Circuit and method for providing temperature compensation of single-ended dcr sensing network in multiphase switching power supplies

Abstract

A circuit for providing temperature compensation for a sensing signal in a single-ended DC resistance (DCR) sensing network of a multiphase switching power supply includes a temperature compensation calculator circuit that generates a compensation adjustment signal indicating the sensing temperature; a compensation impedance network that receives the positive sensing signals of all phases and generates a correction signal for each phase in response to at least the positive sensing signal and the compensation adjustment signal of each phase; a coupling averaging circuit that averages the correction signals of all phases, wherein a copy of the averaged correction signal is applied to modify the positive sensing signal; and an amplifier circuit that receives a summed positive sensing signal and a summed negative sensing signal as the sum of the modified positive sensing signals of all phases to generate an output signal having a substantially zero temperature coefficient over a first frequency range.

Description

Technical Field

[0001] The present invention relates to a circuit and method for providing temperature compensation for a sensing signal, and more particularly to a temperature compensation circuit and method for applying a single-ended DCR sensing network in a multi-phase switching power supply. Prior Art

[0002] Electronic systems, such as laptops, typically include a power management integrated circuit for regulating the power consumption of the electronic system. In addition, an electronic system containing an integrated circuit typically employs a voltage regulator to convert the main bus voltage from the power source supplying the system into one or more voltages required to drive the integrated circuit therein. For example, a 5V power supply voltage provided to the electronic system may need to be reduced to 1.8V to drive the integrated circuit in the electronic system. Embedded systems, such as Internet of Things (IoT) devices, include a processor (or microcontroller) and local memory coupled to components and execute embedded software to perform certain tasks. In practice, the processor power supply is provided by a voltage regulator that converts the input voltage from the power source into the voltage value specified for the processor.

[0003] A switch-mode power supply or switch regulator, also known as a DC-DC converter, is a voltage regulator commonly used to convert an input power supply voltage into the required output voltage at a voltage level selected for the integrated circuit. In one example, a power supply voltage of 12V or 5V can be reduced to 1V for powering an embedded processor. The switch regulator provides power functions through low-loss components such as capacitors, inductors, and transformers, as well as power switches that can be turned on and off to transfer energy from the input to the output in the form of discrete data packets. A feedback control circuit is used to regulate the energy transfer to maintain a constant output voltage within the desired load limit of the circuit.

[0004] Some switching regulators use pulse width modulation (PWM) to control the duty cycle of a power switch. That is, by adjusting the pulse width, the conduction time of the power switch can be controlled at a given fixed or variable frequency. A switching regulator using PWM control includes a PWM controller or modulator for driving a power block that includes a power switch, a driver circuit for the power switch, and an LC filter circuit. In some cases, the switching regulator is a single-phase converter, and the PWM controller generates a single-phase PWM clock signal to drive the single-phase power block. In other cases, the switching regulator is a multi-phase converter or a multi-phase switched power supply, and a multi-phase PWM controller generates clock signals with different phase shifts to drive the multi-phase power block, with each clock signal driving a corresponding power block unit. The multi-phase PWM controller is ideal when the voltage regulator must provide a regulated output voltage with high precision over a wide range of load conditions.

[0005] In an electronic system that includes a voltage regulator, it is usually necessary to measure the output current of the voltage regulator to implement power management functions. In a multi-phase converter, accurate output current sensing is also important for output voltage load line control and phase current balance in a multi-phase switched power supply. For example, the load current of each power block is measured to determine the load balance between the power blocks. Summary of the Invention

[0006] The present invention discloses a temperature compensation circuit, substantially as shown and / or described below, for example in combination with at least one of the accompanying drawings, as more fully set forth in the claims.

[0007] In some embodiments, a circuit for providing temperature compensation for a sensed signal in a single-ended DC resistance (DCR) sensing network of a multiphase switched-mode power supply, wherein the inductor current in each phase of the multiphase switched-mode power supply is sensed by a resistor-capacitor (RC) network connected in parallel with the inductor of the corresponding phase, and the voltage across the capacitor of the RC network is provided as a sensed signal indicative of the inductor current, the sensed signal includes a positive sensed signal and a negative sensed signal, and has a first temperature coefficient. The circuit includes a temperature compensation calculator circuit that receives a temperature sensing signal indicative of a temperature associated with the temperature of the sensed signal and a reference temperature signal, and generates a compensation adjustment signal in response to a difference between the temperature sensing signal and the reference temperature signal; a compensation impedance network that receives the positive sensed signals of all phases of the multiphase switched-mode power supply, a total negative sensed signal that is the sum of the negative sensed signals of all phases, and the compensation adjustment signal, the compensation impedance network generates a correction signal for each phase of the multiphase switched-mode power supply at least in response to the positive sensed signal of each phase and the compensation adjustment signal, the correction signal for each phase having a second temperature coefficient; an averaging circuit that is coupled to average the correction signals of all phases of the multiphase switched-mode power supply to generate an average correction signal, the average correction signal or a copy of the average correction signal being applied to modify each positive sensed signal to provide a modified positive sensed signal having a substantially zero temperature coefficient within a first frequency range for each phase; and an amplifier circuit that receives a total positive sensed signal that is the sum of the modified positive sensed signals of all phases and the total negative sensed signal, the amplifier circuit generates an output signal indicative of a difference between the total positive sensed signal and the total negative sensed signal, the output signal having a substantially zero temperature coefficient within the first frequency range.

[0008] In some embodiments, a method provides temperature compensation to sense signals in a single-ended DC resistance (DCR) sensing network of a multiphase switched-mode power supply, wherein the inductor current in each phase of the multiphase switched-mode power supply is sensed by a resistor-capacitor (RC) network connected in parallel with the inductor of the corresponding phase. The voltage across the capacitor of the RC network is provided as a sensed signal indicative of the inductor current, wherein the sensed signal includes a positive sensed signal and a negative sensed signal and has a first temperature coefficient. The method includes: receiving a temperature sensing signal indicative of a temperature associated with the sensed signal; generating a compensation adjustment signal in response to a difference between the temperature sensing signal and a reference temperature signal; generating a correction signal for each phase of the multiphase switched-mode power supply in response to at least the positive sensed signal of the corresponding phase and the compensation adjustment signal, wherein the correction signal for each phase has a second temperature coefficient; generating an average correction signal indicative of an average of the correction signals of all phases of the multiphase switched-mode power supply; applying the average correction signal to each of the positive sensed signals to generate a modified positive sensed signal having a substantially zero temperature coefficient within a first frequency range for each phase; generating a total positive sensed signal and a total negative sensed signal, wherein the total positive sensed signal is a sum of the modified positive sensed signals of all phases of the multiphase switched-mode power supply; and generating an output signal indicative of a difference between the total positive sensed signal and the total negative sensed signal, wherein the output signal has a substantially zero temperature coefficient within the first frequency range.

[0009] These and other advantages, aspects, and novel features of the present invention, as well as details of the illustrated embodiments thereof, will be more fully understood from the following description and the drawings. Brief Description of the Drawings

[0010] Various embodiments of the present invention are disclosed in the following detailed description and the drawings. Although the drawings depict various examples of the present invention, the present invention is not limited to the depicted examples. It should be understood that in the drawings, like reference numerals represent like structural elements. Additionally, it can be understood that the descriptions in the figures are not necessarily to scale.

[0011] FIG. 1 shows a schematic diagram of a voltage regulator including a multiphase current mode modulator in some examples.

[0012] FIG. 2 shows a circuit diagram illustrating the implementation of DCR current sensing in a voltage regulator in some examples.

[0013] FIG. 3 reproduces FIG. 5 of U.S. Patent No. 10,795,390 ('390) and illustrates an exemplary implementation of the temperature compensation scheme described in the '390 patent.

[0014] Figure 4 shows an exemplary implementation of the temperature compensation scheme described in the '390 patent in a multiphase switched-mode power supply in some examples.

[0015] Figure 5 shows a circuit diagram of a temperature compensation circuit implemented for a single-ended DC sensing network in a multiphase switched-mode power supply in an embodiment of the present invention.

[0016] Figure 6 shows a circuit diagram of a temperature compensation circuit implemented for a single-ended DC sensing network in a multiphase switched-mode power supply in an embodiment of the present invention.

[0017] Figure 7 shows a circuit diagram of an averaging circuit in some embodiments.

[0018] Figure 8 shows a flowchart of a method for providing temperature compensation for a sensed signal in a single-ended direct current resistance (DCR) sensing network of a multiphase switched-mode power supply in some embodiments. Embodiments

[0019] According to an embodiment of the present invention, a temperature compensation circuit provides temperature compensation for a sensed signal in a single-ended direct current resistance (DCR) sensing network implemented for a multiphase switched-mode power supply, wherein the sensed signal measures the inductor current in each phase of the multiphase switched-mode power supply. The sensed signal generated from the DCR sensing network has a first temperature coefficient, and the temperature compensation circuit generates a compensation adjustment signal in response to a temperature difference to provide a correction signal to the sensed signal, wherein the correction signal has a second temperature coefficient. The correction signal is applied to modify the sensed signal to provide a modified sensed signal having a substantially zero temperature coefficient within a given frequency range. Then, the modified sensed signal can be averaged and applied as a single-ended signal to generate an output signal indicating the average inductor current of the multiphase switched-mode power supply, wherein the output signal has a substantially zero temperature coefficient within a given frequency range.

[0020] In some embodiments, a temperature compensation circuit is incorporated in a PWM controller integrated circuit for a multiphase switching power supply and is coupled to sense the output current of a voltage regulator. In some cases, an inductor DC resistance (DCR) sensing scheme is used to sense the inductor current of each phase of the multiphase switching power supply to indicate the output current of the voltage regulator. The current sensing signal generated by the inductor DCR sensing typically has a temperature coefficient. The temperature compensation circuit of the present invention is incorporated in the controller integrated circuit to generate a correction signal that is used to modify the current sensing signal to provide the modified current sensing signal with a substantially zero temperature coefficient. The controller integrated circuit uses the modified current sensing signal to generate an output signal indicative of the output current of the voltage regulator, where the output signal has a substantially zero temperature coefficient within a given frequency range.

[0021] A significant feature of the temperature compensation circuit of the present invention is that the circuit provides accurate temperature compensation over a wide frequency range. In traditional solutions, temperature compensation is typically only accurate for DC signals, and when the sensing signal varies at a given frequency, the temperature compensation becomes inaccurate. In embodiments of the present invention, the temperature compensation circuit provides accurate temperature compensation at DC (0 Hz) and high frequencies (such as several MHz). In one embodiment, the temperature compensation circuit provides accurate temperature compensation over a frequency range from DC to 10 MHz, which represents a significant improvement over traditional solutions.

[0022] In the present invention, the term "temperature coefficient M" refers to the relative change in the physical characteristic of a signal associated with a given temperature change. In particular, the temperature coefficient describes the rate of change of the physical characteristic relative to a given temperature change. Generally, a positive temperature coefficient refers to a characteristic that increases with increasing temperature, and a negative temperature coefficient refers to a characteristic that decreases with increasing temperature. A characteristic or signal that does not vary much with temperature is described as having a zero or substantially zero temperature coefficient. For example, in this specification, the sensing signal is described as having a positive temperature coefficient. That is, the sensed value (voltage or current) of the sensing signal increases with increasing temperature. The temperature-compensated sensing signal should have a zero or substantially zero temperature coefficient. That is, the temperature-compensated sensing signal senses a current or voltage value that does not change with temperature.

[0023] Generally speaking, the temperature coefficient can be linear or non-linear in nature. In some examples of the present invention, the temperature coefficient is expressed as a function having a slope and an offset. For example, the temperature coefficient can have a positive temperature coefficient with a positive slope and a given offset. In another example, the temperature coefficient can have a negative temperature coefficient with a negative slope and a given offset.

[0024] FIG. 1 is a schematic diagram of a voltage regulator including a multiphase current mode modulator in some examples. Referring to FIG. 1, voltage regulator 10 includes a multiphase modulator 12 (“modulator 12”), which is coupled to drive a multiphase power block 14. In this example, voltage regulator 10 is implemented using a multiphase modulator to enable the voltage regulator to provide a regulated output voltage with high precision under a wide range of load conditions. The use of a multiphase modulator is illustrative only and is not meant to be limiting. In other examples, the voltage regulator may be implemented using a single-phase modulator that drives a single-phase power block. In this example, multiphase modulator 12 includes three phases, and power block 14 includes three power stages 20, which have associated output inductors L1 to L3 and an output capacitor C OUT.

[0025] More specifically, voltage regulator 10 receives an input voltage V IN at input node 18 and generates a regulated output voltage VOUT at output node 20 to power load 22. Multiphase power block 14 includes power stages 16 driven by respective PWM signals PWM1 to PWM3. Each power stage 16 includes a pair of power switches that are turned on and off by the corresponding PWM signal to regulate the output voltage VOUT with reference to a target voltage. The power switches in each power stage 16 are alternately turned on and off to generate a switched output voltage Vsw at the switched output node 25. The switched output node of each power stage 16 is coupled to a corresponding output inductor L1 to L3. Inductors L1 to L3 are coupled to output capacitor C OUT to form an LC circuit for providing current to output node 20 while maintaining a substantially constant output voltage V OUT. The output voltage V OUT can then be used to drive load 22.

[0026] The multi-phase modulator 12 receives a feedback voltage VFB indicative of the regulated output voltage VOUT at the output node 20. In one example, the feedback voltage VFB is a stepped-down voltage of the output voltage VOUT. For example, a resistive voltage divider including resistors R11 and R12 coupled to the output voltage node 20 can be used to generate the feedback voltage VFB. The multi-phase modulator 12 also receives a target voltage VTARG, which indicates the voltage value required to regulate the output voltage. In some examples, the target voltage can be indicated by signaling a voltage identification code for the desired regulator output voltage. For example, when applied to mobile voltage positioning, the modulator 12 can receive a voltage identification (VID) code that tells the modulator what output voltage value it should provide. Each VID code is associated with a voltage value. A decoder decodes the VID code to generate the target voltage. The modulator 12 includes circuitry for implementing a feedback control loop of the voltage regulator to generate multi-phase PWM signals PWM1 to PWM3 to drive the respective power stages 16 in the multi-phase power block 14.

[0027] Configured thusly, the voltage regulator 10 can be incorporated into an electronic system to provide the desired regulated output voltage VOUT to the electronic system. In some applications, the electronic system includes a power integrated circuit that performs power management functions, and the power integrated circuit typically requires precise measurement of the output current or load current of the voltage regulator 10. In other examples, the multi-phase modulator itself includes circuitry for current sensing and power measurement. In some examples, the output current of the voltage regulator 10 is measured by measuring the current flowing through the inductor L. In the case of a multi-phase voltage regulator, the inductor current through the inductor in each phase can be measured to derive the output current or load current provided by the voltage regulator. In some examples, an inductor DC resistance (DCR) current sensing scheme is used to measure the inductor current.

[0028] FIG. 2 is a circuit diagram illustrating the implementation of DCR current sensing in a voltage regulator in some examples. Referring to FIG. 2, DCR current sensing is used to measure the current at the output inductor L of the voltage regulator. The voltage regulator includes a power stage 16 formed by a power MOSFET device that generates a switched output voltage Vsw (node 25), which is coupled to drive an inductor L connected between the switched output node 25 and the output node 20 of the voltage regulator that provides the output voltage VOUT. An output capacitor COUT is coupled between the output node 20 and ground potential to generate an output voltage VOUT having a substantially constant magnitude.

[0029] In many applications, inductor DC resistance (DCR) current sensing is used to sense the output current of a voltage regulator. In particular, inductor DCR current sensing refers to measuring the output current of a voltage regulator using the parasitic resistance of the inductor winding, thus eliminating the need for a sense resistor in series with the inductor L. The parasitic resistance of the inductor L is represented as resistor Rdcr in Figure 2, where the dashed box indicates that the resistor is a parasitic element rather than an actual resistor in the circuit. DCR current sensing uses a resistor-capacitor (RC) network in parallel with the series combination of the inductor and the parasitic resistance L and Rdcr. Specifically, the RC network includes a sense resistor Rsns and a sense capacitor Csns connected in series across the inductor L, i.e., across nodes 25 and 20. The sense voltage Vsns is measured across the sense capacitor Csns between node 26 and node 20. By appropriately selecting the component values of the resistor Rsns and the capacitor Csns, the voltage across the capacitor Csn can be made proportional to the inductor current. More specifically, when the RC time constant of the RC network is equal to the ratio of the inductance (L) of the inductor L and the series resistance (Rdcr), the voltage across the sense capacitor Csns will be proportional to the inductor current IL, as shown in the equation Rsns*Csns = L / Rdcr. To sense the capacitor voltage Vsns, Kelvin sensing is used to sense a pair of differential sense signals: a positive sense signal and a negative sense signal.

[0030] The DCR of a wire-wound inductor varies with temperature. The temperature coefficient of the inductor DCR causes the sensed voltage Vsns to have a temperature coefficient. More specifically, the inductor DCR typically has a positive temperature coefficient. That is, the resistance Rdcr increases with increasing temperature. Therefore, the sensed voltage Vsns also has a positive temperature coefficient. For high-precision current sensing, inductor DCR current sensing must be temperature compensated to match the measurement offset caused by the DCR temperature coefficient. In some examples, a linearized NTC (negative temperature coefficient) resistor network is used to provide temperature compensation, as shown in Figure 2.

[0031] More specifically, the linearized NTC resistor network includes a series combination of resistors Rntcs and resistor Rntc, connected in parallel with resistor Rntcp. The linearized NTC resistor network is connected between the sense voltage node 26 and the output node 20. Resistor Rntc provides a resistance that varies with temperature. In particular, resistor Rntc has a negative temperature coefficient (NTC). The linearized NTC resistor network operates to counteract the temperature coefficient of the sense voltage Vsns, which is caused by the temperature coefficient of the DCR of the inductor. The temperature-compensated sense voltage (between node 26 and node 20) is then measured by the current sense amplifier 28, which can be formed as part of the power integrated circuit 30 or as part of a modulator or controller of a voltage regulator. The current sense amplifier 28 generates an output signal at the output node 29 indicating the current sense value. In one example, the current sense amplifier 28 generates a voltage signal V(Imon) indicating the current sense value. In other examples, the current sense amplifier 28 generates a current signal Imon indicating the current sense value.

[0032] In particular, the inductor DCR, i.e., resistor Rdcr, has a positive linear temperature coefficient. Resistor Rntc provides a negative temperature coefficient to compensate for the positive temperature coefficient of the inductor DCR. However, the negative temperature coefficient of resistor Rntc has an exponential behavior. Therefore, resistors Rntcs and Rntcp are used to linearize the exponential behavior of resistor Rntc. In operation, the linearized NTC resistor network provides temperature compensation that matches the temperature coefficient of the inductor DCR, represented as resistance Rdcr.

[0033] In practice, since resistor Rntc is not typically placed at or near the inductor L on the PC board of an electronic system, resistor Rntc cannot sense the same temperature experienced by the inductor L. Therefore, it is necessary to specifically design the linearized NTC network for each inductor in each new board design. The linearized NTC resistor network needs to be tuned so that the sensing network can accurately sense current over a wide frequency range, such as from DC to ~10 MHz. The tuning process is iterative, and each iteration requires refolding the NTC resistor network and measuring the sensing accuracy of the current over frequency and temperature. The iterative process is performed to determine a set of resistance values for the resistors in the NTC resistor network that can be used for temperature compensation in a specific PC board design. The iterative process must be performed for each PC board design to determine the optimal values of the NTC resistor network. In addition, for a multi-phase converter, a separate linearized NTC resistor network is constructed and tuned for each inductor of the multi-phase power block.

[0034] U.S. Patent No. 10,795,390, issued on October 6, 2020, describes a temperature compensation scheme for inductor DCR current sensing to generate a current sensing signal having a substantially zero temperature coefficient over a wide frequency range. The entire content of the '390 patent is incorporated herein by reference. FIG. 3 is a repetition of FIG. 5 of the '390 patent and illustrates an exemplary implementation of the temperature compensation scheme described in the '390 patent. Referring to FIG. 3, the power integrated circuit 60 includes a current sensing amplifier 66 for measuring a sensing voltage Vsns across a sensing capacitor Csns, the voltage Vsns indicating an inductor current IL flowing through an inductor L. The current sensing amplifier 66 generates an output signal at node 67, the output signal being a voltage signal V(Imon), the voltage signal V indicating the sensing voltage and thus indicating the inductor current IL. In an embodiment of the present invention, the power integrated circuit 60 includes a temperature compensation circuit for providing temperature compensation for the sensing voltage Vsns having a first temperature coefficient.

[0035] In this embodiment, the temperature compensation circuit includes a temperature compensation adjustment circuit 62 and a voltage controlled resistor VCRntceq as a compensation impedance circuit 64. The temperature compensation adjustment circuit 62 receives a temperature sensing signal TSEN (node 40) and provides a control signal (node 63) to the voltage controlled resistor VCRntceq. In this embodiment, the control signal is a control voltage signal. The voltage controlled resistor VCRntceq provides a resistance value that varies in response to the control voltage. In particular, the voltage controlled resistor VCRntceq provides a compensation impedance signal in response to the control voltage signal, where the compensation impedance signal has a second temperature coefficient and has an impedance value indicative of the temperature sensing signal TSEN. In some embodiments, the temperature compensation adjustment circuit 62 is digitally configured to generate a control signal that compensates for the first temperature coefficient of the sensed voltage. For example, the temperature compensation adjustment circuit 62 may be digitally configured or programmed by a digital configuration circuit 55 using one or more digital signals 58.

[0036] Accordingly, the temperature compensation adjustment circuit 62 generates a control voltage such that the voltage controlled resistor VCRntceq provides a resistance value that varies with the sensed temperature and also has a temperature coefficient that compensates for the temperature coefficient of the sensed voltage Vsns. In other words, the temperature compensation adjustment circuit 62 generates a control signal to set the resistance value of the voltage controlled resistor VCRntceq and to control how the resistance value of the resistor VCRnt varies with temperature. Configured in this way, the resistor VCRntceq applies a compensation impedance signal to node 26 to modify the sensed voltage Vsns such that the modified or temperature-compensated sensed voltage has a zero or substantially zero temperature coefficient over a given frequency range. The current sensing amplifier 66 receives the modified sensed voltage and thus generates an output signal V(Imon) that indicates the sensed voltage and has a zero or substantially zero temperature coefficient over a given frequency range. The temperature compensation circuit of the present invention ensures that the power integrated circuit 60 can accurately measure the inductor current over a wide frequency range and a wide temperature range.

[0037] The inductor DCR sensing scheme described in FIGS. 2 and 3 employs Kelvin sensing to measure the sensed voltage Vsns across the sense capacitor Csns. The voltage sensing signal is thus a differential sensing signal that includes a positive sensing signal (ISENP) and a negative sensing signal (ISENN) that are coupled to the positive and negative input terminals of the current sensing amplifier. In a multiphase switching power supply, a fully differential DCR sensing scheme requires two signal pins per phase to implement. For a multiphase switching power supply with a large number of phases (N), the implementation cost of the differential DCR sensing scheme is high due to the large number of pins, and it may be difficult to implement due to pin limitations on the integrated circuit package of the multiphase controller. For example, in an N-phase voltage regulator, 2N pins are required to implement fully differential inductor DCR current sensing. In the case where the voltage regulator has 12 to 16 phases, 24 to 32 pins are required to implement fully differential inductor DCR current sensing.

[0038] FIG. 4 shows an exemplary implementation of the temperature compensation scheme described in the '390 patent in a multi-phase switched-mode power supply. In the example shown in FIG. 4, the multi-phase switched-mode power supply 70 is shown as having two phases - phase 1 and phase 2, and separate power blocks 71-2 and 72-2. Inductor DCR sensing is implemented by providing an RC network in parallel with the inductor in each phase. The inductor current of inductor L1 in phase 1 is sensed by the capacitor voltage across sensing capacitor Cns1 using sensing signals ISENP1 and ISENN1. The inductor current of inductor L2 in phase 2 is sensed by the capacitor voltage across sensing capacitor Cns2 using sensing signals ISENP2 and ISENN2. Thus, for two phases, four signal pins are required to implement current sensing. In this example, the four sensing signals are provided to the controller 80. Temperature compensation is applied to each pair of differential sensing signals ISENPn / ISENNn (where "n" represents the corresponding phase). For example, corresponding compensation calculators 84-1 and 84-2 are provided for each phase to generate corresponding control signals for controlling the corresponding compensation impedance circuits 82-1 and 82-2. The compensated sensing signals are then sensed by current sensing amplifiers 86-1 and 86-2. The output signals of current sensing amplifiers 86-1 and 86-2 can be added together to generate an output signal V(Imon) (node 88) indicative of the load current of the multi-phase switch regulator 70.

[0039] To overcome the limitations of the differential DCR sensing scheme, single-ended DCR sensing has been developed to reduce the number of signal pins required to provide current sensing signals for a multi-phase switched-mode power supply. In one example, the negative sensing signals across all phases are added together to generate a total negative sensing signal. The positive sensing signal and the total negative sensing signal are then applied to perform current sensing. For an N-phase voltage regulator, the single-ended DCR sensing scheme can be implemented using only N + 1 signal pins, whereas in the case of a fully differential DCR sensing scheme, 2N signal pins are required. In an embodiment of the present invention, a temperature compensation circuit is provided to implement temperature compensation for a single-ended DCR sensing network to ensure that the derived current sensing signal has a substantially zero temperature coefficient over a wide frequency range. In some embodiments, the temperature compensation is implemented based on the temperature compensation scheme described in the above '390 patent.

[0040] FIG. 5 is a circuit diagram showing a temperature compensation circuit implemented for a single-ended DC sensing network in a multiphase switching power supply in an embodiment of the present invention. Referring to FIG. 5, the temperature compensation circuit is implemented in a controller 100, which can be a multiphase modulator or a PWM controller integrated circuit for a multiphase switching power supply. The controller 100 receives a sensing signal from a single-ended DC sensing network to measure the load current provided by the multiphase switching power supply. The temperature compensation circuit of the present invention is implemented in the controller 100 to provide temperature compensation to the sensing signal that measures the inductor current of all phases, which indicates the load current of the multiphase switching power supply.

[0041] In the embodiment shown in FIG. 5, the temperature compensation circuit is applied to a multiphase switching power supply having two phases - Phase 1 and Phase 2. For simplicity of discussion, the switching power supply circuit is not shown, and the two phases are represented by the switching output signals Vsw of each phase coupled to the corresponding inductors L1 and L2 at the corresponding switch output nodes 74-1 and 74-2. The inductors are connected to an output voltage node 78, to which an output capacitor C OUT is coupled. An output voltage V OUT of the multiphase switching power supply having a substantially constant amplitude is generated at the output voltage node 78.

[0042] In an embodiment of the present invention, inductor DCR current sensing is applied to sense the inductor current IL flowing through the inductors L1 and L2 in each phase. In each phase, an RC network of a series-connected sensing resistor Rsns and a sensing capacitor Csns is connected in parallel with the inductor L and the parasitic resistance Rdcr of the inductor. The voltage Vsns across the sensing capacitor Csns is sensed as a sensing signal indicating the inductor current. In particular, the voltage Vsns is sensed by a pair of sensing signals, which includes a positive sensing signal ISENPn at one plate (node 75-n) of the capacitor Csns and a negative sensing signal ISENNn at the other plate (output voltage node 78) of the capacitor Cnss (where "n" represents the respective phase). The inductor current of the inductor L2 of Phase 2 is sensed by the capacitor voltage Vsns2 across the sensing capacitor Cns2 using the sensing signals ISENP2 and ISENN2. The temperature coefficient (Rdcr) of the inductor DCR causes the sensed voltage Vsns to have a temperature coefficient. For example, the inductor DCR typically has a positive temperature coefficient, so the sensed voltage Vsns has a positive temperature coefficient. The sensing signals ISENPn and ISENNn that measure the sensed voltage Vsns also have the same positive temperature coefficient.

[0043] In this embodiment, a single-ended DCR sensing scheme is used to measure the sensing signals of all phases of a multi-phase switching power supply. Thus, the single-ended DCR sensing scheme feeds back one negative sensing signal and all positive sensing signals, rather than feeding back all positive and negative sensing signals, thereby generating 2N signals for an N-phase switching power supply. In this embodiment, each negative sensing signal ISENNn at node 78 of each sensing capacitor Csns is converted into a current signal by a corresponding resistor R2, and the resulting current signals from all phases are added at the summing node 92. The total negative sensing signal ISENNS is the single negative sensing signal fed back to the controller 100. In practice, the single total negative sensing signal ISENNS of all phases is fed back to the controller 100 together with the positive sensing signal ISENPn for current sensing. In this example, the total negative sensing signal ISENNS and two positive sensing signals ISENP1 and ISENP2 are fed back to the controller 100.

[0044] At the controller 100, each of the positive sensing signals ISENPn of all phases is converted into a current signal by a corresponding resistor R1, and the resulting current signals from all phases are added at the summing node 102. The total positive sensing signal (node 102) is provided to the positive input terminal of the current sensing amplifier 104. The total negative sensing signal (node 92) is provided to the negative input terminal of the current sensing amplifier 104. The current sensing amplifier compares the total positive sensing signal and the negative sensing signal to generate an output signal at the output node 106 indicating the sensed voltage value Vsns of all phases, which indicates the inductor current generated by all phases, thereby indicating the load current of the multi-phase switching power supply. In this embodiment, the current sensing amplifier 104 is an operational amplifier, and the output signal is a current signal Imon indicating the load current of the multi-phase switching power supply.

[0045] As described above, as a result of inductor DCR sensing, the sensed signal has a temperature coefficient that can affect the measurement accuracy, such as a positive temperature coefficient. In an embodiment of the present invention, a temperature compensation circuit is provided to perform temperature compensation on the sensed signal to correct the temperature coefficient of the sensed signal generated due to the use of inductor DCR sensing. Specifically, the temperature compensation circuit generates an average correction signal Iavg based on all positive sensed signals and a temperature correction factor, and assigns the average correction signal Iavg to all positive sensed signals ISENPn. Therefore, each positive sensed signal is temperature-compensated to have a zero temperature coefficient, and all phases of the compensated or modified positive sensed signals are then converted into current signals using corresponding resistors R1 and added at the summing node 102 for use by the current sensing amplifier 104 for comparison with the total negative sensed signal ISENNS. In this specification, the total positive sensed signal (node 102) is thus the sum of the modified or compensated positive sensed signals of all phases of the multiphase switching power supply.

[0046] Still referring to FIG. 5, the temperature compensation circuit includes a temperature compensation calculator circuit 115 that receives the sensed temperature signal TSEN and a precise temperature reference signal as input signals. In an embodiment of the present invention, the temperature sensing signal TSEN measures the temperature of the inductor L. In some embodiments. The temperature sensing signal TSEN can be generated by a temperature sensor located near the inductor L. In one embodiment, a DrMOS (driver and MOSFET module) placed near the inductor L can be used to implement the temperature sensor to generate the temperature sensing signal TSEN. Alternatively, the temperature sensor can be implemented using a linearized NTC network that uses a negative temperature coefficient resistor (Rntc) to generate a voltage reference indicating the sensed temperature. The precise temperature reference signal is generated by a resistor having a predetermined RTC (resistance temperature coefficient). The temperature compensation calculator circuit 115 determines the temperature difference between the sensed temperature signal TSEN and the temperature reference signal (RTC) and generates a compensation adjustment signal ADJ indicating the temperature difference. In this embodiment, N copies of the compensation adjustment signal ADJ are generated (e.g., ADJ1, ADJ2), where all compensation adjustment signals ADJn have the same signal value. Each copy of the compensation adjustment signal ADJ will be applied to the positive phase current to generate a corresponding per-phase correction signal Icorr. That is, the temperature compensation calculator 115 indicates the same temperature compensation to all phases through the adjustment signal ADJ. The correction signal Icorr for each phase is generated as a function of the positive sensed signal and the adjustment signal ADJ for that phase. Therefore, the correction signal Icorr for one phase can be different from the correction signal Icorl for another phase. In this embodiment, the correction signal is a current signal, which can be referred to as a correction current in this specification.

[0047] The temperature compensation circuit includes a compensation impedance network to generate a correction signal. The compensation impedance network receives the positive sensing signal ISENPn and the total negative sensing signal ISENNS. The compensation impedance network generates a correction signal for each phase of the multiphase switching power supply in response to at least the positive sensing signal ISENPn and the compensation adjustment signal ADJ of each phase. In particular, the compensation adjustment signal ADJ modifies the effective impedance as indicated by the positive sensing signal ISENPn of each phase to generate a correction signal Icorr for that phase, whose temperature coefficient is opposite to that of the positive sensing signal ISENPn.

[0048] In one embodiment, the compensation impedance network includes a set of buffers 110 for receiving and buffering the input signals ISENPn and ISENNS. Each buffer 110 receives one of the sensing signals. In this embodiment, the first buffer receives the positive sensing signal ISENP1 of phase 1, the second buffer receives the total negative sensing signal ISENNS, and the third buffer receives the positive sensing signal ISENP2 of phase 2. The voltage-controlled impedance network is coupled to the output terminals of the buffer set 110 to generate a correction signal for each phase of the multiphase switching power supply in response to at least the positive sensing signal ISENPn and the compensation adjustment signal ADJ of each phase. In one embodiment, the voltage-controlled impedance network includes a set of voltage-controlled resistors Radj connected in series between the output terminal of the first buffer and the output terminal of the last buffer. In particular, each voltage-controlled resistor Radj is connected to the output terminal of the buffer receiving the positive sensing signal ISENPn and the input terminal of the buffer receiving the total negative sensing signal ISENNS. The voltage-controlled resistor Radj provides an effective impedance value having a temperature coefficient opposite to that of the positive sensing signal ISENPn. In operation, each copy of the compensation adjustment signal ADJ (e.g., ADJ1, ADJ2) is applied to modify the impedance of each voltage-controlled resistor. Thus, the effective impedance of each voltage-controlled resistor is modified according to the sensed temperature or the temperature difference between the sensed temperature and the reference temperature.

[0049] The voltage-controlled impedance network generates a correction signal Icorr for each phase of the multiphase switching power supply. In particular, a correction signal Icorr is generated for each positive sensing signal ISENPn. Thus, a correction signal Icorr is generated at the output terminal of the buffer receiving the corresponding positive sensing signal ISENPn, where the positive sensing signal ISENPn is modified by the impedance of the voltage-controlled resistor Radj, and where the impedance of the voltage-controlled resistor Radj is modified by the adjustment signal ADJ as a function of the sensed temperature or the sensed temperature difference. In this example, a first correction signal Icorr1 is generated for the positive sensing signal ISENP1, and a second correction signal Icrr2 is generated for the positive sensing signal ISENP2.

[0050] Then, the correction signals Icorr1 and Icorr2 are averaged to generate an average correction signal Iavg. For example, the averaging circuit 112 receives the correction signals Icorr1 and Icorr2. The averaging circuit 112 adds up the correction signals of all the received phases, and then divides the correction signals by the number of phases to generate the average correction signal Iavg. Then, the average correction signal Iavg is copied or duplicated to generate a plurality of copies of the average correction signal, one copy for each phase of the multi-phase switching power supply. In this embodiment, the correction signal is a correction current signal, and the average correction signal is also an average correction current signal. The average correction current signal Iavg is copied by using a current mirror 114 or other suitable circuits to generate a plurality of copies of the correction current signal Iang. In another embodiment, the output stage of the averaging circuit 112 can be duplicated to generate a plurality of copies of the average correction signal Iavg.

[0051] Copies of the average correction signal are applied to the positive sensing signal ISENPn to correct the temperature coefficient of the sensing signal. Specifically, each copy of the average correction signal is fed or applied to the corresponding positive sensing signal ISENPn to produce a modified or compensated positive sensing signal having a zero or substantially zero temperature coefficient. In this embodiment, the positive sensing signal is compensated by the average correction signal. For some phases, the positive sensing signal may be over-compensated, while for other phases, the positive sensing signal may be under-compensated. However, high compensation accuracy can be achieved over all phases and many switching cycles.

[0052] With the positive sensing signal ISENPn compensated in this way, the amplifier 104 generates an output signal Imon indicating the load current of the switching power supply, where the output signal Imn has a substantially zero temperature coefficient over a wide frequency range.

[0053] FIG. 6 is a circuit diagram showing a temperature compensation circuit implemented for a single-ended DC sensing network in a multi-phase switching power supply in an embodiment of the present invention. In particular, FIG. 6 illustrates the implementation of the temperature compensation circuit in two or more phases in FIG. 5. For simplicity of discussion, similar elements in FIGS. 5 and 6 are given similar reference numerals. Referring to FIG. 6, in the case where the multi-phase switching power supply has three or more phases, the compensation impedance network is extended to include additional buffers 110 to receive the positive sensing signals ISENPn of all phases. The voltage-controlled impedance network is also extended to include additional voltage-controlled resistors Radj, which are coupled to the output terminals of the respective buffers receiving the positive sensing signals ISENPn. More specifically, each voltage-controlled resistor Radj is connected to the output terminal of the buffer receiving the positive sensing signal ISENPn and the input terminal of the buffer receiving the total negative sensing signal ISENNS. The voltage-controlled resistor Radj provides an effective impedance value that has a temperature coefficient opposite to that of the positive sensing signal ISENPn. In operation, each copy of the compensation adjustment signal ADJ (e.g., ADJ1, ADJ2) is applied to modify the impedance of each voltage-controlled resistor Radj.

[0054] A correction signal Icorr is generated for each positive sensing signal ISENPn. Thus, the correction signal Icorr is generated at the output terminal of the buffer receiving the corresponding positive sensing signal ISENPn. In the example shown in FIG. 6, the compensation impedance network generates correction signals Icorr1, Icorr2, Icorr3, and Icorr4. All four correction signals are provided to the averaging circuit 112 and added by the adder 120 to generate an added signal Isum. Then, the divider 125 divides the added signal Isum by the number of phases (i.e., 4) to generate an average correction signal Iavg. The average correction signal Iavg is replicated, for example, by the current mirror 114, to generate a copy of the average correction signal Iang. Each copy of the average correction signal Iavg is applied to the corresponding positive sensing signal ISENPn to compensate for the temperature coefficient of the sensing signal.

[0055] FIG. 7 is a circuit diagram of an averaging circuit in some embodiments. Referring to FIG. 7, in the case where the correction signal is a correction current signal, the averaging circuit 152 can be implemented as a total current adder for the correction current signals (such as Icorr1, Icorr2, Icorr3) using PMOS transistors (such as M1, M2, and M3). Then, the total current signal Isum is coupled to a current mirror formed by NMOS transistors M4 and M5. The total current is divided by connecting NMOS transistors in series to the current mirror. To divide the total current by 3, NMOS transistors M6 and M7 are connected in series with transistor M5. In this way, an average correction current Iavg is generated at the drain terminal of transistor M7. Then, an additional current mirror can be used to replicate or duplicate the average correction current Iavg.

[0056] FIG. 8 is a flowchart illustrating a method for providing temperature compensation for a sensed signal in a single-ended DC resistance (DCR) sensing network for a multiphase switched-mode power supply in some embodiments. Referring to FIG. 8, method 200 provides temperature compensation for a sensed signal in a single-ended DC resistance (DCR) sensing network for a multiphase switched-mode power supply, where the inductor current in each phase of the multiphase switched-mode power supply is sensed by a resistor-capacitor (RC) network connected in parallel to the inductor of the corresponding phase. The voltage across the capacitor of the RC network is provided as a sensed signal indicating the inductor current, where the sensed signal includes a positive sensed signal and a negative sensed signal and has a first temperature coefficient.

[0057] Method 200 receives a temperature sensing signal (202) indicating the temperature associated with the sensed signal. Method 200 generates a compensation adjustment signal (204) in response to the difference between the temperature sensing signal and a reference temperature signal. Then, the method generates a correction signal for each phase of the multiphase switched-mode power supply in response to at least the positive sensed signal of the corresponding phase and the compensation adjustment signal, where the correction signal for each phase has a second temperature coefficient (206). Method 200 then generates an average correction signal that indicates the average of the correction signals for all phases of the multiphase switched-mode power supply (208).

[0058] Method 200 then applies the average correction signal to each of the positive sensed signals to generate a modified positive sensed signal for each phase having a substantially zero temperature coefficient over a first frequency range (210). Method 200 generates a total positive sensed signal that is the sum of the modified positive sensed signals for all phases of the multiphase switched-mode power supply, and a total negative sensed signal that is the sum of the negative sensed signals in all phases of the multiphase switched-mode power supply (212). Finally, method 200 generates an output signal indicating the difference between the total positive sensed signal and the total negative sensed signal, where the output signal has a substantially zero temperature coefficient over the first frequency range.

[0059] In this detailed description, even if a processing step is not explicitly described in different embodiments, the processing steps described for one embodiment can be used in different implementations. When a method involving two or more defined steps is mentioned herein, the defined steps can be executed in any order or simultaneously, unless the context otherwise indicates or is specifically stated herein. Additionally, unless the context otherwise provides or clearly indicates, the method can also include one or more other steps that are executed before any defined step, between two defined steps, or after all defined steps.

[0060] In this detailed description, various embodiments or examples of the present invention can be implemented in multiple ways, including as a process; a device; a system; and a composition of matter. A detailed description of one or more embodiments of the present invention and the accompanying drawings showing the principles of the present invention are provided above. The present invention is described in connection with these embodiments, but the present invention is not limited to any embodiment. Many modifications and variations can be made within the scope of the present invention. The scope of the present invention is only limited by the claims, and the present invention includes many alternatives, modifications, and equivalents. To provide a thorough understanding of the present invention, many specific details are set forth in the specification. These details are provided for illustrative purposes, and the present invention can be practiced according to the claims without some or all of these specific details. For clarity, technical materials known in the technical field related to the present invention are not described in detail, so the present invention is not unnecessarily obscured. The present invention is defined by the appended claims.

[0061] 10: Voltage regulator 12: Multiphase modulator 14: Multiphase power block 16: Power stage 18: Input node 20: Output node 22: Load 25: Switch output voltage 26: Sense voltage node 28: Current sense amplifier 29: Output node 30: Power integrated circuit 40: Node 55: Digital configuration circuit 58: Digital signal 60: Power integrated circuit 62: Temperature compensation adjustment circuit 63: Node 64: Compensation impedance circuit 66: Current sensing amplifier 67: Node 70: Multiphase switching power supply 72-1: Power supply block 72-2: Power supply block 74-1: Switching output node 74-2: Switching output node 78: Output voltage node 80: Controller 82-1: Compensation impedance circuit 82-2: Compensation impedance circuit 84-1: Compensation calculator 84-2: Compensation calculator 86-1: Current sensing amplifier 86-2: Current sensing amplifier 88: Node 92: Summing node 100: Controller 102: Node 104: Current sensing amplifier 106: Output node 110: Buffer 112: Averaging circuit 114: Current mirror 115: Temperature compensation calculator circuit 120: Adder 125: Frequency divider 152: Averaging circuit 200: Method

Claims

1. A circuit for providing temperature compensation for a sensing signal in a single-ended DC resistance (DCR) sensing network of a multiphase switching power supply, wherein the inductor current in each phase of the multiphase switching power supply is sensed by a resistor-capacitor (RC) network connected in parallel to the inductors of the respective phase, and the voltage across the capacitors of the RC network is provided as a sensing signal indicating the inductor current, the sensing signal comprising a positive sensing signal and a negative sensing signal and having a first temperature coefficient, the circuit comprising: a temperature compensation calculator circuit that receives a temperature sensing signal and a reference temperature signal indicating a temperature associated with the sensing signal, and generates a compensation adjustment signal in response to the difference between the temperature sensing signal and the reference temperature signal; A compensation impedance network receives positive sensing signals from all phases of the multiphase switching power supply, a total negative sensing signal that is the sum of negative sensing signals from all phases of the multiphase switching power supply, and a compensation adjustment signal. The compensation impedance network generates a correction signal for each phase of the multiphase power supply in response to at least the positive sensing signal and the compensation adjustment signal of each phase. The correction signal of each phase has a second temperature coefficient. An averaging circuit coupled to average the correction signal of all phases of the multiphase switching power supply to generate an average correction signal, or a copy thereof, being applied to modify each of the positive sensing signals to provide each phase with a modified positive sensing signal having a substantially zero temperature coefficient over a first frequency range; and an amplifier circuit receiving a total positive sensing signal as the sum of the modified positive sensing signals of all phases, and the total negative sensing signal, the amplifier circuit generating an output signal indicating the difference between the total positive sensing signal and the total negative sensing signal having a substantially zero temperature coefficient over the first frequency range.

2. The circuit as claimed in claim 1, wherein the compensation impedance network comprises: a plurality of buffers, a first buffer of the plurality of buffers receiving a total negative sensing signal, each of the remaining buffers receiving a corresponding positive sensing signal for each phase of the multiphase switching power supply, the buffers providing a corresponding sensing signal at a corresponding output terminal; and a voltage-controlled impedance network coupled to the corresponding output terminal of the plurality of buffers, the voltage-controlled impedance network providing the correction signal having the second temperature coefficient for each phase of the multiphase switching power supply in response to at least the positive sensing signal and the compensation adjustment signal for each phase.

3. The circuit as claimed in claim 2, wherein the voltage-controlled impedance network includes a plurality of voltage-controlled resistors having the second temperature coefficient, each voltage-controlled resistor being coupled between the output terminal of the first buffer and the output terminal of a buffer receiving a corresponding positive sensing signal for each phase of the multiphase switching power supply, and modifying the impedance of each voltage-controlled resistor in response to the compensation adjustment signal.

4. The circuit as described in claim 3, wherein the modified impedance of each voltage-controlled resistor includes a positive impedance value or a negative impedance value.

5. The circuit as claimed in claim 3, wherein the correction signal includes a correction current signal, and the modified impedance of each voltage-controlled resistor is applied to modify the positive sensing signal of each phase received by the corresponding buffer to generate the corresponding correction current signal for that phase.

6. The circuit as claimed in claim 5, wherein a correction current for each phase is generated at the output terminal of the buffer that receives the positive sensing signal of the corresponding phase.

7. The circuit as claimed in claim 1, wherein the averaging circuit comprises: an adder circuit coupled to receive correction signals from all phases of the multiphase switching power supply and generate an adder signal as the sum of the correction signals from all phases; and a divider circuit coupled to receive the adder signal and divide the adder signal by the number of phases of the multiphase switching power supply to generate the average correction signal.

8. The circuit as claimed in claim 1, wherein the correction signal includes a correction current signal and the average correction signal includes an average correction current signal, and the averaging circuit further includes a plurality of current mirrors to generate copies of the average correction current signal, the copies being applied to modify each of the respective positive sensing signals.

9. The circuit as claimed in claim 1, wherein the first frequency range includes a frequency range from DC to 10 MHz.

10. The circuit as claimed in claim 1, wherein the amplifier circuit includes a positive input terminal and a negative input terminal, the positive input terminal being coupled to receive the total positive sensing signal, the negative input terminal being coupled to receive the total negative sensing signal, the amplifier circuit having an output terminal that provides an output signal indicating the difference between the total positive sensing signal and the total negative sensing signal, the correction signal being applied to the corresponding positive sensing signal of the corresponding phase to generate a modified positive sensing signal added at the positive input terminal of the amplifier circuit.

11. The circuit as claimed in claim 10, wherein the amplifier circuit includes an operational amplifier circuit, the total positive sensing signal and the total negative sensing signal include current signals and have the first temperature coefficient, and the output signal includes a voltage or current signal indicating the difference between the total positive sensing signal and the total negative sensing signal and having a temperature coefficient substantially zero in the first frequency range.

12. The circuit as claimed in claim 1, wherein the total positive sensing signal is generated by coupling the modified positive sensing signal of each phase to a first terminal of a corresponding first resistor and connecting the second terminals of all phases corresponding to the first resistor together; and the total negative sensing signal is generated by coupling the negative sensing signal of each phase to a first terminal of a corresponding second resistor and connecting the second terminals of all phases corresponding to the second resistor together.

13. A method for providing temperature compensation for a sensing signal in a single-ended DC resistance (DCR) sensing network of a multiphase switching power supply, wherein an inductor current in each phase of the multiphase switching power supply is sensed by a resistor-capacitor (RC) network connected in parallel to a corresponding inductor, and the voltage across a capacitor in the RC network is provided as a sensing signal indicating the current of the inductor, the sensing signal comprising a positive sensing signal and a negative sensing signal and having a first temperature coefficient, the method comprising: receiving a temperature sensing signal indicating a temperature associated with the sensing signal; generating a compensation adjustment signal in response to a difference between the temperature sensing signal and a reference temperature signal; generating a correction signal for each phase of the multiphase switching power supply, the correction signal having a second temperature coefficient, in response at least to the positive sensing signal of each phase of the multiphase switching power supply and the compensation adjustment signal; and generating an average correction signal indicating the average value of the correction signals of all phases of the multiphase switching power supply. The average correction signal is applied to each of the positive sensing signals to generate a modified positive sensing signal for each phase with a temperature coefficient substantially zero in a first frequency range; a total positive sensing signal is generated as the sum of the modified positive sensing signals for all phases of the multiphase switching power supply, and a total negative sensing signal is generated as the sum of the negative sensing signals for all phases; and an output signal is generated indicating the difference between the total positive sensing signal and the total negative sensing signal, the output signal having a temperature coefficient substantially zero in the first frequency range.

14. The method of claim 13, wherein generating the correction signal in response to at least the positive sensing signal of each phase of the multiphase switching power supply and the compensation adjustment signal comprises: receiving a total negative sensing signal at a first buffer and receiving positive sensing signals of all phases of the multiphase switching power supply at a plurality of buffers; and generating a correction signal having the second temperature coefficient of each phase of the multiphase switching power supply at the output of the plurality of buffers in response to at least the positive sensing signal of each phase and the compensation adjustment signal.

15. The method of claim 14, wherein generating a correction signal having the second temperature coefficient for each phase of the multiphase switching power supply at the output terminals of the plurality of buffers comprises: coupling a plurality of voltage-controlled resistors having the second temperature coefficient to the output terminals of the first buffer and the plurality of buffers, each voltage-controlled resistor being coupled between the output terminal of the first buffer and the output terminal of a corresponding one of the plurality of buffers; modifying the impedance of each voltage-controlled resistor in response to the compensation adjustment signal; and generating a correction current for each phase at the output terminal of the corresponding buffer receiving the positive sensing signal of the corresponding phase in response to the modified impedance of the voltage-controlled resistor coupled thereto.

16. The method of claim 13, wherein the correction signal includes a correction current signal and the average correction signal includes an average correction current signal, and applying the average correction signal to each of the positive sensing signals to generate the modified positive sensing signal for each phase comprises: generating a copy of the average correction current signal; and applying each copy of the average correction current signal to the corresponding positive sensing signal to generate the modified positive sensing signal for each phase.

17. The method of claim 13, wherein applying the average correction signal to each of the positive sensing signals to generate a modified positive sensing signal with a temperature coefficient substantially zero in each phase over the first frequency range comprises: applying the average correction signal to each of the positive sensing signals to generate a modified positive sensing signal with a temperature coefficient substantially zero in each phase over a frequency range from DC to 10 MHz.

18. The method of claim 13, wherein generating the total positive sensing signal and the total negative sensing signal comprises: generating the total positive sensing signal by coupling a modified positive sensing signal of each phase to a first terminal of a corresponding first resistor and connecting the corresponding second terminals of all phases to the first resistor together; and generating the total negative sensing signal by coupling a negative sensing signal of each phase to a first terminal of a corresponding second resistor and connecting the corresponding second terminals of all phases to the second resistor together.

19. The method of claim 13, wherein generating the output signal indicating the difference between the total positive sensing signal and the summed negative sensing signal comprises: coupling the total positive sensing signal to a positive input terminal of an operational amplifier circuit; coupling the total negative sensing signal to a negative input terminal of the operational amplifier circuit; and generating an output signal at an output terminal of the operational amplifier circuit, the output signal comprising a voltage or current signal indicating the difference between the total positive sensing signal and the total negative sensing signal, and having a temperature coefficient substantially zero within the first frequency range.

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