TPS readout circuit

Abstract

The invention discloses a TPS reading circuit. In order to improve the precision after TPS quantization, the TPS reading circuit comprises a TPS, a multiplexer, an ADC, a reference voltage generation circuit and a digital signal processing module, when the multiplexer outputs a non-TPS analog signal to the ADC, the digital signal processing module outputs a fixed reference voltage control code to the reference voltage generation circuit, so that the reference voltage generation circuit outputs a stable reference voltage; when the multiplexer outputs a TPS analog signal to the ADC, the digital signal processing module obtains a target reference voltage control code corresponding to a digital output code according to the received digital output code, and sends the target reference voltage control code to the reference voltage generation circuit; the reference voltage generation circuit applies the target reference voltage control code and outputs a target reference voltage corresponding to the target reference voltage control code to the ADC. According to the invention, not only is curvature compensation of the TPS analog signal realized, but also the universality of the ADC is maintained. The invention is suitable for the integrated circuit field.

Description

Technical Field

[0001] The present invention relates to the field of integrated circuits, and in particular to a TPS readout circuit. Background Art

[0002] Temperature is one of the most common physical quantities in nature. Temperature sensors are widely used in modern industry, medical treatment, transportation, smart home and other fields. According to the degree of integration, temperature sensors (TPS) can be divided into two categories: discrete and integrated. Discrete sensors include thermocouples, thermistors and resistance temperature detectors. These sensors require an external analog to digital converter (ADC) to digitize the temperature data. Therefore, they are large in size and high in cost, and are not suitable for scenarios with high requirements for integration.

[0003] With the development of integrated circuit technology, integrated complementary metal oxide semiconductor (CMOS) temperature sensors are widely used in on-chip systems, industrial Internet of Things, wireless sensor networks and other fields because of their small size, easy system integration, low cost, and ability to be integrated with ADC and directly output digital signals.

[0004] The shrinking of integrated circuit process nodes and the increase in circuit integration have led to an increasingly serious problem of chip self-heating. Therefore, many chip designs require on-chip temperature sensors for real-time temperature detection to adjust the frequency and voltage, and achieve dynamic adjustment of chip performance and overheating protection. Among CMOS temperature sensors, bipolar junction transistor (BJT) temperature sensors have become the most widely used sensors due to their good linearity, low power consumption, and simple structure. In addition to the temperature sensing device, the integrated CMOS temperature sensor also includes the bias circuit required by the temperature sensing device and the analog-to-digital converter that further digitizes the electrical signal. In actual chip design, the area and power consumption of the readout circuit are usually much larger than the temperature sensing device itself. Therefore, the performance and cost of CMOS temperature sensors depend to a large extent on the design of the sensor interface circuit.

[0005] Figure 1 The schematic diagram of the analog-to-digital conversion scheme of TPS in the traditional scheme is shown. The analog signal generated by TPS is sent to the ADC, and the digital output code is obtained after analog-to-digital conversion in the ADC. The ADC requires a temperature-independent reference voltage V' ref , which can be obtained by using the bandgap reference voltage V bg The general voltage domain ADC quantizes the signal into a digital output code.

[0006] At the same time, the ADC is also used to convert the output signals of other sensors, such as detecting battery voltage and other low-frequency measurement signals. By inputting multiplexed sensor signals into the ADC through a multiplexer, the chip area can be reduced and the cost can be reduced.

[0007] Figure 2 The schematic diagram of the TPS analog-to-digital conversion solution based on a dedicated high-precision transistor is shown. This solution usually uses a customized dedicated voltage domain ADC interface, which is different from the traditional solution to generate a temperature-independent reference voltage V' ref , the customized voltage domain ADC requires an equivalent reference voltage V with a slightly positive temperature coefficient characteristic ref_ptat , in order to achieve curvature compensation of the sensor output voltage.

[0008] The equivalent reference voltage Vref_ptat is usually obtained by using the base and emitter voltage difference V between the transistors in the TPS. be And the base-emitter voltage difference ΔV of the two transistors be This will limit the versatility of the ADC. If the ADC also needs to process the sensor signals of other channels, the signal processing of other channels will be more difficult. Summary of the invention

[0009] In order to alleviate or partially alleviate the above technical problems, the solution of the present invention is as follows: A TPS readout circuit comprises a TPS, a multiplexer and an ADC, wherein the TPS readout circuit further comprises a reference voltage generating circuit and a digital signal processing module; the TPS outputs a TPS analog signal to the multiplexer, and outputs a bandgap reference voltage to the reference voltage generating circuit; the multiplexer receives the TPS analog signal and the non-TPS analog signal; the ADC receives the reference voltage output by the reference voltage generating circuit, and generates a digital output code; when the multiplexer outputs the non-TPS analog signal to the ADC, the digital signal processing module outputs a fixed reference voltage control code to the reference voltage generating circuit, so that the reference voltage generating circuit outputs a stable reference voltage; when the multiplexer outputs the TPS analog signal to the ADC, the digital signal processing module obtains a target reference voltage control code corresponding to the digital output code according to the received digital output code, and sends the target reference voltage control code to the reference voltage generating circuit, and the reference voltage generating circuit applies the target reference voltage control code and outputs a target reference voltage corresponding to the target reference voltage control code to the ADC.

[0010] Furthermore, according to the measurement result of the TPS analog signal output by the TPS regarding the temperature, the correspondence between the digital output code and the target reference voltage control code is stored in the digital signal processing module; the digital signal processing module obtains the target reference voltage control code corresponding to the digital output code according to the received digital output code and the correspondence.

[0011] Further, when the multiplexer outputs the TPS analog signal to the ADC, the target reference voltage control code or the target reference voltage is variable.

[0012] Furthermore, the reference voltage generating circuit includes a PMOS tube, a first resistor, a second resistor and a first comparator.

[0013] Furthermore, the first resistor and the second resistor are both connected to a first node; the first comparator receives the bandgap reference voltage and receives the voltage of the first node.

[0014] Furthermore, the output of the first comparator is connected to the gate of the PMOS tube.

[0015] Furthermore, the source of the PMOS tube is connected to the device operating voltage, the drain of the PMOS tube is connected to the first end of the first resistor; the second end of the first resistor is connected to the first node, the first node is also connected to the first end of the second resistor, and the second end of the second resistor is grounded.

[0016] Furthermore, the first end of the first resistor serves as an output node to output a reference voltage.

[0017] Furthermore, the first resistor is an adjustable resistor, and different resistance values ​​are obtained by applying different reference voltage control codes to the first resistor.

[0018] Furthermore, in the corresponding relationship between the digital output code and the target reference voltage control code, the digital output codes in the same numerical interval correspond to the same target reference voltage control code.

[0019] The technical solution of the present invention has the following beneficial technical effects: Under the premise of not affecting the ADC as a general ADC, the curvature compensation of the TPS analog signal is realized to achieve high-precision quantization output.

[0020] In addition, other beneficial effects of the present invention will be mentioned in the specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of a TPS readout circuit in the prior art; Figure 2 It is a schematic diagram of a high-precision TPS readout circuit in the prior art; Figure 3 It is a schematic diagram of the TPS readout circuit of the present invention; Figure 4 This is a circuit diagram of a reference voltage generation circuit in the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] In order to clearly describe the technical solutions of the embodiments of the present invention, in the embodiments of the present invention, words such as "first" and "second" are used to distinguish the same or similar items with substantially the same functions and effects. Those skilled in the art can understand that words such as "first" and "second" do not limit the quantity and execution order.

[0024] Figure 3 The TPS readout circuit diagram of the present invention is shown in FIG. The TPS outputs a TPS analog signal, which is used as one of the input signals of the multiplexer. Through configuration, the TPS analog signal can be used as the output signal of the multiplexer.

[0025] In addition, the multiplexer also receives sensor signal 1 and sensor signal 2 from other types of sensors. Sensor signal 1 and sensor signal 2 may be various low-frequency acquisition type signals, such as battery voltage signals and other sensor signals outside the chip, which often do not require real-time measurement.

[0026] Through a multiplexer, multiple sensors can share one ADC, reducing silicon cost and power consumption.

[0027] Furthermore, the TPS analog signal is a voltage signal.

[0028] When the multiplexer is configured to output a non-TPS analog signal, such as sensor signal 1 or sensor signal 2, the ADC receives a fixed reference voltage V ref , which can be achieved by configuring the reference voltage generation circuit. For example, with a fixed reference voltage control code VREF_CTL <n:0>To control the reference voltage generating circuit so that the reference voltage output by the reference voltage generating circuit is stable.

[0029] In the above working mode, the ADC performs analog-to-digital conversion on the output signal of the multiplexer and generates a digital output code just like a regular ADC.

[0030] When the multiplexer is configured to output the TPS analog signal, the ADC also obtains a digital output code and sends the digital output code to the digital signal processing module.

[0031] The digital signal processing module generates a corresponding reference voltage control code VREF_CTL according to the digital output code <n:0>, where N is a positive integer. Different digital output codes correspond to different reference voltage control codes VREF_CTL <n:0>.

[0032] In other words, in the current mode, the ADC reference voltage V ref It no longer has a fixed voltage value, but changes continuously with the digital output code of the ADC.

[0033] Furthermore, when the digital output code of the ADC belongs to a certain value interval, it corresponds to the same reference voltage control code VREF_CTL <n:0>.

[0034] Furthermore, the digital output code of the ADC is divided into a plurality of value intervals in all codeword spaces, and each value interval corresponds to a specific target reference voltage control code.

[0035] For the same batch of chips, the corresponding relationship between the numerical value interval and the reference voltage control code can be obtained by means of sampling measurement.

[0036] During sampling measurement, for different temperature intervals, the voltage value of the TPS analog signal output by the TPS in the chip has different slopes with respect to temperature. Through measurement, the division method of the temperature interval can be obtained, that is, the temperature intervals with basically the same slope can be artificially divided into the same temperature interval.

[0037] For ADC, different slopes have a corresponding target reference voltage V ref , that is, there is a corresponding target reference voltage control code. Through the above sampling measurement, the corresponding relationship between the digital output code representing the temperature and the target reference voltage control code can be obtained.

[0038] The digital signal processing module receives the digital output code, and then obtains the target reference voltage control code that should be applied to the reference voltage generating circuit according to the corresponding relationship between the digital output code and the target reference voltage control code.

[0039] The digital signal processing module sends the target reference voltage control code to the reference voltage generation circuit and applies it to the reference voltage generation circuit to generate the target reference voltage V ref .

[0040] In other words, according to the measurement result of the TPS analog signal output by the TPS about the temperature, the correspondence between the digital output code and the target reference voltage control code is stored in the digital signal processing module; the digital signal processing module obtains the target reference voltage control code corresponding to the digital output code according to the received digital output code and the correspondence.

[0041] That is, when the multiplexer is configured to output the TPS analog signal, the present invention achieves this by matching the temperature and the reference voltage V applied to the ADC. ref , realizing curvature compensation of TPS analog signal, making the digitized TPS analog signal have higher accuracy without affecting the versatility of ADC, and maintaining the versatility of ADC without affecting the difficulty of processing other types of sensor signals.

[0042] Figure 4 The reference voltage generation circuit of the present invention includes a P-channel Metal Oxide Semiconductor (PMOS) tube P1, a first resistor, a second resistor and a first comparator, wherein the first resistor is an adjustable resistor and can be adjusted by applying a reference voltage control code VREF_CTL. <n:0>The resistance value is adjusted, and the first resistor and the second resistor are both connected to the first node.

[0043] The first comparator receives the bandgap reference voltage V bg , and also receives the voltage of the first node. The output of the first comparator is connected to the gate of the PMOS tube P1. The source of the PMOS tube P1 is connected to the device operating voltage (Voltage Drain-to-Drain, VDD), the drain of the PMOS tube P1 is connected to the first end of the first resistor R1, the second end of the first resistor R1 is connected to the first node, the first node is also connected to the first end of the second resistor, and the second end of the second resistor is grounded.

[0044] In addition, the first end of the first resistor R1 serves as an output node to output a reference voltage V ref .

[0045] In order to better illustrate the present invention, numerous specific details are provided in the above specific embodiments. It should be understood by those skilled in the art that the present invention can also be implemented without certain specific details. In some examples, methods, means, components and circuits well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present invention.

[0046] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A TPS readout circuit, comprising a TPS, a multiplexer and an ADC, characterized in that: The TPS readout circuit also includes a reference voltage generation circuit and a digital signal processing module; The TPS outputs a TPS analog signal to a multiplexer, and outputs a bandgap reference voltage to a reference voltage generating circuit; The multiplexer receives TPS analog signals and non-TPS analog signals; The ADC receives a reference voltage output by a reference voltage generating circuit and generates a digital output code; When the multiplexer outputs a non-TPS analog signal to the ADC, the digital signal processing module outputs a fixed reference voltage control code to the reference voltage generating circuit, so that the reference voltage generating circuit outputs a stable reference voltage; When the multiplexer outputs the TPS analog signal to the ADC, the digital signal processing module obtains the target reference voltage control code corresponding to the digital output code based on the received digital output code, and sends the target reference voltage control code to the reference voltage generation circuit. The reference voltage generation circuit applies the target reference voltage control code and outputs the target reference voltage corresponding to the target reference voltage control code to the ADC.

2. The TPS readout circuit according to claim 1, characterized in that: According to the measurement result of the TPS analog signal output by the TPS about the temperature, the corresponding relationship between the digital output code and the target reference voltage control code is stored in the digital signal processing module; The digital signal processing module obtains a target reference voltage control code corresponding to the digital output code according to the received digital output code and the corresponding relationship.

3. The TPS readout circuit according to claim 2, characterized in that: When the multiplexer outputs the TPS analog signal to the ADC, the target reference voltage control code or the target reference voltage is variable.

4. The TPS readout circuit according to claim 3, characterized in that: The reference voltage generating circuit comprises a PMOS tube, a first resistor, a second resistor and a first comparator.

5. The TPS readout circuit according to claim 4, characterized in that: A first resistor and a second resistor are both connected to a first node; The first comparator receives the bandgap reference voltage and receives the voltage of the first node.

6. The TPS readout circuit according to claim 5, characterized in that: The output of the first comparator is connected to the gate of the PMOS tube.

7. The TPS readout circuit according to claim 6, characterized in that: The source of the PMOS tube is connected to the device operating voltage, and the drain of the PMOS tube is connected to the first end of the first resistor; The second end of the first resistor is connected to the first node, the first node is also connected to the first end of the second resistor, and the second end of the second resistor is grounded.

8. The TPS readout circuit according to claim 7, characterized in that: The first end of the first resistor serves as an output node to output a reference voltage.

9. The TPS readout circuit according to claim 8, characterized in that: The first resistor is an adjustable resistor, and different resistance values ​​are obtained by applying different reference voltage control codes to the first resistor.

10. The TPS readout circuit according to claim 9, characterized in that: In the corresponding relationship between the digital output code and the target reference voltage control code, the digital output codes in the same numerical interval correspond to the same target reference voltage control code.

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