TPS digital-to-analog conversion circuit

Abstract

The invention discloses a TPS digital-to-analog conversion circuit. In order to improve the precision of converting a TPS analog signal by an ADC, the TPS digital-to-analog conversion circuit of the present invention comprises: a TPS for outputting a TPS analog signal as one of the input signals of a multiplexer; the multiplexer is used for receiving multiple paths of sensing signals, and an output signal of the multiplexer is used as an input signal of the ADC; the hysteresis comparator receives the TPS analog signal and a first comparison voltage output by the reference voltage generation circuit, and sends an output signal of the hysteresis comparator to the reference voltage generation circuit; a reference voltage generating circuit which receives the band-gap reference voltage and the output signal of the hysteresis comparator, generates a first comparison voltage as one of the input signals of the hysteresis comparator, and generates a reference voltage; and the ADC is used for receiving the reference voltage and outputting a digital output code according to the reference voltage. According to the invention, the curvature compensation of the TPS analog signal is realized, and the ADC has good versatility. 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 digital-to-analog conversion 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 discrete and integrated types. Discrete sensors use discrete devices such as thermocouples, thermistors, and resistance temperature detectors. They require an external analog to digital converter (ADC) to digitize temperature data. Therefore, they are large in size and high in cost, and are not suitable for scenarios with high integration requirements.

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

[0004] As the process nodes of integrated circuits shrink, the integration of circuits continues to increase, resulting in increasingly serious chip self-heating problems. Therefore, many chip designs require on-chip temperature sensors for real-time temperature detection, feedback adjustment of frequency and voltage, and dynamic adjustment of chip performance and overheating protection.

[0005] Among CMOS temperature sensors, bipolar junction transistor (BJT) temperature sensors are 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, so the performance and cost of CMOS temperature sensors depend to a large extent on the design of the sensor interface circuit.

[0006] Figure 1 The schematic diagram of the TPS analog-to-digital conversion scheme in the traditional scheme is shown. The TPS analog signal generated by the TPS is sent to the ADC, and the digital output code is obtained after analog-to-digital conversion in the ADC.

[0007] The ADC requires a temperature-independent reference voltage V ref , reference voltage V refThis can be achieved by using the bandgap reference voltage V bg It is obtained by the reference voltage generating circuit and is quantized and output as a digital output code after passing through the universal voltage domain ADC in the ADC.

[0008] At the same time, since the ADC is also used to convert the sensor signal 1 and sensor signal 2 output by other sensors, such as detecting the battery voltage and other low-frequency measurement signals outside the chip, the chip area and cost can be reduced by using the multiplexer to use multiple sensor signals as the input of the ADC.

[0009] Figure 2 The schematic diagram of the TPS analog-to-digital conversion solution based on a dedicated high-precision transistor is shown. This solution generally uses a customized dedicated voltage domain ADC interface, and unlike the traditional solution, it generates 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 , which is used to realize curvature compensation of sensor output voltage.

[0010] Equivalent reference voltage V ref_ptat Usually, the voltage difference between the base and emitter of the transistor in TPS is used. be The base and emitter voltage difference of the two transistors is V be The difference △V be However, this will limit the versatility of the ADC. If the ADC also processes the sensor signals of other channels, the signal processing of other channels will be more difficult. Summary of the invention

[0011] In order to alleviate or partially alleviate the above technical problems, the solution of the present invention is as follows: A TPS digital-to-analog conversion circuit comprises: a TPS, which outputs a TPS analog signal as one of the input signals of a multiplexer; a multiplexer, which receives multi-channel sensor signals, and the output signal of the multiplexer is used as the input signal of an ADC; a hysteresis comparator, which receives the TPS analog signal and a first comparison voltage output by a reference voltage generating circuit, and sends the output signal of the hysteresis comparator to the reference voltage generating circuit; a reference voltage generating circuit, which receives a bandgap reference voltage and the output signal of the hysteresis comparator, generates a first comparison voltage as one of the input signals of the hysteresis comparator, and generates a reference voltage; and an ADC, which receives the reference voltage and outputs a digital output code according to the reference voltage.

[0012] Further, when the multiplexer is configured to select the TPS analog signal as the output signal of the multiplexer, the reference voltage generating circuit outputs different first comparison voltages to obtain a target first comparison voltage closest to the voltage of the TPS analog signal, and determines the reference voltage based on the target first comparison voltage.

[0013] Further, the reference voltage generating circuit obtains different first comparison voltages by applying different first comparison voltage control codes.

[0014] Further, when a target first comparison voltage closest to the voltage of the TPS analog signal is obtained, the first comparison voltage control code being applied by the reference voltage generating circuit is a first comparison voltage target control code; based on the first comparison voltage target control code, a reference voltage target control code is obtained; the reference voltage generating circuit generates the reference voltage by applying the reference voltage target control code.

[0015] Further, when the multiplexer is configured to select the non-TPS analog signal as the output signal of the multiplexer, the reference voltage generating circuit fixes the reference voltage by applying a fixed reference voltage control code.

[0016] Furthermore, the first comparison voltage control code is used to control the size of an adjustable resistor in a reference voltage generating circuit.

[0017] Further, the reference voltage target control code is obtained according to the first comparison voltage target control code, specifically, the reference voltage target control code is obtained by querying in a reference voltage generating circuit according to the first comparison voltage target control code.

[0018] Further, a correspondence between the first comparison voltage target control code and the reference voltage target control code is stored in a digital circuit in the reference voltage generating circuit.

[0019] Further, the bandgap reference voltage is generated by a TPS.

[0020] Furthermore, obtaining a target first comparison voltage closest to the voltage of the TPS analog signal by outputting different first comparison voltages through a reference voltage generation circuit is achieved through a successive approximation step.

[0021] The technical solution of the present invention has the following beneficial technical effects: It not only realizes the curvature compensation of TPS output voltage, making the digital output accuracy of TPS relatively high, but also reduces the difficulty of information processing after ADC converts the sensor signals of other input channels, making ADC have good versatility, thereby avoiding the waste of silicon cost and reducing power consumption.

[0022] In addition, other beneficial effects of the present invention will be mentioned in the specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the TPS analog-to-digital conversion scheme in the traditional scheme; Figure 2This is a schematic diagram of the TPS analog-to-digital conversion solution based on a dedicated high-precision transistor; Figure 3 This is the block diagram of the TPS digital-to-analog conversion circuit; Figure 4 It is an analog circuit diagram in a reference voltage generating circuit; Figure 5 This is a schematic diagram of the relationship between TPS analog signal voltage and temperature. DETAILED DESCRIPTION

[0024] 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.

[0025] 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.

[0026] Figure 3 This is a block diagram of the TPS digital-to-analog conversion circuit. The TPS digital-to-analog conversion circuit includes a TPS, a hysteresis comparator, a reference voltage generation circuit, a multiplexer, and an ADC, wherein the reference voltage generation circuit includes an analog circuit and a digital circuit, and the digital circuit is a digital circuit designed according to the control logic.

[0027] The multiplexer can receive multiple input signals, such as sensor signal 1 and sensor signal 2. These sensor signals may not be sensor signals from TPS, but may be sensor signals from other types of sensors.

[0028] Furthermore, the multiplexer receives the TPS analog signal output by the TPS. The TPS analog signal can be the voltage difference V between the base and emitter of the transistor in the TPS. be , or the voltage difference between the base and emitter of the two transistors V be The difference △V be , or other voltage signals related to temperature.

[0029] Optionally, the TPS also outputs a bandgap reference voltage V bg To the reference voltage generation circuit.

[0030] The hysteresis comparator receives the TPS analog signal and a first comparison voltage COMP output by the reference voltage generating circuit.

[0031] For example, the TPS analog signal is connected to the non-inverting input terminal of the hysteresis comparator, and the first comparison voltage COMP is connected to the inverting input terminal of the hysteresis comparator. The output signal of the hysteresis comparator is transmitted to the reference voltage generating circuit, especially the digital circuit in the reference voltage generating circuit.

[0032] The reference voltage V output by the reference voltage generation circuit ref , transmitted to ADC as the reference voltage of ADC. ADC receives the output signal of the multiplexer, which can be the TPS analog signal, or the sensor signal 1, sensor signal 2 or other sensor signals. ADC quantizes the multiplexer output signal into a digital output code.

[0033] Figure 4 This is an analog circuit diagram in the reference voltage generation circuit. The source of P-channel Metal Oxide Semiconductor (PMOS) tube P1 and PMOS tube P2 are both connected to the device operating voltage (Voltage Drain-to-Drain, VDD).

[0034] The gates of the PMOS tubes P1 and P2 are both connected to the output of the first comparator, and the non-inverting input of the first comparator is connected to the bandgap reference voltage V bg .

[0035] The drain of the PMOS tube P1 is connected to the first end of the third resistor R3 , and the second end of the third resistor R3 is connected to the first end of the second resistor R2 .

[0036] The drain of the PMOS transistor P2 is connected to the first end of the fourth resistor R4, and the second end of the fourth resistor R4 is connected to the first end of the first resistor R1. The second end of the second resistor R2 and the second end of the first resistor R1 are both grounded.

[0037] In addition, the first resistor R1 and the third resistor R3 are adjustable resistors, which are respectively controlled by the first comparison voltage control code COMP_CTL <m:0>And the reference voltage control code VREF_CTL <n:0>, where M and N are both positive integers.

[0038] The first end of the third resistor R3 is used as a reference voltage V ref The second end of the third resistor R3 is connected to the inverting input terminal of the first comparator. The second end of the fourth resistor R4 is used as the output node of the first comparison voltage COMP.

[0039] When the multiplexer selects the TPS analog signal as the multiplexer output signal, the present invention uses the successive approximation (SA) method to adjust and control the first comparison voltage control code COMP_CTL <m:0>The value of the first resistor R1 is adjusted to obtain different first comparison voltages COMP.

[0040] Different first comparison voltages COMP and TPS analog signals are compared in the hysteresis comparator to obtain corresponding comparison results.

[0041] For example, if the first comparison voltage control code COMP_CTL is controlled <m:0>When it is "13", the hysteresis comparator outputs a high level, and controls the first comparison voltage control code COMP_CTL <m:0>When it is "14", the hysteresis comparator outputs a low level, that is, the output signal of the hysteresis comparator is reversed. At this time, it can be considered that the control code COMP_CTL of the first comparison voltage is controlled. <m:0>The first comparison voltage COMP corresponding to "14" is the target first comparison voltage, and the first comparison voltage control code COMP_CTL is fixed. <m:0>The value of the TPS analog signal voltage can be represented by the first comparison voltage target control code obtained by the successive approximation step.

[0042] In the present invention, a reference voltage generating circuit outputs different first comparison voltages to obtain a target first comparison voltage or / and a first comparison voltage target control code that is closest to the voltage of the TPS analog signal.

[0043] Furthermore, in the successive approximation step, the output result of the hysteresis comparator is stored in a register.

[0044] Furthermore, the digital circuit in the reference voltage generating circuit includes the register.

[0045] Figure 5 It is a schematic diagram of the relationship between the TPS analog signal voltage and temperature. For a batch of chips containing TPS, they are regarded as having the same TPS analog signal voltage and temperature relationship curve in the present invention. The TPS analog signal voltage and temperature relationship curve can be obtained by actual measurement of one or several chips. For example, the temperature change range can be from -40 degrees to 125 degrees.

[0046] For example, in the first temperature interval, the TPS analog signal voltage has a slope k with respect to temperature. 1 In the second temperature range, the TPS analog signal voltage has a slope k with respect to temperature 2 In the third temperature range, the TPS analog signal voltage has a slope k with respect to temperature. 3 In the fourth temperature range, the TPS analog signal voltage has a slope k with respect to temperature 4 .

[0047] For different slopes of the TPS analog signal voltage with respect to temperature, different reference voltages V ref In other words, the aforementioned successive approximation method can obtain the value of the TPS analog signal voltage. Thanks to the aforementioned actual measurement, after obtaining the value of the TPS analog signal voltage, the temperature value can be obtained, and the temperature value corresponds to the slope of the different TPS analog signal voltages with respect to temperature. In other words, after obtaining the value of the TPS analog signal voltage through the successive approximation steps, the corresponding reference voltage V ref .

[0048] In order to generate a corresponding reference voltage V in the analog circuit in the reference voltage generating circuit ref A corresponding reference voltage control code VREF_CTL can be generated by the digital circuit in the reference voltage generation circuit <n:0>, and acts on the third resistor R3.

[0049] In other words, if the first comparison voltage target control code corresponding to the value of the TPS analog signal voltage is obtained through the successive approximation steps, and the first comparison voltage target control code corresponds to a reference voltage control code VREF_CTL <n:0>, i.e., the reference voltage target control code. By means of a lookup table, an array, etc., after obtaining the first comparison voltage target control code, the corresponding reference voltage target control code can be obtained (e.g., through a query step) in the digital circuit in the reference voltage generating circuit, and the reference voltage target control code can be applied to the third resistor R3.

[0050] Optionally, the correspondence between the first comparison voltage target control code and the reference voltage target control code may be stored in a digital circuit in the reference voltage generating circuit to facilitate the execution of the aforementioned query step.

[0051] The first end of the third resistor R3 is used as a reference voltage V ref The output node outputs the corresponding reference voltage V ref .

[0052] Therefore, the present invention realizes the reference voltage V of ADC through the above method. ref Matching with TPS or TPS analog signal, the reference voltage V ref , adjust the digital output code of the ADC to achieve curvature compensation of the TPS analog signal.

[0053] When non-TPS analog signals such as sensor signal 1 or sensor signal 2 are used as the output signal of the multiplexer, the fixed reference voltage control code VREF_CTL is used. <n:0>The fixed reference voltage V ref , so that the ADC can be used as a general ADC.

[0054] 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.

[0055] 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 digital-to-analog conversion circuit, characterized in that: include: TPS, outputs TPS analog signal as one of the input signals of the multiplexer; A multiplexer receives multiple sensing signals, and the output signal of the multiplexer is used as an input signal of the ADC; A hysteresis comparator receives the TPS analog signal and a first comparison voltage output by a reference voltage generating circuit, and sends an output signal of the hysteresis comparator to the reference voltage generating circuit; a reference voltage generating circuit, receiving a bandgap reference voltage and an output signal of a hysteresis comparator, generating a first comparison voltage as one of input signals of the hysteresis comparator, and generating a reference voltage; and The ADC receives the reference voltage and outputs a digital output code according to the reference voltage.

2. The TPS digital-to-analog conversion circuit according to claim 1, characterized in that: When the multiplexer is configured to select the TPS analog signal as the output signal of the multiplexer, the reference voltage generating circuit outputs different first comparison voltages to obtain a target first comparison voltage closest to the voltage of the TPS analog signal, and determines the reference voltage based on the target first comparison voltage.

3. The TPS digital-to-analog conversion circuit according to claim 2, characterized in that: The reference voltage generating circuit obtains different first comparison voltages by applying different first comparison voltage control codes.

4. The TPS digital-to-analog conversion circuit according to claim 3, characterized in that: When a target first comparison voltage closest to the voltage of the TPS analog signal is obtained, the first comparison voltage control code being applied by the reference voltage generating circuit is the first comparison voltage target control code; Obtaining a reference voltage target control code according to the first comparison voltage target control code; The reference voltage generating circuit generates the reference voltage by applying a reference voltage target control code.

5. The TPS digital-to-analog conversion circuit according to claim 4, characterized in that: When the multiplexer is configured to select the non-TPS analog signal as the output signal of the multiplexer, the reference voltage generating circuit fixes the reference voltage by applying a fixed reference voltage control code.

6. The TPS digital-to-analog conversion circuit according to claim 5, characterized in that: The first comparison voltage control code is used to control the size of an adjustable resistor in a reference voltage generating circuit.

7. The TPS digital-to-analog conversion circuit according to claim 6, characterized in that: The reference voltage target control code is obtained according to the first comparison voltage target control code, specifically, the reference voltage target control code is obtained by querying in a reference voltage generating circuit according to the first comparison voltage target control code.

8. The TPS digital-to-analog conversion circuit according to claim 7, characterized in that: A correspondence relationship between the first comparison voltage target control code and the reference voltage target control code is stored in a digital circuit in the reference voltage generating circuit.

9. The TPS digital-to-analog conversion circuit according to claim 8, characterized in that: The bandgap reference voltage is generated by the TPS.

10. The TPS digital-to-analog conversion circuit according to claim 9, characterized in that: The target first comparison voltage closest to the voltage of the TPS analog signal is obtained by outputting different first comparison voltages through the reference voltage generation circuit, which is achieved through a successive approximation step.

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