Temperature sensor with series resistance cancellation and beta compensation

Abstract

This disclosure relates to a temperature sensor with series resistance elimination and β compensation. A device includes a current source circuit (112) having an output coupled to a first terminal. A first resistive device (121) is coupled between a second terminal and a third terminal. A second resistive device (122) is coupled between the first terminal and the second terminal. A control circuit (130) is coupled to the current source circuit and to both the first resistive device (121) and the second resistive device (122). The control circuit (130) is configured to: enable the first resistive device (121) and control the current source circuit (112) to provide a first current to the first terminal; and enable the second resistive device (122) and control the current source circuit (112) to generate a second current to the first terminal, the second current being different from the first current.

Description

Technical Field

[0001] This disclosure relates to temperature measurement. Background Technology

[0002] The technique used to measure temperature involves using a temperature-sensitive device, such as a bipolar junction transistor (BJT). For a BJT, the base-to-emitter voltage (Vbe) is proportional to the transistor's thermal voltage Vt. The thermal voltage Vt of a BJT is... Where k represents the Boltzmann constant, T represents the temperature, and q represents the charge of the electron. By forcing an electric current through the BJT, its Vbe can be measured, and the temperature can be calculated from its Vbe. Summary of the Invention

[0003] In one example, a device includes a current source circuit having an output coupled to a first terminal. A first resistive device is coupled between a second terminal and a third terminal. A second resistive device is coupled between the first terminal and the second terminal. Control circuitry is coupled to the current source circuitry and to both the first and second resistive devices. The control circuitry is configured to: enable the first resistive device and control the current source circuitry to provide a first current to the first terminal; and enable the second resistive device and control the current source circuitry to generate a second current to the first terminal, the second current being different from the first current.

[0004] In another example, a device includes a first current source having an output coupled to a first terminal. A second current source has an output coupled to the first terminal. A third current source has an output coupled to the first terminal. A first controllable resistive device is coupled between a second terminal and a ground terminal. The first controllable resistive device has a first resistance. A second controllable resistive device is coupled between the second terminal and the ground terminal. The second controllable resistive device has a second resistance different from the first resistance. A third controllable resistive device is coupled between the second terminal and the ground terminal. The third controllable resistive device has a third resistance different from the first and second resistances. An analog-to-digital converter (ADC) has an input coupled to the first terminal. Attached Figure Description

[0006] To gain a more complete understanding of this disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

[0007] Figure 1 This is a circuit diagram of a temperature sensor according to an embodiment of the present disclosure;

[0008] Figure 2 This is a circuit diagram of a temperature sensor according to an embodiment of the present disclosure;

[0009] Figure 3 This is a circuit diagram of a temperature sensor according to an embodiment of the present disclosure; and

[0010] Figure 4 This is a circuit diagram of a temperature sensor according to an embodiment of the present disclosure.

[0011] Unless otherwise indicated, corresponding reference numerals and symbols in different figures generally refer to corresponding parts. The figures are drawn to clearly illustrate relevant aspects of the preferred embodiments, and the figures are not necessarily drawn to scale. Detailed Implementation

[0012] The following section discusses in detail the making and use of the disclosed embodiments. However, it should be understood that this disclosure provides many applicable inventive concepts that can be embodied in various specific situations. The specific embodiments discussed are merely illustrative of specific ways of making and using this disclosure and do not limit the scope of this disclosure.

[0013] The following description illustrates various specific details to provide a thorough understanding of several exemplary embodiments based on the description. Embodiments may be obtained without one or more specific details or by utilizing other methods, components, materials, etc. In some cases, known structures, materials, or operations have not been shown or described in detail so as not to obscure different aspects of the embodiments. References to "embodiment" in this specification indicate that a particular configuration, structure, or feature described with respect to the embodiment is included in at least one embodiment. Therefore, phrases such as "in one embodiment" that may appear in different places in this specification do not necessarily refer exactly to the same embodiment. Furthermore, specific forms, structures, or features may be combined in any suitable manner in one or more embodiments.

[0014] The following description uses illustrative examples to illustrate several aspects of this disclosure. It should be understood that many specific details, relationships, and methods are set forth to provide an understanding of this disclosure. This disclosure is not limited to the described order of actions or events, as some actions may occur in a different order and / or simultaneously with other actions or events.

[0015] In the example, the temperature sensor may include a bipolar junction transistor (BJT) coupled to a circuit. The circuit allows current to flow through the BJT and measures the resulting Vbe of the BJT. In one example, the emitter and base of the PNP BJT are coupled to the circuit, and the collector is coupled to ground. The circuit forces current to flow into the emitter (Ie) of the PNP BJT, causing current to flow out from the base (Ib) and collector (Ic) of the BJT. The sum of the base and collector currents equals the emitter current. The current gain β of a BJT is the ratio of the collector current to the base current. .

[0016] Several concurrent conditions can reduce the accuracy of temperature determination using a BJT. First, a series resistance Rs may exist between the circuit and the emitter of the BJT. This series resistance Rs can be contained within the physical resistance and / or parasitic resistance of the traces on the printed circuit board (PCB) between the circuit and the BJT's emitter. Current flowing into the BJT's emitter also flows through the series resistance Rs, causing a voltage drop across it. The voltage measured by the circuit is the sum of the BJT's Vbe and the voltage drop across the series resistance Rs. The value of the series resistance Rs is not necessarily known beforehand by the circuit determining the BJT's temperature. Therefore, the presence of the series resistance can affect the accuracy of the temperature value determined by the circuit. The second issue concerns the BJT's... The β of a BJT can vary based on the collector current of the BJT. The relationship between β and collector current may not be linear. The β of a BJT can be different values ​​for different levels of collector current, which may also cause inaccuracies in temperature determination.

[0017] Figure 1 This is a schematic diagram of a temperature determination system 100 according to an embodiment of the present disclosure. The temperature determination system 100 includes a BJT 180 coupled to terminals 110a and 110b of an integrated circuit (IC) 110. The BJT 180 is a temperature-sensitive device. Figure 1 In the example, BJT 180 is a PNP BJT. The emitter of BJT 180 is coupled to terminal 110a. The base of BJT 180 is coupled to terminal 110b. The collector of the BJT is coupled to ground. Other types of temperature-sensitive devices can be used instead of BJT 180. Examples of other types of temperature-sensitive devices include NPN BJTs, diodes, etc.

[0018] The circuitry of IC 110 determines the temperature of BJT 180, as described below. In one example, IC 110 and BJT 180 are mounted on a PCB. The series resistor Rs may be or may be included in the parasitic resistance of the trace on the PCB between terminal 110a and the emitter of BJT 180. A physical resistor may be included on the PCB between terminal 110a and the emitter of the BJT; in this case, the series resistor is or includes such a resistor. In some examples, BJT 180 is a transistor within an IC other than IC 110 (e.g., a processor). In such examples, IC 110 may determine the temperature of another IC.

[0019] IC 110 includes a current source circuit 112, controllable resistive devices (also referred to as resistive devices) 121, 122, and 123, a control circuit 130, and an analog-to-digital converter (ADC) 140. The current source circuit 112 has a control input 112a and an output 112b. Output 112b is coupled to terminal 110a of IC 110. ADC 140 has inputs 140a and 140b, a control input 140c, and an output 140d. Terminal 110a is coupled to input 140a. Input 140b is coupled to ground. Control circuit 130 has input 130a and control outputs 130b, 130c, 130d, 130e, and 130f. Output 140d of ADC 140 is coupled to input 130a of control circuit 130. Resistive device 121 has terminals 121a and 121b and a control input 121c. Resistive device 122 has terminals 122a and 122b and a control input 122c. Resistive device 123 has terminals 123a and 123b and a control input 123c. Terminals 121a, 122a, and 123a are coupled to terminal 110b of IC 110. Terminals 121b, 122b, and 123b are coupled to ground. The control output 130f of control circuit 130 is coupled to the control input 140c of ADC 140. Control outputs 130c, 130d, and 130e are coupled to the control inputs 121c, 122c, and 123c of resistive devices 121, 122, and 123, respectively. Figure 1 In the example, IC 110 includes three resistive devices 121 to 123. In other examples, the number of resistive devices may not be three, such as two resistive devices or four or more resistive devices.

[0020] Resistive device 121 can be enabled to apply resistance between its terminals 121a and 121b based on a control signal from control circuitry 130 at its control input 121c. In the example, resistive device 121 applies resistance between terminals 121a and 121b in response to a first logic state (e.g., logic high) at control input 121c. In response to a second logic state (e.g., logic low) at control input 121c, resistive device 121 represents an open circuit between terminals 121a and 121b. Similarly, resistive devices 122 and 123 may be able to apply resistance or an open circuit between their respective terminals 122a / 122b and 123a / 123b in response to control signals from control circuitry 130 at their respective control inputs 122c and 123c.

[0021] In some embodiments, control circuitry 130 may be implemented as a general-purpose or custom processor or controller having or being coupled to memory and configured to execute instructions in such memory (e.g., to perform the functionality described herein). Control circuitry 130 may also be implemented as or include a hardware accelerator and / or a state machine (e.g., to perform the functionality described herein). In some embodiments, control circuitry 130 may be implemented as programmable circuitry, such as a field-programmable gate array (FPGA) (e.g., to perform the functionality described herein). In some embodiments, control circuitry 130 is a non-programmable digital circuit.

[0022] In some embodiments, in response to a control signal from control circuitry 130 at control input 140c of the ADC, ADC 140 samples the input voltage (e.g., relative to ground) from terminal 110a at input 140a and converts it into a digital value. For example, based on the techniques described below, ADC 140 determines a digital value (dVeb) indicating the temperature of BJT 180 (e.g., proportional to the temperature of the BJT) based on multiple analog-to-digital conversions of the voltage at input 140a, each conversion based on the current from current source circuitry 112 to BJT 180. The digital value dVeb is provided to control circuitry 130 and can be retrieved by another device (e.g., another IC).

[0023] In some embodiments, the temperature determination system 100 determines the temperature of the BJT 180 while eliminating the effect of the voltage generated across the series resistor Rs when current from the current source circuit 112 flows to the emitter of the BJT 180. The current source circuit 112 provides two or more currents of different magnitudes to the emitter of the BJT 180 in response to a control signal from the control circuit 130 at its control input 112a. In one example, the current source circuit 112 provides three currents of different magnitudes to the emitter of the BJT 180 in response to a control signal from the control output 130b of the control circuit 130. For example, the current source circuit 112 may generate currents I1, I6, and I16, where I6 is six (6) times the current I1, and I16 is sixteen (16) times the current I1.

[0024] Ignoring resistive devices 121 to 123 and assuming terminal 110b is coupled to ground, control circuit 130 can control current source circuit 112 to generate any one of three currents I1, I6, and I16 via control signals at its control outputs 130b and 130f, and cause ADC 140 to sample and digitize the resulting voltage difference between terminal 110a and ground. The voltage between terminal 110a and ground is the sum of the voltage drop across the series resistor Rs and Vbe of BJT 180. For the current I1 from current source circuit 112, the voltage between terminal 110a and ground is referred to as Vbe1. Similarly, for currents I6 and I16, the voltages between terminal 110a and ground are referred to as Vbe6 and Vbe16, respectively. In some embodiments, control circuit 130 determines the temperature, for example indicated by BJT 180, while eliminating the series resistance Rs. Each time the control circuit 130 controls the current source circuit 112 to generate current I16, the control circuit 130 can control the current source circuit 112 to generate current I6 three times and control the current source circuit 112 to generate current I1 twice. Under the control of the control circuit 130, each time one of the currents I1, I6 and I16 is generated, the ADC 140 samples the voltage at terminal 110a. Therefore, for each temperature determination, the ADC determines Vbe1 twice, Vbe6 three times, and Vbe16 once. As an integrating ADC, the ADC 140 subtracts the sum of two Veb1 from Veb16, and also subtracts the sum of three Veb6 from Veb16. Mathematically, the subtraction can be expressed as the following equation (1):

[0025] (Equation 1)

[0026] The equation for Veb in BJT can be given by the following formula:

[0027] (Equation 2)

[0028] Where n represents the ideality factor (usually between 1 and 2), Is represents the saturation current of the BJT, Vt represents the thermal voltage, and Ic represents the collector current. Substituting equation (2) into equation (1) yields:

[0029] (Equation 3)

[0030] The control circuit 130 can use equation (3) to determine the temperature of the BJT 180 by, for example, dividing dVeb from the ADC 140 by ln(13.5) to determine “n”. The value of Vt is then used to calculate the temperature using the formula for thermal voltage (kT / q).

[0031] Equation (3) is based on the assumption that β of the BJT 180 is constant for different values ​​of the collector current of the BJT 180. As noted above, β can vary based on the collector current Ic of the BJT 180. Changing the emitter current causes a change in the collector current. Additional terms can be introduced into equation (3) to be based on Figure 1 Considering the β variability of the various emitter currents I1, I6, and I16, as shown in equation (4) below:

[0032] (Equation 4)

[0033] in This refers to the β value of the BJT 180 for current I1. This refers to the β value for the current I6, and This refers to the β value for the current I16. (Item) Indicates based on And the error introduced into dVeb. Similarly, the item and Indicates based on and The error in dVeb. Considering resistive devices 121 to 123, in response to a specific current I1, I6, or I16 supplied to the emitter of the BJT 180 by the current source circuit 112, the base current from the BJT 180 flows through one of the three resistive devices 121, 122, and 123. For example, when the control circuit 130 controls the current source circuit 112 to generate current I1, the control circuit 130 also enables resistive device 121 and disables resistive devices 122 and 123. Similarly, when the control circuit 130 controls the current source circuit 112 to generate current I6, the control circuit 130 also enables resistive device 122 and disables resistive devices 121 and 123. When the control circuit 130 controls the current source circuit 112 to generate current I16, the control circuit 130 also enables resistive device 123 and disables resistive devices 121 and 122. The voltage obtained across the specific resistive devices 121 to 123 activated by control circuitry 130 is included as a portion of the voltage received by input 140a of ADC 140. ADC 140 receives the voltage between terminal 110a and ground, which includes the sum of Vbe of BJT 180 and the voltage across the activated resistive devices 121 to 123. The resulting voltage dVeb, including the voltage across resistive devices 121 to 123, is:

[0034] (Equation 5)

[0035] Where R_121, R_122 and R_123 represent the resistances of resistive devices 121, 122 and 123, respectively.

[0036] The resistance of each resistive device 121 to 123 can be determined in any of a variety of ways, for example by using the following equation:

[0037] (Equation 6)

[0038] Where R b This represents the resistance of one of the resistive devices 121, 122, and 123 for a given emitter current Ie, where Ie is one of currents I1, I6, and I16. For example, assuming a specific β value and Ie equal to I1, the resistance of resistive device 121 can be calculated. After calculating the resistance of resistive device 121 for said specific β value, the resistances of resistive devices 122 and 123 can then be calculated for the same β value. The resistance of resistive device 122, activated for current I6, is one-sixth the resistance of resistive device 121. Similarly, the resistance of resistive device 123, activated for current I16, is one-sixteenth the resistance of resistive device 121. This specific set of resistances for resistive devices 121 to 123 is calculated for a specific β value.

[0039] In addition to depending on the collector current, β can also be temperature-dependent. For example, β can increase with increasing temperature. All other things being equal, a larger β for a given emitter current results in a smaller base current from the BJT 180. The reduction in base current can be partially compensated by implementing the resistors of resistive devices 121 to 123 with a positive temperature coefficient, resulting in a voltage drop that remains approximately the same despite the reduction in base current. For example, in some embodiments, the resistors R_121, R_122, and R_123 in equation (5) above can have a positive absolute temperature (PTAT) dependence. In this example, the current source circuit 112 can generate currents I1, I6, and I16 with minimal (if present) temperature dependence by, for example, applying a bandgap voltage (which has minimal (if present) temperature dependence) to the resistors to generate current. The resulting temperature-independent current can be provided to the current mirror to generate currents I1, I6, and I16.

[0040] In some embodiments, the current source circuit 112 is implemented to have a positive temperature dependence on the currents I1, I6, and I16 generated therefrom, to compensate for the temperature dependence of β on the BJT 180. When the current is the PTAT current and the resistances R_121, R_122, and R_123 have minimal (if any) temperature dependence, equation (5) can be rewritten as:

[0041] (Equation 7)

[0042] The term "constant" refers to a constant value, and Rbias represents the resistor to which dVeb is applied to generate a bias current. This bias current has a positive temperature coefficient and, as described above, can be applied to the current mirror to generate currents I1, I6, and I16.

[0043] For a fairly narrow range of β values, variations in β can be particularly significant in their impact on the accuracy of temperature measurements. For example, variations in β values ​​between 2 and 10 can be significant in terms of temperature measurement accuracy. The voltage generated across resistive devices 121, 122, and 123 reduces temperature measurement errors that would otherwise occur in the absence of resistive devices 121 to 123. For β values ​​greater than, for example, 10, the voltage across resistive devices 121 to 123 may contribute relatively little to a further reduction in temperature measurement error. For β values ​​less than, for example, 1, including resistive devices 121 to 123 may not significantly improve the temperature measurement error. Therefore, in some embodiments, the resistance of resistive devices 121 to 123 is determined for β values ​​within, for example, a range between 1 and 10.

[0044] In some embodiments, BJT 180 may be a discrete temperature sensing device. In some embodiments, BJT 180 is part of an integrated circuit, such as a processor or application-specific integrated circuit (ASIC), wherein BJT 180 is used to determine the (e.g., internal) temperature of the integrated circuit.

[0045] Figure 2 It is similar to Figure 1 The circuit diagram is shown, but additional details of the current source circuit 112 and resistive devices 121 to 123 are illustrated. In this example, the current source circuit 112 includes current sources 201, 202, and 203. When enabled by the control circuit 130, current sources 201, 202, and 203 provide currents I1, I6, and I16, respectively. Resistive device 121 includes a resistor R1 series coupled to a switch (e.g., a transistor) SW1 between terminals 121a and 121b. Resistive device 122 includes a resistor R2 series coupled to a switch (e.g., a transistor) SW2 between terminals 122a and 122b. Resistive device 123 includes a resistor R3 series coupled to a switch (e.g., a transistor) SW3 between terminals 123a and 123b. Control outputs 130c, 130d, and 130e from control circuit 130 are coupled to corresponding control terminals of switches SW1 to SW3 (e.g., coupled to the gates of the transistors implementing switches SW1 to SW3). Therefore, control circuit 130 can turn any of switches SW1 to SW3 on or off to enable the corresponding resistive devices 121, 122, or 123. When control circuit 130 enables current source 201, it also turns on switch SW1 and turns off switches SW2 and SW3. When control circuit 130 enables current source 202, it also turns on switch SW2 and turns off switches SW1 and SW3. When control circuit 130 enables current source 203, it also turns on switch SW3 and turns off switches SW1 and SW2.

[0046] Figure 3 To a large extent, as Figure 2 The circuit diagram. Figure 3 Resistors R1, R2, and R3 are shown to be adjustable, as indicated by the arrows passing through the resistors. As described above, the resistance of resistors R1 to R3 is determined for a specific β value within a relatively narrow range (e.g., β = 5). Resistors R1 to R3 can be adjusted for different β values. In one example, IC 150 may have a programmable register through which different values ​​for resistors R1 to R3 can be specified based on external control values ​​(e.g., provided via an Interconnect Integrated Circuit (IIC) interface). Each resistor R1, R2, and R3 can be configured for use with any of a plurality of resistive devices, for example, through series and / or parallel combinations of resistors and switches.

[0047] Figure 4 yes Figure 3 The circuit diagram of the temperature determination system 400 is shown, but it has two BJTs 180 and 480 coupled to terminals 110a and 110b of IC 110. BJT 480 is also a PNP BJT. A series resistor RS_A (a physical resistor and / or parasitic resistance as described above) is between terminal 110b and the emitter of BJT 480. As described above, the emitter and base of BJT 180 are coupled to terminals 110a and 110b, respectively. The emitter and base of BJT 480 are coupled to terminals 110b and 110a, respectively. IC 110 also includes a switching circuit 410. The switching circuit 410 couples the output 112b of the current source circuit 112 to terminal 110a or terminal 110b based on the control circuit from the control output 130g of control circuit 130 to the control input 410a of switching circuit 410.

[0048] The switching circuit 410 operates in one of two states based on a control signal at control input 410a. The first state involves current from the current source circuit 112 being supplied through the switching circuit 410 to terminal 110a and to the emitter of the BJT 180, while base current from the BJT 180 flows through terminal 110b, the switching circuit 410, and to the activated resistive devices 121 to 123. In this state, with current flowing out of terminal 110a, the BJT 480 is turned off. The second state involves current from the current source circuit 112 being supplied through the switching circuit 410 to terminal 110b and to the emitter of the BJT 480, while base current from the BJT 480 flows through terminal 110a, the switching circuit 410, and to the activated resistive devices 121 to 123. In this state, with current flowing out of terminal 110b, the BJT 180 is turned off.

[0049] Similar to the BJT 180, the BJT 480 is a temperature-sensitive device whose Vbe is proportional to its temperature. In the case of multiple BJT 180s and 480s, a single IC 110 and its circuitry can sequentially determine the temperature of each of the BJT 180s and 480s. For example, the technique described above can be used to determine the temperature of the BJT 180, and then the same technique can be used to determine the temperature of the BJT 480. Thus, two temperature-sensitive devices can be coupled to the same pair of terminals 110a and 110b, and the temperature of each temperature-sensitive device can be determined while eliminating the associated series resistance (RS of the BJT 180 and RS_A of the BJT 480) and reducing the effects of β variations, as described above. In one example, the BJT 180 and 480 are in the same IC, but said IC is different from IC 110.

[0050] Exemplary embodiments of this disclosure are outlined herein. Other embodiments may be understood from the entire specification and claims submitted herein.

[0051] Example 1. A device comprising: a current source circuit having an output coupled to a first terminal; a first resistive device coupled between a second terminal and a third terminal; a second resistive device coupled between the first terminal and the second terminal; and a control circuit coupled to the current source circuit and to the first resistive device and the second resistive device, the control circuit being configured to: enable the first resistive device and control the current source circuit to provide a first current to the first terminal; and enable the second resistive device and control the current source circuit to generate a second current to the first terminal, the second current being different from the first current.

[0052] Example 2. The device according to Example 1, wherein the second current is six times the first current.

[0053] Example 3. The device according to any one of Examples 1 or 2, wherein the control circuit is configured to: control the current source circuit to provide the first current when the first resistive device is enabled and the second resistive device is disabled; and control the current source circuit to provide the second current when the first resistive device is disabled and the second resistive device is enabled.

[0054] Example 4. The device according to any one of Examples 1 to 3, further comprising a third resistive device coupled between the second terminal and the third terminal, wherein the current source circuit is configured to enable the third resistive device and provide a third current to the first terminal, the third current being sixteen times the first current and the second current being six times the first current.

[0055] Example 5. The device according to any one of Examples 1 to 4, wherein the control circuit is coupled to the third resistive device, and the control circuit is configured to: enable the third resistive device, disable the first resistive device and the second resistive device, and control the current source circuit to provide the third current; each time the third resistive device is enabled, enable the second resistive device, disable the first resistive device and the third resistive device, and control the current source circuit to provide the second current three times; and each time the third resistive device is enabled, enable the first resistive device, disable the second resistive device and the third resistive device, and control the current source circuit to provide the first current twice.

[0056] Example 6. The device according to any one of Examples 1 to 5, further comprising an analog-to-digital converter (ADC) having an input coupled to the first terminal.

[0057] Example 7. The device according to any one of Examples 1 to 6, wherein the ADC is an integrating ADC.

[0058] Example 8. The device according to any one of Examples 1 to 7, wherein the control circuit is coupled to the ADC and configured to: cause the ADC to provide a first ADC conversion when the current source circuit provides the first current to the first terminal; cause the ADC to provide a second ADC conversion when the current source circuit provides the second current to the first terminal; and determine a value indicating temperature based on the first ADC conversion and the second ADC conversion.

[0059] Example 9. The device according to any one of Examples 1 to 8, wherein the first resistive device has a first resistance, and the second resistive device has a second resistance different from the first resistance.

[0060] Example 10. The device according to any one of Examples 1 to 9, wherein: the first resistive device includes a first resistor coupled to a first switch; and the second resistive device includes a second resistor coupled to a second switch.

[0061] Example 11. The device according to any one of Examples 1 to 10, wherein: the first switch has a first control terminal coupled to the control circuit; and the second switch has a second control terminal coupled to the control circuit.

[0062] Example 12. The device according to any one of Examples 1 to 11, wherein the first resistor and the second resistor are trimmable.

[0063] Example 13. The device according to any one of Examples 1 to 12 further includes a temperature sensing device having a first temperature sensing device terminal coupled to the first terminal and a second temperature sensing device terminal coupled to the second terminal.

[0064] Example 14. The device according to any one of Examples 1 to 13, wherein the current source circuit, the first resistive device, and the second resistive device are on a first integrated circuit, and the temperature-sensitive device is on a second integrated circuit.

[0065] Example 15. The device according to any one of Examples 1 to 14, wherein the temperature-sensitive device comprises a bipolar junction transistor having a base coupled to the second terminal and an emitter coupled to the first terminal.

[0066] Example 16. The device according to any one of Examples 1 to 15 further includes another temperature-sensitive device, the other temperature-sensitive device including another bipolar junction transistor having a base coupled to the first terminal and an emitter coupled to the second terminal.

[0067] Example 17. A device comprising: a first current source having an output coupled to a first terminal; a second current source having an output coupled to the first terminal; a third current source having an output coupled to the first terminal; a first controllable resistive device coupled between a second terminal and a ground terminal, the first controllable resistive device having a first resistance; a second controllable resistive device coupled between the second terminal and the ground terminal, the second controllable resistive device having a second resistance different from the first resistance; a third controllable resistive device coupled between the second terminal and the ground terminal, the third controllable resistive device having a third resistance different from the first resistance and the second resistance; and an analog-to-digital converter (ADC) having an input coupled to the first terminal.

[0068] Example 18. The device according to Example 17, wherein: the first controllable resistive device includes a first resistor coupled to a first switch; the second controllable resistive device includes a second resistor coupled to a second switch; and the third controllable resistive device includes a third resistor coupled to a third switch.

[0069] Example 19. The device according to any one of Examples 17 or 18, further comprising a control circuit coupled to the first current source, the second current source and the third current source, wherein: the first switch has a first control terminal coupled to the control circuit; the second switch has a second control terminal coupled to the control circuit; and the third switch has a third control terminal coupled to the control circuit.

[0070] Example 20. The device according to any one of Examples 17 to 19, wherein the first resistor, the second resistor, and the third resistor are trimmable.

[0071] Example 21. The device according to any one of Examples 17 to 20, wherein the first switch comprises a first transistor, the second switch comprises a second transistor, and the third switch comprises a third transistor.

[0072] Example 22. The device according to any one of Examples 17 to 21 further includes a temperature sensing device having a first temperature sensing device terminal coupled to the first terminal and a second temperature sensing device terminal coupled to the second terminal.

[0073] Example 23. The device according to any one of Examples 17 to 22, wherein the first current source, the second current source, and the third current source, as well as the first controllable resistive device, the second controllable resistive device, and the third controllable resistive device, are on a first integrated circuit, and the temperature-sensitive device is on a second integrated circuit.

[0074] Example 24. The device according to any one of Examples 17 to 23, wherein the temperature-sensitive device is a bipolar junction transistor (BJT).

[0075] Example 25. The device according to any one of Examples 17 to 24, further comprising: a first bipolar junction transistor (BJT) having a first emitter coupled to the first terminal and a first base coupled to the second terminal; and a second BJT having a second emitter coupled to the second terminal and a second base coupled to the first terminal.

[0076] In this specification, the term "coupled" may encompass a connection, communication, or signal path that achieves a functional relationship consistent with this specification. For example, if device A generates a signal to control device B to perform an action, then: (a) in a first example, device A is coupled to device B via a direct connection; or (b) in a second example, device A is coupled to device B via an intermediate component C, provided that the intermediate component C does not alter the functional relationship between device A and device B such that device B is controlled by device A via the control signal generated by device A.

[0077] The circuits or devices described herein as containing certain components can conversely be adapted to couple to those components used to form the described circuit system or device. For example, a structure described as containing one or more semiconductor elements (e.g., transistors), one or more passive elements (e.g., resistors, capacitors, and / or inductors), and / or one or more sources (e.g., voltage sources and / or current sources) may actually contain only semiconductor elements within a single physical device (e.g., a semiconductor die and / or integrated circuit (IC) package), and may be adapted to couple to at least some passive elements and / or sources to form the described structure during or after manufacturing, for example, by an end user and / or a third party.

[0078] While the use of specific transistors is described herein, other transistors (or equivalent devices) may be used alternatively with minimal alteration to the rest of the circuitry. For example, field-effect transistors (“FETs”) (e.g., n-channel FETs (NFETs) or p-channel FETs (PFETs)), bipolar junction transistors (BJTs—e.g., NPN or PNP transistors), insulated-gate bipolar transistors (IGBTs), and / or junction field-effect transistors (JFETs) may be used in place of or in combination with the devices described herein. Transistors may be depletion-mode devices, drain-extended devices, enhancement-mode devices, natural transistors, or other types of device structure transistors. Furthermore, the devices may be implemented on / above a silicon (Si) substrate, a silicon carbide (SiC) substrate, a gallium nitride (GaN) substrate, or a gallium arsenide (GaAs) substrate.

[0079] The claims may refer to the control input and current terminals of a transistor. In the case of a FET, the control input is the gate, and the current terminals are the drain and source. In the case of a BJT, the control input is the base, and the current terminals are the collector and emitter. The gate, source, and drain of a FET, and the base, collector, and emitter of a BJT, are the terminals of a transistor.

[0080] The circuits described herein may be reconfigurable to include additional or different components to provide functionality at least partially similar to that available before the component replacement. Unless otherwise stated, components shown as resistors generally represent any one or more elements coupled in series and / or parallel to provide the amount of impedance represented by the shown resistor. For example, a resistor or capacitor shown and described herein as a single component may actually be multiple resistors or capacitors coupled in parallel between the same nodes. For example, a resistor or capacitor shown and described herein as a single component may actually be multiple resistors or capacitors coupled in series between the same two nodes as the single resistor or capacitor.

[0081] While some elements of the described examples are included in the integrated circuit and others are outside the integrated circuit, in other example embodiments, additional or fewer features may be incorporated into the integrated circuit. Additionally, some or all of the features shown as being outside the integrated circuit may be included in the integrated circuit, and / or some features shown as being inside the integrated circuit may be incorporated outside the integrated circuit. As used herein, the term "integrated circuit" means one or more circuits that are: (i) incorporated in / above a semiconductor substrate; (ii) incorporated in a single semiconductor package; (iii) incorporated in the same module; and / or (iv) incorporated in / on the same printed circuit board.

[0082] The use of the phrase "grounding" in the foregoing description may include chassis grounding, earth grounding, floating grounding, virtual grounding, digital grounding, common grounding, and / or any other form of grounding connection applicable to or suited to the teachings of this specification. In this specification, unless otherwise stated, "about," "approximately," or "substantially" preceding a parameter means within + / - 10% of said parameter, or, if the parameter is zero, within a reasonable range of approximately zero.

[0083] Although this disclosure has been described with reference to illustrative embodiments, this specification is not restrictive. Those skilled in the art will understand, upon referring to this specification, various modifications and combinations of the illustrative embodiments and other embodiments.

Claims

1. An apparatus comprising: A current source circuit having an output coupled to a first terminal; A first resistive device is coupled between the second terminal and the third terminal; A second resistive device is coupled between the first terminal and the second terminal; as well as A control circuit, coupled to the current source circuit and to the first resistive device and the second resistive device, is configured to: The first resistive device is activated and the current source circuit is controlled to provide a first current to the first terminal; and The second resistive device is activated and the current source circuit is controlled to generate a second current to the first terminal, the second current being different from the first current.

2. The device according to claim 1, wherein the second current is six times the first current.

3. The device according to claim 1, wherein the control circuit is configured to: When the first resistive device is enabled and the second resistive device is disabled, the current source circuit is controlled to provide the first current; and When the first resistive device is deactivated and the second resistive device is activated, the current source circuit is controlled to provide the second current.

4. The device of claim 1, further comprising a third resistive device coupled between the second terminal and the third terminal, wherein the current source circuit is configured to enable the third resistive device and provide a third current to the first terminal, the third current being sixteen times the first current and the second current being six times the first current.

5. The device of claim 4, wherein the control circuit is coupled to the third resistive device, and the control circuit is configured to: The third resistive device is enabled, the first and second resistive devices are disabled, and the current source circuit is controlled to provide the third current. Each time the third resistive device is activated, the second resistive device is activated, the first resistive device and the third resistive device are deactivated, and the current source circuit is controlled to provide the second current three times. and Each time the third resistive device is activated, the first resistive device is activated, the second resistive device and the third resistive device are deactivated, and the current source circuit is controlled to provide the first current twice.

6. The device of claim 1, further comprising an analog-to-digital converter (ADC) having an input coupled to the first terminal.

7. The device according to claim 6, wherein the ADC is an integrating ADC.

8. The device of claim 6, wherein the control circuitry is coupled to the ADC and configured to: The ADC provides a first ADC conversion when the current source circuit provides the first current to the first terminal; The ADC provides a second ADC conversion when the current source circuit provides the second current to the first terminal; and The indicated temperature value is determined based on the first ADC conversion and the second ADC conversion.

9. The device according to claim 1, wherein the first resistive device has a first resistance, and the second resistive device has a second resistance different from the first resistance.

10. The device according to claim 1, wherein: The first resistive device includes a first resistor coupled to the first switch; and The second resistive device includes a second resistor coupled to the second switch.

11. The device according to claim 10, wherein: The first switch has a first control terminal coupled to the control circuit; and The second switch has a second control terminal coupled to the control circuit.

12. The device of claim 10, wherein the first resistor and the second resistor are adjustable.

13. The device of claim 1, further comprising a temperature sensing device having a first temperature sensing device terminal coupled to the first terminal and a second temperature sensing device terminal coupled to the second terminal.

14. The device of claim 13, wherein the current source circuit, the first resistive device, and the second resistive device are on a first integrated circuit, and the temperature-sensitive device is on a second integrated circuit.

15. The device of claim 13, wherein the temperature-sensitive device comprises a bipolar junction transistor having a base coupled to the second terminal and an emitter coupled to the first terminal.

16. The device of claim 14, further comprising another temperature-sensitive device, the other temperature-sensitive device comprising another bipolar junction transistor having a base coupled to the first terminal and an emitter coupled to the second terminal.

17. An apparatus comprising: A first current source having an output coupled to a first terminal; A second current source having an output coupled to the first terminal; A third current source having an output coupled to the first terminal; A first controllable resistive device is coupled between a second terminal and a ground terminal, the first controllable resistive device having a first resistance; A second controllable resistive device is coupled between the second terminal and the ground terminal, and the second controllable resistive device has a second resistance different from the first resistance; A third controllable resistive device is coupled between the second terminal and the ground terminal, and the third controllable resistive device has a third resistance that is different from the first resistance and the second resistance; as well as An analog-to-digital converter (ADC) having an input coupled to the first terminal.

18. The apparatus according to claim 17, wherein: The first controllable resistive device includes a first resistor coupled to a first switch; The second controllable resistive device includes a second resistor coupled to the second switch; and The third controllable resistive device includes a third resistor coupled to a third switch.

19. The device of claim 18, further comprising a control circuit coupled to the first current source, the second current source, and the third current source, wherein: The first switch has a first control terminal coupled to the control circuit; The second switch has a second control terminal coupled to the control circuit; and The third switch has a third control terminal coupled to the control circuit.

20. The device of claim 18, wherein the first resistor, the second resistor, and the third resistor are adjustable.

21. The device of claim 18, wherein the first switch comprises a first transistor, the second switch comprises a second transistor, and the third switch comprises a third transistor.

22. The device of claim 17, further comprising a temperature sensing device having a first temperature sensing device terminal coupled to the first terminal and a second temperature sensing device terminal coupled to the second terminal.

23. The device of claim 22, wherein the first current source, the second current source, and the third current source, as well as the first controllable resistive device, the second controllable resistive device, and the third controllable resistive device, are on a first integrated circuit, and the temperature-sensitive device is on a second integrated circuit.

24. The device of claim 22, wherein the temperature-sensitive device is a bipolar junction transistor (BJT).

25. The device according to claim 17, further comprising: A first bipolar junction transistor (BJT) has a first emitter coupled to the first terminal and a first base coupled to the second terminal; as well as The second BJT has a second emitter coupled to the second terminal and a second base coupled to the first terminal.

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