Abstract:
In general, in one aspect, the disclosure describes a semiconductor device that includes a functional circuit and a dc-to-dc power converter. The power converter converts, regulates, and filters a DC input voltage to produce a DC output voltage and provides the DC output voltage to the functional circuit. The dc-to-dc power converter has an operating frequency above 10 MHz.

Description:
BACKGROUND 
   Growing demand for integrated circuits (ICs), for example microprocessors, with ever higher levels of performance and functionality have driven these devices to circuit densities beyond 100 million transistors per die. This number may soon exceed one billion transistors on a single die. The growth in transistor density has been made possible by the use of MOSFET transistors with gate lengths below 100 nm. As gate length has shortened, power supply voltages have fallen, in some cases, to below 1 V. 
   High-speed microprocessors, with clock speeds above 3 GHz, may require in excess of 100 watts of power when operating at maximum load. With operating voltages below 1 V, this translates to power supply currents that reach beyond 100 A. Additionally, the current requirements may change from idle (&lt;20 A) to full power in a small number of clock cycles, leading to current transitions (di/dt) exceeding 30 GA/s. 
   Integrated circuits are typically powered from one or more DC supply voltages provided by external supplies and converters. The power is provided through pins, leads, lands, or bumps on the integrated circuit package. The traditional method for providing such high power to integrated circuits may involve the use of a high-efficiency, programmable DC-to-DC (switch-mode) power converter located near the IC package. This type of converter (buck regulator) may use a DC input voltage as high as 48 V and provide a DC output voltage below 2 V. Conventional DC-to-DC power converters use switching frequencies in the neighborhood of 200 KHz, with some high-end units in the 1-2 MHz range. Such converters usually require a handful of relatively large components, including a pulse-width modulation (PWM) controller, one or more power transistors, filter and decoupling capacitors, and one or more large inductors and/or transformers. These components are costly and require significant space on the printed circuit board in the neighborhood of the integrated circuit. 
   Another problem with having to provide currents in excess of 100 A and a di/dt above 30 GA/s to an integrated circuit is the need to use a significant number of input/output (I/O) pins on the integrated circuit package to feed power to the chip. For example, a 3.8 GHz Intel® Pentium® 4 microprocessor (from Intel Corporation of Santa Clara, Calif.) in a 775-land Land Grid Array package uses 226 power lands (V CC ) and 273 ground lands (V SS ) to support a maximum current of 119 A. This amounts to nearly ⅔ of all of the I/O lands dedicated to feeding power to the processor core. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features and advantages of the various embodiments will become apparent from the following detailed description in which: 
       FIG. 1  illustrates an simplified system block diagram of a personal computer, according to one embodiment; 
       FIG. 2A  illustrates a top view of an example integrated circuit, according to one embodiment; 
       FIG. 2B  illustrates an edge view of an example integrated circuit, according to one embodiment; 
       FIG. 2C  illustrates a bottom view of an example integrated circuit, according to one embodiment; 
       FIG. 3A  illustrates an example integrated circuit with an external power converter, according to one embodiment; 
       FIG. 3B  illustrates an example integrated circuit with an external power converter, according to one embodiment; 
       FIG. 4  illustrates an example integrated circuit with a power converter mounted on or within a package substrate, according to one embodiment; 
       FIG. 5  illustrates an example integrated circuit with a power converter integrated on an integrated circuit die, according to one embodiment; 
       FIG. 6  illustrates an example power converter integrated on an integrated circuit die, according to one embodiment; 
       FIG. 7  illustrates another example power converter integrated on an integrated circuit die, according to one embodiment; and 
       FIGS. 8A-D  illustrate an example integrated circuit die with the inclusion of power transistors, according to several embodiments. 
   

   DETAILED DESCRIPTION 
     FIG. 1  is a simplified block diagram of an example embodiment of a processor-based computer system  100 . The computer system  100  includes a motherboard  105  and a power supply  110 . The motherboard  105  contains all of the core processing and interface components for the computer system  100 . Other components typically used in the computer system  100 , but not shown in  FIG. 1 , include a hard disk drive, optical disk drive (CD-ROM, DVD-ROM), network interface, video/graphics adapter, video monitor, and keyboard. The power supply  110  transforms AC input from a wall outlet or other primary supply to one or more DC voltages (illustrated as power bus  115 ) appropriate for use by the motherboard  105 , as well as other components in computer system  100 . 
   The motherboard  105  includes a processor  120  (sometimes called a Central Processing Unit (CPU)), a power converter  125 , a graphics/memory controller hub (GMCH)  130 , system memory  135 , a graphics connector  140 , an input/output (I/O) controller hub (ICH)  145 , I/O ports  150 , and Peripheral Component Interconnect bus (PCI) slots  155 . The combination of the GMCH  130  and the ICH  145  are often referred to as a “PC Chip Set,” or simply, “Chip Set”. In one embodiment, the processor  120  is from the Intel® family of processors, including the Pentium® II, Pentium® III, Pentium® IV, and Itanium processors available from Intel Corporation of Santa Clara, Calif. In alternate embodiments, other processors may be used. 
   The GMCH  130  may include a memory controller that couples the system memory  135  to the processor  120 . The system memory  135  stores data and program instructions that may be executed by processor  120 . The system memory  135  may include dynamic random access memory (DRAM) or may be implemented using other memory types. The GMCH  130  may also include a high-speed video/graphics interface such as the Accelerated Graphics Port (AGP) or the PCI Express™ interface. 
   The ICH  145 , coupled to the GMCH  130 , provides an interface to most I/O devices within the computer system  100 . The ICH  145  may be coupled to one or more I/O ports  150 . The I/O ports  150  may include RS-232 serial ports, parallel ports, and Universal Serial Bus (USB) ports. The ICH  145  may also be coupled to one or more PCI slots  155 . The ICH  145  provides a bridge from the processor  120  to peripheral equipment and peripheral cards (not shown) that may be connected to one or more I/O ports  150  or plugged into one or more PCI slots  155 . 
   The processor  120  requires a core supply voltage that varies depending on the particular technology, speed, and other characteristics of the processor  120 . To accommodate the needs of various processors, the power converter  125  (also referred to as a DC-to-DC converter or voltage regulator), converts one or more of the voltages from the power bus  115  to the voltage required for the particular processor  120 . 
     FIGS. 2A-C  illustrate several views of a typical integrated circuit  200  (for example, the processor  120  in  FIG. 1 ).  FIG. 2A  illustrates an example of a top view of the integrated circuit  200 , including a package substrate  205 , a die  210 , and one or more passive components  220  (capacitors, resistors, and/or inductors). The die  210  illustrated in  FIG. 2A  is of a type known as a “flip-chip”. A flip-chip die has its contacts on the bottom face of the die and is surface mounted on the package substrate  205 . In one embodiment, the die  210  has a large plurality of Controlled Collapse Chip Connection (C4) bumps. The C4 bumps are typically Lead/Tin (Pb/Sn) solder that has been evaporatively deposited or plated onto the die face. A die  210  with C4 bumps may be reflow soldered onto the package. In other embodiments, the die  210  may use wire-bond technology or Tape Automated Bonding (TAB) to connect the die  210  to the package substrate  205 . 
     FIG. 2B  illustrates an edge view of the integrated circuit  200  showing the package substrate  205 , the die  210 , the passive components  220 , and the C4 bumps  230 .  FIG. 2C  illustrates an example bottom view of the integrated circuit  200  showing the bottom of the package substrate  205 , including a plurality of interconnections  225 . The interconnections  225  provide a means for connecting electrical signals from the die  210  (not shown in  FIG. 2C ) to other electronic components (e.g., the power converter  125 , the GMCH  130 ).  FIG. 2C  illustrates a “Land-Grid-Array” (LGA) package in which the interconnections  225  are “lands”. An LGA package may be inserted into a socket mounted on a circuit board (for example, motherboard  105  in  FIG. 1 ). In other embodiments, the interconnections  225  may be pins, bumps, or balls. 
   The package substrate  205  may provide connections between selected C4 bumps on the die  210  and selected interconnections  225 . The package substrate  205  may provide connections between selected C4 bumps on the die  210  and additional components mounted on or contained within the package substrate  205 . These additional components may include passive electronic devices such as capacitors  320 , resistors (not shown), inductors (not shown), and transformers (not shown). The package substrate  205  may provide connections between selected C4 bumps on the die  210  and active surface-mounted components, such as transistors and other integrated circuits (not shown). 
     FIG. 3A  illustrates an example embodiment of an integrated circuit  300  with an external power converter. The circuit board  300  includes an integrated circuit  305  and a power converter  315 . The integrated circuit  305  includes a package substrate  307  and die  310 . The power converter  315  is implemented with discrete components mounted on the circuit board  300 , external to the integrated circuit  305 . The power converter  315  provides one or more supply voltages  320  to the integrated circuit  305 . In some embodiments, the integrated circuit  305  may feed information  322 , in the form of analog and/or digital signals to the power converter  315 . The information  322  may be used by the power converter  315  to set one or more parameters (e.g., voltage levels of the supply voltages  320 ). 
     FIG. 3B  illustrates an example embodiment of an integrated circuit  330  with an external power converter. In this embodiment, the circuit board  330  includes the integrated circuit  305  (package substrate  307  and die  310 ) and a power converter module  325 . The power converter module  325  is implemented on a separate circuit board or other substrate that is plugged into or solder mounted onto the circuit board  330 . The power converter module  325  is external to the integrated circuit  305  and provides one or more supply voltages  320  to integrated circuit  305  and may receive information  322  from the integrated circuit  305 . 
     FIG. 4  illustrates an example embodiment of a circuit board  400  containing an integrated circuit with a power converter mounted on or within a package substrate. The circuit board  400  includes an integrated circuit  405  and may include additional discrete components  425 . The integrated circuit  405  includes package substrate  407 , die  410 , and power converter  415  (e.g., DC-to-DC switching converter). The power converter  415  may include one or more modulators (e.g., PWM, PFM), one or more power stages (e.g., bipolar transistors, MOSFETs), one or more capacitors, one or more resistors, one or more inductors, and one or more transformers. The power converter  415  may also include one or more controllers. Individual components making up the power converter  415  may be mounted on one of the surfaces of the package substrate  407 , or may be formed by deposition on or inside the package substrate  407  (e.g., the package substrate  407  may comprise multiple layers). The power converter  415  may, in some embodiments, use the additional discrete components  425  mounted external to the integrated circuit  405 . These components  425  may include, but are not limited to, capacitors, inductors, and transformers. 
   The power converter  415  may receive one or more source supply voltages  420  from an external power supply, voltage converter, or other power source (not shown). The power converter  415  may provide one or more supply voltages to the die  410 . The die  410  may provide information (analog and/or digital signals) to the power converter  415  to set one or more parameters (e.g., supply voltage levels). 
     FIG. 5  illustrates an example embodiment of a circuit board  500  containing an integrated circuit with a power converter mounted on the integrated circuit die. The circuit board  500  includes an integrated circuit  505  and may include additional discrete components  525  (e.g., capacitors, inductors, transformers). The integrated circuit  505  includes a package substrate  507  and die  510 , and may include additional components  515  on the package substrate  507 . A DC-to-DC power converter (not illustrated) is fully integrated on the die  510 . That is, all of the active components, and, optionally, all of the passive components, making up the DC-to-DC power converter are located on the die  510 . The additional components  515  (e.g., capacitors) may be mounted on one of the surfaces of the package substrate  507 , or may be formed by deposition on or inside the package substrate  507  (e.g., the package substrate  507  may comprise multiple layers). The power converter may, in some embodiments, use the additional discrete components  525  mounted external to the integrated circuit  505 . 
   The integrated power converter on the die  510  may receive one or more source supply voltages  520  from an external power supply, voltage converter, or other power source (not shown). 
     FIG. 6  illustrates an example embodiment of an integrated circuit  600  having a power converter integrated on an integrated circuit die. The integrated circuit  600  includes a package substrate  610  and die  605  located therewithin. The die  605  includes a functional circuit  615  and power converter circuitry. The functional circuit  615  performs the primary function of the integrated circuit  600  and may include any type of electronic circuitry, including analog, digital, or a combination of these. The functional circuit  615  may perform any type of function, including computation, signal processing, image processing, packet processing, and the like. In one embodiment, the functional circuit  615  is a microprocessor. In another embodiment, the functional circuit  615  is a network processor. 
   The power converter circuitry provides one or more supply voltages (V OUT )  675  to the functional circuit  615 . The power converter circuitry, in one embodiment, includes a main control  620 , one or more phase controls  625 , one or more power stages  630 , a main control bus  635 , and one or more filter/decoupling capacitors  640 . One or more input voltage supplies (V IN )  660  and auxiliary supplies (V AUX )  665  supply current to the power converter circuitry on the die  605 . A ground return is provided by a V SS  line  670 . As illustrated, passive components (e.g., inductors, transformers)  645  and capacitors  650  that make up part of the power converter circuitry are located on the package substrate  610 . These components are mounted or deposited on or inside the package substrate  610 . 
   As illustrated, the power converter is a multiphase power converter as it includes N phases (N phase controls  625  and N power stages  630 ). Multiphase power converters may provide higher power output, faster response to changes in load, and lower output ripple. Multiphase power converters may have as few as two phases and as many as several hundred phases. However, the various embodiments described herein are not limited to multiphase power converters. Rather, a single phase power converter (one phase control  625  and one power stage  630 ) may be used without departing from the scope. 
     FIG. 7  illustrates an example embodiment of an integrated circuit  700  having a power converter integrated on an integrated circuit die. The integrated circuit  700  includes a package substrate  710  and die  705  located therewithin. The die  705  includes a functional circuit  715  and power converter circuitry. The functional circuit  715  performs the primary function of integrated circuit  700 . As described above with respect to the embodiment of  FIG. 6  the functional circuit  715  may include any type of electronic circuitry. 
   The power converter circuitry provides one or more supply voltages (V OUT )  775  to the functional circuit  715 . The power converter circuitry may include a main control  720 , one or more phase controls  725 , one or more power stages  730 , a main control bus  735 , one or more filter/decoupling capacitors  740 , and inductors and/or transformers  745 . Additional passive components, such as capacitors  750  may be mounted or deposited on the package substrate  710 . 
   One or more input voltage supplies (V IN )  760  and auxiliary supplies (V AUX )  765  supply current to the power converter circuitry on the die  705 . A ground return is provided by a V SS  line  770 . As discussed above with reference to the embodiment illustrated in  FIG. 6 , the power converter of  FIG. 7  may include one or more phases (phase control  725  and power stage  730 ). 
   In the embodiments illustrated in  FIGS. 4-7 , the use of high frequency switching circuitry allows for the miniaturization of the power converter components. For example, at switching frequencies above 10 MHz, and preferably above 50 MHz, the discrete components become small enough to fit entirely on the package substrate, or, preferably, on the die itself. The high frequency switching circuitry described with respect to  FIGS. 4-7  may be used on very large scale integration (VLSI) chips. For example, the integrated dc-to-dc switching converters may be utilized on chips having over one million transistors. The dc-to-dc switching converters may be integrated on computer/central processing unit (CPU) chips. 
   In some embodiments, multiple power converters (e.g.,  600 ,  700 ) may be present, with each power converter providing power to a segment of the functional circuit. Each power converter may be tailored to optimize powering of an associated segment of the functional circuit. For example, in one embodiment, each power converter may have a different number of phases, where the number of phases may be selected to match the particular demand of the functional circuit segment. 
   In one embodiment, a power stage (e.g.,  630  in  FIG. 6 ,  730  in  FIG. 7 ) includes power transistors (e.g., MOSFETs) that are fabricated on the same die as the functional circuit. At frequencies above 50 MHz, the power stage transistors have low capacitance and low resistance to provide acceptable power conversion efficiency. By limiting the voltage seen by the power transistors, the standard transistors offered on same process used to build the functional circuit may be used. These transistors may, in some embodiments, be located on the edge of the functional circuit (see  FIGS. 8B-8D ). Interconnection of the power transistors to the remaining die requires a significant use of power resources. On some integrated circuits there is an abundance of underutilized C4 (Controlled Collapse Chip Connection) bumps (see  FIGS. 8A-D ). 
   For example, on a microprocessor die the power density of the cache memory is only about 2% of the power density of the processor core which translates into significant availability of C4 bumps over the cache area (see  FIGS. 8A-D ). In one embodiment, the power stage transistors may use these underutilized C4 bumps over the cache memory area to carry the large currents required (see  FIGS. 8C-8D ). These cache bumps may be used to couple the supply current to the die. A thick on-die metal layer (˜10 um) may be employed to move this current laterally across the cache to the location of the power stage transistors (see  FIG. 8D ). It may also use the thick metal to laterally distribute cache current, and to distribute the gated current away from the power stage transistors and towards the core (see  FIGS. 8B-D ). In another embodiment, power stage transistors may be distributed throughout the functional circuit. 
   In one embodiment, the power converter circuitry may use one or more control parameters from the functional circuit to enhance the performance, accuracy, and efficiency of the power converter and the functional circuit. Examples of such parameters include functional circuit supply voltage, functional circuit supply current, functional circuit operating temperature, functional circuit activity (including counters, clock enable states, etc.), functional circuit oscillator frequency, and functional circuit power-states. The control parameters may be fed to a main control (e.g.,  620  in  FIG. 6 ,  720  in  FIG. 7 ) and phase control modules (e.g.,  630  in  FIG. 6 ,  730  in  FIG. 7 ) of the power converter to alter the operation of the power converter. 
   According to one embodiment, an adaptive noise guard band may be implemented in the power converter. When parts of the functional circuit are powered down or run at a lower power active state to save power, less noise is generated. Accordingly, the power converter noise guard band may be reduced. Variations in functional activity of the functional circuit is a source of self induced noise and may also be used in a similar manner to alter the noise guard band. In some embodiments, functional activity may be used as a predictor of future current demands and voltage drops. In these embodiments, functional activity can be used by the power converter to begin a corrective action prior to noise actually occurring. 
   According to one embodiment, the temperature of the functional circuit may be used to increase or reduce the supply voltage to the functional circuit. For example, a microprocessor needs less voltage for a given speed at lower temperatures. 
   According to one embodiment, circuit power and reliability may be traded off for increased operating frequency by raising the supply voltage to the functional circuit. 
   The embodiments described above can be used on both programmable and non-programmable integrated circuits. The integrated circuits utilizing the various embodiments may be used in different systems and in multiple environments. For example, the various embodiments described herein could be part of a computer or could be part of high-speed telecommunications equipment (e.g., store-and-forward devices). If an integrated circuit utilizing the various embodiments discussed herewithin was part of a computer the integrated circuit may contain memory on the die, separate off die memory may be included, or memory may be provided both on and off die. If an integrated circuit utilizing the various embodiments discussed herewithin was part of a store-and-forward device the integrated circuit may be located on a telecommunications board contained therewithin. The telecommunications boards may be Ethernet (e.g., Gigabit, 10 Base T), ATM, Fibre channel, Synchronous Optical Network (SONET), and Synchronous Digital Hierarchy (SDH), amongst others. 
   Although the various embodiments have been illustrated by reference to specific embodiments, it will be apparent that various changes and modifications may be made. Reference 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. Thus, the appearances of the phrase “in one embodiment” or “in an embodiment” appearing in various places throughout the specification are not necessarily all referring to the same embodiment. 
   Different implementations may feature different combinations of hardware, firmware, and/or software. It may be possible to implement, for example, some or all components of various embodiments in software and/or firmware as well as hardware, as known in the art. Embodiments may be implemented in numerous types of hardware, software and firmware known in the art, for example, integrated circuits, including ASICs and other types known in the art, printed circuit broads, components, etc. 
   The various embodiments are intended to be protected broadly within the spirit and scope of the appended claims.