High-precision temperature detection circuit in analog switch

Abstract

The application discloses a high-precision temperature detection circuit in an analog switch and relates to the technical field of analog switch chip detection. The high-precision temperature detection circuit in the analog switch comprises a control logic module, an analog switch module and a temperature detection module. The control logic module simultaneously sends control signals VA to the analog switch module and the temperature detection module. The main switch tube of the analog switch module is arranged with a detection unit thermocouple in the temperature detection module. The layout of the detection tube and the switch tube is arranged by using the thermocouple, so that the real-time temperature rise of the main switch tube can be directly captured, an additional substrate PN junction or metal resistance sensor is not needed, the temperature of the detection tube can follow the hot spot temperature rise of the main switch tube without delay and deviation, protection hysteresis and detection distortion are avoided, and the response speed and precision of temperature detection are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of analog switch chip testing technology, and in particular to a high-precision temperature detection circuit for analog switches. Background Technology

[0002] In the field of analog switching chips, accurate temperature detection is crucial for ensuring the linearity of signal transmission, the stability of on-resistance (Ron), and long-term reliability. As chips develop towards high-density, multi-functional integration, the heat generated by internal power dissipation significantly affects the performance of MOSFET switching channels, leading to increased Ron temperature drift, decreased bandwidth, and exacerbated harmonic distortion.

[0003] Existing technologies mostly use temperature sensors based on substrate PN junctions or metal resistors, but their detection points are usually far from the core switch array, making it impossible to sense hot spot temperature rise in real time, resulting in protection delay. Especially in multiplexer (MUX) or high-bandwidth switching applications, the local temperature rise caused by instantaneous current may rapidly degrade performance, and traditional solutions are difficult to achieve accurate monitoring. Although existing attempts have been made to integrate sensors, the problem of the contradiction between electrical noise interference caused by switching action and detection accuracy has not been solved.

[0004] Therefore, a high-precision temperature detection circuit for analog switches is needed to solve the aforementioned technical problems. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the high-precision temperature detection circuits of the above and / or existing analog switches, the present invention is proposed.

[0007] Therefore, the problem this invention aims to solve is how to address the issues of protection hysteresis and inaccurate real-time monitoring of hotspot temperature rise caused by poor thermal coupling between the sensor and the core switch array in existing analog switch temperature detection methods, and how to resolve the contradiction between electrical noise interference caused by switch operation and detection accuracy.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a high-precision temperature detection circuit in an analog switch, comprising a control logic module, an analog switch module, and a temperature detection module. The control logic module simultaneously sends control signals VA to the analog switch module and the temperature detection module. The main switch transistor of the analog switch module is connected to the thermocouple of the detection unit in the temperature detection module. The temperature detection module further comprises a substrate leakage current amplification unit, a conversion unit, and an over-temperature comparison unit. The signal input terminal of the substrate leakage current amplification unit is electrically connected to the leakage current of the detection unit. The substrate leakage current amplification unit amplifies the acquired substrate leakage current and converts the current signal into a voltage signal through the conversion unit. The over-temperature comparison unit receives the converted voltage signal, compares it with a reference voltage Vref, and outputs an over-temperature detection signal to the control logic module. The control logic module controls the main switch transistor and the detection unit to turn on or off based on the received over-temperature detection signal.

[0009] Preferably, the analog switch module includes a switch transistor NM0, which is an NM0S type analog switch, and the detection unit includes a detection transistor NM1. The gates of both the switch transistor NM0 and the detection transistor NM1 receive a control signal VA from the control logic module to control the switching transistor NM0 and the detection transistor NM1 to turn on or off. The switch transistor NM0 and the detection transistor NM1 are thermocoupled.

[0010] Preferably, the substrate leakage current amplification unit includes a transistor NPN0 and a current mirror. The base of the transistor NPN0 is directly connected to the substrate of the detection transistor NM1. The detection transistor NM1 provides substrate leakage current Ib1 to the base of the transistor NPN0. The collector of the transistor NPN0 is electrically connected to the current mirror. The transistor NPN0 amplifies the substrate leakage current Ib1 in one stage.

[0011] The current mirror includes a mirror transistor PM0 and a mirror transistor PM1. The sources of the mirror transistors PM0 and PM1 are both connected to the power supply VDD, and their gates are shorted to each other. The gate of the mirror transistor PM0 is shorted to its own drain. The mirror transistors PM0 and PM1 amplify the substrate leakage current Ib1 after the first stage amplification, and generate a second stage substrate leakage current Id1 at the drain of the mirror transistor PM1.

[0012] Preferably, the conversion unit includes a fixed resistor R1, one end of which is connected to the drain of the mirror transistor PM1, and the other end of which is grounded. The secondary substrate leakage current Id1 flows through the fixed resistor R1, generating a voltage signal VC across the fixed resistor R1.

[0013] Preferably, the over-temperature comparison unit includes a comparator COMP and a reference generation module. The reference generation module inputs a reference voltage Vref to the negative input terminal of the comparator COMP, and the positive input terminal of the comparator COMP is connected to a voltage signal VC. The output terminal of the comparator COMP is an over-temperature detection signal OUT, and the over-temperature detection signal OUT provides a feedback signal to the control logic module.

[0014] Preferably, the substrate leakage current amplification unit further includes a transistor NPN1, the collector and base of which are connected in parallel with the collector and emitter of transistor NPN0, respectively. The conversion unit includes an adjustable resistor R1, one end of which is connected to the drain of the mirror transistor PM1, and the other end of which is grounded. The secondary substrate leakage current Id1 flows through the adjustable resistor R1, generating a voltage signal VC across the adjustable resistor R1.

[0015] Preferably, the analog switch module includes a switch transistor PM0, which is a PMOS type analog switch, and the detection unit includes a detection transistor PM1. The gates of both the switch transistor PM0 and the detection transistor PM1 receive a control signal VA from the control logic module to control the switching transistor PM0 and the detection transistor PM1 to turn on or off. The switch transistor PM0 and the detection transistor PM1 are thermocoupled.

[0016] Preferably, the substrate leakage current amplification unit includes a transistor PNP1, the base of the transistor PNP1 is directly connected to the substrate of the detection transistor PM1, the detection transistor PM1 provides substrate leakage current Ib1 to the transistor PNP1, the emitter of the transistor PNP1 is connected to the power supply VDD, and the transistor PNP1 outputs amplified current Ic1 at the collector due to the substrate leakage current Ib1 at the base.

[0017] Preferably, the conversion unit includes a fixed resistor R1, one end of which is connected to the collector of the transistor PNP1, and the other end of which is grounded. The amplified current Ic1 flows through the fixed resistor R1, generating a voltage signal VC across the fixed resistor R1.

[0018] The over-temperature comparison unit includes a comparator COMP and a reference generation module. The reference generation module inputs a reference voltage Vref to the negative input terminal of the comparator COMP. The positive input terminal of the comparator COMP is connected to a voltage signal VC. The output terminal of the comparator COMP is an over-temperature detection signal OUT. The over-temperature detection signal OUT provides a feedback signal to the control logic module.

[0019] Preferably, the substrate leakage current amplification unit includes a transistor PNP0, the base of the transistor PNP0 is connected to the emitter of the transistor PNP1, the emitter of the transistor PNP0 is connected to the power supply VDD, and the collector of the transistor PNP0 is connected to the collector of the transistor PNP1.

[0020] The conversion unit includes an adjustable resistor R1, one end of which is connected to the collector of a transistor PNP1, and the other end of which is grounded.

[0021] The beneficial effects of this invention are:

[0022] 1. This technical solution directly captures the real-time temperature rise of the main switch by using a thermocouple arrangement for the detection tube and the switching tube. It eliminates the need for additional substrate PN junctions or metal resistance sensors, solving the problems of detection points being far from the core switch array and poor thermal coupling in traditional solutions. This allows the temperature of the detection tube to follow the hot spot temperature rise of the main switch tube without delay or deviation, avoiding protection hysteresis and detection distortion, and significantly improving the response speed and accuracy of temperature detection. At the same time, the detection tube and the main switch tube are synchronously driven to turn on / off by control signals, ensuring that temperature detection is only effective when the switch is working, further improving the targeting and real-time performance of the detection. It is especially suitable for the precise monitoring needs of instantaneous temperature rise scenarios such as multiplexers and high-bandwidth switches.

[0023] Furthermore, the elimination of additional sensor devices significantly reduces chip area and power consumption, while improving circuit integration.

[0024] 2. This technical solution introduces a parallel compensation mechanism of transistors in the substrate leakage current amplification unit to achieve temperature drift compensation and overcurrent protection for the amplification transistor. When the temperature rises and causes the current gain of the amplification transistor to drift, the compensation transistor cancels the temperature drift through the current shunting effect, ensuring the stability of the output of the amplification unit. When the main switching transistor is overloaded and causes the substrate leakage current to surge instantaneously, the compensation transistor shunts and limits the current to avoid damage to the amplification transistor due to overcurrent, thus improving the long-term reliability of the circuit.

[0025] Meanwhile, the adjustable resistor R1 in the conversion unit enables temperature detection hysteresis. By adjusting the resistance of R1 and the shunting degree of the compensation transistor, the difference between the temperature rise trigger threshold and the temperature drop recovery threshold is set, avoiding frequent jumps (jitter) in the detection signal caused by small temperature fluctuations, and further suppressing the interference of high-frequency electrical noise generated by switching action on the detection signal. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a system block diagram of a high-precision temperature detection circuit in an analog switch.

[0028] Figure 2 This is a circuit diagram of Example 2 of a high-precision temperature detection circuit in an analog switch.

[0029] Figure 3 The circuit diagram is an optimized scheme for Example 2 of a high-precision temperature detection circuit in an analog switch.

[0030] Figure 4 This is a circuit diagram of Example 3 for a high-precision temperature detection circuit in an analog switch.

[0031] Figure 5 The circuit diagram is an optimized scheme for Example 3 of a high-precision temperature detection circuit in an analog switch.

[0032] Figure 6 This is a reference circuit diagram for generating a high-precision temperature detection circuit in an analog switch.

[0033] Figure 7 The waveform diagram for the detection operation of the high-precision temperature detection circuit in the simulation switch is shown in Example 2. Detailed Implementation

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0035] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0036] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0037] Example 1, referring to Figures 1-2This is the first embodiment of the present invention. This embodiment provides a high-precision temperature detection circuit in an analog switch, including a control logic module, an analog switch module and a temperature detection module. The control logic module sends control signals VA to the analog switch module and the temperature detection module simultaneously. The main switch tube of the analog switch module is connected to the thermocouple detection unit in the temperature detection module.

[0038] The temperature detection module also includes a substrate leakage current amplification unit, a conversion unit, and an over-temperature comparison unit. The signal input terminal of the substrate leakage current amplification unit is electrically connected to the leakage current of the detection unit. After amplifying the acquired substrate leakage current, the substrate leakage current amplification unit converts the current signal into a voltage signal through the conversion unit. The over-temperature comparison unit receives the converted voltage signal, compares it with the reference voltage Vref, and outputs an over-temperature detection signal to the control logic module. The control logic module controls the main switch and the detection unit to turn on or off based on the received over-temperature detection signal.

[0039] This circuit addresses the problems of poor thermal coupling between the sensor and the main heat source, delayed detection response, and insufficient accuracy in traditional analog switch temperature detection schemes. It utilizes the temperature correlation of the leakage current of the MOS transistor substrate to achieve high-precision detection without the need for additional temperature sensors, such as PN junctions or metal resistors. By tightly thermally coupling the detection unit with the main switching transistor of the analog switch, it directly captures the real-time temperature rise of the main switching transistor, thereby achieving fast and accurate over-temperature protection.

[0040] It should be noted that, in the prior art, according to the substrate leakage current formula of the MOSFET, the following can be obtained:

[0041]

[0042] In the formula:

[0043] Substrate leakage current of MOSFET

[0044] K1, K2: Process parameters

[0045] Voltage from drain to source of a MOSFET

[0046] Minimum Vds voltage value in the operating amplification region of the MOSFET

[0047] Drain current of MOSFET

[0048] Wherein, parameter K2 is a parameter positively correlated with temperature, and its expression is:

[0049]

[0050] in K2 is a positive coefficient, where T is the absolute temperature. Therefore, as the temperature increases, K2 increases. Decrease.

[0051] The overall working principle is as follows: The control logic module outputs a control signal VA, which simultaneously turns on the main switch and the detection unit, simulating the switch entering the working state. The main switch generates power dissipation, causing a temperature rise. The detection unit is thermally coupled with the main switch, and its substrate leakage current increases with the temperature, serving as the original temperature signal. The substrate leakage current is amplified by the amplification unit and then converted into a voltage signal VC by the conversion unit. The over-temperature comparison unit compares VC with the reference voltage Vref and outputs an over-temperature detection signal. If over-temperature is detected, the control logic module receives the alarm signal and turns off the main switch and the detection unit to achieve over-temperature protection. If the temperature returns to normal, the normal working state is restored. Thus, the temperature of the core heat source can be directly monitored through the tight thermal coupling between the detection unit and the main switch, avoiding the detection distortion caused by the separation of traditional sensors and hot spots.

[0052] Example 2, refer to Figures 2-3 As shown, this is the second embodiment of the present invention, which is based on embodiment 1. This embodiment is an over-temperature detection scheme for an NMOS analog switch. The analog switch module includes a switching transistor NM0, which is an NMOS analog switch. The detection unit includes a detection transistor NM1. The gates of both the switching transistor NM0 and the detection transistor NM1 receive control signals VA from the control logic module to control the switching transistor NM0 and the detection transistor NM1 to turn on or off. The switching transistor NM0 and the detection transistor NM1 are thermocoupled.

[0053] The switching transistor NM0, acting as the main switch in the analog switch, is responsible for turning the IN / OUT signal path on and off. The sensing transistor NM1, used for temperature detection, is thermocoupled with the switching transistor NM0, forming a tightly coupled thermal layout. This is similar to chips arranged adjacent to each other, sharing a substrate or metal heat sink, ensuring real-time temperature synchronization between the two. The control signal VA output by the control logic module is simultaneously connected to the gates of both the switching transistor NM0 and the sensing transistor NM1, causing them to turn on or off synchronously. When VA is high, both the switching transistor NM0 and the sensing transistor NM1 are off; when VA is low, both are on synchronously. This ensures that the operating state of the sensing transistor NM1 is completely consistent with that of the switching transistor NM0, providing a true and delay-free original signal source for subsequent temperature detection and solving the detection distortion problem caused by the separation of traditional sensors and hot spots.

[0054] Specifically, the substrate leakage current amplification unit includes a transistor NPN0 and a current mirror. The base of the transistor NPN0 is directly connected to the substrate of the detection transistor NM1. The detection transistor NM1 provides the substrate leakage current Ib1 to the base of the transistor NPN0. The collector of the transistor NPN0 is electrically connected to the current mirror. The transistor NPN0 amplifies the substrate leakage current Ib1 in one stage.

[0055] When the detection transistor NM1 is turned on, its drain depletion region generates a substrate leakage current Ib1 due to lattice collisions and temperature effects. This current is positively correlated with temperature; the higher the temperature, the larger Ib1 becomes. It is the original weak signal for temperature detection. Ib1 is directly connected to the base of the transistor NPN0 and serves as the base current of the transistor NPN0. According to the current amplification characteristics of the NPN transistor, the collector output current Id0 = k1 * Ib1, realizing the first-stage current amplification of the weak Ib1. The amplified collector current Id0 is output from the collector of NPN0 and flows into the subsequent current mirror, providing the input signal for the second-stage amplification.

[0056] The current mirror includes a mirror transistor PM0 and a mirror transistor PM1. The sources of both mirror transistors PM0 and PM1 are connected to the power supply VDD, and their gates are shorted to each other. The gate of mirror transistor PM0 is shorted to its own drain. Mirror transistors PM0 and PM1 amplify the substrate leakage current Ib1 after the first stage of amplification, and generate a second-stage substrate leakage current Id1 at the drain of mirror transistor PM1.

[0057] The mirror transistors PM0 and PM1 are PMOS transistors of the same type, forming a current mirror circuit. The gate and drain of the mirror transistor PM0 are shorted together, serving as the input transistor of the current mirror. The gate of the mirror transistor PM1 is shorted together with the mirror transistor PM0, serving as the output transistor. The sources of both the mirror transistors PM1 and PM0 are connected to the power supply VDD. When the current Id0 after the first stage amplification flows into the drain of the mirror transistor PM0, the proportional amplification characteristic of the current mirror is used to achieve the second stage proportional amplification of Id0, and the second stage substrate leakage current Id1 is output.

[0058] Specifically, the conversion unit includes a fixed resistor R1. One end of the fixed resistor R1 is connected to the drain of the mirror transistor PM1, and the other end of the fixed resistor R1 is grounded. The secondary substrate leakage current Id1 flows through the fixed resistor R1, generating a voltage signal VC across the fixed resistor R1.

[0059] The current Id1, after being amplified by two stages, flows through the fixed resistor R1. According to Ohm's law, a voltage drop is generated across R1. Since the lower end of R1 is grounded, the potential of the voltage signal VC directly reflects the magnitude of Id1. Since Id1 is positively correlated with Ib1, and Ib1 is positively correlated with temperature, the voltage signal VC is linearly positively correlated with temperature, thus realizing the conversion from temperature signal to voltage signal.

[0060] Specifically, the over-temperature comparison unit includes a comparator COMP and a reference generation module. The reference generation module inputs a reference voltage Vref to the negative input terminal of the comparator COMP. The positive input terminal of the comparator COMP is connected to a voltage signal VC. The output terminal of the comparator COMP is an over-temperature detection signal OUT, and the over-temperature detection signal OUT provides a feedback signal to the control logic module.

[0061] The reference generation module outputs a stable reference voltage Vref as a preset over-temperature threshold voltage, the magnitude of which corresponds to the highest operating temperature allowed by the chip. The comparator COMP compares the voltage signal VC at the positive input terminal in real time, that is, the voltage corresponding to the temperature, with the reference voltage Vref at the negative input terminal. When the chip temperature is normal, Ib1 is small → Id1 is small → VC < Vref, and the comparator COMP outputs a low level 0, indicating normal temperature. When the chip temperature is too high, Ib1 increases significantly → Id1 increases → VC > Vref, and the comparator COMP outputs a high level 1, indicating over-temperature alarm. The over-temperature detection signal OUT is fed back to the control logic module, and the control logic adjusts the VA level according to the OUT signal, turning off the switching transistor NM0 and the detection transistor NM1 to achieve over-temperature protection.

[0062] Among them, the reference generation module includes a MOS transistor PM2, a triode PNP2, and a resistor R2. The source of the MOS transistor PM2 is connected to the input voltage VIN. The gate of the MOS transistor PM2 is connected to the control voltage VA. The substrate of the MOS transistor PM2 is electrically connected to the base of the triode PNP2. The emitter of the triode PNP2 is connected to the charging input voltage VIN. The collector of the triode PNP2 is electrically connected to one end of the resistor R2. The other end of the resistor R2 is grounded. The positive input terminal of the comparator COMP is connected to the connection node of the collector of the triode PNP2 and the resistor R2.

[0063] When Id0 = Id0_max, VC = Vref, generating a reference voltage Vref that precisely corresponds to the maximum allowable charging current, replacing the traditional external reference source, ensuring that the reference voltage Vref is perfectly matched with the ratio of Ib0 and Id0 in the detection circuit, and improving the accuracy of the over-current threshold.

[0064] As an optimized technical solution of this embodiment: the substrate leakage current amplification unit further includes a triode NPN1. The collector and base of the triode NPN1 are respectively connected in parallel with the collector and emitter of the triode NPN0. The conversion unit includes a variable resistor R1. One end of the variable resistor R1 is connected to the drain of the mirror transistor PM1. The other end of the variable resistor R1 is grounded. The secondary substrate leakage current Id1 flows through the variable resistor R1, generating a voltage signal VC at both ends of the variable resistor R1.

[0065] The collector and base of transistor NPN1 are connected in parallel with the collector and emitter of transistor NPN0, respectively, forming a current shunt compensation structure. When the temperature rises, the current gain β1 of transistor NPN0 increases, causing Id0 to drift with temperature. At this time, the emitter junction voltage of transistor NPN1 decreases with temperature, and the conduction degree increases, shunting part of Id0 to keep the effective current flowing into the current mirror stable, compensating for the temperature drift of transistor NPN0. When Ib1 is instantaneously too large, such as when the main switch is overloaded, transistor NPN1 conducts to shunt current, limiting the collector current of transistor NPN0 and preventing it from being damaged by overcurrent.

[0066] The adjustable resistor R1 replaces the fixed resistor R1. By adjusting the resistance value, the conversion ratio of the voltage signal VC = Id1 × R1 is changed. Increasing the resistance value of R1 increases VC for the same Id1, lowers the over-temperature threshold, and triggers the alarm earlier. Decreasing the resistance value of R1 decreases VC for the same Id1, raises the over-temperature threshold, and triggers the alarm later. Combined with the current shunting effect of the NPN1 transistor, the threshold can be adjusted, thereby achieving the function of temperature detection hysteresis. This avoids frequent jumps in the detection signal caused by small temperature fluctuations and improves circuit stability.

[0067] Example 3, referring to Figures 4-5 This is the third embodiment of the present invention. This embodiment is based on the first two embodiments. The analog switch module includes a switch transistor PM0, which is a PMOS type analog switch. The detection unit includes a detection transistor PM1. The gates of both the switch transistor PM0 and the detection transistor PM1 receive control signals VA issued by the control logic module to control the switching transistor PM0 and the detection transistor PM1 to turn on or off. The switch transistor PM0 and the detection transistor PM1 are thermocoupled.

[0068] This embodiment is an over-temperature detection scheme for a PMOS analog switch. The switching transistor PM0 is the main switching transistor of the analog switch, responsible for turning on and off the IN / OUT signal path. The detection transistor PM1 is the temperature detection transistor, and the switching transistor PM0 is set with a thermocouple to ensure that the temperature of the two is synchronized in real time.

[0069] The control signal VAN output by the control logic module turns on the PMOS gate when it is low, and simultaneously connects to the gates of the switching transistor PM0 and the detection transistor PM1, so that the switching transistor PM0 and the detection transistor PM1 are turned on / off synchronously. When VAN is low, the switching transistor PM0 and the detection transistor PM1 are turned on, and when it is high, they are turned off, ensuring that the working state of the detection transistor PM1 is completely consistent with that of the switching transistor PM0.

[0070] Specifically, the substrate leakage current amplification unit includes a transistor PNP1. The base of transistor PNP1 is directly connected to the substrate of the detection transistor PM1. The detection transistor PM1 provides substrate leakage current Ib1 to transistor PNP1. The emitter of transistor PNP1 is connected to the power supply VDD. Due to the substrate leakage current Ib1 at the base, transistor PNP1 outputs amplified current Ic1 at the collector.

[0071] When the detection transistor PM1 is turned on, its substrate generates a substrate leakage current Ib1 due to lattice collisions and temperature effects. This current is positively correlated with temperature; the higher the temperature, the larger Ib1 becomes. It is the original weak signal for temperature detection. Ib1 is directly injected into the base of transistor PNP1 as the base current of transistor PNP1. The emitter of transistor PNP1 is connected to the power supply VDD. The base current Ib1 turns on transistor PNP1. According to the current amplification characteristics of PNP transistor, the weak current Ib1 is amplified. The amplified collector current Ic1 is output from the collector of transistor PNP1 and flows into the subsequent conversion unit.

[0072] Specifically, the conversion unit includes a fixed resistor R1. One end of the fixed resistor R1 is connected to the collector of the transistor PNP1, and the other end of the fixed resistor R1 is grounded. The amplified current Ic1 flows through the fixed resistor R1, generating a voltage signal VC across the fixed resistor R1.

[0073] The current Ic1, after being amplified by the first stage, flows out from the collector of the transistor PNP1 and through the fixed resistor R1, generating a voltage drop VC across the fixed resistor R1. Since Ic1 is positively correlated with Ib1, and Ib1 is positively correlated with temperature, VC is linearly positively correlated with temperature, thus realizing the conversion of temperature signal to voltage signal and adapting to the voltage input requirements of the subsequent comparator COMP.

[0074] The over-temperature comparison unit includes a comparator COMP and a reference generation module. The reference generation module inputs a reference voltage Vref to the negative input terminal of the comparator COMP, and a voltage signal VC is connected to the positive input terminal of the comparator COMP. The output terminal of the comparator COMP is the over-temperature detection signal OUT, which provides a feedback signal to the control logic module.

[0075] The reference generation module is consistent with the reference generation module in Embodiment 2 in principle, and will not be described in detail here. The reference generation module outputs a stable reference voltage Vref as a preset over-temperature threshold voltage, the magnitude of which corresponds to the highest allowable operating temperature of the chip. The comparator COMP compares the VC at the positive input terminal with the reference voltage Vref at the negative input terminal in real time.

[0076] When the chip temperature is normal, Ib1 is small → Ic1 is small → VC < Vref, and the comparator COMP outputs a low level 0, indicating that the temperature is normal. When the chip temperature is too high, Ib1 increases significantly → Ic1 increases → VC > Vref, and the comparator COMP outputs a high level 1, indicating over-temperature alarm. The over-temperature detection signal OUT is fed back to the control logic module, and the control logic adjusts the VAN level according to the OUT signal, turns off the switch transistor PM0 and the detection transistor PM1, realizes over-temperature protection, ensures that the analog switch is turned off in time when overheated, and avoids device damage.

[0077] As an optimized technical solution of this embodiment: The substrate leakage current amplification unit includes a triode PNP0. The base of the triode PNP0 is connected to the emitter of the triode PNP1. The emitter of the triode PNP0 is connected to the power supply VDD, and the collector of the triode PNP0 is connected to the collector of the triode PNP1.

[0078] The conversion unit includes an adjustable resistor R1. One end of the adjustable resistor R1 is connected to the collector of the triode PNP1, and the other end of the adjustable resistor R1 is grounded.

[0079] The triode PNP0 and the triode PNP1 form a complementary parallel structure. When the temperature rises, the current gain β1 of the triode PNP1 increases, resulting in the drift of Ic1 with temperature. At this time, the emitter junction voltage of the triode PNP0 decreases with temperature, and the conduction degree increases, shunting part of Ic1, so that the effective current flowing into the adjustable resistor R1 remains stable, compensating for the temperature drift of the triode PNP1. When Ib1 is instantaneously too large, such as when the main switch transistor is overloaded, the triode PNP0 conducts and shunts, limiting the collector current of PNP1 and avoiding its overcurrent damage, improving the circuit reliability, ensuring the stability of the output of the amplification unit, and improving the detection accuracy.

[0080] The adjustable resistor R1 replaces the fixed resistor R1. By adjusting the resistance value, the conversion ratio of VC = Ic1 × R1 is changed. Increasing the resistance value of the adjustable resistor R1, VC increases under the same Ic1, and the over-temperature threshold decreases, triggering the alarm earlier. Decreasing the resistance value of R1, VC decreases under the same Ic1, and the over-temperature threshold increases, triggering the alarm later.配合三极管PNP0的分流作用,可实现阈值调节:升温时,调大可调电阻R1并减小三极管PNP0分流,降温时,调小可调电阻R1并增大三极管PNP0分流,低放大倍数,形成温度检测迟滞。With the shunting effect of the triode PNP0, the threshold adjustment can be realized: when the temperature rises, the adjustable resistor R1 is adjusted larger and the shunting of the triode PNP0 is reduced; when the temperature drops, the adjustable resistor R1 is adjusted smaller and the shunting of the triode PNP0 is increased, with a low magnification, forming a temperature detection hysteresis.

[0081] 如 Figure 7 所示,基于实施例2的技术方案,实施例2的NMOS型模拟开关中,温度升高时各关键电信号的变化趋势及过温触发逻辑,各曲线的变化趋势与电路工作原理直接对应。As shown, based on the technical solution of Embodiment 2, in the NMOS-type analog switch of Embodiment 2, the change trends of each key electrical signal and the over-temperature trigger logic when the temperature rises, and the change trends of each curve directly correspond to the circuit working principle.

[0082] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A high-precision temperature detection circuit for analog switches, characterized in that: It includes a control logic module, an analog switch module, and a temperature detection module. The control logic module simultaneously sends a control signal VA to the analog switch module and the temperature detection module. The main switch tube of the analog switch module is connected to the thermocouple detection unit in the temperature detection module. The temperature detection module further includes a substrate leakage current amplification unit, a conversion unit, and an over-temperature comparison unit. The signal input terminal of the substrate leakage current amplification unit is electrically connected to the leakage current of the detection unit. The substrate leakage current amplification unit amplifies the collected substrate leakage current and converts the current signal into a voltage signal through the conversion unit. The over-temperature comparison unit receives the converted voltage signal, compares it with the reference voltage Vref, and outputs an over-temperature detection signal to the control logic module. The control logic module controls the main switch and the detection unit to turn on or off based on the received over-temperature detection signal.

2. The high-precision temperature detection circuit in the analog switch as described in claim 1, characterized in that: The analog switch module includes a switch transistor NM0, which is an NM0S type analog switch. The detection unit includes a detection transistor NM1. The gates of both the switch transistor NM0 and the detection transistor NM1 receive a control signal VA from the control logic module to control the switching transistor NM0 and the detection transistor NM1 to turn on or off. The switch transistor NM0 and the detection transistor NM1 are thermocoupled.

3. The high-precision temperature detection circuit in the analog switch as described in claim 2, characterized in that: The substrate leakage current amplification unit includes a transistor NPN0 and a current mirror. The base of the transistor NPN0 is directly connected to the substrate of the detection transistor NM1. The detection transistor NM1 provides the substrate leakage current Ib1 to the base of the transistor NPN0. The collector of the transistor NPN0 is electrically connected to the current mirror. The transistor NPN0 amplifies the substrate leakage current Ib1 in one stage. The current mirror includes a mirror transistor PM0 and a mirror transistor PM1. The sources of the mirror transistors PM0 and PM1 are both connected to the power supply VDD, and their gates are shorted to each other. The gate of the mirror transistor PM0 is shorted to its own drain. The mirror transistors PM0 and PM1 amplify the substrate leakage current Ib1 after the first stage amplification, and generate a second stage substrate leakage current Id1 at the drain of the mirror transistor PM1.

4. The high-precision temperature detection circuit in the analog switch as described in claim 3, characterized in that: The over-temperature comparison unit includes a comparator COMP and a reference generation module. The reference generation module inputs a reference voltage Vref to the negative input terminal of the comparator COMP. The positive input terminal of the comparator COMP is connected to a voltage signal VC. The output terminal of the comparator COMP is an over-temperature detection signal OUT. The over-temperature detection signal OUT provides a feedback signal to the control logic module.

5. The high-precision temperature detection circuit in the analog switch as described in claim 4, characterized in that: The conversion unit includes a fixed resistor R1. One end of the fixed resistor R1 is connected to the drain of the mirror transistor PM1, and the other end of the fixed resistor R1 is grounded. The leakage current Id1 of the secondary substrate flows through the fixed resistor R1, generating a voltage signal VC across the fixed resistor R1.

6. The high-precision temperature detection circuit in the analog switch as described in claim 4, characterized in that: The substrate leakage current amplification unit also includes a transistor NPN1, the collector and base of which are connected in parallel with the collector and emitter of transistor NPN0, respectively. The conversion unit includes an adjustable resistor R1, one end of which is connected to the drain of the mirror transistor PM1, and the other end of which is grounded. The secondary substrate leakage current Id1 flows through the adjustable resistor R1, generating a voltage signal VC across the adjustable resistor R1.

7. The high-precision temperature detection circuit in the analog switch as described in claim 1, characterized in that: The analog switch module includes a switch transistor PM0, which is a PMOS type analog switch. The detection unit includes a detection transistor PM1. The gates of both the switch transistor PM0 and the detection transistor PM1 receive a control signal VA from the control logic module to control the switching transistor PM0 and the detection transistor PM1 to turn on or off. The switch transistor PM0 and the detection transistor PM1 are thermocoupled.

8. The high-precision temperature detection circuit in the analog switch as described in claim 7, characterized in that: The substrate leakage current amplification unit includes a transistor PNP1. The base of the transistor PNP1 is directly connected to the substrate of the detection transistor PM1. The detection transistor PM1 provides a substrate leakage current Ib1 to the transistor PNP1. The emitter of the transistor PNP1 is connected to the power supply VDD. Due to the substrate leakage current Ib1 at the base, the transistor PNP1 outputs an amplified current Ic1 at the collector.

9. The high-precision temperature detection circuit in the analog switch as described in claim 8, characterized in that: The conversion unit includes a fixed resistor R1. One end of the fixed resistor R1 is connected to the collector of the transistor PNP1, and the other end of the fixed resistor R1 is grounded. The amplified current Ic1 flows through the fixed resistor R1, generating a voltage signal VC across the fixed resistor R1. The over-temperature comparison unit includes a comparator COMP and a reference generation module. The reference generation module inputs a reference voltage Vref to the negative input terminal of the comparator COMP. The positive input terminal of the comparator COMP is connected to a voltage signal VC. The output terminal of the comparator COMP is an over-temperature detection signal OUT. The over-temperature detection signal OUT provides a feedback signal to the control logic module.

10. The high-precision temperature detection circuit in the analog switch as described in claim 8, characterized in that: The substrate leakage current amplification unit includes a transistor PNP0, the base of which is connected to the emitter of a transistor PNP1, the emitter of which is connected to the power supply VDD, and the collector of which is connected to the collector of which is connected to the collector of which is connected to the collector of which is connected to the collector of which is connected to the collector of the transistor PNP1. The conversion unit includes an adjustable resistor R1, one end of which is connected to the collector of a transistor PNP1, and the other end of which is grounded.

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