Abstract:
Embodiments of the present invention relate to independently switched inductors in a voltage converter. Each voltage transforming inductor of a voltage converter may be designated a switch or bridge at each opposing terminal. The function of these switches is to periodically reverse the polarity of voltage across the inductors. By configuring independently switched inductors in series, the frustration of voltage tolerance limitations of the switches is mitigated.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The field of the invention generally relates to electronics.  
           [0003]    2. Background of the Related Art  
           [0004]    Electronics are very important in the lives of many people. In fact, electronics are present in almost all electrical devices (e.g. radios, televisions, toasters, and computers). Many times electronics are virtually invisible to the user because they can be made up of very small devices inside a case. Although electronics may not be readily visible, they can be very complicated. It may be desirable in many electrical devices for the electronics to become smaller and smaller. This may be desirable, as smaller devices are more portable and convenient to use by a user. Additionally, smaller electronic devices may actually work better as they are miniaturized (e.g., work faster or more efficiently). Electronics. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]    [0005]FIG. 1 is an exemplary global diagram of a portion of a computer.  
         [0006]    [0006]FIGS. 2A, 2B,  3 A,  3 B,  4 A, and  4 B are exemplary diagrams of voltage converters.  
         [0007]    [0007]FIGS. 5A, 5B,  6 A,  6 B,  7 A,  7 B,  8 A,  8 B,  9 A,  9 B,  10 A,  10 B,  11 A, and  11 B are exemplary diagrams of voltage converters including at least two inductors that are independently switched. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0008]    Electrical hardware (e.g. a computer) may include many electrical devices. In fact, a computer may include millions of electrical devices (e.g. transistors, resistors, and capacitors). These electrical devices must work together in order for hardware to operate correctly. Accordingly, electrical devices of hardware may be electrically coupled together. This coupling may be either direct coupling (e.g. direct electrical connection) or indirect coupling (e.g. electrical communication through a series of components).  
         [0009]    [0009]FIG. 1 is an exemplary global illustration of a computer. The computer may include a processor  4 , which acts as a brain of the computer. Processor  4  may be formed on a die. Processor  4  may include an Arithmetic Logic Unit (ALU)  8  and may be included on the same die as processor  4 . ALU  8  may be able to perform continuous calculations in order for the processor  4  to operate. Processor  4  may include cache memory  6  which may be for temporarily storing information. Cache memory  6  may be included on the same die as processor  4 . The information stored in cache memory  6  may be readily available to ALU  8  for performing calculations. A computer may also include an external cache memory  2  to supplement internal cache memory  6 . Power supply  7  may be provided to supply energy to processor  4  and other components of a computer. A computer may include a chip set  12  coupled to processor  4 . The chip set  12  may intermediately couple processor  4  to other components of the computer (e.g. graphical interface  10 , Random Access Memory (RAM)  14 , and/or a network interface  16 ). One exemplary purpose of chip set  12  is to manage communication between processor  4  and these other components. For example, graphical interface  10 , RAM  14 , and/or network interface  16  may be coupled to chip set  12 .  
         [0010]    Power supply  7  may output a different voltage level than an operating voltage level of processor  4 . Accordingly, voltage converter may be utilized on or proximate to the processor to transform a voltage level of the power supply to an operating voltage level of processor  4 . As one of ordinary skill in the art would appreciate, voltage converters may be implanted in other hardware configurations.  
         [0011]    [0011]FIGS. 2A and 2B illustrate buck DC-DC converters. The buck DC-DC converters may receive an input voltage V in  and output an output voltage V out . The voltage converters illustrated in FIGS. 2A and 2B may each include an inductor [ 20  or  32 ] and a capacitor [ 22  or  34 ] connected in series. FIG. 2A illustrates switch  18  with an output coupled to inductor  20 . Inductor  20  and capacitor  22  may be coupled in series. Inputs of switch  18  may receive V in  and a ground voltage. Capacitor  22  may be connected to ground. V out  may be connected at the interface of capacitor  22  and inductor  20 .  
         [0012]    [0012]FIG. 2B illustrates bridge  28  with output  31  coupled to inductor  32 . Inductor  32  and capacitor  34  may be connected in series. Bridge  28  may receive V in  at first input  26  and may receive a ground voltage at second input  30 . Bridge  28  may include control input  24 . A voltage output V out  may be drawn at an interface of inductor  32  and capacitor  34 . In the exemplary illustrations of FIGS. 2A and 2B, switch  18  [or bridge  28 ] may periodically switch between inputting V in  and inputting ground. Accordingly, when switch  18  [or bridge circuit  28 ] is switched to V in , inductor  20  [or inductor  32 ] is connected between V in  and V out . Likewise, when switch  18  [or bridge  28 ] is switched to ground, inductor  20  [or inductor  32 ] is connected between ground and V out . Capacitor  22  [or capacitor  34 ] may be an output filter for V out . The structure illustrated in FIG. 2B may be a particular application of a bridge as a switch. In the operation of the examples illustrated in FIGS. 2A and 2B, V out  can be arranged to output a voltage between 0 volts (ground) and V in , depending on the switching of switch  18  [or bridge  28 ].  
         [0013]    Bridge  28  may include a plurality of electrical devices (e.g. diodes and/or transistors). As illustrated in FIG. 2B, bridge include control input  24 , first input  26 , second input  30 , and output  31 . Output  31  may receive either first input  26  or second input  30 , depending on a control signal input to control input  24 . In other words, based on the selectivity of control input  24 , bridge  28  is switched to either first input  26  or second input  30 .  
         [0014]    Switches and bridges do have tolerances. For example, the voltage difference between first input  26  and second input  30  cannot exceed a maximum voltage tolerance V max  of a given bridge. V max  may be determined based on material characteristics of a switch [or a bridge] and/or the configuration of electrical components of a switch [or a bridge]. In this example, if V max  is exceeded, then bridge  28  will not operate correctly and a hardware device including bridge  28  may not work.  
         [0015]    For example, if V max =2V, then a voltage difference between first input  26  and second input  30  must be less than 2V. In this example, assuming that ground is 0V, V in  must be less than 2V if V max =2V.  
         [0016]    As another example, if V max  is routinely exceeded, the lifetime over which bridge  28  may be dependable, may be unnecessarily shortened. In other words, although bridge  28  may initially operate correctly, bridge  28  may eventually exhibit temporary or permanent failure if V max  is exceeded for a period of time.  
         [0017]    [0017]FIGS. 3A and 3B illustrate exemplary voltage converters that utilize autotransformers. The voltage converters may be DC-DC converters. The examples illustrated in FIGS. 3A and 3B each include a first inductor [ 40  or  52 ], a second inductor [ 44  or  56 ], and capacitor [ 46  or  60 ]. Capacitor [ 46  or  60 ] may be coupled at the interface of first inductor [ 40  or  52 ] and second inductor [ 44  or  56 ]. Additionally, the examples illustrated in FIGS. 3A and 3B include first switch  36  [or first bridge  50 ] and second switch  38  [or second bridge  58 ]. In FIG. 3A, first switch  36  receives V in  at input  37  and receives a ground voltage at input  39 . Second switch  38  receives V in  at input  43  and receives ground voltage at input  41 . Switch  36  selects either input  37  or input  39  to be connected to output terminal  45 . Likewise, switch  38  selects either input  41  or input  43  to be outputted at output terminal  47 .  
         [0018]    In FIG. 3B, bridge  50  receives V in  at input terminal  37  and receives a ground voltage at input terminal  39 . Accordingly, bridge  50  outputs either V in  or ground at output terminal  49  in accordance with a control signal inputted into control terminal  48 . Likewise, bridge  58  receives V in  at input terminal  41  and ground at input terminal  43 . Bridge  58  may output at output terminal  51  either V in  or ground depending on the input signal at control terminal  53 . Input terminal  37  and input terminal  41  may be coupled together, as both receive V in . Likewise, input terminal  39  and input terminal  43  may be coupled together, as both received the ground voltage. The structure illustrated in FIG. 3B is a particular application of a bridge as a switch.  
         [0019]    One exemplary purpose of switches [ 36 ,  38 ] or bridges [ 50 ,  58 ] is to prevent saturation of inductors  40 ,  44 ,  52 , and  56  during operation of a voltage converter. First inductor [ 40  or  52 ] and second inductor [ 44  or  56 ] may have the same inductance value. If first inductor [′or  52 ] and second inductor [ 44  or  56 ] have the same inductance value, then the magnitude of V out  will be approximately half the magnitude of V in . Likewise, the current at V out  will be approximately twice the current of V in . In this arrangement, first inductor [ 40  or  52 ] and second inductor [ 44  or  56 ] may operate as a voltage divider. First inductor [ 40  or  52 ] and second inductor [ 44  or  56 ] are both electrically coupled and magnetically coupled. Accordingly, power supplied at V in  is substantially output at V out  with a reduced voltage and an increased current.  
         [0020]    In embodiments, the polarity of voltage across first inductor [ 40  or  52 ] and second inductor [ 44  or  56 ] must be periodically reversed to avoid magnetic saturation of inductors  40 ,  44 ,  52 , and  56 . In embodiments, the polarity of voltage across first inductor [ 40  or  52 ] and second inductor [ 44  or  56 ] must be periodically reversed to limit the magnitude of current passing through first inductor [ 40  or  52 ] and/or second inductor [ 44  or  56 ]. Accordingly, switches [ 36 ,  38 ] or bridges [ 50 ,  58 ] may be arranged to periodically change polarity of voltage across first inductor [ 40  or  52 ] and second inductor [ 44  and  56 ]. This is accomplished by switches [ 36 ,  38 ] or bridges [ 50 ,  58 ] being switched substantially in tandem. Additionally, output terminal  45  of first switch  36  [or output terminal  49  of first bridge  50 ] and output terminal  47  of second switch  38  [or output terminal  51  of second bridge  58 ] are never connected to V in  or ground at the same time. During this periodic switching in tandem and because first inductor [′or  52 ] and second inductor [ 44  or  56 ] have the same inductance value, the voltage level of the mid point (which is directly connected to V out ) remains at the same voltage level throughout switching. Periodic switching must occur to prevent first inductor [ 40  or  52 ] and second inductor [ 44  and  56 ] from being saturated with energy and unable to perform a voltage conversion function. The frequency of the periodic switching of the inductors is dependent on the size of the inductors. Smaller inductors require more frequent switching, as saturation of these inductors occurs more quickly and must be prevented by reversing the polarity of voltage. In embodiments of the present invention, the frequency of switching may be between 1 Hz and 10 Ghz.  
         [0021]    Problems do exist in the exemplary configurations illustrated in FIGS. 3A and 3B. For example, because each switch [ 36 ,  38 ] or bridge [ 50 ,  58 ] is connected to both V in  and ground, V in  is limited to the maximum operating voltage (V max ) of each switch [ 36 ,  38 ] or each bridge [ 50 ,  58 ]. Accordingly, more costly switches or bridges must be utilized to convert relatively high voltages (over V max ) to lower voltages. Another limitation with the arrangements illustrated in FIGS. 3A and 3B is that V out  is limited to half the voltage of V in . To maintain a constant level of V out  and avoid saturation of first inductor [ 40  or  52 ] and second inductor [ 40  or  56 ] by periodic switching, V out  must be half the voltage magnitude of V in . These limitations may frustrate the ability to down convert a voltage at a reasonable cost.  
         [0022]    [0022]FIGS. 4A and 4B illustrate an example of a voltage converter with multiple output windings. In these arrangements, switches [ 62 ,  64 ] operate similar to switches [ 36 ,  38 ] of FIG. 3A. Similarly, bridges [ 82 ,  84 ] operate similar to bridges [ 50 ,  58 ] of FIG. 3B. However, only a single inductor [ 68  or  86 ] is between an output terminal of first switch  62 , [or first bridge  82 ] and second switch  64  [or second bridge  84 ]. The output voltages [V out 2  and/or V out1 ] are not electrically coupled to the single inductor [ 68  or  86 ]. V out1  is electrically coupled (through output rectifier and filter [ 76  or  96 ]) to output inductor [ 72  or  92 ]. Likewise, V out2  is electrically coupled (through output rectifier and filter [ 74  or  94 ]) to output inductor [ 70  or  90 ]. Similar limitations exist in the exemplary arrangements illustrated in FIGS. 4A and 4B as the exemplary arrangements illustrated in FIGS. 3A and 3B. For instance, V in  will be limited to the V max  of each switch [ 62 ,  64 ] or each bridge [ 82 ,  84 ].  
         [0023]    [0023]FIGS. 5A and 5B are exemplary illustrations of embodiments of the present invention. The arrangements of FIGS. 5A and 5B include first inductor [ 106  or  144 ] and second inductor [ 108  or  146 ]. First inductor [ 106  or  144 ] is connected between a first output terminal [ 101  or  125 ] of first switch  98  [or first bridge  120 ] and a second output terminal [ 103  or  127 ] of second switch  100  [or second bridge  122 ]. Likewise, second inductor [ 108  or  146 ] is connected between third output terminal [ 105  or  129 ] of third switch  102  [or bridge  124 ] and fourth output terminal [ 107  or  131 ] of fourth switch  104  [or fourth bridge  126 ]. V in  may be connected to first input [ 109  or  128 ] and first input [ 115  or  132 ]. V out  may be connected to first input [ 117  or  136 ] and first input [ 123  or  140 ]. In embodiments, V out  may also be connected to second input [ 111  or  130 ] and second input [ 113  or  134 ]. Second input [ 119  or  138 ] and second input [ 121  or  142 ] may be connected to ground. First input [ 109  or  128 ] and second input [ 111  or  130 ] may be inputs to first switch  98  [or first bridge  120 ]. First input [ 115  or  132 ] and second input [ 113  or  134 ] may be inputs of second switch  100  [or second bridge  122 ]. First input [ 117  or  136 ] and second input [ 119  or  138 ] may be inputs of third switch  102  [or third bridge  124 ]. First input [ 123  or  140 ] and second input [ 121  or  142 ] may be inputs of fourth switch  104  [or fourth bridge  126 ]. Capacitor  110  and capacitor  150  may be arranged as an output filter.  
         [0024]    In the exemplary arrangements illustrated in FIGS. 5A and 5B, first inductor [ 106  or  144 ] and second inductor [ 108  or  146 ] are independently switched. Additionally, first inductor [ 106  or  144 ] and second inductor [ 108  or  146 ] are both electrically coupled and magnetically coupled. This arrangement may allow for voltage conversion. These exemplary arrangements are advantageous, as voltages across switches or bridges can be kept below V max  of the switches or bridges. Accordingly, V in  will not be limited to V max . For example, V max  1.5V for bridge  120 , V in =2V, and V out =1V. Accordingly, the voltage difference between first input terminal  128  (e.g. 2V) and second input terminal  130  (e.g. 1V) is 1V. Accordingly, the voltage difference across bridge  120  (e.g. 1V) is less than the V max  of bridge  120  (e.g. 1.5V). Accordingly, the tolerances of bridges will not limit V in  to be less than 1.5V (which is the exemplary value of V max ).  
         [0025]    In embodiments, first switch  98  and second switch  100  switch periodically and switch substantially in tandem to avoid saturation of first inductor  106 . Likewise is true for first switch  102  and fourth switch  104  with second inductor  108 , first bridge  120  and second bridge  122  with first inductor  144 , and/or first bridge  124  and second bridge  126  with second inductor  146 . Embodiments of the present invention are advantageous, as the voltage difference between V in  and ground is not limited by the value of V max  of switches or bridges. It may be advantageous that less costly switches or bridges, having a relatively low V max , may be implemented to reduce costs and/or physical size. In embodiments, different voltage outputs may be coupled to different input terminals of switches or bridges [ 98 ,  100 ,  102 ,  104 ,  120 ,  122 ,  124 , and/or  126 ].  
         [0026]    In embodiments, mote than two independently switched inductors may be both electrically and magnetically coupled in a circuit. FIGS. 6A and 6B are exemplary illustration of some of these embodiments. In FIGS. 6A and 6B, first inductor [ 166  or  184 ], second inductor [ 168  or  186 ], and third inductor [ 170  or  188 ] are all electrically and magnetically coupled. Additionally, first inductor [ 166  or  184 ], second inductor [ 168  or  186 ], andthirdinductor [ 170  or  188 ] are each independently switched. First inductor  166  is independently switched by first switch  152  and second switch  154  in a similar manner that first inductor  106  of FIG. 5A is independently switched by first switch  98  and second switch  100 . Likewise is true for third switch  156  and fourth switch  158  with second inductor  168  and/or fifth switch  160  and sixth switch  162  with third inductor  170 . One of ordinary skill in the art would appreciate that more than three independently switched inductors may be implemented.  
         [0027]    First inductor  184  may be independently switched by bridge  172  and bridge  174  in a similar manner as first inductor  144  of FIG. 5B with bridge  120  and bridge  122 . Likewise is true for the switching of second inductor  186  with third bridge  176  and fourth bridge  178  and third inductor  188  with fifth bridge  180  and sixth bridge  182 . One of ordinary skill in the art would appreciate that additional independently switched inductors could be added to the circuits illustrated in FIGS. 6A and 6B according to the tolerances of the bridges and the input and output voltages. In embodiments, V out  may be coupled to any of the input terminals of switches or bridges [ 152 ,  154 ,  156 ,  158 ,  160 ,  162 ,  172 ,  174 ,  176 ,  178 ,  180 , and/or  182 ]. In embodiments, different voltage outputs may be coupled to different input terminals of switches or bridges [ 152 ,  154 ,  156 ,  158 ,  160 ,  162 ,  172 ,  174 ,  176 ,  178 ,  180 , and/or  182 ].  
         [0028]    [0028]FIGS. 7A and 7B illustrate embodiments of the present invention wherein V out  is connected to the middle of an inductor. The embodiments illustrated in FIG. 7A are similar to the embodiments illustrated in FIG. 6A. Likewise, the embodiments illustrated in FIG. 7B are similar to the embodiments illustrated in  6 B. However, in the embodiments illustrated in FIGS. 7A and 7B, V out  is connected to the center of third inductor [ 170  or  188 ]. Accordingly, V out  is equal to one half of the voltage swing across third inductor  188 . Some of these embodiments may be advantageous, as V out  may not necessarily need to be limited to an increment of a voltage swing across an independently switched inductor. Accordingly, the resolution of voltage of V out  can be refined to half of a voltage swing across a particular independently switched inductor. In embodiments, V out  may be coupled to any center of any inductor [ 166 ,  168 ,  170 ,  184 ,  186 , or  188 ]. In embodiments, different voltage outputs may be coupled to the center of different inductors [ 166 ,  168 ,  170 ,  184 ,  186 , and  188 ].  
         [0029]    Embodiments of the present invention are exemplarily illustrated in FIGS. 8A and 8B. These embodiments may be similar to the embodiments illustrated in FIGS. 6A and 6B. In the embodiments exemplarily illustrated in FIGS. 8A and 8B, V out1  may be electrically coupled to output inductor [ 306  or  358 ] through output rectifier and filter [ 310  or  362 ]. Output inductor  306  may be magnetically coupled to at least one of first inductor [ 166  or  184 ], second inductor [ 168  or  186 ], and third inductor [ 170  or  188 ]. As illustrated in FIGS. 8A and 8B, additional outputs (e.g. V out2 ) may be implemented. For example, V out2  may be implemented with second output inductor [ 304  or  356 ] and output rectifier and filter [ 308  or  360 ].  
         [0030]    [0030]FIGS. 9A and 9B are exemplary illustrations of embodiments where the V out  has a greater voltage magnitude than V in . Embodiments illustrated in FIGS. 9A and 9B ate similar to the embodiments illustrated in FIGS. 5A and 5B. However, in the embodiments illustrated in FIGS. 9A and 9B, V out  may be coupled to first input [ 109  or  128 ] and first input [ 115  or  132 ]. V in  may be coupled to second input [ 111  or  130 ], second input [ 113  or  134 ], first input [ 117  or  136 ], and first input [ 123  or  140 ]. FIGS. 10A and 10B are exemplary illustrations of embodiments where V out  has a greater magnitude than V in . FIGS. 10A and 10B illustrate sinilat embodiments as illustrated in FIGS. 9A and 9B. However, in these embodiments, more than two independently switched inductors are both electrically and magnetically coupled. In embodiments, V out  may be coupled to any of the input terminals of switches or bridges [ 152 ,  154 ,  156 ,  158 ,  160 ,  162 ,  172 ,  174 ,  176 ,  178 ,  180 , and/or  182 ]. In embodiments, different voltage outputs may be coupled to different input terminals of switches or bridges [ 152 ,  154 ,  156 ,  158 ,  160 ,  162 ,  172 ,  174 ,  176 ,  178 ,  180 , and/or  182 ].  
         [0031]    [0031]FIGS. 11A and 11B illustrate embodiments similar to embodiments illustrated in FIG. 10A or  10 B, wherein V in  may be electrically coupled to an input inductor [ 486  or  522 ] through input bridge [ 484  or  524 ]. Input inductor  486  may be magnetically coupled to third inductor [ 170  or  188 ] In embodiments, V out  may be coupled to any of the input terminals of switches or bridges [ 152 ,  154 ,  156 ,  158 ,  160 ,  162 ,  172 ,  174 ,  176 ,  178 ,  180 , and/or  182 ]. In embodiments, different voltage outputs may be coupled to different input terminals of switch or bridges [ 152 ,  154 ,  156 ,  158 ,  160 ,  162 ,  172 ,  174 ,  176 ,  178 ,  180 , and/or  182 ].  
         [0032]    The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. The description of the present invention is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art.