A temperature sensor circuit

Abstract

The application discloses a temperature sensor circuit, comprising: a bias current source; a front-end temperature sensing circuit; a sigma-delta analog-to-digital converter, characterized in that further comprising: a dynamic element matching logic circuit for eliminating element process errors in the sigma-delta analog-to-digital converter; and a correction modulator for eliminating intermodulation distortion by applying output bit stream control technology. The application proposes a high-precision and high-resolution temperature sensor integrated circuit solution based on a CMOS process, and eliminates errors caused by element mismatch and intermodulation distortion and the like through technologies such as dynamic element matching, correction and bit stream control, so that the temperature detection precision and resolution are significantly improved.

Description

Technical Field

[0001] This invention relates to a temperature sensor circuit, belonging to the field of sensor integrated circuits. Background Technology

[0002] The medical device, industrial, scientific instrument, and consumer electronics industries require high-precision, high-resolution temperature sensing chip solutions based on CMOS technology. Traditional temperature sensors use a BJT (bit-joint transistor) as the sensing element to generate a voltage proportional to the absolute temperature. A Σ-Δ analog-to-digital converter (ADC) then converts this voltage into a bitstream. Finally, by calculating the duty cycle of the bitstream, the voltage magnitude can be determined, and the ambient temperature can be inferred. However, BJTs are susceptible to the effects of bias current sources and other component mismatches, leading to a decrease in the overall resolution and accuracy of the temperature sensor. Summary of the Invention

[0003] The technical problem to be solved by this invention is that the temperature sensing element used in traditional temperature sensors is easily affected by the mismatch of bias current source and other components, which affects the resolution and accuracy of the temperature sensor.

[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is to provide a temperature sensor circuit, comprising:

[0005] A bias current source is used to provide a current of pI to the front-end temperature sensing circuit. bias and I bias The bias current;

[0006] The front-end temperature sensing circuit is connected to a bias current pI. bias and I bias The voltage ΔV is generated afterward. BE and V BE Wherein, voltage ΔV BE It has the characteristic of being proportional to absolute temperature, voltage V BE It has the property that its temperature decreases as the temperature increases;

[0007] Σ-Δ analog-to-digital converter, with simultaneous input common-mode voltage V REF and input voltage V PTAT Then, the duty cycle of the generated bitstream signal bs is the corresponding digital reading of the temperature, V. REF =αΔV BE +V BE V PTAT =αΔV BE α is the gain factor, characterized in that it further includes:

[0008] The dynamic component matching logic circuit is used to select different combinations of components to be connected to the temperature sensor circuit, so that the equivalent error of different component combinations is much smaller than the error caused by component mismatch, thereby eliminating the component process error in the ∑-Δ analog-to-digital converter.

[0009] Correct the modulator and apply output bit stream control technology to eliminate intermodulation distortion.

[0010] Preferably, the Σ-Δ analog-to-digital converter is driven by two external clock signals φ1 and φ2 with the same frequency but opposite phase. When φ1 is high and φ2 is low, the Σ-Δ analog-to-digital converter uses the sampling capacitor C. s Acquire input voltage V PTAT When φ1 is low and φ2 is high, the Σ-Δ analog-to-digital converter will accumulate the collected charge into the integrating capacitor C of the Σ-Δ analog-to-digital converter. int Up, and the integrating capacitor C int The voltage and common-mode voltage V REF In comparison, the integrating capacitor C int The voltage is greater than the common-mode voltage V. REF The output is 1, and the integrating capacitor is C. int The voltage is less than or equal to the common-mode voltage V. REF The output is 0, and the comparator result is the output bitstream signal bs.

[0011] The dynamic element matching logic circuit controls (p+1) bias current sources I. bias，0 I bias，1 , ..., I bias，p Each is connected to the front-end temperature sensing circuit, and the ratio of the bias current magnitude of the front-end temperature sensing circuit is kept at 1:p; within the current clock cycle: if bs = 0, the dynamic element matching logic circuit changes its own state at the rising edge of φ1 and switches the combination of bias current source access; if bs = 1, the dynamic element matching logic circuit will not change its own state and the combination of bias current source access.

[0012] Preferably, the Σ-Δ analog-to-digital converter is driven by two external clock signals φ1 and φ2 with the same frequency but opposite phase. When φ1 is high and φ2 is low, the Σ-Δ analog-to-digital converter uses the sampling capacitor C. s Acquire input voltage V PTAT When φ1 is low and φ2 is high, the Σ-Δ analog-to-digital converter will accumulate the collected charge into the integrating capacitor C of the Σ-Δ analog-to-digital converter. int Up, and the integrating capacitor C int The voltage and common-mode voltage V REF In comparison, the integrating capacitor C int The voltage is greater than the common-mode voltage V. REFThe output is 1, and the integrating capacitor is C. int The voltage is less than or equal to the common-mode voltage V. REF The output is 0, and the comparator result is the output bitstream signal bs.

[0013] The correction modulator consists of a digital accumulator and a digital comparator. The value in the internal register of the digital accumulator increments continuously with the clock cycle and resets to zero after exceeding a maximum range. The digital comparator compares the value in the digital accumulator with a set correction value and controls the Vo of the corresponding BJT transistor in the front-end temperature sensing circuit based on the comparison result. BE As the output of the front-end temperature sensing circuit, which uses a pair of diode-connected BJTs:

[0014] Within the current clock cycle: if bs = 1, the digital accumulator in the correction modulator increments on the rising edge of φ1, and controls the output V of the front-end temperature sensing circuit based on the comparison result of the digital comparator. BE As the input to the Σ-Δ analog-to-digital converter; if bs = 0, the digital accumulator in the correction modulator pauses its self-incrementing, the output remains unchanged, and the current V is set... BE As input to the Σ-Δ analog-to-digital converter.

[0015] This invention proposes a high-precision, high-resolution temperature sensor integrated circuit solution based on CMOS technology. By using technologies such as dynamic component matching, calibration, and bit stream control, errors caused by component mismatch and intermodulation distortion are eliminated, significantly improving the accuracy and resolution of temperature detection. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the present invention;

[0017] Figure 2 Schematic diagram of logic circuit for matching dynamic components;

[0018] Figure 3 The switching principle of the dynamic element matching logic circuit is illustrated. Detailed Implementation

[0019] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0020] like Figure 1As shown, the temperature sensor circuit disclosed in this embodiment includes five parts: a bias current source, a front-end temperature sensing circuit, a second-order Σ-Δ analog-to-digital converter, a dynamic element matching logic circuit, and a correction modulator. The second-order Σ-Δ analog-to-digital converter, the dynamic element matching logic circuit, and the correction modulator are all driven by the same external oscillator.

[0021] The bias current source is used to provide a current of pI to the front-end temperature sensing circuit. bias and I bias The bias current, where p represents the ratio of the magnitude of the bias current.

[0022] The front-end temperature sensing circuit uses a pair of diode-connected BJTs (Q1, Q2), with a bias current pI applied to the BJTs. bias and I bias Generated voltage ΔV BE and V BE Due to ΔV BE and V BE They respectively possess the characteristics of being proportional to absolute temperature and decreasing with increasing temperature. Therefore, a specific gain factor α is chosen to make (αΔV) BE +V BE This can be approximated as a temperature-insensitive quantity, denoted as the common-mode voltage V. REF And αΔV BE Let it be denoted as input voltage V PTAT The common-mode voltage V REF and input voltage V PTAT Simultaneously input to the Σ-Δ analog-to-digital converter, the duty cycle of the bit stream generated by the Σ-Δ analog-to-digital converter is the digital reading of the corresponding temperature.

[0023] Because mismatches occur during chip manufacturing due to discrepancies between the actual dimensions and electrical properties of components and their expected values, this embodiment employs dynamic component matching to mitigate the impact of these mismatches. This embodiment uses dynamic component matching logic circuitry to eliminate component manufacturing process errors within the Σ-Δ analog-to-digital converter and applies output bitstream control technology to eliminate intermodulation distortion.

[0024] Combination Figure 2 Dynamic component matching logic circuits select different combinations of components to connect to the circuit, making the equivalent error of different component combinations much smaller than the error caused by component mismatch. Essentially, a dynamic component matching logic circuit is a state machine controlled by its current state and external inputs. Figure 2 Taking the bias current source section as an example, the dynamic element matching logic circuit controls (p+1) bias current sources I. bias，0 I bias，1 , ..., I bias，pTwo BJTs are connected to each other, maintaining a BJT bias current ratio of approximately 1:p. φ1 and φ2 are two external clock signals with the same frequency but opposite phase that drive the Σ-Δ analog-to-digital converter (ADC). When φ1 is high and φ2 is low, the Σ-Δ ADC uses the sampling capacitor C... s Acquire input voltage V PTAT When φ1 is low and φ2 is high, the Σ-Δ analog-to-digital converter will accumulate the collected charge into the integrating capacitor C of the Σ-Δ analog-to-digital converter. int Up, and the integrating capacitor C int The voltage and common-mode voltage V REF In comparison, the integrating capacitor C int The voltage is greater than the common-mode voltage V. REF The output is 1, and the integrating capacitor is C. int The voltage is less than or equal to the common-mode voltage V. REF The output is 0, and the comparator result is the output bitstream signal bs. Combined with... Figure 3 Within the current clock cycle: if bs = 0, the dynamic element matching logic circuit will change its own state at the rising edge of φ1 and switch the combination of bias current source access; if bs = 1, the dynamic element matching logic circuit will not change its own state and the combination of bias current source access.

[0025] The correction modulator can be implemented using an incrementer to meet the calibration accuracy requirements, and output bitstream control technology is also applied to eliminate intermodulation distortion. In this embodiment, the correction modulator essentially consists of a digital accumulator and a digital comparator. The value in the internal register of the digital accumulator increments continuously with the clock cycle and resets to zero after exceeding the maximum range. The digital comparator compares the value in the digital accumulator with the set correction value and controls the V of the corresponding BJT transistor based on the comparison result. BE This is the output of the front-end temperature sensing circuit. During the current clock cycle: if bs = 1, the digital accumulator in the correction modulator will increment on the rising edge of φ1, and control the V output of the front-end temperature sensing circuit based on the comparison result of the digital comparator. BE As the input to the Σ-Δ analog-to-digital converter; if bs = 0, the digital accumulator in the correction modulator pauses its self-incrementing, the output remains unchanged, and the current V is set... BE As input to the Σ-Δ analog-to-digital converter.

[0026] The dynamic element matching technology employed in this invention eliminates the influence of first-order errors caused by mismatched elements by averaging the components. The dynamic element matching logic circuit and correction modulator controlled by the bit stream ensure that there are no mutually canceling peaks in the spectrum of the output bit stream, thereby avoiding noise affecting the quality of the low-frequency signal.

Claims

1. A temperature sensor circuit, comprising: A bias current source is used to provide a current of magnitude [value missing] to the front-end temperature sensing circuit. and The bias current; Front-end temperature sensing circuit, with bias current applied and Voltage generated afterwards and Among them, voltage It has the characteristic of being proportional to absolute temperature, voltage It has the property that its temperature decreases as the temperature increases; Σ-Δ analog-to-digital converter, with simultaneous input common-mode voltage and input voltage The resulting bitstream signal The duty cycle is the digital reading of the corresponding temperature. , , For gain ratio, the Σ-Δ analog-to-digital converter is powered by two external clock signals with the same frequency but opposite phase. and Drive, in High level and When the signal is low, the Σ-Δ analog-to-digital converter will use the sampling capacitor. Acquire input voltage ,exist Low level and When the voltage level is high, the Σ-Δ analog-to-digital converter will accumulate the collected charge into the integrating capacitor of the Σ-Δ analog-to-digital converter. Up, and integrate capacitor voltage and common-mode voltage In comparison, integrating capacitor The voltage is greater than the common-mode voltage. The output is 1, and the integrating capacitor is used. The voltage is less than or equal to the common-mode voltage. The output is 0, and the comparator result is the output bitstream signal. Its characteristic is that it further includes: A dynamic component matching logic circuit is used to select different combinations of components to be connected to the temperature sensor circuit, so that the equivalent error of different component combinations is much smaller than the error caused by component mismatch, thereby eliminating the component manufacturing process error within the Σ-Δ analog-to-digital converter; the dynamic component matching logic circuit controls One bias current source They are respectively connected to the front-end temperature sensing circuit, and the ratio of the magnitudes of the bias currents of the front-end temperature sensing circuit is maintained at . Within the current clock cycle: if Dynamic element matching logic circuit in The rising edge changes its own state and switches the combination of bias current sources connected; if The dynamic element matching logic circuit will not change its own state and the combination of bias current source access; The correction modulator, employing output bitstream control technology to eliminate intermodulation distortion, consists of a digital accumulator and a digital comparator. The value in the internal register of the digital accumulator continuously increments with the clock cycle and resets to zero after exceeding a maximum range. The digital comparator compares the value in the digital accumulator with a set correction value and controls the corresponding BJT transistor in the front-end temperature sensing circuit based on the comparison result. As the output of the front-end temperature sensing circuit, which uses a pair of diode-connected BJTs: Within the current clock cycle: If The digital accumulator within the correction modulator is in The rising edge of the signal is used for incrementing, and the output of the front-end temperature sensing circuit is controlled based on the comparison result of the digital comparator. As the input of the Σ-Δ analog-to-digital converter; if The digital accumulator within the correction modulator pauses its self-incrementing, the output remains unchanged, and the current value is set to zero. As input to a Σ-Δ analog-to-digital converter.

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