Soft start circuit of analog switch with wide transmission range and equipment comprising soft start circuit
By controlling high-voltage domain signals with a low-side level converter, a soft-start circuit for analog switches with a wide transmission range is designed. This solves the problems of high cost and high voltage withstand requirements of components in voltage domain conversion of traditional analog switches, and achieves low-cost smooth voltage domain conversion.
Patent Information
- Application Number
- CN202511084244.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-04
- Publication Date
- 2025-11-14
AI Technical Summary
Traditional analog switch soft-start circuits require a high-side converter to switch between different voltage domains, which increases costs and places high voltage requirements on components. Furthermore, the high-side converter may not be able to control the chip's operation in certain situations.
A low-side level converter is used to automatically control the high-voltage domain signal through the low-voltage domain logic signal. A wide transmission range analog switch soft-start circuit is designed, which includes a low-side level converter, a routing switch, a charge pump, a current source, resistors and a level shifting module. The wide transmission range is achieved using only low-voltage CMOS devices.
It achieves smooth switching between different voltage domains, avoids additional power consumption and component withstand voltage requirements, reduces costs, and is suitable for analog switches that exceed the power supply voltage range.
Smart Images
Figure CN120956256A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of analog switch technology, specifically relating to a soft-start circuit for a wide transmission range analog switch and a device including the same. Background Technology
[0002] Soft-start circuits are typically used to prevent inrush current damage caused by rapid power-up in a circuit. Traditional soft-start circuits in analog switches operating outside the power supply voltage range require a high-side converter to generate the signal controlling the soft-start circuit.
[0003] When the chip transmits a negative voltage, the low-side selection circuit in the soft-start circuit outputs a negative voltage. The high and low potentials inside the chip are the charge pump voltage, ground potential, and the output of the low-side selection circuit, respectively. At this time, the voltage difference between the charge pump voltage and ground is low, and a high-side level converter is not required.
[0004] When the chip transmits a positive voltage higher than the power supply voltage, the internal potentials of the chip are: charge pump voltage, output of the low-side selection circuit, power supply voltage, and ground potential, respectively. At this time, the low-side level converter cannot control the chip's operation, and an additional high-side level converter is required to generate the signal to control the soft-start circuit, increasing additional costs. Moreover, simple high-side level converters have high voltage withstand requirements for components. Summary of the Invention
[0005] The purpose of this invention is to provide a soft-start circuit for a wide-range analog switch and a device including the same, which uses only a low-side level converter to automatically control a high-voltage domain signal through a low-voltage domain logic signal, thereby achieving soft-start of the analog switch with a wide transmission range.
[0006] On one hand, the present invention provides a soft-start circuit for a wide transmission range analog switch, applicable to analog switches that exceed the power supply voltage transmission range. The analog switch includes a soft-start circuit, a switch drive circuit, and a main switch.
[0007] The soft-start circuit includes a low-side level converter, a routing switch, a charge pump, a current source, resistors R0 and R1, a level shifting module, and a low-side selection circuit. The inputs of the low-side selection circuit are connected to the two ends of the main switch, and the voltages at the two ends of the routing switch are ground voltage and the output voltage of resistor R1, respectively. The charge pump serves as the power source for the current source.
[0008] The signal generated by the low-side level converter through the power-disabling signal controls the closing or opening of the routing switch, thereby determining whether the current from the current source flows into resistor R0 or resistor R1.
[0009] When the routing switch is closed, the current from the current source flows into resistor R1, the voltage of resistor R1 rises, and the voltage after level shifting by the level shifting module rises accordingly. The main switch slowly closes and enters the soft start mode.
[0010] When the routing switch is disconnected, the current from the current source flows into the low-selection circuit. At this time, the main switch exits the soft-start mode and is driven by the switch drive circuit.
[0011] Furthermore, the soft-start circuit also includes a buffer;
[0012] The output of the low-side selection circuit generates a voltage for the level shifting module via a buffer; the current source is connected to one end of resistor R0, one end of resistor R1, and the input of the level shifting module via the buffer; the output of the level shifting module is connected to the switch driving circuit; the other end of resistor R0 is connected to the output of the low-side selection circuit; the other end of resistor R1 is grounded via the selection switch; and the output of the low-side level converter is connected to the selection switch.
[0013] Furthermore, the analog switch includes a soft-start circuit, a switch driving circuit, and an NMOS transistor Q0, wherein the NMOS transistor Q0 is the main switch;
[0014] The soft-start circuit includes a charge pump, a first current source ISOFT1, a second current source ISOFT2, a third current source ISOFT3, a low-side selection circuit, a buffer, a low-side level converter, NMOS transistors Q1~Q8, and a resistor R2.
[0015] The output of the switch driving circuit is connected to the gate of NMOS transistor Q0. The input (IN) and output (OUT) of NMOS transistor Q0 are connected to the input of the low-select circuit, respectively. The output of the low-select circuit serves as the input of NMOS transistor Q1, and is connected to the gate of NMOS transistor Q1, the drain of NMOS transistor Q8, and the source of NMOS transistor Q3. The drain of NMOS transistor Q1 is connected to the output of the first current source ISOFT1, the gate of NMOS transistor Q3, and the gate of NMOS transistor Q5. The source of NMOS transistor Q1 is connected to the drain of NMOS transistor Q3, the source of NMOS transistor Q5, the source of NMOS transistor Q6, and one end of resistor R2. The first current source is connected to the source of NMOS transistor Q4; the output of the second current source ISOFT2 is connected to the drain of NMOS transistor Q5 and the gate of NMOS transistor Q6; the output of the third current source ISOFT3 is connected to the drain and gate of NMOS transistor Q2 and the input of the switch drive circuit; the source of NMOS transistor Q2 is connected to the drain of NMOS transistor Q6; the disable signal is connected to the gate of NMOS transistor Q7 and the gate of NMOS transistor Q8 after passing through the bottom-side converter; the source of NMOS transistor Q8 is connected to the drain of NMOS transistor Q4; the gate of NMOS transistor Q4 and the source of NMOS transistor Q7 are grounded; the other end of resistor R2 is connected to the drain of NMOS transistor Q7.
[0016] Furthermore, the first current source ISOFT1, the second current source ISOFT2, and the third current source ISOFT3 in the soft start circuit module are replicated from the linear ramp current ISOFT generated by the ramp current generating circuit.
[0017] Furthermore, the ramp current generating circuit includes a charge pump, a current source I1, an NMOS transistor Q9, a PMOS transistor Q10, NMOS transistors Q11~Q13, an operational amplifier OAMP, a comparator COMP, a resistor R3, and a capacitor C1;
[0018] The output of current source I1 is connected to the drain of NMOS transistor Q11. The output of comparator COMP is connected to the gate of NMOS transistor Q11 and the gate of PMOS transistor Q10. The source of NMOS transistor Q11 is connected to the non-inverting input of operational amplifier OAMP and one end of capacitor C1. The inverting input of operational amplifier OAMP is connected to the source of NMOS transistor Q9, one end of resistor R3, and the non-inverting input of comparator COMP. The output of operational amplifier OAMP is connected to the gate of NMOS transistor Q9 and the drain of PMOS transistor Q10. The inverting input of comparator COMP is connected to the reference voltage VREF. The other end of capacitor C1, the other end of resistor R3, and the source of PMOS transistor Q10 are grounded. The drain of NMOS transistor Q9 is connected to the drain and gate of NMOS transistor Q12 and the gate of NMOS transistor Q13. The drain of NMOS transistor Q12 and the source of NMOS transistor Q13 are connected to the output of charge pump. The drain of NMOS transistor Q13 outputs the linear ramp current ISOFT.
[0019] Furthermore, the low-selection circuit consists of two gate-drain coupled NMOS transistors Q14 and Q15; the input terminal A of the low-selection circuit is connected to the gate of NMOS transistor Q14 and the drain of NMOS transistor Q15, the input terminal B of the low-selection circuit is connected to the gate of NMOS transistor Q15 and the drain of NMOS transistor Q14, and the sources of NMOS transistors Q14 and Q15 are connected to form the output terminal Y.
[0020] On the other hand, the present invention also provides an analog switch, including a switch driving circuit, a main switch, and a soft-start circuit for the aforementioned wide transmission range analog switch.
[0021] In another aspect, the present invention also provides an electronic device including the above-described analog switch.
[0022] The advantages of the soft-start circuit of the wide transmission range analog switch of the present invention and the device including the same are as follows:
[0023] The soft-start circuit for a wide-range analog switch and the device including it of the present invention use only a low-voltage domain signal generated by a low-side level converter to control the soft-start circuit, avoiding the additional power consumption caused by switching to a high-voltage domain. The soft-start circuit can be applied to wide-range analog switches that exceed the power supply voltage range, uses only basic low-voltage CMOS devices, and is low in cost. Attached Figure Description
[0024] Figure 1 This is a block diagram of the soft-start circuit principle of a wide transmission range analog switch according to an embodiment of the present invention.
[0025] Figure 2 This is a schematic diagram of the soft-start circuit of a wide transmission range analog switch according to an embodiment of the present invention.
[0026] Figure 3 This is a schematic diagram of the ramp current generating circuit according to an embodiment of the present invention.
[0027] Figure 4 This is a schematic diagram of the low-level selection circuit according to an embodiment of the present invention. Detailed Implementation
[0028] The present invention will now be described in further detail with reference to the embodiments and the accompanying drawings.
[0029] One embodiment of the present invention provides a soft-start circuit for a wide-range analog switch, applicable to analog switches operating beyond their power supply voltage transmission range. The analog switch includes a soft-start circuit, a switch drive circuit, and a main switch. The soft-start circuit prevents inrush current damage to the circuit caused by rapid power-up. This soft-start circuit eliminates the need for a high-side level converter, using only a low-side level converter. By automatically controlling the high-voltage domain signal with a low-voltage domain logic signal, it achieves soft-start of the analog switch with a wide transmission range. Electronic devices incorporating this analog switch have lower costs compared to analog switches employing both low-side and high-side level converters.
[0030] The analog switch operates in two modes when enabled: a soft-start mode and a normal operating mode where it is driven by the switch driver circuit after the soft-start mode ends. In soft-start mode, the soft-start circuit operates, and the switch driver circuit does not. In normal operating mode, the soft-start circuit does not operate, and the switch driver circuit operates. The operating mode of the analog switch is controlled by the signal generated by the low-side level converter of the disable signal.
[0031] like Figure 1As shown, the analog switch includes a soft-start circuit, a switch driver circuit, and a main switch. The soft-start circuit includes a low-side level shifter, a selector switch, a charge pump, a current source, resistors R0 and R1, a level shifting module, and a low-side selection circuit. Because the analog switch's transmission range is higher than the power supply voltage, a charge pump is needed to generate a sufficiently high potential as the power supply for current sources ISOFT1, ISOFT2, and ISOFT3. The inputs of the low-side selection circuit are connected to the two ends of the main switch, and the voltages across the selector switch are ground and the output voltage of resistor R1, respectively.
[0032] The signal generated by the low-side level converter through the power-disabling signal controls the closing or opening of the routing switch, thereby determining whether the current from the current source flows into resistor R0 or resistor R1.
[0033] When the routing switch is closed, the current from the current source flows into resistor R1, the voltage of resistor R1 rises, and the voltage rises accordingly after being level-shifted by the level shifting module. The main switch closes slowly, and the analog switch enters soft-start mode.
[0034] When the circuit selection switch is turned off, the current from the current source flows into the low selection circuit. At this time, the analog switch exits the soft start mode and is driven by the switch drive circuit.
[0035] Preferably, in another embodiment, the soft-start circuit further includes a buffer; the output of the low-side selection circuit passes through the buffer to generate a voltage that can power the level shifter. A current source is connected via the buffer to one end of resistor R0, one end of resistor R1, and the input of the level shift module. The output of the level shift module is connected to the switch drive circuit. The other end of resistor R0 is connected to the output of the low-side selection circuit, and the other end of resistor R1 is grounded via the selection switch. The output of the low-side level converter is connected to the selection switch.
[0036] A low-side level converter controls the closing or opening of the selector switch, determining whether the current from the current source flows into resistor R0 or R1. When the selector switch is closed, current flows into resistor R1, causing the voltage across R1 to rise. Correspondingly, the voltage after level shifting by the level shifting module rises, and the main switch slowly closes, entering soft-start mode for the analog switch. When the selector switch is open, current from the current source flows into the low-side selection circuit. At this time, the analog switch exits soft-start mode and is driven by the switch driver circuit. The voltages across the selector switch are ground and the output of resistor R1, respectively. This voltage range is within the withstand voltage range of conventional CMOS devices; therefore, no additional high-side level converter is needed to control the operating mode of the analog switch.
[0037] Preferably, in another embodiment, such as Figure 2As shown, the analog switch includes a soft-start circuit, a switch driver circuit, and an NMOS transistor Q0. NMOS transistor Q0 is the main switch. The soft-start circuit includes a charge pump, a first current source ISOFT1, a second current source ISOFT2, a third current source ISOFT3, a low-side selection circuit, a low-side level converter, NMOS transistors Q1~Q8, and a resistor R2. The output of the switch driver circuit is connected to the gate of NMOS transistor Q0. The input IN and output OUT of NMOS transistor Q0 are connected to the input of the low-side selection circuit, respectively. The output of the low-side selection circuit serves as the input of NMOS transistor Q1, connected to the gate of Q1, the drain of NMOS transistor Q8, and the source of NMOS transistor Q3. The drain of NMOS transistor Q1 is connected to the output of the first current source ISOFT1, the gate of NMOS transistor Q3, and the gate of NMOS transistor Q5. The source of NMOS transistor Q1 is connected to the drain of NMOS transistor Q3, the source of NMOS transistor Q5, the source of NMOS transistor Q6, one end of resistor R2, and the NMOS transistor Q8. The source of S-channel transistor Q4; the output of the second current source ISOFT2 is connected to the drain of NMOS transistor Q5 and the gate of NMOS transistor Q6; the output of the third current source ISOFT3 is connected to the drain and gate of NMOS transistor Q2 and the input of the switch drive circuit; the source of NMOS transistor Q2 is connected to the drain of NMOS transistor Q6; the disable signal is connected to the gate of NMOS transistor Q7 and the gate of NMOS transistor Q8 after passing through the bottom-side converter; the source of NMOS transistor Q8 is connected to the drain of NMOS transistor Q4; the gate of NMOS transistor Q4 and the source of NMOS transistor Q7 are grounded; the other end of resistor R2 is connected to the drain of NMOS transistor Q7.
[0038] Figure 2 The first current source ISOFT1, the second current source ISOFT2, and the third current source ISOFT3 correspond to Figure 1 Medium current source. NMOS transistor Q1 is a low-threshold device; as a source follower, it corresponds to… Figure 1 The buffer in the circuit. NMOS transistor Q2 is connected via a diode, with its drain voltage higher than its source voltage by one gate-source voltage (VGS). Figure 1 Level shifting in the NMOS transistor Q3. Figure 1In the circuit, R0 is used; the gate of NMOS transistor Q4 is grounded and closes when the main switch transmits a negative voltage, connecting the voltage of resistor R2 to the negative voltage. NMOS transistor Q5 generates a signal to control NMOS transistor Q6; NMOS transistor Q6 acts as the first routing switch, determining whether the current from the third current source ISOFT3 in the branch containing NMOS transistor Q2 flows to the soft-start circuit or the switch drive circuit; NMOS transistors Q7 and Q8 act as the second routing switches, determining whether the current from the first current source ISOFT1 flows to resistor R2 or NMOS transistor Q3. The gates of NMOS transistors Q7 and Q8 are connected to the output of the low-side level converter. When the soft-start circuit module is working, NMOS transistors Q7 and Q8 are closed; when not working, NMOS transistors Q7 and Q8 are open. Resistor R2 corresponds to... Figure 1 The resistor R1 in the middle.
[0039] When the main switch transmits a positive voltage, the initial output of the low-select circuit is ground potential. The analog switch enters soft-start mode, NMOS transistors Q7 and Q8 are closed, and NMOS transistor Q4 is open. The current from the first current source ISOFT1 flows into resistor R2, and NMOS transistor Q1 enters the linear region. Since no current flows through NMOS transistor Q3, NMOS transistor Q3 enters the cutoff region, and its gate voltage is low. The gate of NMOS transistor Q5 is connected to the gate of NMOS transistor Q3 (the drain of NMOS transistor Q1), so NMOS transistor Q5 is turned off. The second current source ISOFT2 charges the gate of NMOS transistor Q6, and NMOS transistor Q6 is closed. The drain voltage is equal to the source voltage. The current from the third current source ISOFT3 flows into resistor R2 through NMOS transistor Q6, generating a ramp voltage across resistor R2. The drain voltage of NMOS transistor Q2 is raised by one gate-source voltage (VGS) higher than the voltage of resistor R2. The main switch closes slowly, and as the output voltage rises, the output voltage of the low-select circuit also rises.
[0040] As the voltage across resistor R2 increases, some current flows into NMOS transistor Q3, causing the gate voltage of NMOS transistor Q3 to rise. NMOS transistor Q3 then moves from the cutoff region into the linear region, while NMOS transistor Q1 moves from the linear region into the saturation region, NMOS transistor Q5 moves from the cutoff region into the saturation region, and NMOS transistor Q6 moves from the linear region into the saturation region. A portion of the current from the third current source ISOFT3 flows into the switch drive circuit.
[0041] When the switch exits soft-start mode, the low-side level converter controls NMOS transistors Q7 and Q8 to turn off via the converted disable signal. All current no longer flows into resistor R2 and instead flows entirely into NMOS transistor Q3. At this time, the gate voltage of NMOS transistor Q3 rises rapidly, and NMOS transistor Q3 fully enters the linear region. NMOS transistor Q1 enters the saturation region, and the source voltage of NMOS transistor Q1 follows the output voltage of the low-select circuit. Simultaneously, the gate voltage of NMOS transistor Q5 rises rapidly, and NMOS transistor Q5 fully enters the linear region, pulling down the gate voltage of NMOS transistor Q6. NMOS transistor Q6 turns off and enters the cutoff region. The current from the third current source ISOFT3 no longer flows through NMOS transistor Q2 and instead flows entirely into the switch drive circuit. At this point, the analog switch exits soft-start mode and enters normal operating mode.
[0042] When the main switch transmits a negative voltage, the output of the low selection circuit is negative. The analog switch enters soft-start mode, NMOS transistors Q7 and Q8 close, NMOS transistor Q4 closes, and resistor R2 is connected to the output of the low selection circuit, which is negative. The first current source ISOFT1 no longer flows into resistor R2, but directly into the output of the low selection circuit. NMOS transistor Q1 enters the linear region. Since no current flows through NMOS transistor Q3, NMOS transistor Q3 enters the cutoff region, and its gate voltage is low. The gate of NMOS transistor Q5 is connected to the gate of NMOS transistor Q3 (the drain of NMOS transistor Q1), so NMOS transistor Q5 also operates in the cutoff region. The second current source ISOFT2 charges the gate of NMOS transistor Q6, and NMOS transistor Q6 closes. The drain voltage equals the source voltage. The current from the third current source ISOFT3 flows into the output of the low selection circuit. The drain voltage of NMOS transistor Q2 is raised by one gate-source voltage (VGS) higher than the output voltage of the low selection circuit. The main switch closes slowly.
[0043] When the switch exits soft-start mode, the low-side level converter controls NMOS transistors Q7 and Q8 to turn off via the converted disable signal. All current no longer flows into the output of the low-select circuit but instead flows entirely into NMOS transistor Q3. At this time, the gate voltage of NMOS transistor Q3 rises rapidly, and Q3 fully enters the linear region. NMOS transistor Q1 enters the saturation region, and the source voltage of NMOS transistor Q1 follows the output voltage of the low-select circuit. Simultaneously, the gate voltage of NMOS transistor Q5 rises rapidly, and Q5 fully enters the linear region, pulling down the gate voltage of NMOS transistor Q6. NMOS transistor Q6 turns off and enters the cutoff region. The current from the third current source ISOFT3 no longer flows through NMOS transistor Q2 but instead flows entirely into the switch drive circuit. At this point, the analog switch exits soft-start mode and enters normal operating mode.
[0044] In the soft-start circuit module, the first current source ISOFT1, the second current source ISOFT2, and the third current source ISOFT3 are replicated from the linear ramp current ISOFT generated by the ramp current generation circuit. For example... Figure 3 As shown, the ramp current generating circuit includes a charge pump, a current source I1, an NMOS transistor Q9, a PMOS transistor Q10, NMOS transistors Q11~Q13, an operational amplifier OAMP, a comparator COMP, a resistor R3, and a capacitor C1. The output of current source I1 is connected to the drain of NMOS transistor Q11. The output of comparator COMP is connected to the gate of NMOS transistor Q11 and the gate of PMOS transistor Q10. The source of NMOS transistor Q11 is connected to the non-inverting input of operational amplifier OAMP and one end of capacitor C1. The inverting input of operational amplifier OAMP is connected to the source of NMOS transistor Q9, one end of resistor R3, and the non-inverting input of comparator COMP. The output of operational amplifier OAMP is connected to the gate of NMOS transistor Q9 and the drain of PMOS transistor Q10. The inverting input of comparator COMP is connected to the reference voltage VREF. The other end of capacitor C1, the other end of resistor R3, and the source of PMOS transistor Q10 are grounded. The drain of NMOS transistor Q9 is connected to the drain and gate of NMOS transistor Q12 and the gate of NMOS transistor Q13. The drain of NMOS transistor Q12 and the source of NMOS transistor Q13 are connected to the output of charge pump. The drain of NMOS transistor Q13 outputs a linear ramp current ISOFT.
[0045] When the analog switch enters soft-start mode, the voltage across resistor R3 is lower than the voltage VREF at the inverting input of comparator COMP. Comparator COMP outputs low, NMOS transistor Q11 closes, PMOS transistor Q10 turns off, and current source I1 charges capacitor C1, generating a linearly rising voltage across C1. This voltage is input to the non-inverting input of operational amplifier OAMP, while the voltage across resistor R3 acts as the inverting input, rising synchronously with the non-inverting input voltage. The ramp current ISOFT generated by the ramp current generation circuit is replicated to other modules in the circuit (e.g., NMOS transistors Q12 and Q13) via a current mirror. Figure 2 (ISOFT1, ISOFT2, ISOFT3). The current continues until the voltage across resistor R3 exceeds the voltage VREF at the inverting input of comparator COMP. Comparator COMP outputs high, NMOS transistor Q11 turns off, PMOS transistor Q10 turns on, and the ramp current generation circuit no longer generates the linear ramp current ISOFT. The analog switch exits soft-start mode.
[0046] like Figure 4As shown, the low-voltage circuit consists of two gate-drain coupled NMOS transistors, Q14 and Q15. Input terminal A is connected to the gate of NMOS transistor Q14 and the drain of NMOS transistor Q15, and input terminal B is connected to the gate of NMOS transistor Q15 and the drain of NMOS transistor Q14. The sources of NMOS transistors Q14 and Q15 are connected together, forming the output terminal Y. When the voltage at input terminal A is higher than the voltage at input terminal B, NMOS transistor Q14 is closed, and NMOS transistor Q15 is turned off. The voltage at input terminal B is transmitted to output terminal Y through NMOS transistor Q14. Conversely, when the voltage at input terminal B is higher than the voltage at input terminal A, NMOS transistor Q14 is turned off, and NMOS transistor Q15 is closed. The voltage at input terminal A is transmitted to output terminal Y through NMOS transistor Q15.
[0047] The present invention relates to a soft-start circuit for a wide-range analog switch and a device including the same, which uses only a low-voltage domain signal generated by a low-side level converter to control the soft-start circuit, avoiding the additional power consumption caused by switching to a high-voltage domain. The soft-start circuit can be applied to wide-range analog switches exceeding the power supply voltage range, uses only basic low-voltage CMOS devices, and is low in cost.
[0048] While the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the invention. Any equivalent changes or modifications made without departing from the spirit and scope of the invention are also within the scope of protection of the invention. Therefore, the scope of protection of the present invention should be determined by the claims of this application.
Claims
1. A soft-start circuit for a wide transmission range analog switch, applied to an analog switch exceeding the power supply voltage transmission range, the analog switch comprising a soft-start circuit, a switch drive circuit, and a main switch, characterized in that, The soft-start circuit includes a low-side level converter, a routing switch, a charge pump, a current source, resistors R0 and R1, a level shifting module, and a low-side selection circuit. The inputs of the low-side selection circuit are connected to the two ends of the main switch, and the voltages at the two ends of the routing switch are ground voltage and the output voltage of resistor R1, respectively. The charge pump serves as the power source for the current source. The signal generated by the low-side level converter through the power-disabling signal controls the closing or opening of the routing switch, thereby determining whether the current from the current source flows into resistor R0 or resistor R1. When the routing switch is closed, the current from the current source flows into resistor R1, the voltage of resistor R1 rises, and the voltage rises accordingly after being level-shifted by the level shifting module. The main switch closes slowly, and the analog switch enters soft-start mode. When the routing switch is disconnected, the current from the current source flows into the low-selection circuit. At this time, the main switch exits the soft-start mode and is driven by the switch drive circuit.
2. The soft-start circuit for a wide transmission range analog switch according to claim 1, characterized in that, The soft-start circuit also includes a buffer; The output of the low-side selection circuit generates a voltage for the level shifting module via a buffer; the current source is connected to one end of resistor R0, one end of resistor R1, and the input of the level shifting module via the buffer; the output of the level shifting module is connected to the switch driving circuit; the other end of resistor R0 is connected to the output of the low-side selection circuit; the other end of resistor R1 is grounded via the selection switch; and the output of the low-side level converter is connected to the selection switch.
3. The soft-start circuit for a wide transmission range analog switch according to claim 1, characterized in that, The analog switch includes a soft-start circuit, a switch drive circuit, and an NMOS transistor Q0, wherein the NMOS transistor Q0 is the main switch; The soft-start circuit includes a charge pump, a first current source ISOFT1, a second current source ISOFT2, a third current source ISOFT3, a low-side selection circuit, a buffer, a low-side level converter, NMOS transistors Q1~Q8, and a resistor R2. The output of the switch driving circuit is connected to the gate of NMOS transistor Q0. The input (IN) and output (OUT) of NMOS transistor Q0 are connected to the input of the low-select circuit, respectively. The output of the low-select circuit serves as the input of NMOS transistor Q1, and is connected to the gate of NMOS transistor Q1, the drain of NMOS transistor Q8, and the source of NMOS transistor Q3. The drain of NMOS transistor Q1 is connected to the output of the first current source ISOFT1, the gate of NMOS transistor Q3, and the gate of NMOS transistor Q5. The source of NMOS transistor Q1 is connected to the drain of NMOS transistor Q3, the source of NMOS transistor Q5, the source of NMOS transistor Q6, and one end of resistor R2. The first current source is connected to the source of NMOS transistor Q4; the output of the second current source ISOFT2 is connected to the drain of NMOS transistor Q5 and the gate of NMOS transistor Q6; the output of the third current source ISOFT3 is connected to the drain and gate of NMOS transistor Q2 and the input of the switch drive circuit; the source of NMOS transistor Q2 is connected to the drain of NMOS transistor Q6; the disable signal is connected to the gate of NMOS transistor Q7 and the gate of NMOS transistor Q8 after passing through the bottom-side converter; the source of NMOS transistor Q8 is connected to the drain of NMOS transistor Q4; the gate of NMOS transistor Q4 and the source of NMOS transistor Q7 are grounded; the other end of resistor R2 is connected to the drain of NMOS transistor Q7.
4. The soft-start circuit for a wide transmission range analog switch according to claim 3, characterized in that, The first current source ISOFT1, the second current source ISOFT2, and the third current source ISOFT3 in the soft start circuit module are replicated from the linear ramp current ISOFT generated by the ramp current generating circuit.
5. The soft-start circuit for a wide transmission range analog switch according to claim 4, characterized in that, The ramp current generating circuit includes a charge pump, a current source I1, an NMOS transistor Q9, a PMOS transistor Q10, NMOS transistors Q11~Q13, an operational amplifier OAMP, a comparator COMP, a resistor R3, and a capacitor C1. The output of current source I1 is connected to the drain of NMOS transistor Q11. The output of comparator COMP is connected to the gate of NMOS transistor Q11 and the gate of PMOS transistor Q10. The source of NMOS transistor Q11 is connected to the non-inverting input of operational amplifier OAMP and one end of capacitor C1. The inverting input of operational amplifier OAMP is connected to the source of NMOS transistor Q9, one end of resistor R3, and the non-inverting input of comparator COMP. The output of operational amplifier OAMP is connected to the gate of NMOS transistor Q9 and the drain of PMOS transistor Q10. The inverting input of comparator COMP is connected to the reference voltage VREF. The other end of capacitor C1, the other end of resistor R3, and the source of PMOS transistor Q10 are grounded. The drain of NMOS transistor Q9 is connected to the drain and gate of NMOS transistor Q12 and the gate of NMOS transistor Q13. The drain of NMOS transistor Q12 and the source of NMOS transistor Q13 are connected to the output of charge pump. The drain of NMOS transistor Q13 outputs the linear ramp current ISOFT.
6. The soft-start circuit for a wide transmission range analog switch according to any one of claims 1-5, characterized in that, The low-selection circuit consists of two gate-drain coupled NMOS transistors Q14 and Q15; the input terminal A of the low-selection circuit is connected to the gate of NMOS transistor Q14 and the drain of NMOS transistor Q15, the input terminal B of the low-selection circuit is connected to the gate of NMOS transistor Q15 and the drain of NMOS transistor Q14, and the sources of NMOS transistors Q14 and Q15 are connected together to form the output terminal Y.
7. An analog switch, characterized in that, It includes a switch drive circuit, a main switch, and a soft-start circuit for a wide transmission range analog switch as described in any one of claims 1-6.
8. An electronic device, characterized in that, Includes the analog switch as described in claim 7.