TWI807429B - Temperature sensing circuit and operating method thereof - Google Patents

Abstract

A temperature sensing circuit, comprising: a searching-control circuit, configured to generate a reference-voltage selection signal according to a plurality of control signals; a voltage reference circuit, configured to select a first reference voltage from a plurality of candidate reference voltages according to the reference-voltage selection signal, and to provide a second reference voltage; a converse-to-absolute-temperature (CTAT) voltage circuit, configured to convert the second reference voltage into a first comparison voltage; a digital-to-analog converter (DAC) circuit, configured to convert the first reference voltage into a second comparison voltage; a comparison circuit, configured to compare the first comparison voltage and the second comparison voltage to generate a comparison-result signal; and a successive approximation register (SAR) control circuit, configured to output each bit of a temperature-segment signal of an operating temperature of the temperature sensing circuit according to the comparison-result signal. The control signals include the temperature-segment signal.

Description

Temperature sensing circuit and method of operation thereof

The present invention relates to a temperature sensing circuit, in particular to a temperature sensing circuit capable of improving local non-linear misalignment and its operating method.

In today's integrated circuits for different applications, a temperature sensing circuit is often configured to detect the operating temperature of the integrated circuit. For example, the temperature sensing circuit can be used to detect whether the operating temperature of the integrated circuit is too high to activate the overheating protection mechanism of the circuit, so as to ensure the working performance of the circuit. However, due to the complex interaction between the manufacturing process and the simulation environment, in the operating temperature range of the integrated circuit, the problem of local non-linearity of the temperature sensing circuit is often encountered, resulting in inaccurate detection of the operating temperature.

In view of this, the present invention provides a temperature sensing circuit and its operation method to solve the above problems.

The present invention provides a temperature sensing circuit, comprising: a search control circuit, used to generate a reference voltage selection signal according to a plurality of control signals; a voltage reference circuit, used to select a first reference voltage from a plurality of candidate reference voltages according to the reference voltage selection signal, and provide a second reference voltage; a temperature reverse voltage circuit, used to convert the second reference voltage into a first comparison voltage; a digital-to-analog conversion circuit, used to convert the first reference voltage into a second comparison voltage; The second comparison voltage is used to generate a comparison result signal; and an asymptotic recorder control circuit is used to sequentially output the bits of a temperature interval signal of the operating temperature of the temperature sensing circuit according to the comparison result signal, wherein the control signals include the temperature interval signal.

The present invention further provides an operation method of a temperature sensing circuit, comprising: generating a reference voltage selection signal according to a plurality of control signals; selecting a first reference voltage from a plurality of candidate reference voltages according to the reference voltage selection signal, and providing a second reference voltage; converting the second reference voltage and the first reference voltage into a first comparison voltage and a second comparison voltage respectively; comparing the first comparison voltage and the second comparison voltage to generate a comparison result signal; Each bit of the interval signal, wherein the modified binary search method dynamically enlarges or reduces the voltage range of the pre-search.

100: temperature sensing circuit

110: Voltage reference circuit

111: multiplexer

120: temperature reverse voltage circuit

130: Digital to analog conversion circuit

131: Operational amplifier

140: Comparison circuit

150: Progressive recorder control circuit

151: sorting control circuit

152: One-shot circuit

153: Progressive Approximation Circuit

160: search control circuit

1531-1534: Control circuit

200: curve

202: straight line

300: temperature range table

320: low temperature area

330: normal temperature area

340: high temperature area

350: normal temperature area

302, 322, 342: curve

3001-3004: temperature zone

400: block

402, 404, 406: curve

CLOCK: clock signal

Latch: Latch circuit

COMP: comparison result signal

SEQ[3:0]: sequence control signal

VREFC, VP: reference voltage

V1: the first comparison voltage

CTATREF: second comparison voltage

VREFCSEL[4:0]: reference voltage selection signal

DAC[3:0]: digital analog conversion signal

TSCODE[3:0]: temperature interval signal

RDAC[15:0]: Resistive digital-to-analog conversion signal

Segment[1:0]: segment signal

INC[1:0]: Amplify control signal

DEC[1:0]: Reduce control signal

N1: node

M1: Transistor

Q: output terminal

CLK: clock input

D: data terminal

CD[3], CD[2], CD[1], CD[0]: comparison delay signal

FIG. 1A is a block diagram of a temperature sensing circuit according to an embodiment of the present invention.

FIG. 1B is a schematic diagram of the progressive recorder control circuit in the embodiment of FIG. 1A according to the present invention.

FIG. 2 is a schematic diagram of a reference voltage curve generated by a voltage reference circuit.

FIG. 3A is a schematic diagram of temperature regions divided according to the temperature range and segmented signals in an embodiment of the present invention.

FIG. 3B is a schematic diagram of a general binary search method according to an embodiment of the present invention.

3C-3D are schematic diagrams of the modified binary search method according to an embodiment of the present invention.

FIG. 4 is a schematic diagram of adjusting the operating temperature and the temperature range curve of the temperature sensing circuit according to an embodiment of the present invention.

FIG. 1A is a block diagram of a temperature sensing circuit according to an embodiment of the present invention. As shown in FIG. 1A, the temperature sensing circuit 100 includes a voltage reference circuit 110, a temperature reverse voltage circuit (complementary to absolute temperature (CTAT) circuit) 120, a digital-to-analog converter (DAC) circuit (digital-to-analog converter (DAC) circuit) 130, a comparison circuit 140, and an asymptotic recorder control circuit (successive approximation register (SAR) control c circuit) 150 and search control circuit 160.

The voltage reference circuit 110 is used to generate according to the search control circuit 160 The generated reference voltage selection signal VREFCSEL[4:0] provides corresponding reference voltages VP and VREFC to the temperature reverse voltage circuit 120 and the digital-to-analog conversion circuit 130 respectively. In some embodiments, the voltage reference circuit 110 can be realized by, for example, a bandgap voltage reference circuit. For example, the voltage reference circuit 110 can provide a plurality of candidate reference voltages, and the voltage reference circuit 110 can include a multiplexer 111 for selecting the reference voltages VP and VREFC to be output from the plurality of candidate reference voltages according to the reference voltage selection signal VREFCSEL[4:0].

The temperature reverse voltage circuit 120 receives the reference voltage VP provided by the voltage reference circuit 110 and converts the reference voltage VP into a first comparison voltage V1. In some embodiments, the effective temperature detection range of the temperature sensing circuit 100 is, for example, between -40 degrees Celsius and 120 degrees Celsius. When the operating temperature of the temperature sensing circuit 100 is higher, the first comparison voltage V1 generated by the temperature reverse voltage circuit 120 is lower. When the operating temperature of the temperature sensing circuit is lower, the first comparison voltage V1 generated by the temperature reverse voltage circuit 120 is higher.

The digital-to-analog conversion circuit 130 can be realized by, for example, a resistive digital-to-analog conversion circuit (resistive DAC). The digital-to-analog conversion circuit 130 generates the second comparison voltage CTATREF according to the digital-to-analog conversion signal DAC[3:0] from the progressive recorder control circuit 150, and the first comparison voltage V1 and the second comparison voltage CTATREF are input to the comparison circuit 140 to generate the comparison result signal COMP. In detail, the positive input terminal of the operational amplifier 131 of the digital-to-analog conversion circuit 130 receives the reference voltage VREFC from the voltage reference circuit 110, and The voltages of the positive input terminal and the negative input terminal of the operational amplifier 131 are equal, so the reference voltage VREFC can also be obtained at the node N1. The transistor M1 is used to provide an operating current to a resistor ladder of the digital-to-analog conversion circuit 130 .

It should be noted that the number of resistors of the resistor ladder of the digital-to-analog conversion circuit 130 and the number of corresponding switch circuits in FIG. 1A are for illustrative purposes only. The reference voltage VREC at the node N1 can generate corresponding resistive digital-to-analog conversion signals RDAC[15:0] at different nodes in the resistance ladder, and the output voltages of each bit of the resistive digital-to-analog conversion signal RDAC[15:0] are connected to corresponding switching circuits, wherein the opening or closing of each switching circuit is controlled by the corresponding bits in the digital-to-analog conversion signal DAC. Therefore, the digital-to-analog conversion circuit 130 can generate the second comparison voltage CTATREF according to the digital-to-analog conversion signal DAC[3:0].

For example, when the first comparison voltage V1 is greater than or equal to the second comparison voltage CTATREF, the comparison result signal COMP generated by the comparison circuit 140 is, for example, in a high logic state. When the first comparison voltage V1 is smaller than the second comparison voltage CTATREF, the comparison result signal COMP generated by the comparison circuit 140 is, for example, in a low logic state.

FIG. 1B is a schematic diagram of the progressive recorder control circuit in the embodiment of FIG. 1A according to the present invention. Please refer to Figure 1A and Figure 1B at the same time.

The progressive recorder control circuit 150 can be regarded as a digital-to-analog conversion circuit, for example. The progressive recorder control circuit 150 includes a sequencing control circuit 151 , a one-shot circuit 152 and a progressive approximation circuit 153 . The sorting control circuit 151 can receive a clock signal CLOCK, and sequentially generate a corresponding sorting control signal SEQ[3:0], It is used to indicate the detection sequence and process of the temperature interval signal TSCODE[3:0]. For example, the sequence control signal SEQ[3:0] generated by the sequence control circuit 151 can be represented by one hot encoding, and its sequence is 1000, 0100, 0010, 0001 to indicate the temperature range signals TSCODE[3], TSCODE[2], TSCODE[1] and TSCODE[0] respectively. The one-shot circuit 152 also receives the clock signal CLOCK and converts the clock signal CLOCK into a latch signal Latch.

The gradual approximation circuit 153 is based on the comparison result signal COMP, the sequence control signal SEQ[3:0] from the sequence control circuit 151, and the latch signal Latch from the one-shot circuit 152 to sequentially output the temperature interval signal TSCODE[3:0] and the bits in the digital-to-analog conversion signal DAC[3:0] (for example, from the highest bit to the lowest bit). For example, when the sequence control signal SEQ[3:0]=4'b1000, it means that the sequence control signal SEQ[3]=1'b1. Therefore, the clock input terminal CLK of the D-type flip-flop in the uppermost control circuit 1531 of the progressive approximation circuit 153 has a clock signal input for operation, and the output terminal Q of the D-type flip-flop generates a comparative delay signal CD[3]. The temperature range signal TSCODE[3] can be obtained after the comparison delay signal CD[3] passes through two inverters, wherein the temperature range signal TSCODE[3] can be stored in a register (not shown), for example. After comparing the delay signal CD[3] and the sorting control signal SEQ[3] through an NOR gate and an inverter, a digital-to-analog conversion signal DAC[3] can be obtained. The operation modes of the control circuits 1532-1534 are similar to the control circuit 1531, so no further description is given. In simple terms, the gradual approximation circuit 153 can sequentially output the operation of the temperature sensing circuit 100 according to the comparison result signal COMP. Bits of the temperature range signal TSCODE[3:0] for the temperature.

The search control circuit 160 generates the reference voltage selection signal VREFCSEL[4:0] according to the sequence control signal SEQ[3:0], the temperature range signal TSCODE[3:0], the segment signal Segment[1:0], the enlargement control signal INC[1:0] and the reduction control signal DEC[1:0]. In some embodiments, the setting values of the segment signal Segment[1:0], the enlargement control signal INC[1:0] and the reduction control signal DEC[1:0], for example, may be pre-stored in a read-only memory (ROM) or other types of non-volatile memory in the temperature sensing circuit 100 . The segment signal Segment[1:0], the enlargement control signal INC[1:0] and the reduction control signal DEC[1:0] can be, for example, external signals of the temperature sensing circuit 100 and can be set by the user.

In some other embodiments, the search control circuit 160 includes a look-up table (not shown), whose input is the sequence control signal SEQ[3:0], the temperature interval signal TSCODE[3:0], the segment signal Segment[1:0], the enlargement control signal INC[1:0] and the reduction control signal DEC[1:0], and the output of the lookup table is the reference voltage selection signal VREFCSEL[4:0]. The above-mentioned lookup table can be realized by, for example, a programmable logic array (programmable logic array, PLA), a complex programmable logic device (complex programmable logic device, CPLD), a processor, a microcontroller (microcontroller), an application-specific integrated circuit (ASIC), or other circuits with the same logic function.

For example, the segment signal Segment[1:0] is used to define same temperature range. Taking the 2-bit segment signal Segment[1:0] as an example, a total of 4 combinations of temperature regions can be defined. As shown in FIG. 3A, when the segment signal Segment[1:0] is respectively 2'b00, 2'b01, 2'b10, and 2'b11, the search control circuit 160 can determine that the temperature areas to use the modified binary search method are temperature areas 3001, 3002, 3003, and 3004, wherein the temperature area 3001 represents a temperature range from -5 degrees Celsius to below -40 degrees Celsius (for example, it can be regarded as a low temperature area), and the temperature area 3002 Indicates the temperature range from 0°C to 35°C, the temperature area 3003 indicates the temperature range from 40°C to 75°C, and the temperature area 3004 indicates the temperature range from 80°C to 120°C (for example, it can be regarded as a high temperature area). It should be noted that the present invention is not limited to the above-mentioned implementation methods, and those skilled in the field of the present invention can set the number of temperature zones and the corresponding temperature ranges according to actual needs.

The amplification control signal INC[1:0] and the reduction control signal DEC[1:0] are used to enlarge or reduce the amplitude magnification within the temperature range indicated by the segment signal Segment[1:0]. For example, when the amplification control signal INC[1:0] is 2'b00 or 2'b11, the temperature sensing circuit 100 does not adjust the temperature range indicated by the segment signal Segment[1:0], that is, the reference voltage VREFC provided by the voltage reference circuit 110 to the digital-to-analog conversion circuit 130 does not change. When the amplification control signal INC[1:0] is 2'b01, the reference voltage VREFC provided by the voltage reference circuit 110 to the digital-to-analog conversion circuit 130 will increase, for example, by 2.1%. When the amplification control signal INC[1:0] is 2'b10, the reference voltage VREFC provided by the voltage reference circuit 110 to the digital-to-analog conversion circuit 130 will increase, for example, by 4.2%.

When the scaling control signal DEC[1:0] is 2’b00 or 2’b11, the temperature sensing circuit 100 does not adjust the temperature range indicated by the segment signal Segment[1:0], which means that the reference voltage VREFC provided by the voltage reference circuit 110 to the digital-to-analog conversion circuit 130 does not change. When the downscaling control signal DEC[1:0] is 2'b01, the reference voltage VREFC provided by the voltage reference circuit 110 to the digital-to-analog conversion circuit 130 decreases, for example, by 2.1%. When the downscaling control signal DEC[1:0] is 2'b10, the reference voltage VREFC provided by the voltage reference circuit 110 to the digital-to-analog conversion circuit 130 is reduced, for example by 4.2%. It should be noted that the present invention is not limited to the ratio of increasing or decreasing the reference voltage VREFC in the above embodiments. Those skilled in the field of the present invention can adjust the adjustment ratio of the reference voltage VREFC according to actual needs.

FIG. 2 is a schematic diagram of a reference voltage curve generated by a voltage reference circuit. The binary search method used in the traditional temperature sensing circuit divides the voltage range corresponding to the operating temperature range to be searched evenly according to the number of binary bits. When the operating temperature of the integrated circuit is higher than a predetermined temperature threshold V _BE (T), the reference voltage generated by the voltage reference circuit has a linear relationship with the temperature, as shown in the curve 200 . However, when the operating temperature of the integrated circuit is lower than a predetermined temperature threshold V _BE (T), the reference voltage generated by the voltage reference circuit will also be out of alignment due to local nonlinearity. When the operating temperature of the voltage reference circuit is 300K, the voltage generated by the voltage reference circuit is V _BE (Tr). However, the curve 200 is not actually a linear relationship. When the operating temperature of the voltage reference circuit is 0K, the actual voltage generated by the voltage reference circuit is V _BE (OK). If the straight line 202 is used to estimate the voltage generated by the voltage reference circuit, the voltage V _BE (OK) ^e is obtained. Therefore, the traditional temperature sensing circuit is prone to inaccurate temperature detection under low temperature conditions.

In one embodiment, the temperature sensing circuit 100 uses a modified binary search method (modified binary search) to represent the voltage range corresponding to the operating temperature range to be searched with a limited number of binary bits, wherein the modified binary search method is different from the traditional binary search method. For example, during the temperature detection process, the temperature sensing circuit 100 can dynamically enlarge or reduce the pre-searched voltage range, which means that the temperature ranges in the temperature range signal TSCODE[3:0] do not need to be equally divided. In addition, the temperature sensing circuit 100 dynamically zooms in or out of a specific temperature range based on the specific temperature. For example, a high temperature condition may indicate that the operating temperature of the temperature sensing circuit 100 is greater than the temperature T1, and a low temperature condition may indicate that the operating temperature of the temperature sensing circuit 100 is less than the temperature T2, wherein the temperature T1 is greater than the temperature T2. Details of the modified binary search method adopted by the temperature sensing circuit 100 will be described in detail in the following embodiments.

FIG. 3A is a schematic diagram of temperature ranges according to an embodiment of the present invention. FIG. 3B is a schematic diagram of a general binary search method according to an embodiment of the present invention. 3C-3D are schematic diagrams of the modified binary search method according to an embodiment of the present invention. Please refer to Figure 1A and Figures 3A~3D at the same time.

FIG. 3A shows a temperature interval table 300, wherein each value of the temperature interval signal TSCODE[3:0] has a corresponding temperature Ta and a hexadecimal value Hex. In Figure 3B, the values on the right represent temperatures in degrees Celsius. N10, N20, N30 and N40 represent -10 degrees Celsius, -20 degrees Celsius, -30 degrees Celsius and -40 degrees Celsius, respectively. Assume that the operating temperature range of the temperature sensing circuit 100 is between -40 degrees Celsius and 120 degrees Celsius, and the temperature inversely The first comparison voltage V1 generated by the voltage circuit 120 is linearly and inversely proportional to the operating temperature, as shown by the curve 302 . Because the temperature sensing circuit 100 uses the 4-bit temperature range signal TSCODE[3:0] and uses the binary search method, in each cycle of determining the temperature range, it takes 4 clock cycles to determine the final value of the temperature range signal TSCODE[3:0], as shown in the left part of FIG. 3B.

For example, in the cycle of determining the temperature range, the highest bit (MSB) TSCODE[3] of the temperature range signal TSCODE is first determined in the first clock cycle, the second highest bit TSCODE[2] of the temperature range signal TSCODE is determined in the second clock cycle, the second lowest bit TSCODE[1] of the temperature range signal TSCODE is determined in the third clock cycle, and the lowest bit (LSB) TSCODE[0] of the temperature range signal TSCODE is determined in the fourth clock cycle.

After every four clock cycles and determining the value of the temperature range signal TSCODE[3:0], the temperature sensing circuit 100 can determine which temperature range the current operating temperature is in. For example, when the temperature range signal TSCODE[3:0]=4'b0000 (or hexadecimal code Hex=0h), the temperature sensing circuit 100 can know that the current operating temperature Ta is below -40 degrees Celsius. When the temperature interval signal TSCODE[3:0]=4'b1111 (or hexadecimal code Hex=Fh), the temperature sensing circuit 100 can know that the current operating temperature Ta is above 120 degrees Celsius. When the temperature interval signal TSCODE[3:0]=4'b0100 (or hexadecimal code Hex=4h), the temperature sensing circuit 100 can know that the current operating temperature Ta is about 0 degrees Celsius. When the temperature interval signal TSCODE[3:0]=4'b1000 (or hexadecimal code Hex=8h), the temperature sensing circuit 100 can know that the current operating temperature Ta is about 40 degrees Celsius, So on and so forth. It should be noted that, for the convenience of description, in the embodiment shown in FIG. 3A , each temperature range is equally divided.

In the embodiment of FIG. 3C , the temperature sensing circuit 100 uses a modified binary search method to correct the temperature range in the low temperature region. For example, due to some factors, when the operating temperature of the temperature sensing circuit 100 is in the low temperature region 320 , the curve 322 of the relationship between the first comparison voltage V1 and the temperature generated by the temperature reverse voltage circuit 120 may become equivalently or actually steeper.

In the cycle of determining the temperature range, the highest two bits TSCODE[3:2] of the temperature range signal TSCODE can be determined after two clock cycles. When the temperature interval signal TSCODE[3:2]=2'b00, it indicates that the operating temperature of the temperature sensing circuit 100 is in the low temperature region 320 (for example, lower than -10 degrees Celsius). At this time, the temperature sensing circuit 100 can modify the temperature range in the low temperature region 320 , for example, the search voltage range can be enlarged (or reduced), and the enlarged (or reduced) search voltage range does not overlap with the original search voltage range. In this embodiment, when the temperature interval signal TSCODE[3:2] is not equal to 2'b00, it means that the operating temperature of the temperature sensing circuit 100 will be in the normal temperature region 330 (for example, between -10 degrees Celsius and 120 degrees Celsius), and the temperature sensing circuit 100 will not modify the search voltage range of any temperature interval at this time, for example, the search can be performed according to the equidistant temperature intervals shown in FIG. 3A. It should be noted that the embodiment in FIG. 3C is used to illustrate that the temperature sensing circuit 100 can amplify the temperature range in the low temperature region 320 , but the present invention is not limited to this embodiment. The temperature sensing circuit 100 can also modify (including enlarge or reduce) the temperature range in the corresponding temperature range according to the predetermined temperature range signal TSCODE.

In the embodiment shown in FIG. 3D, the temperature sensing circuit 100 uses a modified binary search method to correct the temperature range in the high temperature region. For example, due to some factors, when the operating temperature of the temperature sensing circuit 100 is in the high temperature region 340 , the curve 342 of the relationship between the first comparison voltage V1 and the temperature generated by the temperature reverse voltage circuit 120 may be equivalently or actually slower.

In the cycle of determining the temperature range, the highest two bits TSCODE[3:2] of the temperature range signal TSCODE can be determined after two clock cycles. When the temperature interval signal TSCODE[3:2]=2'b11, it indicates that the operating temperature of the temperature sensing circuit 100 is located in the high temperature region 340 (for example, higher than 80 degrees Celsius). At this time, the temperature sensing circuit 100 can modify the temperature range in the high temperature region 340 , for example, the search voltage range can be reduced (or enlarged), and the reduced (or enlarged) search voltage range does not overlap with the original search voltage range. In this embodiment, when the temperature interval signal TSCODE[3:2] is not equal to 2'b00, it means that the operating temperature of the temperature sensing circuit 100 will be in the normal temperature region 350 (for example, between -10 degrees Celsius and 80 degrees Celsius), and the temperature sensing circuit 100 will not modify the search voltage range of any temperature interval at this time, for example, the search can be performed according to the equidistant temperature intervals shown in FIG. 3A. It should be noted that the embodiment in FIG. 3D is used to illustrate that the temperature sensing circuit 100 can amplify the temperature range in the high temperature region 340 , but the present invention is not limited to this embodiment. The temperature sensing circuit 100 can also modify (including enlarge or reduce) the temperature range in the corresponding temperature range according to the predetermined temperature range signal TSCODE.

FIG. 4 is a schematic diagram of adjusting the temperature curve of the temperature sensing circuit according to an embodiment of the present invention. The table below Figure 4 shows each of the curves 402, The temperature interval values of 404 and 406 at each temperature, wherein the temperature interval values can refer to the representation in FIG. 3A , for example. The curve 404 represents the temperature curve of the temperature sensing circuit 100 when the reference voltage VREFC generated by the voltage reference circuit 110 is not adjusted by the modified binary search method, wherein the reference voltage VREFC in the low temperature region (block 400, corresponding to the segment signal Segment[1:0]=2'b00) is, for example, 1.2V. When the operating temperatures of the temperature sensing circuit 100 are respectively -40 degrees Celsius, -30 degrees Celsius and -20 degrees Celsius, the curve 404 is located in the temperature interval 0. When the operating temperatures of the temperature sensing circuit 100 are respectively -10 degrees Celsius and 0 degrees Celsius, the curves 404 are respectively located in the temperature ranges 1 and 3, which means that the temperature range 2 is skipped in the middle. When the operating temperature of the temperature sensing circuit 100 is 10 degrees Celsius and 20 degrees Celsius, the curve 404 is located in temperature intervals 3 and 5, respectively. In other words, the curve 404 is in the low temperature region, as the operating temperature increases or decreases linearly, the corresponding temperature range does not show a linear relationship.

The curve 402 represents an ideal linear temperature curve, which is the design goal of the temperature sensing circuit 100 , that is, the curve 402 is within the operating temperature range, and the corresponding temperature range exhibits a linear relationship as the operating temperature increases or decreases linearly.

The curve 406 represents the temperature curve of the temperature sensing circuit 100 when adjusting the reference voltage VREFC generated by the voltage reference circuit 110 after using the modified binary search method. For example, the designer of the temperature sensing circuit 100 can measure the curve 404 of the temperature sensing circuit 100 in advance without using the modified binary search method, and can adjust the reference voltage VREFC for a temperature region with serious nonlinear misalignment (for example, a low temperature region, a high temperature region, or any specified temperature region), so that the corrected temperature curve of the temperature sensing circuit 100 can be more in line with the ideal temperature curve (that is, the curve 402), that is, The accuracy of the temperature sensing circuit 100 in detecting the operating temperature can be improved.

To sum up, the present invention provides a temperature sensing circuit and its operation method, which can use the modified binary search method to adjust the temperature curve of the reference voltage generated by the voltage reference circuit, and can adjust the reference voltage for the temperature region with serious nonlinear misalignment (for example, it can be a low temperature region, a high temperature region, or any specified temperature region), so that the corrected temperature curve of the temperature sensing circuit can be more in line with the ideal temperature curve, so as to increase the accuracy of the temperature sensing circuit 100 when detecting the operating temperature.

100: temperature sensing circuit

110: Voltage reference circuit

111: multiplexer

120: temperature reverse voltage circuit

130: Digital to analog conversion circuit

131: Operational amplifier

140: Comparison circuit

150: Progressive recorder control circuit

151: sorting control circuit

152: One-shot circuit

153: Progressive Approximation Circuit

160: search control circuit

CLOCK: clock signal

Latch: Latch circuit

COMP: comparison result signal

SEQ[3:0]: sequence control signal

VREFC, VP: reference voltage

V1: the first comparison voltage

CTATREF: second comparison voltage

VREFCSEL[4:0]: reference voltage selection signal

DAC[3:0]: digital analog conversion signal

TSCODE[3:0]: temperature interval signal

RDAC[15:0]: Resistive digital-to-analog conversion signal

Segment[1:0]: segment signal

INC[1:0]: Amplify control signal

DEC[1:0]: Reduce control signal

N1: node

M1: Transistor

Claims (15)

A temperature sensing circuit, comprising: a search control circuit, used to generate a reference voltage selection signal according to a plurality of control signals; a voltage reference circuit, used to select a first reference voltage from a plurality of candidate reference voltages according to the reference voltage selection signal, and provide a second reference voltage; a temperature reverse voltage circuit, used to convert the second reference voltage into a first comparison voltage; a digital-to-analog conversion circuit, used to convert the first reference voltage into a second comparison voltage; a comparison circuit, used to compare the first comparison voltage and the second comparison voltage to generate a comparison result signal; and an asymptotic recorder control circuit for outputting each bit of a temperature interval signal of the operating temperature of the temperature sensing circuit according to the comparison result signal, wherein the control signals include the temperature interval signal. The temperature sensing circuit according to claim 1, wherein the voltage reference circuit is a bandgap voltage reference circuit. The temperature sensing circuit as claimed in item 1, wherein the progressive recorder control circuit uses a modified binary search method to sequentially output the bits of the temperature interval signal, Wherein during sequentially outputting the bits of the temperature range signal, when one or more predetermined bits in the temperature range signal meet a predetermined condition, the search control circuit changes the reference voltage selection signal so that the voltage reference circuit adjusts the first reference voltage; wherein the predetermined condition refers to that the operating temperature of the temperature sensing circuit is higher than the first special temperature or lower than the second special temperature, and the first special temperature is greater than the second special temperature. Such as the temperature sensing circuit of claim 3, wherein the control signals further include: a sequence control signal, a segmentation signal, an amplification control signal, and a reduction control signal, wherein the sequence control signal controls the order of the bit bits outputting the temperature range signal, and the segmentation signal represents a specific temperature region to be adjusted in the temperature sensing circuit, wherein the amplification control signal and the reduction control signal represent the amplitude magnification of increasing and decreasing the first reference voltage, respectively. The temperature sensing circuit according to claim 4, wherein the predetermined condition indicates that one or more predetermined bits in the temperature interval signal match the segment signal. The temperature sensing circuit according to claim 4, wherein the search control circuit includes a look-up table to record the relationship between the sorting control signal, the segmentation signal, the amplification control signal, the reduction control signal and the reference voltage selection signal. The temperature sensing circuit according to claim 6, wherein the look-up table is implemented by a programmable logic array, a complex programmable logic device, a processor, a microcontroller or an application-oriented integrated circuit. The temperature sensing circuit of claim 1, wherein the progressive recorder control circuit includes a sorting control circuit, a one-shot circuit and a gradual approximation circuit, wherein the one-shot circuit receives a clock signal to generate a latch signal, and the sorting control circuit receives the clock signal to sequentially generate the sorting control signal corresponding to each bit of the temperature range signal. The temperature sensing circuit according to claim 8, wherein the gradual approximation circuit generates the temperature range signal and a digital-to-analog conversion signal according to the comparison result signal, the sequence control signal and the latch signal. The temperature sensing circuit according to claim 9, wherein the digital-to-analog conversion signal is input to the digital-to-analog conversion circuit to convert the first reference voltage into the second comparison voltage. The temperature sensing circuit according to claim 1, wherein the digital-to-analog conversion circuit is a resistive digital-to-analog conversion circuit. The temperature sensing circuit according to claim 1, wherein the voltage reference circuit includes a multiplexer to select the first reference voltage from the candidate reference voltages according to the reference voltage selection signal. An operating method of a temperature sensing circuit, comprising: generating a reference voltage selection signal according to a plurality of control signals; selecting a first reference voltage from a plurality of candidate reference voltages according to the reference voltage selection signal, and providing a second reference voltage; converting the second reference voltage and the first reference voltage into a first comparison voltage and a second comparison voltage; comparing the first comparison voltage and the second comparison voltage to generate a comparison result signal; When one or more predetermined bits meet a predetermined condition, the reference voltage selection signal is changed to enable the voltage reference circuit to adjust the first reference voltage, wherein the predetermined condition refers to that the operating temperature of the temperature sensing circuit is higher than the first special temperature or lower than the second special temperature, and the first special temperature is greater than the second special temperature, wherein the modified binary search method dynamically enlarges or reduces the voltage range of the pre-search. Such as the temperature sensing method of claim 13, wherein the control signals further include: a sorting control signal, a segmentation signal, an amplification control signal and a reduction control signal, Wherein the sequence control signal controls the order of each bit of the temperature range signal output, and the segment signal represents a specific temperature region to be adjusted in the temperature sensing circuit, wherein the amplification control signal and the reduction control signal represent the amplitude magnification of increasing and decreasing the first reference voltage respectively. The temperature sensing method according to claim 14, wherein the predetermined condition indicates that one or more predetermined bits in the temperature interval signal match the segment signal.

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