Analog switch capable of transmitting positive and negative voltages beyond power rail

Abstract

The invention relates to an analog switch capable of transmitting positive and negative voltages beyond a power rail, and belongs to the technical field of circuit structures. According to the analog switch capable of transmitting the positive and negative voltages beyond the power supply rail, the control logic module is used for controlling one of the on function module and the off function module of the complementary charge pump to work so as to control the on-off of the switch module, so that the problem that a power supply is lower than a signal range can be solved without constructing a negative-voltage charge pump; positive and negative voltages can be transmitted beyond a power rail, signals are not distorted, and the power consumption and the cost of an analog switch chip are greatly reduced. And the switch module adopts two NMOS (N-channel metal oxide semiconductor) tubes which are connected back to back, so that the switch does not generate electric leakage under negative voltage, the VISO can be always kept higher than the potential of the substrate by processing positive and negative voltages of the isolating ring, and the isolating ring always keeps reverse bias on a parasitic diode of the P-type substrate.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit structures, in particular to the technical field of analog switches, and specifically refers to an analog switch capable of transmitting positive and negative voltages beyond a power rail. Background Art

[0002] The analog switch in the prior art needs to construct a negative voltage pump in order to transmit a negative voltage signal beyond the power rail, but adding a negative voltage pump increases the functionality and cost of the analog switch chip.

[0003] How to provide an analog switch that can transmit positive and negative voltages beyond the power rail without the need to additionally construct a negative voltage pump has become an urgent problem to be solved in this field. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide an analog switch that can solve the problem of power supply being lower than the signal range without the need to construct an additional negative voltage charge pump and can transmit positive and negative voltages beyond the power rail.

[0005] In order to achieve the above-mentioned purpose, the analog switch capable of transmitting positive and negative voltage beyond the power rail of the present invention has the following structure:

[0006] It includes:

[0007] Internal power processing module 1, providing internal stable power V_INVCC;

[0008] The opening function module 2 and the closing function module 3 are CMOS complementary boost charge pumps, both connected to the power supply V_INVCC;

[0009] A control logic module 4, used to provide mutually inverse control signals to the opening function module 2 and the closing function module 3, so as to control one of the opening function module 2 and the closing function module 3 to work and the other not to work;

[0010] The switch module 5 includes two NMOS tubes NM1 and NM2 connected back to back, wherein the gate and source of the NMOS tube NM1 are respectively connected to the output ends of the start function module 2 and the shutdown function module 3, and the gate and source of the NMOS tube NM2 are also respectively connected to the output ends of the start function module 2 and the shutdown function module 3, the drain of the NMOS tube NM1 serves as the drain end of the switch module 5, and the drain of the NMOS tube NM2 serves as the source end of the switch module 5.

[0011] The analog switch, which can transfer positive and negative voltages beyond the supply rails, also includes:

[0012] The isolation ring 6 is connected to the power supply VCC, and is also connected to the start function module 2, the shutdown function module 3 and the switch module 5. The isolation ring 6 has an isolation ring voltage VISO, which is greater than the substrate potential of each MOS tube in the analog switch.

[0013] In this analog switch that can transfer positive and negative voltages beyond the power rails,

[0014] The start function module 2 and the shut down function module 3 are both connected to a complementary oscillation signal CLKN and an oscillation signal CLKP, and the amplitudes of the oscillation signals CLKN and CLKP are equal to the power supply V_INVCC;

[0015] The control signal of the control logic module 4 is directly connected to the start function module 2, and the control signal is also connected to the shut-down function module 3 through the inverter 8; the start function module 2 provides an output voltage Vg connected to the gates of the NMOS tubes NM1 and NM2, and also has a voltage Vcs connected to the sources of the NMOS tubes NM1 and NM2; the shut-down function module 3 provides an output voltage Vdis connected to the gates of the NMOS tubes NM1 and NM2, and also has a voltage Vcs connected to the sources of the NMOS tubes NM1 and NM2;

[0016] When the start function module 2 is working and the shutdown function module 3 is not working, the gate-source voltage Vg-Vcs of the NMOS tubes NM1 and NM2 is equal to the power supply V_INVCC;

[0017] When the shut-down function module 3 is working and the start-up function module 2 is not working, the gate-source voltage Vg-Vcs of the NMOS tubes NM1 and NM2 is 0.

[0018] In this analog switch that can transfer positive and negative voltages beyond the power rails,

[0019] The start-up function module 2 includes two NMOS tubes NM3 and NM4 and two PMOS tubes PM1 and PM2. The sources of the two NMOS tubes NM3 and NM4 are connected to the voltage Vcs, and the sources of the two PMOS tubes PM1 and PM2 are connected to the output voltage Vg; the drains of the two NMOS tubes NM3 and NM4 and the two PMOS tubes PM1 and PM2 are connected and connected to the oscillation signals CLKN and CLKP; the gate of the NMOS tube NM3 is connected to the gate of the PMOS tube PM1 and connected to the oscillation signals CLKN and CLKP; the gate of the NMOS tube NM4 is connected to the gate of the PMOS tube PM2;

[0020] The shutdown function module 3 includes two NMOS tubes NM5 and NM6 and two PMOS tubes PM3 and PM4, the sources of the two NMOS tubes NM5 and NM6 are connected to the voltage Vcs, and the sources of the two PMOS tubes PM3 and PM4 are connected to the output voltage Vdis; the drains of the two NMOS tubes NM5 and NM6 and the two PMOS tubes PM3 and PM4 are connected and connected to the oscillation signals CLKN and CLKP; the gate of the NMOS tube NM5 is connected to the gate of the PMOS tube PM3 and connected to the oscillation signals CLKN and CLKP; the gate of the NMOS tube NM6 is connected to the gate of the PMOS tube PM4.

[0021] The analog switch, which can transfer positive and negative voltages beyond the supply rails, also includes:

[0022] The discharge path 7 is opened and closed, connected to the control signal of the control logic module 4 , and also connected to the switch module 5 and the isolation ring 6 .

[0023] In this analog switch that can transfer positive and negative voltages beyond the power rails,

[0024] The on / off discharge path 7 includes four NMOS tubes NM7, NM8, NM9, and NM10.

[0025] The control signal of the control logic module 4 is directly connected to the gate of the NMOS tube NM7, and the control signal is also connected to the gate of the NMOS tube NM8 through the inverter 8; when the start function module 2 is working, the NMOS tube NM7 is turned on and the NMOS tube NM8 is turned off; when the shutdown function module 3 is working, the NMOS tube NM8 is turned on and the NMOS tube NM7 is turned off;

[0026] The gates of the NMOS tube NM7 and the NMOS tube NM8 are both connected to the voltage Vcs, and the drains of the NMOS tube NM9 and the NMOS tube NM10 are also connected to the voltage Vcs;

[0027] The drain of the NMOS tube NM7 is connected to the source of the NMOS tube NM9 and the gate of the NMOS tube NM10, and is also connected to the output voltage Vg of the start-up function module 2;

[0028] The drain of the NMOS tube NM8 is connected to the source of the NMOS tube NM10 and the gate of the NMOS tube NM9 , and is also connected to the output voltage Vdis of the shutdown function module 3 .

[0029] The analog switch of the invention that can transmit positive and negative voltages beyond the power rail controls the operation of one of the complementary charge pump opening function module and the closing function module through the control logic module, thereby controlling the closing of the switch module. Therefore, the problem of the power supply being lower than the signal range can be solved without building a negative voltage charge pump, and the positive and negative voltages can be transmitted beyond the power rail without signal distortion, which greatly reduces the power consumption and cost of the analog switch chip. The switch module uses two NMOS tubes connected back to back, so that the switch does not generate leakage when the voltage is negative, and VISO can always be kept greater than the substrate potential by processing the positive and negative voltages of the isolation ring, so that the parasitic diode of the isolation ring to the P-type substrate is always reverse biased. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the functional module structure of the analog switch of the present invention that can transmit positive and negative voltages beyond the power rail;

[0031] Figure 2 The schematic diagram of the circuit structure of the analog switch of the present invention is capable of transmitting positive and negative voltages beyond the power rail.

[0032] Reference numerals:

[0033] Internal power processing module 1, opening function module 2, closing function module 3, control logic module 4, switch module 5, isolation ring 6, opening and closing discharge path 7 DETAILED DESCRIPTION

[0034] In order to more clearly understand the technical content of the present invention, the following embodiments are given in detail.

[0035] See also Figure 1 , which is a schematic diagram of the functional module structure of an analog switch capable of transmitting positive and negative voltages beyond the power rail of the present invention.

[0036] In one embodiment, the analog switch capable of transmitting positive and negative voltages beyond the power rail has the following configuration:

[0037] Internal power processing module 1, providing internal stable power V_INVCC;

[0038] The opening function module 2 and the closing function module 3 are CMOS complementary boost charge pumps, both connected to the power supply V_INVCC;

[0039] A control logic module 4, used to provide mutually inverse control signals to the opening function module 2 and the closing function module 3, so as to control one of the opening function module 2 and the closing function module 3 to work and the other not to work;

[0040] The switch module 5 includes two NMOS tubes NM1 and NM2 connected back to back, wherein the gate and source of the NMOS tube NM1 are respectively connected to the output ends of the start function module 2 and the shutdown function module 3, and the gate and source of the NMOS tube NM2 are also respectively connected to the output ends of the start function module 2 and the shutdown function module 3, the drain of the NMOS tube NM1 serves as the drain end of the switch module 5, and the drain of the NMOS tube NM2 serves as the source end of the switch module 5.

[0041] like Figure 2 As shown, the analog switch capable of transmitting positive and negative voltages beyond the power rail also includes an isolation ring 6, which is connected to the power supply VCC, and is also connected to the start function module 2, the shutdown function module 3 and the switch module 5. The isolation ring 6 has an isolation ring voltage VISO, which is greater than the substrate potential of each MOS tube in the analog switch.

[0042] In a preferred embodiment, Figure 2 As shown, the start function module 2 and the shutdown function module 3 are both connected to the complementary oscillation signal CLKN and the oscillation signal CLKP, and the amplitudes of the oscillation signals CLKN and CLKP are equal to the power supply V_INVCC;

[0043] The control signal of the control logic module 4 is directly connected to the start function module 2, and the control signal is also connected to the shut-down function module 3 through the inverter 8; the start function module 2 provides an output voltage Vg connected to the gates of the NMOS tubes NM1 and NM2, and also has a voltage Vcs connected to the sources of the NMOS tubes NM1 and NM2; the shut-down function module 3 provides an output voltage Vdis connected to the gates of the NMOS tubes NM1 and NM2, and also has a voltage Vcs connected to the sources of the NMOS tubes NM1 and NM2;

[0044] When the start function module 2 is working and the shutdown function module 3 is not working, the gate-source voltage Vg-Vcs of the NMOS tubes NM1 and NM2 is equal to the power supply V_INVCC;

[0045] When the shut-down function module 3 is working and the start-up function module 2 is not working, the gate-source voltage Vg-Vcs of the NMOS tubes NM1 and NM2 is 0.

[0046] In a further preferred embodiment, Figure 2As shown, the start-up function module 2 includes two NMOS tubes NM3 and NM4 and two PMOS tubes PM1 and PM2, the sources of the two NMOS tubes NM3 and NM4 are connected to the voltage Vcs, and the sources of the two PMOS tubes PM1 and PM2 are connected to the output voltage Vg; the drains of the two NMOS tubes NM3 and NM4 and the two PMOS tubes PM1 and PM2 are connected, and connected to the oscillation signals CLKN and CLKP; the gate of the NMOS tube NM3 is connected to the gate of the PMOS tube PM1 and connected to the oscillation signals CLKN and CLKP; the gate of the NMOS tube NM4 is connected to the gate of the PMOS tube PM2;

[0047] The shutdown function module 3 includes two NMOS tubes NM5 and NM6 and two PMOS tubes PM3 and PM4, the sources of the two NMOS tubes NM5 and NM6 are connected to the voltage Vcs, and the sources of the two PMOS tubes PM3 and PM4 are connected to the output voltage Vdis; the drains of the two NMOS tubes NM5 and NM6 and the two PMOS tubes PM3 and PM4 are connected and connected to the oscillation signals CLKN and CLKP; the gate of the NMOS tube NM5 is connected to the gate of the PMOS tube PM3 and connected to the oscillation signals CLKN and CLKP; the gate of the NMOS tube NM6 is connected to the gate of the PMOS tube PM4.

[0048] In a more preferred embodiment, Figure 2 As shown, the analog switch capable of transmitting positive and negative voltages beyond the power rail also includes an on / off discharge path 7 , which is connected to the control signal of the control logic module 4 , and is also connected to the switch module 5 and the isolation ring 6 .

[0049] Furthermore, the on-off discharge path 7 includes four NMOS tubes NM7, NM8, NM9, and NM10.

[0050] The control signal of the control logic module 4 is directly connected to the gate of the NMOS tube NM7, and the control signal is also connected to the gate of the NMOS tube NM8 through the inverter 8; when the start function module 2 is working, the NMOS tube NM7 is turned on and the NMOS tube NM8 is turned off; when the shutdown function module 3 is working, the NMOS tube NM8 is turned on and the NMOS tube NM7 is turned off;

[0051] The gates of the NMOS tube NM7 and the NMOS tube NM8 are both connected to the voltage Vcs, and the drains of the NMOS tube NM9 and the NMOS tube NM10 are also connected to the voltage Vcs;

[0052] The drain of the NMOS tube NM7 is connected to the source of the NMOS tube NM9 and the gate of the NMOS tube NM10, and is also connected to the output voltage Vg of the start-up function module 2;

[0053] The drain of the NMOS tube NM8 is connected to the source of the NMOS tube NM10 and the gate of the NMOS tube NM9 , and is also connected to the output voltage Vdis of the shutdown function module 3 .

[0054] In practical applications, the basic architecture of the analog switch of the present invention is as follows: Figure 1 As shown. First, the power rail is processed by the internal power processing module 1, which can complete the functions required by the analog switch chip, such as over-temperature protection, bandgap reference, internal V_INVCC=4.8V stable power supply, digital logic reset signal, etc. After that, the control logic module 4 controls the opening function module 2 and the closing function module 3 to realize the opening and closing of the switch module 5. For the transmission of positive and negative voltage signals, in order to ensure that the power tube is not damaged by the negative voltage breakdown, the switch module 5 selects two back-to-back NMOS tubes NM1 and NM2 as the transmission structure, and uses its back-to-back body diode structure to prevent leakage when the voltage is negative.

[0055] The specific working principle is as follows: Figure 2 As shown, in order to ensure that both positive and negative voltages do not cause leakage, the isolation ring VISO is processed through the isolation ring 6, and its function makes VISO always greater than the substrate potential, so that the parasitic diode of the isolation ring to the P-type substrate is always reverse biased. When the transmission voltage of the two NMOS tubes NM1 and NM2 is greater than VCC, VISO has no reverse leakage path to VCC. When the transmission voltage is less than VCC, VCC is the highest potential of the isolation ring of the two NMOS tubes NM1 and NM2 of the switch tube, ensuring that VISO will not cause leakage to any port when transmitting any signal.

[0056] For the opening and closing of the switch module 5, Figure 2The opening function module 2 and the closing function module 3 are CMOS complementary boost charge pumps, which are controlled by the control logic module 4. The inverter 8 realizes the opposite control signal, and only one module controls the opening and closing functions. When the switch module 5 is turned on, the charge pump of the opening function module 2 starts to work, CLKN and CLKP are complementary oscillation signals, and their amplitude is V_INVCC. Due to the charge pump boost, the Vg voltage is equal to Vcs+V_INVCC, that is, the gate-source voltage Vg-Vcs of the switch tubes NM1 and NM2 always maintains a value of V_INVCC, and the charge pump of the closing function module 3 does not work at this time, and the NMOS tube NM8 in the opening and closing discharge path 7 is opened by the control logic module 4. Since Vg-Vcs=V_INVCC, the NMOS tube NM10 is turned on, so that Vdis-Vcs=0, and the closing function is closed. On the contrary, when the switch module 5 is in the closed state, the control logic module 4 enables the charge pump of the shutdown function module 3 to start working, and at the same time turns on the NMOS tube NM7 in the shutdown discharge path 7. At this time, Vdis=Vcs+V_INVCC, and Vdis turns on the NMOS tube NM9, so that Vg-Vcs=0, that is, the gate-source voltage of the switch tubes NM1 and NM2 is constant to 0, and the switch module 5 is closed.

[0057] The advantage of the analog switch of the present invention is that the transmission of positive and negative voltage signals no longer requires the design of a negative voltage charge pump related to the transmission signal as the substrate potential, which not only greatly reduces power consumption and chip area, but also realizes that the power rail is independent of the transmission signal. The key is that two complementary charge pumps are used for opening and closing, and the opening and closing method different from the existing analog switch is realized through the control logic module and the opening and closing discharge path.

[0058] The analog switch of the invention that can transmit positive and negative voltages beyond the power rail controls the operation of one of the complementary charge pump opening function module and the closing function module through the control logic module, thereby controlling the closing of the switch module. Therefore, the problem of the power supply being lower than the signal range can be solved without building a negative voltage charge pump, and the positive and negative voltages can be transmitted beyond the power rail without signal distortion, which greatly reduces the power consumption and cost of the analog switch chip. The switch module uses two NMOS tubes connected back to back, so that the switch does not generate leakage when the voltage is negative, and VISO can always be kept greater than the substrate potential by processing the positive and negative voltages of the isolation ring, so that the parasitic diode of the isolation ring to the P-type substrate is always reverse biased.

[0059] In this specification, the present invention has been described with reference to specific embodiments thereof. However, it is apparent that various modifications and variations may be made without departing from the spirit and scope of the present invention. Therefore, the specification and drawings should be regarded as illustrative rather than restrictive.

Claims

1. An analog switch capable of transmitting positive and negative voltages beyond a power rail, characterized in that: include: An internal power processing module (1) provides an internal stable power supply V_INVCC; The opening function module (2) and the closing function module (3) are CMOS complementary boost charge pumps, both connected to the power supply V_INVCC; A control logic module (4) is used to provide mutually inverse control signals to the opening function module (2) and the closing function module (3), so as to control one of the opening function module (2) and the closing function module (3) to work and the other to not work; The switch module (5) comprises two NMOS tubes NM1 and NM2 connected back to back, wherein the gate and source of the NMOS tube NM1 are respectively connected to the output ends of the opening function module (2) and the closing function module (3), and the gate and source of the NMOS tube NM2 are also respectively connected to the output ends of the opening function module (2) and the closing function module (3), the drain of the NMOS tube NM1 serves as the drain end of the switch module (5), and the drain of the NMOS tube NM2 serves as the source end of the switch module (5).

2. The analog switch capable of transmitting positive and negative voltages beyond the power rail according to claim 1, characterized in that: Also includes: The isolation ring (6) is connected to a power supply VCC and is also connected to the start function module (2), the shutoff function module (3) and the switch module (5). The isolation ring (6) has an isolation ring voltage VISO, which is greater than the substrate potential of each MOS tube in the analog switch.

3. The analog switch capable of transmitting positive and negative voltages beyond the power rail according to claim 2, characterized in that: The opening function module (2) and the closing function module (3) are both connected to a complementary oscillation signal CLKN and an oscillation signal CLKP, and the amplitudes of the oscillation signals CLKN and CLKP are equal to the power supply V_INVCC; The control signal of the control logic module (4) is directly connected to the start function module (2), and the control signal is also connected to the shutoff function module (3) through an inverter (8); the start function module (2) provides an output voltage Vg connected to the gates of the NMOS tubes NM1 and NM2, and also has a voltage Vcs connected to the sources of the NMOS tubes NM1 and NM2; the shutoff function module (3) provides an output voltage Vdis connected to the gates of the NMOS tubes NM1 and NM2, and also has a voltage Vcs connected to the sources of the NMOS tubes NM1 and NM2; When the start function module (2) is working and the shut down function module (3) is not working, the gate-source voltage Vg-Vcs of the NMOS tubes NM1 and NM2 is equal to the power supply V_INVCC; When the shut-off function module (3) is working and the start-up function module (2) is not working, the gate-source voltage Vg-Vcs of the NMOS tubes NM1 and NM2 is 0.

4. The analog switch capable of transmitting positive and negative voltages beyond the power rail according to claim 3, characterized in that: The start-up function module (2) comprises two NMOS tubes NM3 and NM4 and two PMOS tubes PM1 and PM2, the sources of the two NMOS tubes NM3 and NM4 are connected to the voltage Vcs, and the sources of the two PMOS tubes PM1 and PM2 are connected to the output voltage Vg; the drains of the two NMOS tubes NM3 and NM4 and the two PMOS tubes PM1 and PM2 are connected and connected to the oscillation signals CLKN and CLKP; the gate of the NMOS tube NM3 is connected to the gate of the PMOS tube PM1 and connected to the oscillation signals CLKN and CLKP; the gate of the NMOS tube NM4 is connected to the gate of the PMOS tube PM2; The shutdown function module (3) comprises two NMOS tubes NM5 and NM6 and two PMOS tubes PM3 and PM4, the sources of the two NMOS tubes NM5 and NM6 are connected to the voltage Vcs, and the sources of the two PMOS tubes PM3 and PM4 are connected to the output voltage Vdis; the drains of the two NMOS tubes NM5 and NM6 and the two PMOS tubes PM3 and PM4 are connected and connected to the oscillation signals CLKN and CLKP; the gate of the NMOS tube NM5 is connected to the gate of the PMOS tube PM3 and connected to the oscillation signals CLKN and CLKP; the gate of the NMOS tube NM6 is connected to the gate of the PMOS tube PM4.

5. The analog switch capable of transmitting positive and negative voltages beyond the power rail according to claim 3, characterized in that: Also includes: The discharge path (7) is opened and closed, connected to the control signal of the control logic module (4), and also connected to the switch module (5) and the isolation ring (6).

6. The analog switch capable of transmitting positive and negative voltages beyond the power rail according to claim 5, characterized in that: The on / off discharge path (7) comprises four NMOS tubes NM7, NM8, NM9 and NM10. The control signal of the control logic module (4) is directly connected to the gate of the NMOS tube NM7, and the control signal is also connected to the gate of the NMOS tube NM8 through the inverter (8); when the start function module (2) is working, the NMOS tube NM7 is turned on and the NMOS tube NM8 is turned off; when the shutdown function module (3) is working, the NMOS tube NM8 is turned on and the NMOS tube NM7 is turned off; The gates of the NMOS tube NM7 and the NMOS tube NM8 are both connected to the voltage Vcs, and the drains of the NMOS tube NM9 and the NMOS tube NM10 are also connected to the voltage Vcs; The drain of the NMOS tube NM7 is connected to the source of the NMOS tube NM9 and the gate of the NMOS tube NM10, and is also connected to the output voltage Vg of the start-up function module (2); The drain of the NMOS tube NM8 is connected to the source of the NMOS tube NM10 and the gate of the NMOS tube NM9, and is also connected to the output voltage Vdis of the shutdown function module (3).

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