Patent Application
20210194360
The present invention generally relates to electronic circuits, and more particularly, relates to voltage regulators with adaptive voltage position and control methods thereof.
For voltage regulators (VRs) used in electronic devices such as laptops, desktops and servers, adaptive voltage position (AVP) control is widely applied to reduce voltage spikes during transient period and achieve better dynamic voltage regulation. The basic idea of conventional AVP control is shown in
However, due to rapid development of electronic devices, new challenges and various requirements for AVP control appear. Under traditional AVP control, the output voltage Vo is dependent of the output current Io, while it is required that the output voltage Vo is maintained to be independent of the output current Io at light load in some scenarios. Accordingly, a new AVP control method and circuit thereof is needed.
There has been provided, in accordance with an embodiment of the present invention, a voltage regulator comprising a switching circuit configured to receive an input voltage and to provide an output voltage and an output current; and a control circuit, configured to provide a control signal to the switching circuit, such that the output voltage is maintained at a clamp voltage level when the output current is lower than a transition current level, and the output voltage decreases as the output current increases when the output current is higher than the transition current level.
There has been provided, in accordance with an embodiment of the present invention, a control circuit used in a voltage regulator, wherein the voltage regulator has a switching circuit configured to receive an input voltage and to provide an output voltage and an output current, the control circuit configured to provide a control signal to the switching circuit, such that the output voltage is maintained at a clamp voltage level when the output current is lower than a transition current level, and the output voltage decreases as the output current increases when the output current is higher than the transition current level.
There has been provided, in accordance with an embodiment of the present invention, a voltage regulating method, comprising providing an output voltage and an output current in response to an input voltage; and regulating the output voltage such that the output voltage is maintained at a clamp voltage level when the output current is lower than a transition current level, and the output voltage decreases as the output current increases when the output current is higher than the transition current level.
The present invention can be further understood with reference to the following detailed description and the appended drawings, wherein like elements are provided with like reference numerals.
Reference will now be made in detail to the preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with the preferred embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be obvious to one of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail so as not to unnecessarily obscure aspects of the present invention.
Vo=Vx (1)
In the second piecewise curve, when the output current Io is higher than Ipp, the output voltage Vo linearly decrease as the output current Io increases, being the same with conventional AVP control, so the relationship between the output voltage Vo and the output current Io in the second piecewise curve may be expressed as:
Vo=Vref−Req*Io (2)
Where Vref is a reference voltage level, and Req is a slope of the second piecewise curve. In one embodiment, the reference voltage level Vref is determined via voltage identification code (VID) from a microprocessor. Persons of ordinary skill in the art should recognize that, if the reference voltage level Vref, the slope Req of the second piece wise curve, and the clamp voltage level Vx are determined, the transition current level Ipp is determined accordingly.
In the example of
Iinj=Ag(Vosen−Vx) (3)
Wherein Ag is a transconductance coefficient of the VCCS. In an example of the present invention, the output voltage sensing signal Vosen equals the output voltage Vo.
The AVP process circuit 24 comprises a current source 51, configured to provide a droop current having a current level Kc*Io based on the output current sensing signal Iosen (not shown here), wherein Kc is a current proportional coefficient; and a resistor 61 with a resistance Rd. The feedback voltage Vfb is provided at a node where the current source 51 is coupled to the resistor 61, so the feedback voltage Vfb may be expressed as:
Vfb=Vosen+Rd(Kc*Io+Iinj) (4)
As persons of ordinary skills in the art should know, the AVP process circuit 24 is typically applied in conventional AVP control, where a load line of the output voltage Vo versus the output current Io is linear and has a slope of Rd*Kc, i.e. the slope Req of the second piecewise curve in
The comparison circuit 26 comprises a comparator, configured to receive the feedback voltage Vfb and the reference voltage level Vref, and to provide the control signal Ctrl based on the feedback voltage Vfb and the reference voltage level Vref. Namely, here is another equation expressed as:
Vfb=Vref (5)
According to equation (2), the transition current level Ipp may be expressed as:
Ipp=(Vref−Vx)/Req=(Vref−Vx)/(Rd*Kc) (6)
According to equations (3)-(6), the injecting current Iinj may be expressed as:
Iinj=(Ipp−Io)*Kc*Rd/(1/Ag+Rd) (7)
If the transconductance coefficient Ag is indefinite, then the injecting current Iinj may be rewritten as:
Iinj=Kc(Ipp−Io) (8)
Plugging equation (8) into equation (4), the output voltage sensing signal Vosen may be rewritten as Vosen=Vref−Rd*(Kc*Io+Kc(Ipp−lo)), namely, Vosen=Vx. Since Vosen equals Vo, it will in fact be Vo=Vx. In another world, the injecting current generation circuit 22 generates the injecting current Iinj designed to help maintain the output voltage Vo as the clamp voltage level Vx.
It should be noted that, according to the unidirectional VCCS, and seen from equation (8), when the output current Io grows higher than the transition current level Ipp, the injecting current Iinj equals zero Hence, the output voltage Vo decreases with increase of the output current Io, as shown in the second piecewise curve in
In an embodiment of the present invention, the AVP process circuit 24 and the comparison circuit 26 are integrated on the same chip, while the injecting current generation circuit 22 is standalone outside the chip. In an embodiment of the present invention, the injecting current generation circuit 22, the AVP process circuit 24 and the comparison circuit 26 are all integrated on the same chip.
Step 801, providing an output voltage and an output current in response to an input voltage.
Step 802, regulating the output voltage such that the output voltage is maintained at a clamp voltage level when the output current is lower than a transition current level, and the output voltage decreases as the output current increases when the output current is higher than the transition current level.
In an embodiment of the present invention, the step 802 comprises: generating an injecting current, wherein, the injecting current is in proportion to a differential between the transition current level and the output current by a current proportional coefficient, and the injecting current is zero when the output current is higher than the transition current level; and generating a feedback voltage, wherein the feedback voltage is a sum of the output voltage and a droop voltage, and the droop voltage is generated based on a sum of the injecting current and a droop current in proportion to the output current by the current proportional coefficient.
In an embodiment of the present invention, the step 802 comprises: generating an injecting current, wherein, the injecting current is in proportion to a differential between the output voltage and the clamp voltage level by a transconductance coefficient designed to be large enough when the output current is lower than the transition current level, and the injecting current is zero when the output current is higher than the transition current level; and generating a feedback voltage, wherein the feedback voltage is a sum of the output voltage and a droop voltage, wherein the droop voltage is generated based on a sum of the injecting current and a droop current in proportion to the output current by a current proportion coefficient.
Obviously many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described. It should be understood, of course, the foregoing disclosure relates only to a preferred embodiment (or embodiments) of the invention and that numerous modifications may be made therein without departing from the spirit and the scope of the invention as set forth in the appended claims. Various modifications are contemplated and they obviously will be resorted to by those skilled in the art without departing from the spirit and the scope of the invention as hereinafter defined by the appended claims as only a preferred embodiment(s) thereof has been disclosed.
