Integrated circuit and signal processing method

Abstract

An integrated circuit includes a current source, a diode device, a switching circuit, an analog-to-digital converter, and a processing circuit. The current source provides a reference current. The switching circuit causes the diode device to provide a first diode having a first size to receive the reference current during a first period of time, and additionally causes the diode device to provide a second diode having a second size to receive the reference current during a second period of time. The analog-to-digital converter converts a first voltage across the first diode to a first diode voltage value, and converts a second voltage across the second diode to a second diode voltage value. The processing circuit performs an arithmetic operation on the first and second diode voltage values to generate a digital bandgap value.

Description

Technical Field

[0001] The present invention relates to integrated circuit design, and more particularly to an integrated circuit that utilizes the same current source to bias diodes of different sizes to generate at least one of a digital bandgap value and a temperature value, and a related signal processing method. Background Art

[0002] A temperature sensor is a device that detects and measures heat and cold and converts it into an electrical signal. For example, a diode can be used as a temperature sensor in various integrated circuits (chips). In traditional temperature sensor designs, the voltage between the two ends of the diode is measured and then converted from the analog domain to the digital domain for further processing. The diode itself may have sensor (diode) mismatch issues, so proper calibration is required. In addition, the analog-to-digital converter (ADC) may have reference voltage mismatch issues, so a very accurate voltage source, such as an analog bandgap reference circuit, is required. Therefore, an innovative temperature sensor design is needed that can generate a digital temperature value with a small sensor (diode) mismatch and without the need for a precise ADC reference voltage. Summary of the Invention

[0003] One of the objectives of the present invention is to provide an integrated circuit and a related signal processing method for using the same current source to bias diodes of different sizes to generate at least one of a digital bandgap value and a temperature value.

[0004] In one embodiment of the present invention, an integrated circuit is disclosed. The integrated circuit includes a current source, a diode device, a switching circuit, an analog-to-digital converter, and a processing circuit. The current source is configured to provide a reference current. The switching circuit is coupled between the current source and the diode device and configured to cause the diode device to provide a first diode having a first size to receive the reference current during a first time period, and to cause the diode device to provide a second diode having a second size to receive the reference current during a second time period. The first size is different from the second size, and each of the first and second diodes is biased by the same current source. The analog-to-digital converter is configured to convert a first voltage across the first diode into a first diode voltage value, and to convert a second voltage across the second diode into a second diode voltage value. The processing circuit is configured to perform an arithmetic operation on the first and second diode voltage values ​​to generate a digital bandgap value.

[0005] In one embodiment of the present invention, a signal processing method is disclosed. The method includes: during a first period, causing a diode device to provide a first diode having a first size to receive a reference current provided by a current source, and performing analog-to-digital conversion on a first voltage across the first diode to generate a first diode voltage value; during a second period, causing the diode device to provide a second diode having a second size to receive the reference current provided by the current source, and performing analog-to-digital conversion on a second voltage across the second diode to generate a second diode voltage value, wherein the first size is different from the second size, and each of the first diode and the second diode is biased by the same current source; and performing an arithmetic operation on the first diode voltage value and the second diode voltage value to generate a digital bandgap value.

[0006] In one embodiment of the present invention, an integrated circuit is disclosed. The integrated circuit includes a current source, a diode device, a switching circuit, an analog-to-digital converter, and a processing circuit. The current source is configured to provide a reference current. The switching circuit is coupled between the current source and the diode device and configured to cause the diode device to provide a first diode having a first size to receive the reference current during a first time period, and to cause the diode device to provide a second diode having a second size to receive the reference current during a second time period. The first size is different from the second size, and each of the first and second diodes is biased by the same current source. The analog-to-digital converter is configured to convert a first voltage across the first diode into a first diode voltage value, and to convert a second voltage across the second diode into a second diode voltage value. The processing circuit is configured to perform an arithmetic operation on the first and second diode voltage values ​​to generate a temperature value.

[0007] Compared to conventional temperature sensor designs that use the diode voltage of a single diode, which requires calibration, the temperature sensor design proposed in the present invention uses the diode voltage difference, which is independent of process variations. Consequently, the proposed temperature sensor design exhibits significantly lower sensor (diode) mismatch. Furthermore, compared to conventional temperature sensor designs that require an analog-to-digital converter (ADC) reference voltage from a very precise voltage source (e.g., a large analog bandgap reference circuit), the proposed temperature sensor design uses a digital bandgap value derived through simple calculations in the digital domain. This eliminates the need for a precise analog-to-digital converter (ADC) reference voltage, significantly saving cost and area by eliminating the need for a large analog bandgap reference circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 FIG. 1 is a schematic diagram of an integrated circuit according to an embodiment of the present invention.

[0009] Figure 2 FIG. 1 is a schematic diagram of another integrated circuit according to an embodiment of the present invention.

[0010] Figure 3 is a flowchart of a signal processing method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0011] Certain words are used in the specification and claims to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different terms to refer to the same component. This specification and claims do not use differences in name as a way to distinguish components, but rather use differences in the functions of the components as the criterion for distinction. The words "include" and "including" mentioned throughout the specification and claims are open-ended terms and should be interpreted as "including but not limited to". In addition, the word "couple" or "coupled" herein includes any direct and indirect electrical connection means. Therefore, if the text describes a first device coupled to a second device, it means that the first device can be directly electrically connected to the second device, or indirectly electrically connected to the second device through other devices and connection means.

[0012] Figure 1 Schematic diagram of an integrated circuit according to an embodiment of the present invention. For example, the integrated circuit 100 may be a temperature sensor chip. For another example, the integrated circuit 100 may be any signal processing chip using the digital bandgap design proposed by the present invention. Figure 1 As shown, the integrated circuit 100 includes a current source 102, a switch circuit 104, a diode device 106, an analog-to-digital converter 108, and a processing circuit 110. The current source 102 is designed to provide a reference current I D The switching circuit 104 is coupled between the current source 102 and the diode device 106. In this embodiment, the diode device 106 includes diode elements D1 and D2 having different sizes (i.e., different cross-sectional areas). For example, each of the diode elements D1 and D2 can be implemented using a diode-connected transistor, such as a bipolar junction transistor (BJT) or a metal-oxide-semiconductor field-effect transistor (MOSFET), and the size ratio (area ratio) of the diode elements D1 and D2 can be 1:M.

[0013] The switching circuit 104 is configured to cause the diode device 106 to provide a first diode (eg, diode element D1) having a first size in a first time period to receive the reference current I D , and further configured to cause the diode device 106 to provide a second diode (eg, diode element D2) having a second size in a second period to receive the reference current ID , where the first and second time periods are non-overlapping. During the first time period, switching circuit 104 connects diode component D1 to current source 102 and disconnects diode component D2 from current source 102. Therefore, diode component D1 functions as a diode with a small size (small area). During the second time period, switching circuit 104 disconnects diode component D1 from current source 102 and connects diode component D2 to current source 102. Therefore, diode component D2 functions as a diode with a large size (large area).

[0014] It should be noted that each of the first diode (e.g., diode element D1) and the second diode (e.g., diode element D2) is biased by the same current source 102. In other words, when operating in the forward bias region, each of the first diode (e.g., diode element D1) and the second diode (e.g., diode element D2) is forced to have the same diode current I D Since the first diode (eg, diode component D1) and the second diode (eg, diode component D2) have different sizes, the first voltage V between the two ends of the first diode (eg, diode component D1) is D1 will be different from the second voltage V between the two ends of the second diode (eg, diode component D2). D2 .

[0015] The analog-to-digital converter 108 operates at a reference voltage V REF In this embodiment, the reference voltage V REF It does not need to be provided by a very accurate voltage source (e.g., an analog bandgap reference circuit). For example, a less accurate supply voltage V DD As the reference voltage V of the analog-to-digital converter 108 REF The analog-to-digital converter 108 is used to convert a first voltage V between two terminals of a first diode (eg, diode element D1) into a voltage V D1 Perform analog-to-digital conversion to generate a first diode voltage value dV D1 (It indicates the analog voltage V D1 The digital output of the second diode (eg, the diode component D2) is used to generate a second voltage V between both ends of the second diode (eg, the diode component D2). D2 Perform analog-to-digital conversion to generate a second diode voltage value dV D2 (It indicates the analog voltage V D2 The prefix "d" indicates digital format.

[0016] The processing circuit 110 is used to process the first diode voltage value dV D1 and the second diode voltage dV D2 Performing an arithmetic operation to generate a digital bandgap value dBG. Specifically, the arithmetic operation may include: calculating the first diode voltage value dV D1 and the second diode voltage dV D2 The voltage difference between the diodes is dΔV D (That is, dΔV D =dV D1 -dV D2 ), where the prefix "d" indicates digital format; and based on the diode voltage difference dΔV D And the diode voltage dV D To calculate the digital band gap value dBG, where the diode voltage value dV D is the voltage value dV from the first diode D1 and the second diode voltage dV D2 Select (ie, dV D =dV D1 or dV D =dV D2 The calculation of the digital band gap value dBG can be expressed by the following formula.

[0017] dBG=dV D +B*dΔV D , where B is a constant (1)

[0018] It should be noted that the diode voltage difference dΔV D It is a term proportional to absolute temperature (hereinafter referred to as "PTAT"). The two simulated diode voltage values ​​V D1 、V D2 The simulated diode voltage difference dΔV between D It can be expressed by the following formula.

[0019]

[0020] In the above formula (2), k is the Boltzmann constant, T is the absolute temperature of the PN junction, q is the elementary charge, and I D1 is the diode current of the first diode, I D2 is the diode current of the second diode, I S1is the reverse saturation current of the first diode, and I S2 is the reverse saturation current of the second diode.

[0021] If both the first diode and the second diode are connected by the same current source (e.g., Figure 1 The current source 102 shown in FIG1 is biased, and the diode current I D1 and the diode current I of the second diode D2 Both will be equal to the same reference current I provided by the current source D (That is, I D1 =I D2 =I D ). In addition, the reverse saturation current (for example, I S(1 or 2) ~=1pA) will be much smaller than the diode current (for example, I D(1 or 2) ~=1~10uA), therefore, in formula (2) The term can be considered as a constant C (i.e., ). Assuming the size ratio of the two diodes is 1:M, the reverse saturation current I S2 Will be the reverse saturation current I S1 M times (i.e., ). Formula (2) can be rewritten as follows.

[0022]

[0023] Therefore, if I D1 =I D2 , then the simulated diode voltage difference dΔV D It is proportional to absolute temperature and almost independent of process variation (PV).

[0024] Compared to the diode voltage difference dΔV D As a PTAT term, since the reverse saturation current of the diode is largely determined by temperature, the diode voltage value dV in formula (1) is D It is a term that is inversely proportional to absolute temperature (CTAT). Therefore, by properly setting the constant B in equation (1), the digital bandgap value dBG can be made temperature independent.

[0025] In some embodiments of the present invention, the constant B can be determined during the chip probe (CP) phase of a wafer. For example, a wafer may include multiple semiconductor dies, each of which has Figure 1 For the integrated circuit 100 shown in FIG. 1 , for each semiconductor die tested during the die test phase of the wafer, the first diode voltage value dV D1 and the second diode voltage dV D2 Each is measured twice, once at low temperature and once at high temperature. For each candidate value of constant B, two digital band gap values ​​dBG are calculated for each semiconductor die, including one based on the diode voltage value dV measured at low temperature. D1 、dV D2 The calculated digital bandgap value dBG for low temperature and another value dV based on the diode voltage measured at high temperature D1 、dV D2 The digital bandgap value dBG for high temperature is calculated. These digital bandgap values ​​dBG provided by all tested semiconductor dies are collected for standard deviation (hereinafter referred to as "STDEV") analysis. For example, an STDEV value of all digital bandgap values ​​dBG obtained under a candidate value of constant B is calculated. Among the multiple STDEV values ​​calculated for all candidate values ​​of constant B2, a candidate value of constant B that can obtain the minimum STDEV value is selected as the target value of constant B. However, this is only an example and not a limitation of the present invention. In fact, any means that can set constant B to make the digital bandgap value dBG have a zero temperature coefficient can be adopted.

[0026] After the processing circuit 110 obtains the digital bandgap value dBG, the digital bandgap value dBG can be used as a reference voltage for various applications. For example, the digital bandgap value dBG can be used for a digital output temperature sensor. Therefore, the processing circuit 110 is further used to calculate the diode voltage difference dΔV. D Another arithmetic operation is performed on the digital band gap value dBG to generate a temperature value Temp (which is a digital output indicating the temperature of the integrated circuit 100 ).

[0027] Specifically, the temperature value Temp can be calculated using the following formula.

[0028]

[0029] The temperature value Temp is obtained by dividing the diode voltage difference dΔV using the digital bandgap value dBG as the denominator. DCompared to the traditional temperature sensor design that uses the diode voltage value of a single diode that needs to be calibrated, the temperature sensor design proposed by the present invention uses the diode voltage difference dΔV that is independent of process deviation. D , thus, the temperature sensor design proposed in the present invention has very low sensor (diode) mismatch. In addition, compared to the traditional temperature sensor design that requires an ADC reference voltage provided by a very accurate voltage source (e.g., a large-scale analog bandgap reference circuit), the temperature sensor design proposed in the present invention uses the digital bandgap value dBG obtained by simple calculation in the digital domain. As a result, the analog-to-digital converter 108 does not require a precise reference voltage V REF , and the large-size analog bandgap reference circuit can be omitted, so the cost and area can be effectively saved.

[0030] about Figure 1 In the illustrated embodiment, only a single diode element from the two diode elements D1 and D2 is selected at a time. That is, the diode elements D1 and D2 can be considered as two independent diodes, each serving as the two differently sized diodes required for the digital bandgap design (or the temperature sensor design) of the present invention. However, this is for illustrative purposes only and is not a limitation of the present invention. In an alternative design, the two diode elements can be jointly used to form a single large diode required for the digital bandgap design (or the temperature sensor design) of the present invention.

[0031] Figure 2 Schematic diagram of another integrated circuit according to an embodiment of the present invention. For example, the integrated circuit 200 may be a temperature sensor chip. For another example, the integrated circuit 200 may be any signal processing chip that adopts the digital bandgap design proposed in the present invention. The main difference between the integrated circuit 100 and the integrated circuit 200 is that the switching circuit 204 allows multiple diode components to be selected at one time. The switching circuit 204 is coupled between the current source 102 and the diode device 206. In this embodiment, the diode device 206 includes two diode components D1 and D2'. For example, both the diode components D1 and D2' can be implemented using diode-connected transistors (for example, BJTs or MOSFETs), and the size ratio (area ratio) of the diode components D1 and D2' can be 1:(M-1).

[0032] The switching circuit 204 is configured to cause the diode device 106 to provide a first diode (eg, diode element D1) having a first size to receive the reference current I D, and further configured to cause the diode device 206 to provide a second diode (eg, diode component D1 and diode component D2 ′) having a second size to receive the reference current I D , wherein the first time period and the second time period are non-overlapping time periods. During the first time period, the switching circuit 204 connects the diode component D1 to the current source 102 and disconnects the diode component D2' from the current source 102. Therefore, the diode component D1 acts as a diode with a small size (small area). During the second time period, the switching circuit 204 connects the diode component D1 to the current source 102 and connects the diode component D2' to the current source 102. Therefore, the diode component D1 and the diode component D2' act as diodes with a large size (large area). Similarly, it can be achieved at the same bias current I D A first voltage V is generated between the two ends of the first diode (eg, the diode element D1 selected in the first period). D1 A second voltage V is generated between two ends of the second diode (eg, the diode element D1 and the diode element D2' selected together in the second period). D2 (V D2 ≠V D1 ) purpose.

[0033] Figure 3 FIG. 1 is a flow chart of a signal processing method according to an embodiment of the present invention. The signal processing method can be used in either integrated circuit 100 or integrated circuit 200. If substantially the same result can be obtained, the steps do not have to be completely followed. Figure 3 In step S302, the switching circuit 104 / 204 causes the diode device 106 / 206 to provide a first diode with a first size in a first period to receive the reference current I from the current source 102. D , and the analog-to-digital converter 108 generates a first voltage V between the two ends of the first diode in the first period. D1 Perform analog-to-digital conversion to generate a first diode voltage value dV D1 In step S304, the switching circuit 104 / 204 causes the diode device 106 / 206 to provide a second diode with a second size in a second period to receive the reference current I from the same current source 102. D , and the analog-to-digital converter 108 generates a second voltage V between the two ends of the second diode in the second period. D2 Perform analog-to-digital conversion to generate a second diode voltage value dV D2 In step S306, the processing circuit 110 processes the first diode voltage dV D1 and the second diode voltage dV D2Perform an arithmetic operation to generate a digital bandgap value dBG. In step S308, the processing circuit 110 processes the diode voltage difference dΔV. D Another arithmetic operation is performed on the digital band gap value dBG to generate a temperature value Temp. Figure 1 and Figure 2 The following description of the embodiment shown can be easily understood Figure 3 For the sake of brevity, further description of the operational details of the steps shown in FIG.

[0034] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the claims of the present invention should fall within the scope of the present invention.

[0035] Reference numerals:

[0036] 100, 200: integrated circuits

[0037] 102: Current Source

[0038] 104, 204: Switching circuit

[0039] 106, 206: diode device

[0040] 108: Analog-to-digital converter

[0041] 110: Processing circuit

[0042] I D : Reference current

[0043] D1, D2, D2': diode components

[0044] V REF : Reference voltage

[0045] V D1 : First voltage

[0046] V D2 : Second voltage

[0047] dV D1 : The first diode voltage value

[0048] dV D2 : Second diode voltage value

[0049] dBG: digital bandgap value

[0050] dΔV D : Diode voltage difference

[0051] Temp: Temperature value

[0052] S302, S304, S306, S308: Steps

Claims

1. An integrated circuit comprising: a current source for providing a reference current; a diode device; a switching circuit coupled between the current source and the diode device, wherein the switching circuit is configured to cause the diode device to provide a first diode having a first size to receive the reference current during a first period, and further configured to cause the diode device to provide a second diode having a second size to receive the reference current during a second period, wherein the first size is different from the second size, and each of the first diode and the second diode is biased by the same current source; an analog-to-digital converter for converting a first voltage between the two ends of the first diode into a first diode voltage value, and converting a second voltage between the two ends of the second diode into a second diode voltage value; and A processing circuit is used for performing an arithmetic operation on the first diode voltage value and the second diode voltage value to generate a digital bandgap value.

2. The integrated circuit of claim 1 , wherein the arithmetic operation performed by the processing circuit comprises: calculating a diode voltage difference between the first diode voltage value and the second diode voltage value; and The digital bandgap value is calculated according to the diode voltage difference and a diode voltage value, wherein the diode voltage value is selected from the first diode voltage value and the second diode voltage value.

3. The integrated circuit of claim 2, wherein the digital bandgap value is set to the sum of the diode voltage value plus the product of the diode voltage difference and a constant. 4 . The integrated circuit of claim 2 , wherein the processing circuit is further configured to perform another arithmetic operation on the diode voltage difference and the digital bandgap value to generate a temperature value. 5 . The integrated circuit of claim 4 , wherein the temperature value is set by dividing the diode voltage difference using the digital bandgap value as a denominator.

6. The integrated circuit of claim 1 , wherein the diode device comprises: a first diode component; and a second diode assembly; Wherein, in the first time period, the switching circuit connects the first diode component to the current source and disconnects the second diode component from the current source; and in the second time period, the switching circuit disconnects the first diode component from the current source and connects the second diode component to the current source.

7. The integrated circuit of claim 1 , wherein the diode device comprises: a first diode component; and a second diode assembly; Wherein, in the first time period, the switching circuit connects the first diode component to the current source and disconnects the second diode component from the current source; and in the second time period, the switching circuit connects the first diode component to the current source and connects the second diode component to the current source.

8. A signal processing method, comprising: During a first period, a diode device is caused to provide a first diode having a first size to receive a reference current provided by a current source, and a first voltage between two ends of the first diode is converted from analog to digital to generate a first diode voltage value; During a second period, causing the diode device to provide a second diode having a second size to receive the reference current provided by the current source, and performing analog-to-digital conversion on a second voltage across the second diode to generate a second diode voltage value, wherein the first size is different from the second size, and each of the first diode and the second diode is biased by the same current source; and An arithmetic operation is performed on the first diode voltage value and the second diode voltage value to generate a digital bandgap value.

9. The signal processing method as claimed in claim 8, wherein the arithmetic operation comprises: calculating a diode voltage difference between the first diode voltage value and the second diode voltage value; and The digital bandgap value is calculated according to the diode voltage difference and a diode voltage value, wherein the diode voltage value is selected from the first diode voltage value and the second diode voltage value. 10 . The signal processing method of claim 9 , wherein the digital bandgap value is set to the sum of the diode voltage value plus the product of the diode voltage difference and a constant.

11. The signal processing method according to claim 10, further comprising: The constant is determined during a wafer's bare die testing phase.

12. The signal processing method according to claim 9, further comprising: Another arithmetic operation is performed on the diode voltage difference and the digital bandgap value to generate a temperature value. 13 . The signal processing method of claim 12 , wherein the temperature value is set by dividing the diode voltage difference using the digital bandgap value as a denominator.

14. The signal processing method of claim 8, wherein the step of causing the diode device to provide the first diode having the first size to receive the reference current provided by the current source comprises: connecting the first diode component to the current source; and disconnecting the second diode assembly from the current source; and The step of causing the diode device to provide the second diode having the second size to receive the reference current provided by the current source comprises: disconnecting the first diode assembly from the current source; and The second diode assembly is connected to the current source.

15. The signal processing method of claim 8, wherein the step of causing the diode device to provide the first diode having the first size to receive the reference current provided by the current source comprises: connecting the first diode component to the current source; and disconnecting the second diode assembly from the current source; and The step of causing the diode device to provide the second diode having the second size to receive the reference current provided by the current source comprises: connecting the first diode component to the current source; and The second diode assembly is connected to the current source.

16. An integrated circuit comprising: a current source for providing a reference current; a diode device; a switching circuit coupled between the current source and the diode device, wherein the switching circuit is configured to cause the diode device to provide a first diode having a first size to receive the reference current during a first period, and further configured to cause the diode device to provide a second diode having a second size to receive the reference current during a second period, wherein the first size is different from the second size, and each of the first diode and the second diode is biased by the same current source; an analog-to-digital converter for converting a first voltage between the two ends of the first diode into a first diode voltage value, and converting a second voltage between the two ends of the second diode into a second diode voltage value; and A processing circuit is used for performing an arithmetic operation on the first diode voltage value and the second diode voltage value to generate a temperature value.

17. The integrated circuit of claim 16, wherein the arithmetic operation performed by the processing circuit comprises: A diode voltage difference is calculated between the first diode voltage value and the second diode voltage value, wherein the calculation of the temperature value is based at least in part on the diode voltage difference.

18. The integrated circuit of claim 16, wherein the diode device comprises: a first diode component; and a second diode assembly; Wherein, in the first time period, the switching circuit connects the first diode component to the current source and disconnects the second diode component from the current source; and in the second time period, the switching circuit disconnects the first diode component from the current source and connects the second diode component to the current source.

19. The integrated circuit of claim 16, wherein the diode device comprises: a first diode component; and a second diode assembly; Wherein, in the first time period, the switching circuit connects the first diode component to the current source and disconnects the second diode component from the current source; and in the second time period, the switching circuit connects the first diode component to the current source and connects the second diode component to the current source.

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