A temperature sensor for calibrating output code values

Abstract

This invention provides a temperature sensor for calibrating output code values, comprising: a temperature sensing circuit; a bias circuit for providing a bias current Ib to the temperature sensing circuit; a differential operational amplifier for receiving the temperature sensing signal output from the temperature sensing circuit and amplifying the temperature sensing signal to output an amplified temperature sensing signal Vtemp; an analog-to-digital converter circuit for receiving the amplified temperature sensing signal Vtemp output from the differential operational amplifier, quantizing the amplified temperature sensing signal Vtemp, and outputting a temperature-related digital signal Dout; the differential operational amplifier also includes a fixed resistor R1 and a variable resistor R2. When the actual output slope of the digital signal Dout deviates from the reference, the amplification factor α of the differential operational amplifier is finely adjusted by changing the resistance value of the variable resistor R2, thereby correcting the output slope error caused by the temperature sensing signal deviation.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a temperature sensor for calibrating output code values. Background Technology

[0002] Temperature sensors can convert sensed ambient temperature into a processable digital signal and are widely used in various fields such as home appliances, medical devices, and environmental monitoring. Figure 1 The diagram shows the principle block diagram of a traditional temperature sensor. The temperature sensing circuit converts the sensed temperature into a voltage signal, and then the analog-to-digital converter converts the voltage into a digital signal related to the temperature.

[0003] Traditional temperature sensor designs typically utilize the negative temperature characteristic of the base-emitter voltage Vbe of a bipolar junction transistor (BJT), or the positive temperature characteristic of ΔVbe biased at different current densities, as the temperature sensing signal. Since the temperature coefficients of Vbe or ΔVbe are relatively small, they are usually amplified by an amplifier (AMP) and then converted to a temperature signal via an analog-to-digital converter (ADC). For high-precision temperature sensors, the substrate parasitic BJT in CMOS technology serves as the core component of the temperature sensing circuit. Its temperature characteristics are significantly affected by bias current, process angle fluctuations, and other factors, causing substantial deviations in the slope of the linearly correlated temperature reading. Combined with amplifier amplification errors and ADC conversion errors, these errors severely impact the temperature sensor's measurement accuracy.

[0004] Although the temperature measurement error of a temperature sensor can be reduced through calibration, the bias of the sensing element and the slope deviation of the output code value caused by process fluctuations will result in different output deviations at each temperature point, making calibration more complicated and increasing manufacturing costs. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a temperature sensor for calibrating output code values, which solves the problem of complex calibration of the output code value slope deviation caused by the bias of the temperature sensing element and process fluctuations in the prior art.

[0006] To achieve the above and other related objectives, the present invention provides a temperature sensor for calibrating output code values, comprising at least:

[0007] Temperature sensing circuit, used to output temperature sensing signal;

[0008] A bias circuit is used to provide a bias current Ib to the temperature sensing circuit; the bias circuit is also used to generate and output temperature-independent voltages Vref1 and Vref2.

[0009] A differential operational amplifier is used to receive the temperature sensing signal output by the temperature sensing circuit, amplify the temperature sensing signal, and output the amplified temperature sensing signal Vtemp; the differential operational amplifier is also used to receive the voltage Vref1 output by the bias circuit, and the voltage Vref1 serves as a reference for the differential operational amplifier.

[0010] The analog-to-digital converter circuit is used to receive the amplified temperature sensing signal Vtemp output by the differential operational amplifier, quantize the amplified temperature sensing signal Vtemp, and output a temperature-related digital signal Dout; the analog-to-digital converter circuit is also used to receive the voltage Vref2 output by the bias circuit, and the voltage Vref2 serves as a reference for the analog-to-digital converter circuit.

[0011] The differential operational amplifier is also equipped with a fixed resistor R1 and a variable resistor R2. When the actual output slope of the digital signal Dout deviates from the reference, the amplification factor α of the differential operational amplifier is finely adjusted by changing the resistance value of the variable resistor R2, thereby correcting the output slope error caused by the temperature sensing signal deviation.

[0012] Preferably, the temperature sensing circuit includes a bipolar transistor, and the temperature sensing circuit utilizes the negative temperature characteristic of the voltage Vbe between the base and emitter of the bipolar transistor to output the voltage Vbe between the base and emitter of the bipolar transistor as a temperature sensing signal.

[0013] Preferably, the analog-to-digital conversion circuit is a 12-bit high-precision SAR ADC.

[0014] Preferably, the temperature coefficient of the voltage Vbe is approximately 1.8 mV / ℃.

[0015] Preferably, the amplification factor α of the differential operational amplifier is α = R1 / R2, where R1 represents the resistance value of the fixed resistor R1 and R2 represents the resistance value of the variable resistor R2.

[0016] Preferably, the digital signal Dout is the 12-bit binary code value output by the analog-to-digital converter circuit.

[0017] Preferably, the variable resistor R2 is a fine-tuning resistor with an accuracy of 5% and an adjustment range of ±50%.

[0018] Preferably, the temperature coefficient relationship between the digital signal Dout and the voltage Vbe is: K _Dout =R1 / R2*K _Vbe *2 12 / Vref2; where K _Dout K represents the temperature coefficient of the digital signal Dout. _VbeThe temperature coefficient of the voltage Vbe is given.

[0019] As described above, the temperature sensor for calibrating output code values ​​of the present invention has the following beneficial effects: The present invention sets a variable resistor in the operational amplifier of the temperature sensor. When the actual output slope of the digital signal Dout deviates from the reference, the amplification factor of the operational amplifier can be finely adjusted by changing the resistance value of the variable resistor, thereby correcting the output slope error caused by the temperature sensing signal deviation. Attached Figure Description

[0020] Figure 1 The diagram shows a schematic of the temperature sensor circuit structure used for calibrating the output code value in this invention.

[0021] Figure 2 This diagram illustrates a comparison between the actual output of the output code value and the calibration result in this invention. Detailed Implementation

[0022] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0023] Please see Figures 1 to 2 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0024] This invention provides a temperature sensor for calibrating output code values, comprising at least:

[0025] Temperature sensing circuit, used to output temperature sensing signal;

[0026] Furthermore, in this embodiment, the temperature sensing circuit includes a bipolar transistor. The temperature sensing circuit utilizes the negative temperature characteristic of the voltage Vbe between the base and emitter of the bipolar transistor to output the voltage Vbe between the base and emitter of the bipolar transistor as a temperature sensing signal.

[0027] Furthermore, in this embodiment, the temperature coefficient of the voltage Vbe is approximately 1.8 mV / ℃.

[0028] A bias circuit is used to provide a bias current Ib to the temperature sensing circuit; the bias circuit is also used to generate and output temperature-independent voltages Vref1 and Vref2.

[0029] A differential operational amplifier is used to receive the temperature sensing signal output by the temperature sensing circuit, amplify the temperature sensing signal, and output the amplified temperature sensing signal Vtemp; the differential operational amplifier is also used to receive the voltage Vref1 output by the bias circuit, and the voltage Vref1 serves as a reference for the differential operational amplifier.

[0030] Furthermore, in this embodiment, the amplification factor α of the differential operational amplifier is α = R1 / R2, where R1 represents the resistance value of the fixed resistor R1 and R2 represents the resistance value of the variable resistor R2.

[0031] The analog-to-digital converter circuit is used to receive the amplified temperature sensing signal Vtemp output by the differential operational amplifier, quantize the amplified temperature sensing signal Vtemp, and output a temperature-related digital signal Dout; the analog-to-digital converter circuit is also used to receive the voltage Vref2 output by the bias circuit, and the voltage Vref2 serves as a reference for the analog-to-digital converter circuit.

[0032] Furthermore, in this embodiment, the analog-to-digital conversion circuit is a 12-bit high-precision SAR ADC.

[0033] In this embodiment, the digital signal Dout is the 12-bit binary code value output by the analog-to-digital converter circuit.

[0034] The differential operational amplifier is also equipped with a fixed resistor R1 and a variable resistor R2. When the actual output slope of the digital signal Dout deviates from the reference, the amplification factor α of the differential operational amplifier is finely adjusted by changing the resistance value of the variable resistor R2, thereby correcting the output slope error caused by the temperature sensing signal deviation.

[0035] The inverting input terminal R1 of the operational amplifier is a feedback resistor, and R2 is an adjustable trimmer resistor. The ratio of R1 to R2 is the amplification factor of the operational amplifier. The other end of the resistor R1 connected to the non-inverting input terminal is grounded.

[0036] Furthermore, in this embodiment, the variable resistor R2 is a fine-tuning resistor with an accuracy of 5% and an adjustment range of ±50%.

[0037] In this embodiment, the temperature coefficient relationship between the digital signal Dout and the voltage Vbe is: K _Dout =R1 / R2*K _Vbe *2 12 / Vref2; where K _DoutK represents the temperature coefficient of the digital signal Dout. _Vbe The temperature coefficient of the voltage Vbe is given.

[0038] like Figure 1 As shown, Figure 1 The diagram shows a schematic of the temperature sensor circuit used for calibrating the output code value in this invention. The temperature sensing circuit utilizes the negative temperature characteristic of the base-emitter voltage Vbe of a bipolar transistor as a temperature sensing signal and amplifies it. A 12-bit high-precision SAR ADC is used to quantize the amplified temperature sensing signal Vtemp and output a temperature-related digital signal Dout.

[0039] Because Vbe has a small temperature coefficient (approximately 1.8 mV / ℃), its absolute value changes little within the temperature measurement range. Therefore, it needs to be amplified before being input into the ADC for conversion. The substrate parasitic BJT is connected as a diode, with a bias current Ib provided to its emitter by a bias circuit. Vref1 and Vref2 are temperature-independent voltages generated by the bias circuit, used as references for the differential op-amp and ADC, respectively. The op-amp's amplification factor α = R1 / R2, Vtemp is the amplified temperature signal, and Dout is the 12-bit binary code value output by the ADC. For ease of calculation, Dout can be converted to a decimal value. The relationship between the decimal code value Dout and Vbe is: Dout = Vtemp / (2*Vref2)*2 12 -1 = α*(Vbe-Vref1) / (Vref2)*2 12 -1.

[0040] Vbe, as a temperature-sensing signal, has its temperature characteristic deviation amplified by a factor of α (α > 1) and input into the ADC, causing a significant deviation in the slope of the output code value Dout as a function of temperature. In this invention, resistor R1 is fixed, while resistor R2 is designed as an adjustable trimmer. When the actual output slope of Dout deviates from the reference, the amplifier's amplification factor α can be finely adjusted by changing R2, thereby correcting the output slope error caused by the Vbe deviation.

[0041] The temperature coefficient relationship between Dout and Vbe is: K _Dout =R1 / R2*K _Vbe *2 12 / Vref2;

[0042] Assuming the temperature coefficient deviation of Vbe is x, the temperature coefficient of the output Dout0 will be K. _Dout0 = (1±x)*K _Dout Then adjust the resistor R20 so that R20 = R2*(1±x), and K will be able to... _Dout0 =K _Dout .

[0043] In this embodiment, resistor R2 is designed as a fine-tuning resistor with an accuracy of 5% and an adjustment range of ±50%, and its resistance value is adjusted by a control code.

[0044] The temperature measurement range is -40 to 125℃, the temperature coefficient of Vbe is 1.926mV / ℃, Vref1 = 0.4V, Vref2 = 2V, and α = R1 / R2 = 4. Therefore, the theoretical output code value Dout's slope with temperature variation is 4 * 1.926 * 4096 / 2 = 15.778 bits / ℃. Due to variations in the bias current Ib and the process corner, the slope of the output code value Dout across the entire temperature range is 19.716 bits / ℃, with a deviation of +24.96%. At this point, by changing the control code according to the magnitude of the deviation and adjusting the value of R2 so that R1 / R2 = 4 / (1 + 1.25%), the fine-tuned output slope of Dout is adjusted to 15.773 bits / ℃, which is basically consistent with the theoretical output slope.

[0045] The fine-tuned output code value has the same slope as the theoretical code value, as shown in the following figure. Figure 2 As shown, Figure 2 This diagram illustrates the comparison between the actual output code value and the calibration result in this invention. After calibration, the output code value deviation ΔDout is the same at each temperature point. A reference temperature point is selected, and the calibrated output code value is shifted to obtain the accurate temperature value.

[0046] In summary, this invention incorporates a variable resistor within the operational amplifier of the temperature sensor. When the actual output slope of the digital signal Dout deviates from the reference, the amplification factor of the operational amplifier can be finely adjusted by changing the value of the variable resistor, thereby correcting the output slope error caused by the temperature sensing signal deviation. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and possesses high industrial applicability.

[0047] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A temperature sensor for calibrating output code values, characterized in that, At least including: A temperature sensing circuit is used to output a temperature sensing signal; the temperature sensing circuit is equipped with a bipolar transistor, and the temperature sensing circuit utilizes the negative temperature characteristic of the voltage Vbe between the base and emitter of the bipolar transistor to output the voltage Vbe between the base and emitter of the bipolar transistor as a temperature sensing signal. A bias circuit is used to provide a bias current Ib to the temperature sensing circuit; the bias circuit is also used to generate and output temperature-independent voltages Vref1 and Vref2. A differential operational amplifier is used to receive the temperature sensing signal output by the temperature sensing circuit, amplify the temperature sensing signal, and output the amplified temperature sensing signal Vtemp; the differential operational amplifier is also used to receive the voltage Vref1 output by the bias circuit, and the voltage Vref1 serves as a reference for the differential operational amplifier. The analog-to-digital converter circuit is used to receive the amplified temperature sensing signal Vtemp output by the differential operational amplifier, quantize the amplified temperature sensing signal Vtemp, and output a temperature-related digital signal Dout; the analog-to-digital converter circuit is also used to receive the voltage Vref2 output by the bias circuit, and the voltage Vref2 serves as a reference for the analog-to-digital converter circuit. The differential operational amplifier also includes a fixed resistor R1 and a variable resistor R2; The negative input terminal of the differential operational amplifier is connected to voltage Vref1 through a variable resistor R2; The positive input terminal of the differential operational amplifier is connected to voltage Vbe through another variable resistor R2; A fixed resistor R1 is connected between the negative input terminal and the output terminal of the differential operational amplifier; The positive input terminal of the differential operational amplifier is connected to ground by another fixed resistor R1; When the actual output slope of the digital signal Dout deviates from the reference, the amplification factor α of the differential operational amplifier is finely adjusted by changing the resistance value of the variable resistor R2, thereby correcting the output slope error caused by the temperature sensing signal deviation.

2. The temperature sensor for calibrating output code values ​​according to claim 1, characterized in that: The analog-to-digital conversion circuit is a 12-bit high-precision SAR ADC.

3. The temperature sensor for calibrating output code values ​​according to claim 1, characterized in that: The temperature coefficient of the voltage Vbe is approximately 1.8 mV / ℃.

4. The temperature sensor for calibrating output code values ​​according to claim 1, characterized in that: The gain of the differential operational amplifier is α = R1 / R2, where R1 represents the resistance value of the fixed resistor R1 and R2 represents the resistance value of the variable resistor R2.

5. The temperature sensor for calibrating output code values ​​according to claim 1, characterized in that: The digital signal Dout is the 12-bit binary code value output by the analog-to-digital converter circuit.

6. The temperature sensor for calibrating output code values ​​according to claim 4, characterized in that: The variable resistor R2 is a fine-tuning resistor with an accuracy of 5% and an adjustment range of ±50%.

7. The temperature sensor for calibrating output code values ​​according to claim 1, characterized in that: The temperature coefficient relationship between the digital signal Dout and the voltage Vbe is: K _Dout =R1 / R2* K _Vbe *2 12 / Vref2; where K _Dout K represents the temperature coefficient of the digital signal Dout. _Vbe The temperature coefficient of the voltage Vbe is given.

Images