Power management integrated circuit

The present application is a continuation of, and claims priority to and incorporates by reference in its entirety, the corresponding U.S. patent application Ser. No. 11/825,252 filed Jul. 30, 2007, and entitled “Power Management Integrated Circuit,” and issued as U.S. Pat. No. 7,671,456 on Mar. 2, 2010, which is a continuation of, and claims priority to and incorporates by reference in its entirety, the corresponding U.S. patent application Ser. No. 10/955,383 filed Sep. 30, 2004, and entitled “Power Management Integrated circuit,” and issued as U.S. Pat. No. 7,247,930 on Jul. 24, 2007.

The present invention relates to computer systems; more particularly, the present invention relates to delivering power to a central processing unit (CPU).

The magnitude of power generated at CPUs is becoming an increasing concern as processing speeds increase. Thus, current power management schemes take advantage of reduced CPU activity to manage the magnitude of power consumed. However, power management circuitry is typically located at a remote location, such as on the CPU motherboard. Managing CPU power from the motherboard typically does not provide for a sufficiently fast response.

The invention is illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements, and in which:

FIG. 1 is a block diagram of one embodiment of a computer system;

FIG. 2 illustrates one embodiment of a CPU die;

FIG. 3 illustrates one embodiment of a power management die; and

FIG. 4 illustrates one embodiment of a CPU.

According to one embodiment, a power management system for a CPU is described. 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 apparent to one skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form, rather than in detail, in order to avoid obscuring the present invention.

Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.

FIG. 1 is a block diagram of one embodiment of a computer system 100 . Computer system 100 includes a central processing unit (CPU) 102 coupled to bus 105 . In one embodiment, CPU 102 is a processor in the Pentium® family of processors including the Pentium® II processor family, Pentium® III processors, and Pentium® IV processors available from Intel Corporation of Santa Clara, Calif. Alternatively, other CPUs may be used.

A chipset 107 is also coupled to bus 105 . Chipset 107 includes a memory control hub (MCH) 110 . MCH 110 may include a memory controller 112 that is coupled to a main system memory 115 . Main system memory 115 stores data and sequences of instructions that are executed by CPU 102 or any other device included in system 100 . In one embodiment, main system memory 115 includes dynamic random access memory (DRAM); however, main system memory 115 may be implemented using other memory types. Additional devices may also be coupled to bus 105 , such as multiple CPUs and/or multiple system memories.

Chipset 107 also includes an input/output control hub (ICH) 140 coupled to MCH 110 to via a hub interface. ICH 140 provides an interface to input/output (I/O) devices within computer system 100 . For instance, ICH 140 may be coupled to a Peripheral Component Interconnect bus adhering to a Specification Revision 2.1 bus developed by the PCI Special Interest Group of Portland, Oreg.

FIG. 2 illustrates one embodiment of a CPU 102 die 200 . Die 200 includes four CPU processing cores (core 1 -core 4 ) 210 . In addition, die 200 includes cache 220 and I/O circuitry 230 . In one embodiment, cache 220 is a L2/L3 cache. I/O circuitry 230 is placed on the periphery (e.g., north, south, east, and west boundaries) to enable efficient vertical current delivery to cores 210

As discussed above, circuitry situated on the motherboard does not provide a sufficient response for power management of a CPU die. In particular, the temperature and activity factor of CPUs change over time during operation due to varying workloads of applications. In addition, on-die Vcc values change due to noises induced by current transients.

Typically CPU frequency is set based on worst-case Vcc and temperature. As the activity factor and temperature change, energy efficiency of the CPU degrades since the optimal Vcc/Vt ratio at constant frequency is a function of activity and temperature. Off-chip VRMs and body bias generators have very large response times and thus their usefulness for dynamic control is limited.

According to one embodiment, a power management die is bonded to CPU die 200 . FIG. 3 illustrates one embodiment of a power management die 300 . Die 300 includes VRM 310 , body bias generators 320 , temperature sensor 330 , voltage sensor 335 and control circuits 340 .

In one embodiment, VRM die 310 provides a regulated voltage supply to components within CPU die 200 . For instance VRM 310 supplies Vcc voltages to Core 1 -Core 4 , cache 220 and I/O components 230 . Body bias generators 320 adjust the body bias voltages of transistors on die 200 . Particularly, a non-zero body to source bias is generated to modulate the threshold voltage of the die 200 transistors to control leakage and frequency.

Temperature sensor 330 measures the temperature of die 200 , while voltage sensor 335 measures the operating voltage. Control circuits 340 controls the transistors on die 200 . In addition, control circuits 340 dynamically determine the optimum body voltage for the die 200 transistors. In a further embodiment, die 300 may include a clock sensor 360 , a current sensor 370 and a power sensor 380 .

According to one embodiment, if the workload is known ahead of time, the Vcc, Vbs and frequency of die 200 can be set to the optimal value to maximize energy efficiency for the workload. Moreover, the time to change Vcc and Vbs should be made is small since having components such as VRM 310 and body bias generators 320 bonded to die 200 provides a fast response time.

According to one embodiment, die 300 is flipped and bonded (metal-side to metal-side), thus bringing the various power management components as close to the CPU die 200 as possible. In a further embodiment, VRM die 300 is in a three dimensional (3D) packaging configuration with die 200 .

FIG. 4 illustrates one embodiment of CPU 102 . CPU 102 includes the multi-Vcc VRM die 300 sandwiched between CPU die 200 and a package substrate 400 . According to one embodiment, VRM die 300 is pad matched to CPU die 200 and package substrate 400 so that die 300 can be an option sandwiched die. Thus, package 400 and CPU 200 design does not need any changes. In addition, FIG. 4 shows the I/O connections between die 200 and 300 , as well as the die/die bonding. A heat spreader and heat sink (not shown) may be coupled to CPU die 200 .

Whereas many alterations and modifications of the present invention will no doubt become apparent to a person of ordinary skill in the art after having read the foregoing description, it is to be understood that any particular embodiment shown and described by way of illustration is in no way intended to be considered limiting. Therefore, references to details of various embodiments are not intended to limit the scope of the claims, which in themselves recite only those features regarded as essential to the invention.