Abstract:
A power delivery device includes a socket to couple and deliver power to an electronic component. A voltage control sensor is coupled to the socket to sense an output voltage at the socket and to provide negative feedback control. An impedance of the socket and an associated baseboard is incorporated into the negative feedback control and may help compensate for voltage droop in the output voltage.

Description:
BACKGROUND 
     This invention relates to a voltage regulator with voltage droop compensation. 
     A voltage regulator on a baseboard can provide power to a central processing unit (CPU). To drive today&#39;s powerful CPUs, more power and current are needed. However, with increased power delivery to the CPU, static and transient voltage droop have become more significant problems. Voltage droop refers to a drop in the voltage in response to a CPU load. A transient voltage droop may occur as an initial drop in voltage when power is supplied to a CPU or when a load changes. A static voltage droop indicates a drop in voltage that is constant over time. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a power delivery system according to an embodiment of the invention. 
     FIG. 2 shows a diagram of a power delivery system according to an embodiment of the invention. 
     FIG. 3 is a simulated voltage performance graph. 
     FIG. 4 is a simulated voltage performance graph using different decoupling capacitors. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows a power delivery system  10  that supplies power from a voltage regulator  12  to a CPU  14 . The CPU  14  is composed of a die  16  and a package  18 . The CPU  14  is anchored through an interposer  19  on a socket  20  which sits on a baseboard  22 . Pins  24  that extend from the socket  20  attach to the baseboard  22  for electrical connection. Components of the voltage regulator  12 , such as field effect transistors, controllers, and passive components such as filter capacitors and inductors, can be distributed on the baseboard  22  and on the socket  20 . 
     FIG. 2 shows how the various components of the voltage regulator  12  are connected. The CPU  14  is coupled to the socket  20 . A negative feedback control loop  26  is coupled at one end to the socket  20  to sense an output voltage of the voltage regulator  12  at the interface of the socket and the CPU  14 . The other end of the control loop  26  is coupled to power switches  28  which may include metal oxide semiconductor field effect transistors (MOSFETs). The output voltage is regulated by turning the switches  28  on and off under negative feedback control. Z 1  and Z 2  include inductors and decoupling capacitors to provide a low-pass filter for a dc/dc converter for the voltage regulator  12 . In FIG. 1, the decoupling capacitor Z 2  is shown mounted to the interposer  19 , but it can also be placed on the package  18 . 
     The power delivery system  10  can help reduce the problem of static and transient voltage droops when the CPU  14  needs power. By having the negative voltage feedback loop  26  sense the output voltage of the voltage regulator  12  at the interface of the socket  20  and the CPU  14 , the system  10  is able to compensate for the impedance of the socket pins  24  which would otherwise exacerbate the voltage droop. That is, the impedance of the pins  24  of the socket  20  are incorporated in the design of the power delivery system  10  with appropriate adjustment of, for example, Z 1  and/or Z 2 . 
     An example of voltage droop is shown in FIG. 3 which is a graph illustrating a voltage performance simulation of the power delivery system  10  that compensates for the impedance of the socket pins  24  (simulation A) and a voltage performance simulation of a conventional power delivery system that does not compensate for the impedance of the socket pins (simulation B). For both simulations, the voltage regulator switching frequency was set at 1 megahertz (MHz), the current was set at 50-amp steps, and the value of the decoupling capacitor Z 2  on the interposer  19  used was 24×100 microfarads (μF). 
     As shown in FIG. 3, simulation A shows a transient voltage droop of approximately 46 mV at around 78 μs. In contrast, the simulation B for the conventional system shows a transient droop of approximately 100 mV at 78 μs. Thus, the system  10  is able to produce a significant reduction in the voltage droop whenever the CPU  14  requires power. 
     FIG. 4 shows a voltage performance simulation of the power delivery system  10  with the decoupling capacitor Z 2  set to a value of 900 μF (simulation C) and a voltage performance simulation of a conventional power delivery system with a corresponding decoupling capacitor set to a value of 2400 μF (simulation D). The corresponding decoupling capacitor of the conventional system would be located on the baseboard and not on the socket  20  or the package  18 . The CPU load was kept the same for both simulations. The graph shows that the system  10  with the smaller decoupling capacitor Z 2  still has a smaller voltage droop problem than the conventional system. One advantage of using a smaller decoupling capacitor is that the cost of the system  10  can be controlled because the cost of multiple layer ceramic capacitors (MLCCs) used in power delivery systems increase in price with increasing capacitive value. 
     Placing the decoupling capacitor Z 2  on the socket  20  or on the package  18  is further made possible because the required decoupling value is significantly reduced as power technology is pushed to higher voltage regulator switching frequencies, for example, 5000 μF at 25 kHZ to 800 μF at 3 MHz. A decoupling capacitor of lower capacitive value is easier and less expensive to locate near a CPU. Furthermore, locating the decoupling capacitor closer to the CPU results in less interconnect inductance and, therefore, less voltage droop. 
     The system  10  can alleviate the voltage droop problem without radically changing the interface between the CPU  14  and the baseboard  22 . It overcomes the problem of voltage droop by incorporating the socket impedance as part of the voltage regulator output filter and sensing the output voltage  12  of the voltage regulator at the interface of the CPU  14  and the socket  20 . This technique can be further extended to any power delivery device through a connector to enhance its performance. 
     Other implementations are within the scope of the claims.