Apparatus and method for operating multiphase voltage regulator, and multiphase voltage regulator system

Abstract

This invention describes a method and system for operating a multiphase voltage regulator. The multiphase voltage regulator may include a plurality of power stages. A controller may be connected to the plurality of power stages. The controller may detect the number of activated power stages among the plurality of power stages. The controller may adjust the gain of a current sensing feedback loop of the controller to control the load transient response of a multiphase voltage regulator. This adjustment of the gain may be based on the number of activated power stages.

Description

[Technical Field]

[0001] This disclosure generally relates to the operation of a power converter. More specifically, this disclosure relates to controlling the stability of a multiphase voltage regulator. [Previous Technology]

[0002] DC-DC voltage conversion can be performed by switching a voltage regulator or power converter to convert a voltage from a higher level to a lower level that a load may require. One example architecture distributes a higher voltage to multiple voltage regulators or power stages, each of which can generate the same or different voltages for one or more loads. A switching voltage regulator can use two or more power transistors to convert energy from one voltage to another. An example of such a switching voltage regulator can be a buck regulator, which typically switches a pair of power transistors to generate a square wave at a common node between the pair. The generated square wave can be smoothed using a resonant circuit (e.g., an inductor-capacitor (LC) circuit) to produce a desired voltage for a load. A feedback control loop can be configured to control the duty cycle of the generated square wave and the resulting value of the output voltage of the voltage converter.

[0003] An example voltage regulator architecture may include a multiphase voltage regulator comprising one of multiple power stages, which may be referred to as phases. Each power stage includes a pair of power transistors (e.g., field-effect transistors (FETs)), an inductor and an output capacitor connected to the output of that power stage, and a controller. The voltage output from each activated power stage can be interleaved at an output node to produce a total output voltage. The phases are connected in parallel, and different numbers of power stages can be activated (e.g., turned on) to output different total output voltages, thereby providing different power levels for a load. Furthermore, parameters (e.g., inductor current and temperature) can be measured between the output node and the output of the power stage. The measured parameters can be fed back to a main controller connected to one of the multiple power stages, which can be used to maintain a satisfactory performance level of the overall system and determine the optimal number of power stages to be activated. [Summary of the Invention]

[0004] In one embodiment, a device for operating a multiphase voltage regulator is generally described. A controller may be connected to a plurality of power stages in the multiphase voltage regulator. The controller may be configured to detect the number of activated power stages among the plurality of power stages. The controller may be further configured to adjust the gain of a current sensing feedback loop of the controller to control a load transient response of the device. This adjustment of the gain may be based on the number of activated power stages.

[0005] In another embodiment, a multiphase voltage regulator system is generally described. The multiphase voltage regulator system may include a plurality of power stages and a controller connected to one of the plurality of power stages. The controller may be configured to detect the number of activated power stages among the plurality of power stages. The controller may be configured to adjust the gain of a current sensing feedback loop of the controller to control the load transient response of the system. This adjustment of the gain may be based on the number of activated power stages.

[0006] In another embodiment, a method for operating a multiphase voltage regulator is generally described. The method may include detecting, by a controller, the number of activated power stages among a plurality of power stages. The controller may be connected to the plurality of power stages in the multiphase voltage regulator. The method may further include adjusting, by the controller, a gain of a current sensing feedback loop of the controller to control a load transient response of the multiphase voltage regulator. This adjustment of the gain may be based on the number of activated power stages.

[0007] The foregoing description of the invention is illustrative only and is not intended to limit it in any way. In addition to the illustrative forms, embodiments and features set forth above, other forms, embodiments and features will also become apparent from the accompanying drawings and the following detailed description. In the drawings, similar element symbols indicate identical or functionally similar elements.

Implementation Method

[0012] Figure 1 is a diagram illustrating an example system of a multiphase voltage regulator with variable phase count stability that can be implemented in one embodiment. System 100 may be an apparatus for implementing a multiphase voltage regulator including a controller 102 and at least one voltage regulator or power stage (such as a power stage 110 and a power stage 120). In one example, controller 102 may be a master controller or a multiphase controller, and power stages 110, 120 may include DC-DC converters. Controller 102 may be configured to control power stage 110 using a PWM signal PWM1 sent from controller 102 to a pulse width modulation (PWM) pin of power stage 110. Power stage 110 may include a power transistor pair 112 and a power stage controller 114. Power transistor pair 112 may include a high-side field-effect transistor (FET) and a low-side FET. The PWM signal PWM1 can be a control signal that switches the power transistor pair 112 to convert an input voltage Vin into an output voltage V1.

[0013] Controller 102 can be configured to control power stage 120 using another PWM signal PWM2 sent from controller 102 to one of the PWM pins of power stage 120. Power stage 120 may include a power transistor pair 122 and a power stage controller 124. Power transistor pair 122 may include a high-side FET and a low-side FET. PWM signal PWM2 can switch power transistor pair 122 to convert input voltage Vin into an output voltage V2 as a control signal. Output voltages V1 and V2 can be combined or interleaved at a node 128 to generate a total output voltage Vout to a load 104. The voltage levels of V1 and V2 may be the same as Vout, but may be interleaved or out of phase.

[0014] In one or more examples, power stages 110 and 120 may be current source devices, voltage source devices, or devices implementing both current source control and voltage source control. In one example, power stages 110 and 120 may be smart power stage (SPS) devices configured to perform voltage regulation using additional features such as feedback control based on feedback voltage and / or feedback current, or other parameters such as temperature measured at the output of the power stage in system 100. For example, power stages 110 and 120 may provide the operating temperature of power stages 110 and 120 from the TMON pin of power stages 110 and 120 to a TSEN pin of controller 102. In another example, power stages 110 and 120 may respectively measure the inductor currents iL1 and iL2 of inductors L1 and L2. Power stages 110 and 120 can provide the measured inductor current to controller 102, from the IMON pin of power stages 110 and 120 to the ISEN_1 and ISEN_2 pins of controller 102, respectively. Furthermore, a measurement of the output voltage Vout can be fed back to controller 102 (e.g., received at one of the VSENSE pins of controller 102) for various control applications.

[0015] In one embodiment, the power stage controllers 114 and 124 of power stages 110 and 120 can be configured to process the measured parameters of power stages 110 and 120 respectively before providing the measured parameters to controller 102. For example, the power stage controllers 114 and 124 can amplify and / or calibrate the measured parameters before providing them to controller 102. The power stage controllers 114 and 124 may also include drivers configured to drive the power transistor pairs 112 and 122 of power stages 110 and 120 respectively.

[0016] Controller 102 can be configured to use feedback signals (such as sensed output voltage Vout, sensed current (e.g., currents iL1, iL2, or currents proportional to iL1, iL2)) and / or temperature information (e.g., operating temperature) to control and maintain the performance of system 100 at a satisfactory level (e.g., within predefined specifications). For example, if the sensed current returned from power stages 110, 120 indicates that load 104 is not drawing more current than expected, controller 102 can deactivate one or more power stages in system 100 to reduce the total power consumption of system 100. In one configuration, controller 102 can individually activate a power stage in system 100 via an enable pin EN of controller 102 and an enable pin EN of each of power stages 110, 120. The enable pin EN of controller 102 can be connected to the enable pin EN of power stages 110 and 120 using a specific bus (e.g., a single wire or a single trace).

[0017] In one example, controller 102 may be a microcontroller that includes hardware components such as integrated circuits (ICs), memory devices, and other hardware and circuit components. Controller 102 may include a modulator 130 configured to generate PWM signals, such as PWM signals PWM1 and PWM2, for power stages connected to controller 102. Modulator 130 may receive an output voltage Vout at a VSENSE pin of controller 102, or a feedback voltage signal that may be a sensed signal or a proportional signal indicating Vout. Controller 102 may include a current synthesizer 140 configured to receive inductor currents iL1, iL2, etc., sensed from the output inductors of the power stages in system 100. Current synthesizer 140 may be configured to simulate or synthesize the inductor currents of power stages 110 and 120 based on the sensed inductor currents iL1 and iL2, respectively. One of the outputs of the current synthesizer 140 (e.g., analog or synthesized current) can be provided to the modulator 130 to generate and / or adjust PWM signals PWM1, PWM2.

[0018] When one power transistor pair (e.g., 112, 122) in a power stage (e.g., 110, 120) switches rapidly between an on and off state, the inductor current (e.g., iL1, iL2 of L1 and L2) of the inductor can repeatedly ramp up and down. The power consumption of system 100 can increase as more power stages are activated. If load 104 needs to draw more power, more power stages can be activated—this is called increasing phase. If load 104 can draw less power, fewer power stages can be activated—this is called decreasing phase. The increasing and decreasing phases used to activate different numbers of power stages can cause load fluctuations, resulting in unstable load transient responses and sometimes slow load transient responses. As will be described in more detail below, controller 102 can be integrated with specific hardware that allows controller 102 to dynamically adjust the gain of controller 102 and / or current synthesizer in response to increasing or decreasing phase procedures to control load transient responses.

[0019] Figure 2 is a diagram illustrating additional details of the system 100 of Figure 1 in one embodiment. In one example shown in Figure 2, a circuit 200 includes one or more parts of the system 100 of Figure 1, including the controller 102, power stage 110, load 104, and other components, all shown in Figure 2. The details and corresponding descriptions of the power stage 110 shown in Figure 2 also apply to the power stage 120 in Figure 1, and / or other power stages connected to the controller 102 in the system 100. In the example shown in Figure 2, the power transistor pair 112 of the power stage 110 (see Figure 1) may include a high-side transistor QU and a low-side transistor QL. The high-side transistor QU and the low-side transistor QL may be FETs. The controller 102 may drive the power transistor pair 112 to alternately turn the high-side transistor QU and the low-side transistor QL on and off. For example, when QU is on, QL is off, and vice versa. A phase voltage VPH can be output from a node between the high-side transistor QU and the low-side transistor QL via switching driven by the PWM1 signal. The phase voltage VPH generates an inductor current iL1 across inductor L1. In response to the phase voltage VPH being applied to inductor L1, the inductance of L1 and one of its inherent resistances RL cause power stage 110 to generate an output voltage V1. Voltage V1 can be interleaved at node 128 with other output voltages from other power stages to form the total output voltage Vout for load 104.

[0020] The current synthesizer 140 of controller 102 may include a transconductance amplifier 210 having a transconductance gain gM. A phase voltage VPH may be received at a non-inverting input of transconductance amplifier 210, and an output voltage V1 may be received at an inverting input of transconductance amplifier 210. An output of transconductance amplifier 210 may be coupled to a ripple node 212. A capacitor with a ripple capacitance CR may be coupled between ripple node 212 and ground GND. A resistor circuit block 230 with a ripple resistor RR may be coupled between ripple node 212 and an internal reference or bias voltage VX. A ripple voltage VR may be generated from ripple node 212 based on the output current of transconductance amplifier 210, capacitor CR, internal reference voltage VX, and ripple resistor RR. The internal reference voltage VX may be injected into ripple node 212 to control the stability of the ripple current VR.

[0021] The transconductance amplifier 210 can be configured to generate its output current proportional to the voltage measured across inductor L1 (e.g., the difference between VPH and V1), so that the ripple voltage VR replicates the ripple current passing through inductor L1. The replicated current can be an analog or synthesized current output from current synthesizer 140. With the ripple resistor RR applied, injecting VX into ripple node 212 can introduce a deviation into the output current from transconductance amplifier 210. The introduced deviation can be an internal reference voltage VX. In one or more embodiments, the internal reference voltage VX can be a midpoint voltage, a functional zero, a voltage representing zero for a corresponding phase or power stage (e.g., power stage 110 in this example), etc.

[0022] The controller 102 may further include a comparator 216. A ripple voltage VR may be received by a non-inverting input of the comparator 216, and a positive window voltage VW+ may be received by an inverting input of the comparator 216. The positive window voltage VW+ may be based on a control or reference voltage VREF. An output of the comparator 216 may be provided to a reset (R) terminal of an SR latch 218 in the controller 102. The SR latch 218 may be part of the modulator 130 shown in FIG. 1. The SR latch 218 may output a PWM1 signal from an output (Q) terminal of the SR latch 218.

[0023] In one state, a relatively high gain gM is desirable because a decrease in gain gM can reduce the window voltage VW+, introduce higher jitter, and reduce the signal-to-noise ratio (SNR). A faster comparator (e.g., a higher bias) may be needed to compensate for these problems. In one state, the transconductance gain gM may comprise the gain of a current-sensing feedback loop along a path from the node across inductor L1 to SR latch 218. Adjusting the transconductance gain gM may be an adjustment of this current-sensing feedback loop. To increase gain gM, the ripple resistance RR can be increased by configuring resistor circuit block 230. Gain gM may vary inversely with the value of ripple resistance RR. For example, gain gM may increase in response to a decrease in ripple resistance RR. In response to an increase in gain gM, the speed of the load transient response of system 100 can be improved (e.g., increased speed) because the reduced ripple resistance RR can reduce the voltage drop used for the load transient response.

[0024] In one embodiment, resistor circuit block 230 may include a variable resistor (e.g., a digital potentiometer). Controller 102 may provide signals of different voltage levels to the variable resistor to change the ripple resistance RR. In another embodiment, resistor circuit block 230 may include a plurality of resistors. Controller 102 may activate and deactivate different numbers of resistors to change the ripple resistance RR. For example, the plurality of resistors in resistor circuit block 230 may be connected in parallel, and each resistor may be connected to a switch. Controller 102 may be configured to open and close different numbers of switches connected to the plurality of resistors to adjust the value of RR. In one embodiment, if resistor circuit block 230 includes a plurality of resistors that can be activated or deactivated, the plurality of resistors may have the same or different resistance values ​​to provide flexible adjustment of the value of the ripple resistance RR.

[0025] In one embodiment, the controller 102 may include a memory device configured to store an association 240 between different values ​​of the ripple resistor RR and different numbers of activated power stages. For example, the association 240 may be stored as a lookup table or a mapping. In the association 240, there may be M different values ​​of the ripple resistor RR associated with N activated power stages. In one instance, M may be equal to N, such that for each of the activated power stages, there may be one value of the ripple resistor RR. In another instance, M may be less than N, such that for each group of activated power stages, there may be one value of the ripple resistor RR, where a group of activated power stages may contain one or more power stages.

[0026] Controller 102 can be configured to configure resistor circuit block 230 based on association 240. Controller 102 can detect the number of activated power stages. For example, controller 102 can interpret an enable signal output on the EN pin of controller 102 to identify which power stages and how many power stages are being activated. In one embodiment, controller 102 can configure the value of ripple resistor RR based on the number of activated power stages, referring to association 240. For example, in response to association 240 indicating that four activated power stages are associated with a resistor value R4, controller 102 can configure the resistor block to adjust the value of RR to R4.

[0027] In one embodiment, the controller 102 can be configured to adjust the value of the ripple resistance RR for all activated power stages. For example, if the system 100 contains N power stages, there may be N replicas of the circuit 200 shown in FIG. 2. If k power stages out of the N power stages are activated in the system 100, the controller 102 can adjust the value of the ripple resistance RR for the k replicas of the circuit 200. Furthermore, the adjustment of the ripple resistance RR for all power stages can be the same. For example, the controller 102 can adjust the resistor circuit block 230 in the k replicas of the circuit 200 to have the same ripple resistance RR value.

[0028] Figure 3 is a diagram illustrating result 300 of one embodiment of a multiphase voltage regulator with variable phase count stability in one embodiment. Result 300 shows two different curves representing the load transient response of system 100 in Figure 1. The first curve, labeled "Original RR (200K)," represents the load transient response with the RR value in Figure 2 fixed at 200 kΩ. The second curve, labeled "Modified RR (50K)," represents the load transient response with the RR value in Figure 2 adjusted to 50 kΩ. The load transient responses represented by the first and second curves can be based on the same number of start-up phases or power stages in system 100. As shown in result 300, a load transient response based on a higher RR value (e.g., the first curve stabilizes at a later time 304) may be slower than a load transient response based on a lower RR value (the second curve stabilizes at an earlier time 302).

[0029] Figure 4 is a flowchart of an example program 400 of a multiphase voltage regulator with variable phase counting stability that can be implemented according to one embodiment of the present disclosure. Program 400 may include one or more operations, actions, or functions illustrated by one or more of blocks 402, 404, and 406 or 408. Although illustrated as discrete blocks, depending on the implementation to be implemented, various blocks may be divided into additional blocks, combined into fewer blocks, eliminated, executed in different orders, or executed in parallel.

[0030] Program 400 may be executed by a controller (e.g., controller 102 in Figures 1 and 2) connected to one of the plurality of power stages in a multiphase voltage regulator. Program 400 may begin at block 402. At block 402, the controller may detect the number of activated power stages among the plurality of power stages. In one embodiment, the gain of a current synthesizer may increase in response to a decrease in ripple resistance. In one embodiment, the current synthesizer may correspond to a specific power stage among the activated power stages. For example, the current synthesizer may simulate an inductor current of a specific power stage among the activated power stages.

[0031] Program 400 may proceed from block 402 to block 404. At block 404, the controller may adjust the gain of one of its current-sensing feedback loops to control the load transient response of one of the multiphase voltage regulators. This adjustment of the gain may be based on the number of power stages activated. In one embodiment, the controller may adjust the gain by adjusting a ripple resistor in one of the controller's current synthesizers. In one embodiment, an increase in the gain may improve the speed of the load transient response of one of the multiphase voltage regulators. The controller may adjust the gain of one of the current-sensing feedback loops in other power stages activated based on the number of power stages activated.

[0032] The operation in block 404 can be performed by executing either block 406 or block 408. In block 406, the controller can adjust the gain by activating a specific number of resistors in the current synthesizer. In block 408, the controller can adjust the gain by adjusting the resistance of one of the variable resistors in the current synthesizer.

[0033] The terminology used herein is for the purpose of illustrating particular embodiments only and is not intended to limit the invention. As used herein, the singular forms "a" and "the" are also intended to include the plural forms unless the context clearly indicates otherwise. It will be further understood that the terms "comprise and / or comprising," when used in this specification, specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0034] The corresponding structures, materials, actions, and equivalents of all components or steps plus functional elements (if present) in the claims below are intended to include any structure, material, or action for performing a function in conjunction with other claimed elements as specifically claimed. The disclosed embodiments of the invention are presented for illustrative and explanatory purposes and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the invention. These embodiments were chosen and described in order to best explain the principles and practical application of the invention and to enable others skilled in the art to understand various embodiments of the invention with various modifications suitable for the particular purpose considered.

[0035] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 210,575, filed on June 15, 2021. The entire disclosure of U.S. Patent Application No. 63 / 210,575 is incorporated herein by reference. [Simplified Explanation of the Diagram]

[0008] Figure 1 is a diagram illustrating an example system of a multiphase voltage regulator with variable phase counting stability that can be implemented in one embodiment.

[0009] Figure 2 is a diagram showing additional details of the system of Figure 1 in one embodiment.

[0010] Figure 3 is a diagram showing the result of one embodiment of a multiphase voltage regulator with variable phase counting stability in one embodiment.

[0011] Figure 4 is a flowchart of an example program for implementing a multiphase voltage regulator with variable phase counting stability according to an embodiment of the present disclosure.

Claims

1. An apparatus for operating a multiphase voltage regulator, comprising: Controller It is connected to a plurality of power stages in a multiphase voltage regulator. The controller is configured to: detect the number of activated power stages among the plurality of power stages; and adjust the gain of the current sensing feedback loop of the controller by adjusting the ripple resistor in the current synthesizer of the controller, so as to control the load-transient response of the device, wherein the adjustment of the ripple resistor is based on the number of activated power stages.

2. The apparatus of claim 1, wherein the controller is configured to adjust the ripple resistance by activating a specific number of resistors in the current synthesizer of the controller.

3. The apparatus of claim 1, wherein the controller is configured to adjust the ripple resistance by adjusting the resistance of a variable resistor in the current synthesizer of the controller.

4. The apparatus of claim 1, wherein the current sensing feedback loop is in a specific power level among the activated power levels, and the controller is configured to adjust the ripple resistance of the current sensing feedback loop in the other power levels among the activated power levels based on the number of activated power levels.

5. The apparatus of claim 1, wherein the controller is configured to use associations stored in a memory device to determine an adjustment level to adjust the ripple resistor, and wherein such associations are mapped to different levels of the ripple resistor via different numbers of startup power stages.

6. The device as requested in claim 1, wherein the adjustment of the ripple resistor improves the speed of the device's load transient response.

7. A multiphase voltage regulator system, comprising: Multiple power levels; A controller connected to the plurality of power stages is configured to: detect the number of activated power stages among the plurality of power stages; and adjust the gain of the current sensing feedback loop of the controller by adjusting the ripple resistor in the current synthesizer of the controller to control the load transient response of the system, wherein the adjustment of the ripple resistor is based on the number of activated power stages.

8. The system of claim 7, wherein the controller is configured to adjust the ripple resistance by activating a specific number of resistors in the current synthesizer of the controller.

9. The system of claim 7, wherein the controller is configured to adjust the ripple resistance by adjusting the resistance of a variable resistor in the current synthesizer of the controller.

10. The system of claim 7, wherein the current sensing feedback loop is in a specific power level among the activated power levels, and the controller is configured to adjust the ripple resistance of the current sensing feedback loop in the other power levels among the activated power levels based on the number of activated power levels.

11. The system of claim 7, further comprising a memory device configured to store associations mapping different numbers of startup power stages to different levels of the ripple resistor, wherein the controller is configured to use the associations stored in the memory device to determine an adjustment level to adjust the ripple resistor.

12. The system as requested in item 7, wherein such adjustment of the ripple resistor improves the speed of the system's load transient response.

13. A method for operating a multiphase voltage regulator, the method comprising: The number of activated power stages among the plurality of power stages is detected by a controller connected to a plurality of power stages in a multiphase voltage regulator; The gain of the current sensing feedback loop of the controller is adjusted by adjusting the ripple resistor in the current synthesizer of the controller to control the load transient response of the multiphase voltage regulator, wherein the adjustment of the ripple resistor is based on the number of power stages activated.

14. The method of claim 13, wherein adjusting the ripple resistor includes activating a specific number of resistors in the current synthesizer of the controller by the controller.

15. The method of claim 13, wherein adjusting the ripple resistor includes adjusting the resistance of a variable resistor in the current synthesizer of the controller by the controller.

16. The method of claim 13, wherein the current sensing feedback loop is in a specific power level among the activated power levels, and the method further includes the controller adjusting the ripple resistance of the current sensing feedback loop in the other power levels among the activated power levels based on the number of activated power levels.

17. The method of claim 13, wherein adjusting the ripple resistor results in an increase in the speed of the load transient response of the multiphase voltage regulator.

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