitance of the coupled inductor, the circuit has more than one resonant point. A low-pass filter is used to attenuate the high-frequency characteristics, prevent oscillations from occurring in the high-frequency range, and avoid circuit oscillations at the resonant point formed by the parasitic capacitance.

[0077] Compared to existing technologies that directly use an oscillator to drive the transformer on the primary side, the embodiments of the present invention increase the amplitude of the output voltage by adding a secondary resonant capacitor. The resonant frequency and oscillation frequency of the LC resonant oscillator of the present invention do not require calibration, and the output voltage amplitude is more stable.

[0078] In a preferred embodiment, the transformer T1 is integrated on a printed circuit board 10 (PCB).

[0079] Specifically, in this embodiment, the transformer T1 is fabricated using a printed circuit board 10, eliminating the need to fabricate an RF transformer on the chip, saving a significant amount of chip area and reducing chip costs. While increasing the area of ​​the transformer T1, the circuit cost is not significantly increased, greatly improving the inductance and coupling coefficient of the transformer T1, thereby enhancing the transmission efficiency of the transformer T1.

[0080] Furthermore, transformer T1 consists of two coils, located on the upper and lower layers of the PCB dielectric layer, respectively. The spacing between the two transformer layers is the same as the spacing between the dielectric layers of the PCB. The increased thickness of the two layers increases the spacing of transformer T1, significantly reducing its coupling capacitance and greatly improving its common-mode transient immunity (CMTI) performance, enabling ultra-high isolation withstand voltage capability.

[0081] In a preferred embodiment, the first clamping circuit 1 and the active nonlinear load 21 are integrated into a first chip 9.

[0082] In a preferred embodiment, the transformer T1, the active nonlinear load 21, and the capacitor circuit are integrated on different substrates.

[0083] Specifically, capacitor C1, rectifier circuit 3, boost module 4, second clamping circuit 5, and shutdown control module 6 are integrated on the second chip 11, the first power device M1 is integrated on the third chip 12, and the second power device M2 is integrated on the fourth chip 13. That is, the analog optical MOS relay of the present invention is packaged together by four chips and a PCB.

[0084] In a preferred embodiment, such as Figure 6 As shown, the boost module 4 includes at least one charge pump unit, which are connected in series.

[0085] Specifically, the boost circuit consists of N stages of charge pump units, where N is a positive integer greater than or equal to 1. When the charge pump unit includes two or more stages, the output of the previous stage charge pump unit is connected to the input of the next stage charge pump unit.

[0086] Furthermore, in this embodiment, the number of charge pump units connected in series can be determined based on the driving voltages (i.e., gate-source voltages) of the first power device M1 and the second power device M2. The relationship between the driving voltage and the number of charge pump units is as follows:

[0087] V GS =Vo=(N+1)*Vdd;

[0088] Among them, V GSVo represents the gate-source voltage of the first power device M1 or the second power device M2; Vdd represents the supply voltage; and N represents the number of charge pump units.

[0089] The above technical solution has the following advantages or beneficial effects: The present invention uses a first clamping circuit to realize the function of an analog diode, which is compatible with the peripheral circuit of the opto-MOS relay. Compared with the traditional light-emitting diode, its on-state voltage drop is more stable, the variation range is smaller, and the consistency is better. The use of a transformer to transmit energy improves the transmission efficiency. Moreover, the transformer, the active nonlinear load, and the capacitor circuit together form an LC resonant oscillator, which can automatically resonate to the resonant frequency. At the same time, except for the transformer and the power devices of the output circuit, other circuits are all fabricated using standard CMOS, which improves the reliability of the circuit.

[0090] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made using the content of this specification and illustrations should be included within the protection scope of the present invention.

Claims

1. An analog light MOS relay, characterized by, The application relates to a voltage regulator, comprising: a first clamping circuit connected to an input end for clamping the voltage of the input end; the first clamping circuit comprises a diode connected between the positive and negative poles of the input end; an LC resonant oscillator connected to the first clamping circuit, the LC resonant oscillator comprising an active nonlinear load, a transformer and a capacitor circuit connected in series; the LC resonant oscillator automatically resonates to a resonant frequency under the action of the clamped voltage output by the first clamping circuit, and the resonant frequency is: ； where L eq represents the resonant inductance of the transformer; C1 represents the resonant capacitance of the capacitor circuit; f0 represents the resonant frequency a rectifier circuit connected to the LC resonant oscillator for rectifying the alternating current signal output by the LC resonant oscillator into a direct current signal; a voltage boosting module connected to the rectifier circuit for boosting the direct current signal; an output circuit comprising a first power device and a second power device, the drain of the first power device being connected to a first output end, the source of the first power device being connected to the source of the second power device, and the drain of the second power device being connected to a second output end.

2. The analog light MOS relay according to claim 1, characterized by, Further comprising: a turn-off control module, the input of the turn-off control module being connected to the voltage boosting module, and the output of the turn-off control module being connected to the gates of the first power device and the second power device for outputting a turn-off control signal when the voltage of the input end is lower than a preset threshold value; the first power device and the second power device are further used for being turned off under the action of the turn-off control signal.

3. The analog light MOS relay according to claim 2, characterized in that, Further comprising: a second clamping circuit connected between the voltage boosting module and the turn-off control module for clamping the gate-source voltage of the first power device and the second power device.

4. The analog light MOS relay of claim 1, wherein, The active nonlinear load comprises: a first field effect transistor, the gate of the first field effect transistor being connected to the gate of a second field effect transistor and the positive primary input end of the transformer, and the drain of the first field effect transistor being connected to the drain of the second field effect transistor and the negative primary input end of the transformer; a third field effect transistor, the gate of the third field effect transistor being connected to the gate of a fourth field effect transistor and the negative primary input end of the transformer, and the drain of the third field effect transistor being connected to the drain of the fourth field effect transistor and the positive primary input end of the transformer; the sources of the first field effect transistor and the third field effect transistor are connected to the positive output end of the first clamping circuit, and the sources of the second field effect transistor and the fourth field effect transistor are connected to the negative output end of the first clamping circuit.

5. The analog light MOS relay of claim 1, wherein, The voltage boosting module comprises at least one level of charge pump unit, and the at least one level of charge pump unit is connected in series.

6. The analog light MOS relay of claim 1, wherein, The transformer is integrated on a printed circuit board.

7. The analog light MOS relay of claim 1, wherein, The first clamping circuit and the active nonlinear load are integrated in a first chip.

8. The analog light MOS relay of claim 1, wherein, The transformer and the active nonlinear load and the capacitor circuit are integrated on different substrates.

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