Temperature compensation for single-ended DCR sensor network in multi-phase switching power supply

Abstract

A circuit for providing temperature compensation for a sensing signal in a single-ended DC resistance (DCR) sensing network of a multi-phase switching power supply includes a temperature compensation calculator circuit generating a compensation adjustment signal indicative of a sensing temperature; the compensation impedance network is used for receiving the positive sensing signals of all phases and generating correction signals of each phase at least in response to the positive sensing signals of each phase and the compensation adjustment signals; coupling an averaging circuit to average 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 sense signal and a summed negative sense signal that are a sum of the modified positive sense signals of all phases to generate an output signal having a temperature coefficient of substantially zero over the first frequency range.

Description

Technical Field

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

[0002] Electronic systems, such as laptop computers, often contain power management integrated circuits that regulate the power consumption of the electronic system. In addition, electronic systems containing integrated circuits often employ voltage regulators to convert the main bus voltage from the power supply that powers the system to one or more voltages required to drive the integrated circuits therein. For example, a 5 volt supply voltage supplied to an electronic system may need to be stepped down to 1.8 volts to drive the integrated circuits in the electronic system. Embedded systems, such as Internet of Things (IoT) devices, contain a processor (or microcontroller) and local memory coupled to the components and execute embedded software to perform certain tasks. In practice, processor power is provided by a voltage regulator that converts the input voltage from the power supply to a voltage value specified by the processor.

[0003] A switch mode power supply or switching regulator, also known as a DC-DC converter, is a voltage regulator that is typically used to convert an input supply voltage to a desired output voltage at a selected voltage level for an integrated circuit. In one example, a 12V or 5V supply voltage can be stepped down to 1V for powering an embedded processor. A switching regulator provides power functionality 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 input to output in discrete packets. Feedback control circuitry is used to regulate the energy transfer to maintain a constant output voltage within the desired load limits of the circuit.

[0004] Some switching regulators use pulse width modulation (PWM) to control the duty cycle of the power switch. That is, by adjusting the pulse width, the on-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 including 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 switching power supply, and the multi-phase PWM controller generates clock signals with different phase shifts to drive the multi-phase power blocks, each clock signal driving a corresponding power block unit. Multi-phase PWM controllers are ideal when the voltage regulator must provide a regulated output voltage with high accuracy over a wide range of load conditions.

[0005] In electronic systems that contain voltage regulators, it is often necessary to measure the voltage regulator output current for power management functions. In multiphase converters, accurate output current sensing is also important for output voltage load line control and phase current balancing in multiphase switching power supplies. 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 hereinafter, such as more fully set forth in the claims with reference to at least one of the accompanying drawings.

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

[0009] These and other advantages, aspects and novel features of the present invention, as well as details of illustrated embodiments thereof, will be more fully understood from the following description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Various embodiments of the present invention are disclosed in the following detailed description and accompanying drawings. Although the accompanying 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 accompanying drawings, the same reference numerals represent the same structural elements. In addition, it should be understood that the descriptions in the drawings are not necessarily to scale.

[0011] Figure 1 A schematic diagram of a voltage regulator that, in some examples, includes a multi-phase current mode modulator is shown.

[0012] Figure 2 A circuit diagram is shown illustrating an implementation of voltage regulator DCR current sensing in some examples.

[0013] Figure 3 Reproduction of U.S. Patent No. 10795390 ('390) Figure 5 , and illustrates an exemplary implementation of the temperature compensation scheme described in the '390 patent.

[0014] Figure 42 shows an exemplary implementation of the temperature compensation scheme described in the '390 patent in a multi-phase switching power supply, in some examples.

[0015] Figure 5 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.

[0016] Figure 6 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.

[0017] Figure 7 A circuit diagram showing an averaging circuit in some embodiments.

[0018] Figure 8 A flow chart illustrating a method of providing temperature compensation for a sense signal in a single-ended direct current resistance (DCR) sensing network of a multi-phase switching power supply in some embodiments. DETAILED DESCRIPTION

[0019] According to an embodiment of the present invention, a temperature compensation circuit provides temperature compensation for a sense signal in a single-ended direct current resistance (DCR) sensing network implemented by a multi-phase switching power supply, wherein the sense signal measures the inductor current in each phase of the multi-phase switching power supply. The sense 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 sense signal, wherein the correction signal has a second temperature coefficient. The correction signal is applied to modify the sense signal to provide a modified sense signal having a temperature coefficient substantially zero within a given frequency range. The modified sense signal can then be averaged and applied as a single-ended signal to generate an output signal indicating an average inductor current of the multi-phase switching power supply, wherein the output signal has a temperature coefficient substantially zero within a given frequency range.

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

[0021] A notable feature of the temperature compensation circuit of the present invention is that the circuit provides accurate temperature compensation over a wide frequency range. In conventional solutions, temperature compensation is typically only accurate for DC signals, and becomes inaccurate when the sensed signal varies at a given frequency. In an embodiment of the present invention, the temperature compensation circuit provides accurate temperature compensation at DC (0 Hz) and high frequencies (e.g., 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 conventional solutions.

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

[0023] In general, the temperature coefficient can be linear or nonlinear 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 slope and a positive temperature coefficient for a given offset. In another example, the temperature coefficient can have a negative slope and a negative temperature coefficient for a given offset.

[0024] Figure 1 is a schematic diagram of a voltage regulator that includes a multiphase current mode modulator in some examples. Figure 1 , the voltage regulator 10 includes a multiphase modulator 12 ("modulator 12") coupled to drive a multiphase power block 14. In the present example, the voltage regulator 10 is implemented using a multiphase modulator to enable the voltage regulator to provide a regulated output voltage with high accuracy over 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 driving a single-phase power block. In the present example, the multiphase modulator 12 includes three phases, and the power block 14 includes three power stages 20 having associated output inductors L1 to L3 and output capacitors C OUT .

[0025] More specifically, the voltage regulator 10 receives an input voltage V at an input node 18. IN, and generates a regulated output voltage VOUT at an output node 20 to supply power to a load 22. The multi-phase power block 14 includes a power stage 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 respective PWM signals 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 switching output voltage Vsw at a switching output node 25. The switching output node of each power stage 16 is coupled to a respective output inductor L1 to L3. The inductors L1 to L3 are coupled to output capacitors C OUT , to form an LC circuit for providing current to the output node 20 while maintaining a substantially constant output voltage V OUT Then, the output voltage VOUT can be used to drive the load 22 .

[0026] The multiphase modulator 12 receives a signal indicating a regulated output voltage V at the output node 20. OUT The feedback voltage V FB In one example, the feedback voltage V FB is the output voltage V OUT For example, a resistor divider including resistors R11 and R12 coupled to the output voltage node 20 may be used to generate the feedback voltage V FB The multiphase modulator 12 also receives a target voltage V TARG , which indicates the voltage value required to regulate the output voltage. In some examples, the target voltage can be indicated by a voltage identification code that signals 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. The decoder decodes the VID code to generate a target voltage. The modulator 12 includes circuitry for implementing a feedback control loop of a voltage regulator to generate multi-phase PWM signals PWM1 to PWM3 to drive each power stage 16 in the multi-phase power block 14.

[0027] Thus configured, the voltage regulator 10 can be incorporated into an electronic system to provide the electronic system with a desired regulated output voltage V OUT. In some applications, the electronic system includes a power integrated circuit that performs power management functions, and the power integrated circuit often needs to accurately measure the output current or load current of the voltage regulator 10. In other examples, the multi-phase modulator itself contains circuits 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, the inductor current is measured using an inductor direct current resistance (DCR) current sensing scheme.

[0028] Figure 2 is a circuit diagram that illustrates the implementation of DCR current sensing in voltage regulators in some examples. Figure 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, which generates a switching output voltage Vsw (node ​​25), which is coupled to drive a switch connected at the switching output node 25 and provides an output voltage V OUT The inductor L is between the output node 20 of the voltage regulator. The output capacitor C OUT is coupled between the output node 20 and ground potential to generate an output voltage V having a substantially constant amplitude OUT .

[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 regulator output current using the parasitic resistance of the inductor winding, thereby eliminating the need for a sense resistor in series with the inductor L. The parasitic resistance of the inductor L is Figure 2denoted as resistor Rdcr in the figure, where the dashed box indicates that the resistor is a parasitic element and not an actual resistor in the circuit. DCR current sensing uses a resistor-capacitor (RC) network in parallel with the series inductor and parasitic resistance combination L and Rdcr. Specifically, the RC network includes a sensing resistor Rsns and a sensing capacitor Csns connected in series across the inductor L, i.e., across nodes 25 and 20. The sensing voltage Vsns is measured across the sensing 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 sensing 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 sensing signals: a positive sensing signal and a negative sensing signal.

[0030] The inductor DCR of the wire winding 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, the 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, such as Figure 2 shown.

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

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

[0033] In practice, because the resistor Rntc is not usually placed at or near the inductor L on the PC board of the electronic system. The resistor Rntc cannot sense the same temperature experienced by the inductor L. Therefore, a linearized NTC network needs to be designed specifically 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 ~10MHz. 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. An 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 of a specific PC board design. An iterative process must be performed for each PC board design to determine the optimal value of the NTC resistor network. In addition, for multi-phase converters, a separate linearized NTC resistor network is built and adjusted 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 produce a current sense signal having a substantially zero temperature coefficient over a wide frequency range. The entire contents of the '390 patent are incorporated herein by reference. Figure 3 The '390 patent Figure 5 Repeat and illustrate an exemplary implementation of the temperature compensation scheme described in the '390 patent. Figure 3 The power integrated circuit 60 includes a current sensing amplifier 66 for measuring a sensing voltage Vsns across the sensing capacitor Csns, the voltage Vsns indicating the inductor current IL flowing through the inductor L. The current sensing amplifier 66 generates an output signal at a node 67, the output signal being a voltage signal V(Imon), the voltage signal V indicating the sensing voltage, thereby 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 the present 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 the temperature sensing signal TSEN (node ​​40) and provides a control signal (node ​​63) to the voltage controlled resistor VCRntceq. In the present embodiment, the control signal is a control voltage signal. The voltage controlled resistor VCRntceq provides a resistance value that changes 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, wherein 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 sensing voltage. For example, the temperature compensation adjustment circuit 62 can be digitally configured or programmed by the digital configuration circuit 55 using one or more digital signals 58.

[0036] Therefore, the temperature compensation adjustment circuit 62 generates a control voltage so that the voltage control resistor VCRntceq provides a resistance value that varies with the sense temperature and also has a temperature coefficient that compensates for the temperature coefficient of the sense voltage Vsns. In other words, the temperature compensation adjustment circuit 62 generates a control signal to set the resistance value of the voltage control resistor VCRntceq and control how the resistance value of the resistor VCRnt changes with temperature. So configured, the resistor VCRntceq applies a compensation impedance signal to the node 26 to modify the sense voltage Vsns so that the modified or temperature compensated sense voltage has a zero or substantially zero temperature coefficient over a given frequency range. The current sense amplifier 66 receives the modified sense voltage and thus generates an output signal V(Imon) indicating the sense voltage and having 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] Figure 2 and Figure 3The inductor DCR sensing scheme described in employs Kelvin sensing to measure the sense voltage Vsns across the sense capacitor Csns. The voltage sense signal is therefore a differential sense signal comprising a positive sense signal (ISENP) and a negative sense signal (ISENN) coupled to the positive and negative input terminals of the current sense amplifier. In a multi-phase switching power supply, a fully differential DCR sensing scheme requires two signal pins per phase to implement. For a multi-phase 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 may be difficult to implement due to the pin limitations on the integrated circuit package of the multi-phase 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] Figure 4 In some examples, an exemplary implementation of the temperature compensation scheme described in the '390 patent in a multi-phase switching power supply is shown. Figure 4 In the example shown, the multi-phase switching power supply 70 is shown to have 2 phases - phase 1 and phase 2, and separate power supply blocks 71-2 and 72-2. Inductor DCR sensing is achieved by providing an RC network in parallel with the inductor in each phase. The inductor current of the inductor L1 of phase 1 is sensed by the capacitor voltage across the sensing capacitor Cns1 using sensing signals ISENP1 and ISENN1. The inductor current of the inductor L2 of phase 2 is sensed by the capacitor voltage across the sensing capacitor Cns2 using sensing signals ISENP2 and ISENN2. Therefore, for two phases, four signal pins are required to achieve current sensing. In this example, 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, a corresponding compensation calculator 84-1 and 84-2 is provided for each phase to generate a corresponding control signal for controlling the corresponding compensation impedance circuit 82-1 and 82-2. The compensated sense signals are then sensed by current sense amplifiers 86-1 and 86-2. The output signals of current sense amplifiers 86-1 and 86-2 may be summed to generate an output signal V(Imon) (node ​​88) indicative of the load current of multi-phase switching regulator 70.

[0039] In order 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 multi-phase switching power supplies. In one example, the negative sense signals on all phases are added to generate a total negative sense signal. The positive sense signal and the total negative sense 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, while 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 of a single-ended DCR sensing network to ensure that the current sense signal derived therefrom 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-mentioned '390 patent.

[0040] Figure 5 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. Figure 5 , the temperature compensation circuit is implemented in the controller 100, which may be a multi-phase modulator or a PWM controller integrated circuit for a multi-phase 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 multi-phase 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 measuring the inductor current of all phases, which indicates the load current of the multi-phase switching power supply.

[0041] exist Figure 5 In the illustrated embodiment, the temperature compensation circuit is applied to a multi-phase switching power supply having two phases - Phase 1 and Phase 2. To simplify the discussion, the switching power supply circuit is not shown, and the two phases are represented by the switching output signal Vsw of each phase coupled to the corresponding inductor L1 and L2 at the corresponding switching output nodes 74-1 and 74-2. The inductor is connected to the output voltage node 78, and the output capacitor C OUT The output voltage V of the multi-phase switching power supply having a substantially constant amplitude is generated at the output voltage node 78. OUT .

[0042] In an embodiment of the present invention, inductor DCR current sensing is applied to sense the inductor current I flowing through the inductors L1 and L2 in each phase. LIn each phase, an RC network of a sensing resistor Rsns and a sensing capacitor Csns connected in series is connected in parallel with an inductor L and a parasitic resistance Rdcr of the inductor. A voltage Vsns across the sensing capacitor Csns is sensed as a sensing signal indicating an inductor current. In particular, the voltage Vsns is sensed by a pair of sense signals including a positive sense signal ISENPn at one plate (node ​​75-n) of the capacitor Csns and a negative sense 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 sense 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 generally has a positive temperature coefficient, and thus the sensed voltage Vsns has a positive temperature coefficient. The sense signals ISENPn and ISENNn measuring the sense voltage Vsns also have the same positive temperature coefficient.

[0043] In the present embodiment, a single-ended DCR sensing scheme is used to measure the sensing signals of all phases of a multi-phase switching power supply. Therefore, the single-ended DCR sensing scheme feeds back a negative sensing signal and all positive sensing signals, instead of feeding back all positive and negative sensing signals, thereby generating 2N signals for an N-phase switching power supply. In the present embodiment, each negative sensing signal ISENNn at the 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 a single negative sensing signal fed back to the controller 100. In practice, a 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 the present 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 sense 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 sense signal (node ​​102) is provided to the positive input terminal of the current sense amplifier 104. The total negative sense signal (node ​​92) is provided to the negative input terminal of the current sense amplifier 104. The current sense amplifier compares the total positive sense signal and the negative sense signal to generate an output signal indicating the sense voltage value Vsns of all phases at the output node 106, which indicates the inductor current generated by all phases, thereby indicating the load current of the multi-phase switching power supply. In the present embodiment, the current sense 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 the inductor DCR sensing, the sense signal has a temperature coefficient, such as a positive temperature coefficient, which can affect the measurement accuracy. In an embodiment of the present invention, a temperature compensation circuit is provided to perform temperature compensation on the sense signal to correct the temperature coefficient of the sense signal generated by the use of inductor DCR sensing. In particular, the temperature compensation circuit generates an average correction signal Iavg based on all positive sense signals and a temperature correction factor, and distributes the average correction signal Iavg to all positive sense signals ISENPn. Therefore, each positive sense signal is temperature compensated to a zero temperature coefficient, and the compensated or modified positive sense signals of all phases are then converted to current signals using corresponding resistors R1 and added at the summing node 102 for use by the current sense amplifier 104 for comparison with the total negative sense signal ISENNS. In the present specification, the total positive sense signal (node ​​102) is therefore the sum of the modified or compensated positive sense signals of all phases of the multi-phase switching power supply.

[0046] Still refer to Figure 5, the temperature compensation circuit includes a temperature compensation calculator circuit 115, which receives a 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 with 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 (e.g., ADJ1, ADJ2) are generated, wherein 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 of each phase is generated as a function of the positive sense signal and the adjustment signal ADJ of the phase. Therefore, the correction signal Icorr of one phase may be different from the correction signal Icorl of another phase. In the present embodiment, the correction signal is a current signal, which may 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 a positive sense signal ISENPn and a total negative sense signal ISENNS. The compensation impedance network generates a correction signal for each phase of the multi-phase switching power supply in response to at least the positive sense signal ISENPn of each phase and the compensation adjustment signal ADJ. In particular, the compensation adjustment signal ADJ modifies the effective impedance, as shown by the positive sense signal ISENPn of each phase, to generate a correction signal Icorr of the phase, whose temperature coefficient is opposite to the temperature coefficient of the positive sense signal ISENPn.

[0048] In one embodiment, the compensation impedance network includes a group of buffers 110 for receiving and buffering 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 group 110 to generate a correction signal for each phase of the multi-phase switching power supply in response to at least the positive sensing signal ISENPn of each phase and the compensation adjustment signal ADJ. In one embodiment, the voltage-controlled impedance network includes a group of voltage-controlled resistors Radj connected in series between the output terminal of the first buffer and the output end 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 the temperature coefficient of the positive sensing signal ISENPn. In operation, each copy (eg, ADJ1, ADJ2) of the compensation adjustment signal ADJ 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 multi-phase switching power supply. In particular, the correction signal Icorr is generated for each positive sense signal ISENPn. Therefore, the correction signal Icorr is generated at the output terminal of the buffer receiving the corresponding positive sense signal ISENPn, wherein the positive sense signal ISENPn is modified by the impedance of the voltage controlled resistor Radj, and wherein 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 sense signal ISENP1, and a second correction signal Icrr2 is generated for the positive sense signal ISENP2.

[0050] The correction signals Icorr1 and Icorr2 are then 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 the correction signals of all phases received, and then divides the correction signal by the number of phases to generate an average correction signal Iavg. The average correction signal Iavg is then replicated or copied to generate multiple copies of the average correction signal, one copy for each phase of the multi-phase switching power supply. In the present 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 replicated by using a current mirror 114 or other suitable circuit to generate multiple copies of the correction current signal Iang. In another embodiment, the output stage of the averaging circuit 112 can be replicated to generate multiple copies of the average correction signal Iavg.

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

[0052] With the positive sense signal ISENPn thus compensated, the amplifier 104 generates an output signal Imon indicative of the load current of the switching power supply, wherein the output signal Imn has a substantially zero temperature coefficient over a wide frequency range.

[0053] Figure 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, Figure 6 Explained Figure 5 The temperature compensation circuit is implemented in more than 2 phases. To simplify the discussion, Figure 5 and Figure 6 Like elements in the drawings are given like reference numerals. Figure 6In the case of a multi-phase switching power supply having 3 or more phases, the compensation impedance network is extended to include an additional buffer 110 to receive the positive sense 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 sense signals ISENPn. More specifically, each voltage-controlled resistor Radj is connected to the output terminal of the buffer receiving the positive sense signal ISENPn and the input terminal of the buffer receiving the total negative sense signal ISENNS. The voltage-controlled resistor Radj provides an effective impedance value having a temperature coefficient opposite to that of the positive sense signal ISENPn. In operation, each copy (e.g., ADJ1, ADJ2) of the compensation adjustment signal ADJ is applied to modify the impedance of each voltage-controlled resistor Radj.

[0054] The correction signal Icorr is generated for each positive sensing signal ISENPn. Therefore, the correction signal Icorr is generated at the output terminal of the buffer receiving the corresponding positive sensing signal ISENPn. Figure 6 In the example shown, 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 the sum signal Isum. The frequency divider 125 then divides the sum signal Isum by the number of phases (i.e., 4) to generate an average correction signal Iavg. The average correction signal Iavg is copied, 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 sense signal ISENPn to compensate for the temperature coefficient of the sense signal.

[0055] Figure 7 is a circuit diagram of an average circuit in some embodiments. Figure 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 signal (e.g., Icorr1, Icorr2, Icorr3) using PMOS transistors (e.g., M1, M2, and M3). The total current signal Isum is then coupled to a current mirror formed by NMOS transistors M4 and M5. The total current is divided by connecting the NMOS transistors in series to the current mirror. In order 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 copy the average correction current Iavg.

[0056] Figure 8is a flow chart illustrating a method for providing temperature compensation for a sense signal in a single-ended DC resistance (DCR) sensing network for a multi-phase switching power supply in some embodiments. Figure 8 The method 200 provides temperature compensation for a sense signal in a single-ended DC resistance (DCR) sensing network of a multi-phase switching power supply, wherein an inductor current in each phase of the multi-phase switching power supply is sensed by a resistor-capacitor (RC) network connected in parallel to an inductor of the corresponding phase. A voltage across a capacitor of the RC network is provided as a sense signal indicative of the inductor current, wherein the sense signal includes a positive sense signal and a negative sense signal and has a first temperature coefficient.

[0057] Method 200 receives a temperature sense signal indicating a temperature associated with the sense signal (202). Method 200 generates a compensation adjustment signal in response to a difference between the temperature sense signal and a reference temperature signal (204). The method then generates a correction signal for each phase of a multi-phase switching power supply in response to at least the positive sense signal and the compensation adjustment signal of the corresponding phase, wherein the correction signal for each phase has a second temperature coefficient (206). Method 200 then generates an average correction signal indicating an average value of the correction signals for all phases of the multi-phase switching power supply (208).

[0058] The method 200 then applies the average correction signal to each of the positive sense signals to generate a modified positive sense signal for each phase having a substantially zero temperature coefficient over a first frequency range (210). The method 200 generates a total positive sense signal as the sum of the modified positive sense signals for all phases of the multi-phase switching power supply, and a total negative sense signal as the sum of the negative sense signals in all phases of the multi-phase switching power supply (212). Finally, the method 200 generates an output signal indicating a difference between the total positive sense signal and the total negative sense signal, wherein the output signal has a substantially zero temperature coefficient over the first frequency range.

[0059] In this detailed description, a processing step described for one embodiment may be used in a different implementation even if the processing step is not explicitly described in a different embodiment. When a method comprising two or more defined steps is referred to herein, the defined steps may be performed in any order or simultaneously, unless the context indicates otherwise or is specifically stated otherwise herein. In addition, the method may also include one or more other steps that are performed before any defined step, between two defined steps, or after all defined steps, unless the context dictates otherwise or explicitly indicates otherwise.

[0060] In this detailed description, various embodiments or examples of the present invention may be implemented in a variety of ways, including as a process; an apparatus; a system; and a composition of matter. A detailed description of one or more embodiments of the present invention and drawings illustrating the principles of the present invention are provided above. The present invention is described in conjunction with these embodiments, but the present invention is not limited to any embodiment. Many modifications and variations may be made within the scope of the present invention. The scope of the present invention is limited only by the claims, and the present invention includes many alternatives, modifications, and equivalents. In order 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 may be practiced according to the claims without some or all of these specific details. For the sake of clarity, technical materials known in the technical field related to the present invention are not described in detail, so that the present invention will not be unnecessarily obscured. The present invention is defined by the appended claims.

Claims

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

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

3. The circuit of claim 2, wherein the voltage controlled impedance network comprises a plurality of voltage controlled resistors having the second temperature coefficient, each voltage controlled resistor being coupled between an output terminal of the first buffer and an output end of a buffer receiving a corresponding positive sense signal of each phase of the multi-phase switching power supply, and wherein the impedance of each voltage controlled resistor is modified in response to the compensation adjustment signal.

4. The circuit of claim 3, wherein the modified impedance of each voltage controlled resistor comprises a positive impedance value or a negative impedance value.

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

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

7. The circuit of claim 1, wherein the averaging circuit comprises: a summing circuit coupled to receive the correction signals of all phases of the multi-phase switching power supply and to generate a summed signal as a sum of the correction signals of all phases; and A divider circuit is coupled to receive the summed signal and divide the summed signal by the number of phases of the multi-phase switching power supply to generate an average correction signal.

8. The circuit of claim 1 , wherein the correction signal comprises a correction current signal and the average correction signal comprises an average correction current signal, and the averaging circuit further comprises 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 sense signals.

9. The circuit of claim 1, wherein the first frequency range comprises a frequency range from DC to 10 MHz.

10. The circuit of claim 1, wherein the amplifier circuit comprises a positive input terminal and a negative input terminal, the positive input terminal being coupled to receive the total positive sense signal, the negative input terminal being coupled to receive the total negative sense signal, the amplifier circuit having an output terminal providing an output signal indicative of a difference between the total positive sense signal and the total negative sense signal, the correction signal being applied to the corresponding positive sense signals of the corresponding phases to generate modified positive sense signals summed at the positive input terminal of the amplifier circuit.

11. The circuit of claim 10, wherein the amplifier circuit comprises an operational amplifier circuit, the total positive sense signal and the total negative sense signal comprise current signals and have a first temperature coefficient, and the output signal comprises a voltage or current signal indicating a difference between the total positive sense signal and the total negative sense signal and having a temperature coefficient substantially zero within a first frequency range.

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

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

14. The method of claim 13, wherein generating the correction signal in response to at least the positive sense signal of each phase of the multi-phase switching power supply and the compensation adjustment signal comprises: receiving a total negative sense signal at a first buffer and receiving positive sense signals of all phases of a multi-phase switching power supply at a plurality of buffers; and A correction signal having a second temperature coefficient for each phase of the multi-phase switching power supply is generated at output terminals of the plurality of buffers in response to at least the positive sense signal for 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 multi-phase switching power supply at output terminals of the plurality of buffers comprises: coupling a plurality of voltage-controlled resistors having a second temperature coefficient to the first buffer and to output terminals of the plurality of buffers, each voltage-controlled resistor being coupled between an output terminal of the first buffer and an 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 A corrective current for each phase is produced at an output terminal of a respective buffer receiving the positive sense signal for the respective phase in response to the modified impedance of the voltage controlled resistor coupled thereto.

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

17. The method of claim 13, wherein applying the average correction signal to each of the positive sense signals to produce each phase of the modified positive sense signal having a substantially zero temperature coefficient within a first frequency range comprises: The average correction signal is applied to each of the positive sense signals to produce a modified positive sense signal for each phase having a substantially zero temperature coefficient over a frequency range from DC to 10 MHz.

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

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

Images