Patent Publication Number: US-11381236-B2

Title: Miller transition control gate drive circuit

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 16/238,348, entitled “MILLER TRANSITION CONTROL GATE DRIVE CIRCUIT,” filed Jan. 2, 2019, which is incorporated by reference herein in its entirety for all purposes. 
    
    
     TECHNICAL FIELD 
     The subject matter disclosed herein relates to techniques for improving driving of metal-oxide-semiconductor field-effect transistor (MOSFET) devices and other suitable switching devices. 
     BACKGROUND 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     In electronic systems, power semiconductor device, or power semiconductor switching devices, such as MOSFET devices, insulated-gate bipolar transistors (IGBTs), bipolar transistors (BJTs), or the like are leveraged to selectively couple one or more components of the electronic systems in response to a control signal. As new developments affect these electronic systems, the switching devices, are expected to switch at an increased rate (e.g., faster, more responsive). For example, MOSFET devices used in electronic systems are expected to switch quickly with minimal switching losses. However, power semiconductor device switching is complicated and is difficult to perform quickly since too fast of a turn-on for some of the power semiconductor devices may lead to electro-magnetic interferences in the electronic systems and undesired losses. 
     BRIEF DESCRIPTION 
     Certain embodiments commensurate in scope with the originally claimed disclosure are summarized below. These embodiments are not intended to limit the scope of the claimed disclosure, but rather these embodiments are intended only to provide a brief summary of possible forms of the disclosure. Indeed, embodiments may encompass a variety of forms that may be similar to or different from the embodiments set forth below. 
     In one embodiment, a circuit may include a first switching device coupled to a load and a first voltage source that generates an electrical signal at a voltage level at least equal to a threshold voltage of the first switching device. The circuit may also include a second switching device between the first switching device and the first voltage source. The second switching device may provide a shaped current to the first switching device in response to a control signal. The shaped current may be generated based at least in part on the electrical signal generated by the first voltage source. The shaped current actuates the first switching device. 
     In another embodiment, a power converter system may include a load that operates based at least in part on a supplied electrical signal. The power converter system also may include a switching network that selectively enables and disables the supplied electrical signal based at least in part on a control scheme associated with operation of the load. The switching network may include a gate driver and a power device. The power device may enable in response to a control signal generated by the gate driver based on the control scheme. Enabling of the power device may selectively enable and disable the supplied electrical signal. The switching network may include an auxiliary control circuit between the gate driver and the power device. The auxiliary control circuit may shape the control signal before the control signal is applied to the power device. 
     In yet another embodiment, an auxiliary control circuit may include a first switching device that enables in response to a control signal generated to control supply of a shaped current to a second switching device. The auxiliary control circuit may also include a first voltage source that generates the control signal. The control signal may include an electrical signal having a voltage level at least equal to a threshold voltage of the first switching device. The auxiliary control circuit may also include one or more devices between the first switching device and a second voltage source. The first switching device may provide the shaped current to the second switching device in response to being enabled by the control signal. The shaped current may be generated based at least in part on the electrical signal generated by second voltage source and an impedance value of the one or more devices. The shaped current may actuate the first switching device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
         FIG. 1  is a circuit diagram of a metal-oxide-semiconductor field-effect transistor (MOSFET) device and a driver circuit, in accordance with aspects of the present approach; 
         FIG. 2A  is a circuit design of another example of a MOSFET device and the driver circuit of  FIG. 1 , in accordance with aspects of the present approach; 
         FIG. 2B  is a graph depicting operational regions associated with turning-on the MOSFET device of  FIG. 2A , in accordance with aspects of the present approach; 
         FIG. 2C  is a graph depicting operational regions associated with turning-off the MOSFET device of  FIG. 2A , in accordance with aspects of the present approach; 
         FIG. 3  is a circuit diagram of the MOSFET device of  FIG. 1 , the driver circuit of  FIG. 1 , and an auxiliary control circuit, in accordance with aspects of the present approach; 
         FIG. 4A  is a graph depicting current and voltage outputs generated during a switching simulation that involved a rapid turn-on operational scheme, in accordance with aspects of the present approach; 
         FIG. 4B  is a graph depicting current and voltage outputs generated during a switching simulation that involved a controlled turn-on operational scheme that uses at least in part the auxiliary control circuit of  FIG. 3 , in accordance with aspects of the present approach; 
         FIG. 4C  is a graph depicting current and voltage outputs generated during a switching simulation that involved a slow turn-on operational scheme, in accordance with aspects of the present approach; 
         FIG. 5  is a circuit diagram of an embodiment of the MOSFET device of  FIG. 3 , in accordance with aspects of the present approach; 
         FIG. 6  is a circuit diagram of another embodiment of the MOSFET device of  FIG. 3 , in accordance with aspects of the present approach; 
         FIG. 7  is a circuit diagram of an embodiment of the MOSFET device of  FIG. 3 , in accordance with aspects of the present approach; 
         FIG. 8  is a circuit diagram of another embodiment of the MOSFET device of  FIG. 3 , in accordance with aspects of the present approach; 
         FIG. 9  is a circuit diagram of another embodiment of the MOSFET device of  FIG. 3 , in accordance with aspects of the present approach; 
         FIG. 10  is a circuit diagram of another embodiment of the MOSFET device of  FIG. 3 , in accordance with aspects of the present approach; 
         FIG. 11  is a circuit diagram of another embodiment of the MOSFET device of  FIG. 3 , in accordance with aspects of the present approach; 
         FIG. 12  is a circuit diagram of another embodiment of the MOSFET device of  FIG. 3 , in accordance with aspects of the present approach; 
         FIG. 13  is a circuit diagram of another embodiment of the MOSFET device of  FIG. 3 , in accordance with aspects of the present approach; 
         FIG. 14  is a circuit diagram of another embodiment of the MOSFET device of  FIG. 3  as used in a control loop or feedback loop, in accordance with aspects of the present approach; and 
         FIG. 15  is a block diagram of an example power converter system implementation of the MOSFET device of  FIG. 3  and/or any of the embodiments described herein, in accordance with aspects of the present approach. 
     
    
    
     DETAILED DESCRIPTION 
     One or more specific embodiments of the present embodiments described herein will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. 
     Technological innovation has led to an increasing demand for transistors, and other switching devices, with faster and/or otherwise improved switching capabilities. For example, when a transistor switches too fast, ringing from excitement of parasitics associated with the transistor may be introduced into the output, while when a transistor switches too slow, ringing may be reduced but overall losses increase due at least in part to losses from operating the transistor in a lossy operational region, such as in the Miller region. This ringing may decrease performance of the transistor, for example, by also increasing electro-magnetic losses associated with the switching. In other words, it is no longer sufficient for a transistor to switch relatively fast without also compensating for parasitic responses and ringing caused by the switching. 
     An auxiliary control circuit may facilitate reducing switching losses associated with switching a power semiconductor device (e.g., open, close), such as losses from intrinsic parasitics (e.g., parasitic capacitances) storing and dissipating energy during switching transitions of the MOSFET device. Examples of power semiconductor devices may include metal oxide semiconductor field effect transistors (MOSFET) devices, insulated-gate bipolar transistors (IGBTs), bipolar transistors (BJTs), or the like. The auxiliary control circuit selectively guides the semiconductor power device through its various switching regions, reducing losses and permitting precise driving of the semiconductor power device. In this way, the auxiliary control circuit may operate to reverse a charge quickly, such as a charge on a Miller capacitance (e.g., gate-drain parasitic capacitance) associated with the semiconductor power device, to reduce time spent by the semiconductor power device in the Miller plateau, therefore reducing switching losses. Furthermore, coupling multiple auxiliary control circuits in parallel may increase control over semiconductor power device switching. For example, the various auxiliary control circuits may each be designed to each cause a MOSFET device to operate in different switching regions, such as by modulating impedance values between respective auxiliary control circuits to facilitate providing an ideal resistance value at the various switching regions of the MOSFET device. The various auxiliary control circuits may respectively receive different control voltages at different times based on when a semiconductor power device is to be operated into its various switching regions (e.g., where presumably one auxiliary control circuit is designed to facilitate switching of the semiconductor power device into a first switching region which is different from a second auxiliary control circuit designed for a second switching region different from the first switching region). Respective selection of each auxiliary control circuit may facilitate fast and controlled switching suited to the particular switching regions and switching characteristics of the semiconductor power device since, at least, the impedance values may be selectively changed between the semiconductor power device entering various switching regions by activating different auxiliary control circuits at different times during the semiconductor power device switching. 
     By way of introduction,  FIG. 1  is a circuit diagram of an example circuit  8  including a MOSFET device  10 . To simplify explanation, embodiments involving a MOSFET device as the semiconductor power device described above are included herein as examples of a suitable practical implementation. This should not be interpreted as a limiting embodiment, since as previously described, the techniques described herein may improve driving techniques for any semiconductor power device having different operational regions, such as a switching region associated with a Miller threshold as is discussed below with respect to  FIG. 2 . The MOSFET device  10  may be used in variety of applications wherever a switching component is to be used. For example, the MOSFET device  10  may be used in AC motor drives, adjustable-speed AC motor drives, certain power supplies, battery applications, or the like. Similarly, a gate driver  12  (e.g., a gate driver circuit) may output a gate voltage to a gate of the MOSFET device  10 . The gate voltage may be used to operate the MOSFET device  10  into one or more operational regions. The gate driver  12  may be (or may be included in) a variety of devices, such as a gate driver, pulse width modulation (PWM) controller, or any suitable voltage source. It should be noted that the gate driver  12  may output a voltage value with respect to a ground voltage (e.g., depicted via the ground symbol on  FIG. 1  and in subsequent figures) or with respect to a common reference voltage, effectively coupling these various nodes to the same voltage. As will be appreciated, the gate driver  12  may be supplied a driving signal, such as a current, from a supply circuit as part of a system-level implementation of the MOSFET device  10  and/or other power devices in a switching network. 
     The circuit  8  also includes a resistor  16  having a resistance value. When the resistor  16  has a relatively large gate resistance value, switching losses may increase as well as a total time of switching, but reduce ringing associated with switching. Alternatively, when the resistor  16  has a relatively small gate resistance value, switching losses may reduce, a total time of switching may reduce, but ringing associated with switching may increase. Thus, typical operation uses a resistance value that balances benefits from the decreased switching speed and switching losses with the increases in the ringing associated with switching. The circuit  8  also includes a load inductance model  14 . The load inductance model  14  represents a load of the MOSFET device  10  which is affected by the MOSFET device  10  actually conducting electricity (e.g., from the source terminal to drain terminal). In some embodiments, however, the load inductance model  14  may include representation of other switching currents that may be directed into and/or away from the MOSFET device  10 . Upon activation of the MOSFET device  10  (e.g., turn-on), a load inductance  18  may receive a supply voltage from voltage source  20 . 
     To complete switching of the MOSFET device  10 , the gate driver  12  applies the gate voltage to switch (e.g., turn-on a normally-off device, turn-off a normally on device) the MOSFET device  10 . To simplify discussion, the MOSFET device  10 , and each MOSFET device of this disclosure, may be considered a normally-off device that is switched to a turned-on state to make an electrical coupling between a drain terminal and a source terminal. During a typical switching operation, the gate voltage is varied by the gate driver  12  to drive the MOSFET device  10  through different operational regions. The MOSFET device  10  has material parameters (e.g., parasitic capacitances) that change requirements for switching of the MOSFET device  10  to occur, such as a threshold voltage, one or more voltages used during switching, or the like. In this way, the gate driver  12  may transmit different voltage levels to the MOSFET device  10  at different times to complete switching operations. 
       FIG. 2A  is a circuit diagram of an example MOSFET device  10  coupled to a load  8  with various outputs and signals labelled to correspond to  FIG. 2B  and  FIG. 2C .  FIG. 2B  is a graph  28 A depicting electrical waveforms of the MOSFET device  10  present during turn-on operations (e.g., the MOSFET device  10  of  FIG. 2A  switching-on or being activated).  FIG. 2C  is a graph  28 B depicting electrical waveforms of the MOSFET device  10  present during turn-off operations (e.g., the MOSFET device  10  of  FIG. 2A  switching-off or being deactivated). For ease of discussion,  FIG. 2A ,  FIG. 2B , and  FIG. 2C  are discussed together herein. Pictured are various regions  30  (e.g.,  30 A,  30 B,  30 C,  30 D,  30 E) that may have different electrical characteristics as the MOSFET device  10  is turned-on. Region  30 A may correspond to an operational state before the device meets a turn-on threshold. Electrical signals may be applied to the gate of the MOSFET device  10  until the gate-source voltage of the MOSFET device  10  reaches the turn-on threshold. At the turn-on threshold of the MOSFET device  10  begins switching through region  30 B and region  30 C onto region  30 D corresponding to a Miller threshold while drain voltage (e.g., voltage  31 , line  33 ) of the MOSFET device  10  decreases. While in the region  30 D, the gate-source voltage of MOSFET device  10  may behave generally linearly in response to the electrical signals while current through the MOSFET device  10  (e.g., current  34 , line  35 ) fully reverses over an effective capacitance (e.g., a Miller capacitance  36 ) disposed between the drain terminal and the gate terminal of the MOSFET device  10  caused at least in part by an increase in carriers associated with the MOSFET device  10  conduction. Once reversal happens, the next region  30 E is entered and the MOSFET device  10  may be completely turned-on. 
     While in the region  30 D, the output of the MOSFET device  10  may correspond at least in part to a Miller plateau. The Miller plateau may be a result of the effective capacitance (e.g., the Miller capacitance  36 ) between the drain and the gate of the MOSFET device  10 . The increase in carriers may cause the gate-to-drain capacitance to increase, causing the Miller plateau from the constant electrical signal input to the gate of MOSFET device  10 . 
     As is depicted in  FIG. 2C , the MOSFET device  10  may also undergo a turn-off process that is subject to similar thresholds and Miller plateau that the turn-on process undergoes. For example, region  30 H of the graph  28 B may be similar to the Miller plateau region associated with the region  30 D of the graph  28 A. Furthermore, the region  30 I and the region  30 J show switching characteristics of the MOSFET device  10  as electrical signals through the MOSFET device  10  decrease in accordance with the threshold voltage, similar but inverse to the switching characteristics depicted in the region  30 A, the region  30 B, and the region  30 C. The electrical characteristics depicted by the graph  28 B in the region  30 F may correspond to the stabilized electrical characteristics depicted by the graph  28 A at the boundary of the region  30 E after turn-on occurred. 
     It is generally understood that some of the switching losses of the MOSFET device  10  (e.g., turning-on or turning-off) arise from operating the MOSFET device  10  in the region  30 D and the region  30 H, that is, in the Miller plateau region. To reduce these losses, the MOSFET device  10  may be switched (e.g., turned-on) relatively fast. However, a fast switching operation may excite parasitic impedances (e.g., parasitic inductances, parasitic capacitances) associated with the MOSFET device  10 . The excited parasitic impedances cause undesirable losses and ringing in the electrical signals associated with the MOSFET device  10  (e.g., ringing depicted with the line  35  representing the current  34 ). Thus, coupling a controllable auxiliary control circuit to the MOSFET device  10  to drive the MOSFET device  10  to enter and/or exit these various operational regions may be useful and/or desired. Furthermore, the auxiliary control circuit may also be able to reverse a charge of the Miller capacitance while also modulating the gate resistance to facilitate decreasing ringing and other undesired effects from excitation of the parasitic impedances. Embodiments of the present disclosure relate at least in part to circuits, systems, and methods for providing the above-described auxiliary control circuit. 
       FIG. 3  shows the circuit  8  of  FIG. 1  including an auxiliary control circuit  44  configured to operate the MOSFET device  10  into one or more operational regions. As depicted, the auxiliary control circuit  44  is an analog circuit used operate the MOSFET device  10  into one or more operational regions, for example, by injecting additional current (e.g., boost current) that has been shaped or specifically parameterized (e.g., current shaping and/or timing control) to facilitate operating the MOSFET device  10  beyond the Miller plateau  32 , or other suitable operation. It should be understood that shaping or current shaping herein refers to intentional adjustment of timing, amplitude, shape, or the like of a current pulse supplied from the auxiliary control circuit  44  to the MOSFET device  10 . In some embodiments, the shaped current pulse (e.g., the current pulse supplied from the auxiliary control circuit  44 ) may be provided as a boost current to supplement, adjust, change, or otherwise affect a main driving signal provided to the MOSFET device  10 .  FIG. 3  depicts an embodiment that provides the shaped current pulse as a boost current while  FIG. 10 , for example, depicts an embodiment that provides the shaped current pulse as a driving current, as is discussed below. Although not specifically depicted, it should be understood that one or more portions of the auxiliary control circuit  44 , including any control circuitry associated with the auxiliary control circuit  44  (e.g., circuitry used to generate a gate voltage from voltage source  46 , supporting circuitry that incorporates the auxiliary control circuit  44  into a feedback loop), may include at least in part one or more digital circuitry components. 
     The auxiliary control circuit  44  includes an auxiliary path  48  to facilitate transitioning the MOSFET device  10  between the on and off states. Although the auxiliary control circuit  44  is depicted as including one switch device (e.g., second MOSFET device  50 ), it should be understood that a variety of switches and/or any suitable number of switches may be used to operate the MOSFET device  10  into the one or more operational regions. For example, a variety of suitable switching devices may be used in addition to or alternative of the MOSFET device  50 , including but not limited to current-controlled switches, voltage-controlled switches, suitable semiconductor power devices, or the like. Furthermore, although depicted as one or more inductors, it should be understood that parasitics of the circuit  8  may be modeled as a variety of suitable components. The auxiliary control circuit  44  may be used to control operation of the MOSFET device  10  via changing the impedance of the auxiliary control circuit  44 . 
     The auxiliary control circuit  44  includes the MOSFET device  50  and the voltage source  46  to generate a control voltage associated with enabling the auxiliary path  48 . The MOSFET device  10  is operated in its different regions (e.g., linear, fully-on) during switching. The auxiliary control circuit  44  couples through the MOSFET device  50  to a main driving path  52  coupled to the gate of the MOSFET device  10 . The MOSFET device  50  is in series with a time element—in particular, a resistor-capacitor (RC) circuit  54 . 
     The time element may be any suitable component(s) that permits the MOSFET device  50  to be programmed to be turned-on for a particular time period. The RC circuit  54  may be programmed to provide a boost current for a particular time duration based on the capacitance value of capacitor  56  and the resistance value of resistor  58 . For example, the RC circuit  54  is designed to have a specific time constant, such that the RC circuit  54  outputs a boost current for a predetermined, programmed, or other preset duration of time based at least in part on the time constant. The resistance value of the resistor  58  and/or the capacitance value of the capacitor  56  may be selected at least in part to define a particular amount of current transmitted for the duration of time specified by the time constant. In this manner described, the auxiliary control circuit  44  may be used to control operation of the MOSFET device  10  via changing the impedance of the auxiliary control circuit  44 . 
     To generally explain operation of the circuit  8  as depicted in  FIG. 3 , the MOSFET device  10  receives a gate voltage from the gate driver  12 . A control voltage from the voltage source  46  is used to bias the MOSFET device  50  to operate the MOSFET device  50  to turn-on and/or turn-off. The control voltage may be active (e.g., have a high voltage) for a duration of time, and after the duration of time passes, the control voltage may be inactive (e.g., have a low voltage, have a ground voltage level). In some embodiments, the control voltage may be a constant output from a voltage source  46  and an additional switch may be used to modulate application of the control voltage to the MOSFET device  50 . 
     Initially, the MOSFET device  50  is operated to be turned-on. While the MOSFET device  50  is turned-on, the capacitor  56  and the resistor  58  affect the boost current provided to the main driving path  52 . The RC circuit  54  provides a boost current to the main driving path  52  of the MOSFET device  10  until a sufficiently long time passes and the capacitor finishes charging. The value of the resistor  58  and the capacitor  56  are selected to define a particular time constant for the output boost current. The time constant facilitates setting a conduction duration (e.g., how long the boost current is non-zero and therefore a duration of time the current boosts the MOSFET device  10  for) of the current while the resistance value of the resistor  58  and/or capacitance value of the capacitor  56  facilitate setting the value of the current transmitted as a gate control signal to the MOSFET device  10 . 
     During operation, as the gate-source voltage increases of the MOSFET device  10 , the MOSFET device  50  may be operated to turn-off. When the capacitor  56  and the resistor  58  are suitably sized, the current through the auxiliary branch may decrease to negligible (e.g., die down, attenuate) before the MOSFET device  50  is operated to turn off. In some embodiments, the resistor  58  has a resistance value less than the resistance value of the resistor  16 , permitting a rapid turn-on of the MOSFET device  10  just past the Miller plateau  32 . While the capacitor  56  charges, a boost current based at least in part on charging of the capacitor  56  is provided to a gate voltage supplied to the MOSFET device  10  from the gate driver  12 . The boost current facilitates transitioning the MOSFET device  10  into a particular operational region until the capacitor  56  has the time to charge to its saturation level, thereby opening the circuit and permitting the boost current to halt affecting the driving of the MOSFET device  10 . As may be appreciated, the auxiliary control circuit  44  may be coupled in parallel with one or more additional auxiliary control circuits, such that each of the auxiliary control circuits (e.g., auxiliary control circuit  44 ) is operable to activate at a particular time and are able to generate different boost currents based on which operational region each auxiliary control circuit  44  is to operate the MOSFET device  10 . It is noted that the components of each auxiliary control circuit  44  may correspond to the operational region that the MOSFET device  10  is to be operated into. In this way, the selection of the impedances value (e.g., the selection of specific resistance and/or capacitance values) of the auxiliary control circuit  44  may be based at least in part on electrical parameters associated with the operational region, for example, voltage levels and/or thresholds associated with the different operational regions of the MOSFET device  10 . 
     The auxiliary control circuit  44  may be thought of as a knob. In this way, similar to a knob, the boost current that is output by the auxiliary control circuit  44  and applied to the gate of the MOSFET device  10  is programmable based on the combination of impedances within the auxiliary control circuit  44 . Thus, the auxiliary control circuit  44  may be programmed to compensate for a parasitic response associated with material parasitics of the circuit  8 , permitting ringing caused by the fast switching to decrease. Since the auxiliary control circuit  44  time constant is programmable through changing resistances and/or capacitance values added into the auxiliary control circuit  44 , the auxiliary control circuit  44  may be used to drive the MOSFET device  10  in a predetermined manner during each switching operation. By leveraging preprogrammed auxiliary control circuits (e.g., auxiliary control circuit  44 ) to drive the MOSFET device  10 , precise switching operations may be permitted relative to current driving techniques used to drive MOSFET devices (e.g., MOSFET device  10 ). Furthermore, the auxiliary control circuits may enable faster switching of the MOSFET devices (e.g., MOSFET device  10 ) relative to the current driving techniques described above. 
       FIG. 4A-4C  are graphs depicting voltages and currents associated with differing switching methods used to turn-on the MOSFET device  10 .  FIG. 4A  is a graph  70  depicting a simulated voltage signal  72  output and a simulated current signal  74  output when driving the MOSFET device  10  without using the auxiliary control circuit  44 . In this example, the MOSFET device  10  is driven using a rapid turn-on operational scheme that attempts to mimic an instantaneous switching operation where the MOSFET device  10  instantaneously turns-on with minimal losses. In the rapid turn-on operational scheme, the resistance value of the resistor  16  is selected to be as small of a resistance value as feasible and the MOSFET device  10  is driven using a driving voltage suitable for fast switching. Losses due at least in part to the time spent by the MOSFET device  10  operating in the Miller plateau  32  region equal about 11 microjoules (μJ). Despite the contribution to the loss levels being relatively low, the outputs actually experience a large amount of ringing (e.g., ringing generally indicated by arrow  76 ). In general, the more the voltage signal  72  and/or the current signal  74  switch back and forth (e.g., from the ringing), the more loss is experienced by the circuit  8 . 
     The ringing depicted in the graph  70  is large relative to the ringing depicted in  FIG. 4B .  FIG. 4B  is a graph  86  depicting a simulated voltage signal  88  output and a simulated current signal  90  output when driving the MOSFET device  10  using the auxiliary control circuit  44 . In this example, the MOSFET device  10  is systematically driven through its various operational regions such that ringing and time spent in the Miller plateau  32  is minimized. In addition, as described above, the auxiliary control circuit  44  is also designed to compensate for parasitics in the circuit  8  and/or associated with the MOSFET device  10 . While losses are maintained at a level generally equal to the losses of the graph  70  (e.g., 11 μJ), the ringing of the voltage signal  88  and the ringing of the current signal  90  (e.g., ringing generally indicated by arrow  92 ) is reduced. Thus, driving the MOSFET device  10  using the auxiliary control circuit  44  may reduce ringing as well as maintain losses at a low level, providing an improvement over merely driving the MOSFET device  10  using a rapid turn-on operational scheme. 
     To help depict this,  FIG. 4C  is a graph  102  depicting a simulated voltage signal  104  output and a simulated current signal  106  output when driving the MOSFET device  10  without using the auxiliary control circuit  44 . In this example, the MOSFET device  10  is driven using a slow turn-on operational scheme. When driving the MOSFET device  10  using the slow turn-on operational scheme, the voltage signal  104  is operated to rise slowly (e.g., indicated by arrow  108 ) in the MOSFET device  10  relative to the rise of the rapid turn-on operational scheme. The slow turn-on operational scheme causes the ringing of the voltage signal  104  and the ringing of the current signal  106  (e.g., ringing generally indicated by arrow  108 ) to be as low as the ringing depicted in  FIG. 4B . 
     However, the low ringing levels comes with a tradeoff—the tradeoff being that the loss levels are higher relative to driving techniques using the auxiliary control circuit  44  (e.g.,  FIG. 4B ) or the rapid turn-on operational scheme (e.g.,  FIG. 4A ). Losses due at least in part to the time spent by the MOSFET device  10  operating in the Miller plateau  32  region equal about 18 μJ. 18 μJ is large relative to the losses by driving the MOSFET device  10  with the auxiliary control circuit  44  (e.g.,  FIG. 4B ) or the rapid turn-on operational scheme (e.g.,  FIG. 4A ). Thus,  FIGS. 4A-4C  show benefits associated with driving the MOSFET device  10  using the auxiliary control circuit  44 . These benefits may include minimizing the total amount of loss caused by the MOSFET device  10  operating in the Miller plateau  32  region while reducing an amount of ringing caused by excitement of MOSFET device  10  and/or circuit  8  parasitics. 
     As described above, the auxiliary control circuit  44  may be designed to compensate for one or more parasitics in the circuit  8  and/or associated with the MOSFET device  10  that may cause a detectable amount of ringing during MOSFET device  10  switching when operated using the rapid turn-on operational scheme. To help illustrate,  FIG. 5  depicts the circuit diagram of  FIG. 3  including parasitics, such as one or more parasitic inductances  116  (e.g.,  116 A,  116 B) and a Miller capacitance  118 . It should be understood that although a particular number and type of parasitics are depicted, the auxiliary control circuit  44  may compensate for a variety of parasitics or non-uniform switching characteristics. 
     These parasitic inductances may affect MOSFET device  10  switching operations. Thus, using the auxiliary control circuit  44  to compensate for effects of the parasitic inductances may facilitate reducing the amount of ringing caused by excitement of the MOSFET device  10 . For example, a parasitic inductance may be compensated by including a particular capacitance into the circuit  8 . When the parasitic inductances are suitably compensated, ringing caused by switching of the MOSFET device  10  may be reduced. 
     In this way, different auxiliary control circuit  44  designs may provide advantageous operation for different applications. Different examples of auxiliary control circuit  44  embodiments are described below. It should be understood that any combination of the following circuits may be used in driving a load of the MOSFET device  10 . 
       FIG. 6  is a circuit diagram depicting an embodiment of the circuit  8 , circuit  8 A, that uses an auxiliary control circuit  44  to drive the MOSFET device  10  without including the resistor  16  (e.g., gate resistor). The circuit  8 A includes a basic variant of a turn-on control circuit (e.g., auxiliary control circuit  44 ). The MOSFET device  50  may act in one of three ways, that is, as a transconductance amplifier (e.g., a controlled current source), as a non-linear resistor, and/or as a cut-off switch. The timing control network impedance (e.g., overall impedance of the RC circuit  54 , specific resistance and/or capacitance values of the resistor  58  and/or capacitor  56 ) regulates the duration for which the pulse is conducted through the channel. In this way, the RC circuit  54  is used for timing control and/or current shaping. The voltage source  46  may be a fixed or variable source. As described above, the gate driver  12  voltage is the main gate driver for the MOSFET device  10 . The gate driver  12  voltage may be a pulse voltage source, an AC voltage source, an offset AC drive voltage, or any combination thereof. In this depicted arrangement, a body diode of the MOSFET device  50  acts to discharge the MOSFET device  10  gate once the signal at the gate driver  12  reverses. However, in some embodiments, a voltage controlled switch without the body diode may be used as the pass element. By modifying the impedance of the RC circuit  54 , the shape and/or duration of the current pulse transmitted to the MOSFET device  10  from the gate driver  12  may be shaped (e.g., current shaping to generate a shaped current) to permit suitable driving of the MOSFET device  10 . Through using the shaped current, the MOSFET device  10  may be driven into different operational regions and thus may be operated to behave differently in different operational regions based on the value of driving signal applied to the gate of the MOSFET device  10 . 
       FIG. 7  is a circuit diagram depicting another embodiment of the circuit  8 , circuit  8 B, that uses the auxiliary control circuit  44  to drive the MOSFET device  10  without including the resistor  16  (e.g., gate resistor) and modifying the resistor  58 . In circuit  8 B, the resistor  58  is used as a source feedback resistor. To phrase differently, the resistor  58  is placed in series with the series pass MOSFET device  50  to form a source feedback amplifier. The capacitor  56  and the resistor  58  may continue to be used to provide timing control and/or current shaping such that the MOSFET device  10  is driven into different operational regions. 
       FIG. 8  is a circuit diagram depicting another embodiment of the circuit  8 , circuit  8 C, that uses the auxiliary control circuit  44  to drive the MOSFET device  10  without including resistor  16  (e.g., gate resistor). The circuit  8 C includes the RC circuit  54  directly coupled to the gate of the MOSFET device  10 . In this way, the RC circuit  54  provides timing control and/or current shaping, as previously discussed, in addition to acting like a non-linear source feedback resistor. The pass element MOSFET device  50  may benefit from including the RC circuit  54  as a non-linear source feedback resistor. 
     As described above, the resistance value of the resistor  58  and the capacitance value of the capacitor  56  are used to shape the response of the MOSFET device  10 . Thus, the time constant defined by the impedances of the auxiliary control circuit  44  may predefine (e.g., before actual driving of the MOSFET device  10 ) a driving pattern to be used to drive the MOSFET device  10 . The preprogrammed auxiliary control circuits  44  may thus facilitate precise switching operations associated with driving the MOSFET device  10 . Additionally or alternatively, one or more auxiliary control circuits (e.g., auxiliary control circuit  44 ) may be used in parallel to drive the MOSFET device  10  through the one or more operational regions. 
     For example,  FIG. 9  is a circuit diagram depicting an embodiment of the circuit  8 , circuit  8 D, that uses one or more auxiliary control circuits  44  (e.g., auxiliary control circuit  44 A, auxiliary control circuit  44 B) coupled in parallel to drive the MOSFET device  10 . Each of the auxiliary control circuits  44  may be sequenced in time and output at different levels. As described above, each of the depicted auxiliary control circuits  44  of the different branches has a predefined (e.g., preset, predetermined) operation based at least in part on the time constant associated with one or more resistors  58  (e.g., resistor  58 A, resistor  58 B) and/or one or more capacitors  56  (e.g., capacitor  56 A, capacitor  56 B) of the respective auxiliary control circuits  44 . In this way, each of the branches (e.g., each of the auxiliary control circuits  44 ) may respectively use different variants of the auxiliary control circuits  44  in combination with each other. In this way, the first auxiliary control circuit  44 A may include the RC circuit  54  as depicted in  FIG. 6  while the second auxiliary control circuit  44 B may include circuitry as depicted in  FIG. 7 . 
     To perform switching operations, the auxiliary control circuits  44  may be individually activated using different voltage control signals outputted by voltage sources  46  (e.g., voltage source  46 A, voltage source  46 B) and used to drive the MOSFET device  10  at different times. Using the preprogrammed auxiliary control circuits  44  may enable faster switching of the MOSFETs (e.g., MOSFET device  10 ) relative to existing driving techniques. In addition, driving the MOSFET device  10  with multiple auxiliary control circuits  44  may enable distinct steps of a single switching operation to be preprogrammed into respective auxiliary control circuits  44 . In this way, one or more impedance values may be selected within each of the auxiliary control circuits  44  to correspond to a particular switching step or driving operation, where sequential activation of the respective auxiliary control circuits  44  may guide the MOSFET device  10  to switch in an improved manner. 
       FIG. 10  is a circuit diagram depicting another embodiment of the circuit  8 , circuit  8 E, that uses the auxiliary control circuit  44  to drive the MOSFET device  10  without including resistor  16  (e.g., gate resistor). Using the depicted arrangement, the auxiliary control circuit  44  provides bidirectional control to the MOSFET device  10 . In the previous embodiments, in particular circuit  8 A of  FIG. 6 , the series pass MOSFET device  50  discharges the MOSFET device  10  gate through the body diode of the MOSFET device  50 . To prevent this operation, a series switch (e.g., MOSFET device  50 B) in an anti-series arrangement may be used. The anti-series arrangement is provided by the opposing body diodes and coupled sources of the MOSFET device  50 B and of the MOSFET device  50 A. The RC circuit  54  may continue to be used for timing control and/or current shaping. In some embodiments, the MOSFET device  50 B may be replaced by a diode for uncontrolled blocking in the reverse direction. It should be appreciated that any of the described embodiments may be combined with the bidirectional control variant discussed in  FIG. 10 . 
     The above-described circuitry has been generally discussed in terms of turn-on operational control of the MOSFET device  10 . However, the above-described circuitry may also be applied and used for turn-off operational control of the MOSFET device  10 . For example,  FIG. 11  is a circuit diagram depicting another embodiment of the circuit  8 , circuit  8 F, that uses the auxiliary control circuit  44  to drive the MOSFET device  10  without including resistor  16  (e.g., gate resistor). Furthermore, the circuit  8 F uses a P-channel MOSFET as the MOSFET device  50 , differing from using the N-channel MOSFET as the MOSFET device  50  described above. 
     In contrast to the turn-on circuitry described above, the turn-off auxiliary control circuit  44  is used to control a rate of change of the drain-source voltage (e.g. dv ds (t)/dt) a peak voltage, as well as ringing harmonics in voltage waveforms generated during the turn-off operations. This may permit sympathetic control of drain current during the turn-off operations, where sympathetic control refers to indirect control of or control based on induced properties (e.g., a voltage causes a current through a resistor such that a change in the voltage sympathetically changes the current). 
     Describing operation of the circuit  8 F, the voltage source  46  sets the gate voltage of the MOSFET device  50 . The gate of the MOSFET device  10  is at the voltage of the source of the MOSFET device  50  (e.g., the series pass element). When the MOSFET device  50  is operated to conduct by the voltage source  46  and when the voltage output from the gate driver (e.g., a pulse voltage, AC voltage, offset AC drive voltage, or the like) is low, the gate voltage of the MOSFET device  10  decreases. At some point, the MOSFET device  50  in combination with the RC circuit  54  (e.g., timing controlling and/or current shaping impedance) shapes and cuts off current associated with the MOSFET device  10 . 
       FIG. 12  is a circuit diagram depicting another embodiment of the circuit  8 , circuit  8 G, which features turn-off operation control circuitry of the bidirectional control variant. In this way, the circuit  8 G is also an embodiment of the circuit  8 E. The bidirectional turn-off operation control circuitry of the circuit  8 G includes many similar elements to the bidirectional turn-on control circuitry of the circuit  8 E. However, instead of including N-channel MOSFET devices as the MOSFET devices  50  (e.g., MOSFET device  50 A, MOSFET device  50 B), the circuit  8 G features P-channel MOSFET devices as the MOSFET devices  50 . In this way, the MOSFET device  50 B is used as a series switch in an anti-series arrangement. The anti-series arrangement is provided by the opposing body diodes and coupled sources of the MOSFET device  50 B and of the MOSFET device  50 A. The RC circuit  54  may continue to be used for timing control and/or current shaping. In some embodiments, the MOSFET device  50 B may be replaced by a diode for uncontrolled blocking in the reverse direction. It should be appreciated that any of the described embodiments may be combined with the bidirectional control variant discussed in  FIG. 10 . 
       FIG. 13  is a circuit diagram depicting another embodiment of the circuit  8 G, circuit  8 H, which features a parallel impedance branch (e.g., including resistor  128 ). It is noted that although depicted with respect to the circuit  8 G, it should be understood that the parallel impedance branch may be included with any of the described circuits. For example,  FIG. 3  generally depicts the parallel impedance branch (e.g., resistor  16 ) as part of the non-bidirectional turn-on control circuitry. Including the parallel impedance branch may facilitate increasing control of switching of the MOSFET device  10 , as described above. 
     In some embodiments, one or more of the auxiliary control circuits  44  may be used as part of a control loop or feedback loop.  FIG. 14  is a circuit diagram depicting another embodiment of the circuit  8 A, circuit  8 I, which features the MOSFET device  10  (e.g., including resistor  128 ), the MOSFET device  8 , the RC circuit  54 , the gate driver  12  supply voltage, and a control signal generator  130  coupled together to form a control loop or feedback loop circuit. It is noted that although depicted with respect to the turn-on circuit variants (e.g., having the N-channel MOSFET  50 ), it should be understood that any of the described circuits may be used in a similar control loop or feedback loop. Although depicted as a feedback control loop, it should be understood that signals may be received by the control signal generator  130  as part of any suitable control scheme, such as but not limited to an open loop control scheme, a feed forward control scheme, a feedback control scheme, or any suitable combination of those listed schemes. 
     During operation, a parameter may be sensed of a load (e.g., load inductance model  14 ) and/or an output (e.g., generally a drain current or drain voltage) from the MOSFET device  10  may be received by the control signal generator  130 . The signal resulting from the sensing of the parameter may be used to change operations of the one or more auxiliary control circuits  44 , as a way to change one or more operations or outputs of the MOSFET device  10 . For example, a drain-source voltage output from MOSFET device  50 , a drain voltage feedback output from the MOSFET device  10 , a gate voltage feedback output from the MOSFET device, a suitable parameter from the load inductance model  14 , or other suitable parameter, may be sensed and used to operate the auxiliary control circuit  44  such that a gate-source voltage output from the MOSFET device  10  may be maintained at a particular peak voltage value or at a particular rate of change. In some embodiments, the MOSFET device  10  is driven to operate in each of its switching regions (or a sub-set of its switching regions) based at least in part on the control signal generator  130  selectively activating and deactivating different MOSFET devices  50  at different times. 
     In addition to reductions to switching losses, benefits of driving the MOSFET device  10  using the auxiliary control circuit  44  also include reduced electro-magnetic interferences (EMI) and increased control over electrical signal peaks that happen during MOSFET switching operations. To elaborate, MOSFET devices (e.g., MOSFET device  10 ) may be used as a switch in circuitry and/or devices sensitive to high (e.g., high relative to expected, average, or normal operation) voltages, or other electrical signals. In these embodiments, special care may be taken to protect the rest of the device from the peak outputs from the MOSFET devices during the switching operations. One way to manage this may be to program one or more auxiliary control circuits  44  (e.g., via at least the respective time constants of the respective auxiliary control circuits  44 ) to drive the MOSFET devices in such a way as to not output too high of a level of voltages or currents. 
     Other possible enhancements to the techniques described above include, for example sensing a peak current associated with ringing (e.g., relative maximum current associated with the portion of the current corresponding to ringing) and adjusting control of the MOSFET device  50  in response to the sensed peak current. Adjustments may include operating the MOSFET device  50  such that the rate of rise of the current associated with the MOSFET device  10  (e.g., the peak current measured at a later time) is changed or operating the MOSFET device  50  to change a rate of turn-on of the MOSFET device  10 . Any suitable parameter may be sensed and used to control operation of the MOSFET device  50  and/or one or more of the auxiliary control circuits  44 , for example, sensing of noise currents or the like. Furthermore, in less sensitive environments, operation of the MOSFET device  50  and/or one or more of the auxiliary control circuits  44  may be based at least in part on dual consideration to losses and electro-magnetic interferences. Furthermore, in some embodiments, the additional auxiliary control circuits  44  may be programmed to facilitate switching through the various operational regions of the MOSFET device  10  in addition to being programmed (or include additional auxiliary control circuits) to facilitate switching through regions having different threshold voltages or other thresholds and/or different timing parameters. The control signal generator  130  may additionally or alternatively be used to balance electromagnetic emissions, regulating change in voltage outputs (e.g., dv(t)/dt), regulating change in current outputs (e.g., di(t)/dt), peak voltage(s), peak current(s), or the like. 
     Additionally or alternatively, the RC circuit  54  described above may be used with other passive elements, such as inductors, to tune the auxiliary control circuit  44  to higher orders. The auxiliary control circuit  44  may also be used to control the rate of change of the current (e.g., di(t)/dt), the peak current value, ringing harmonics, or the like, associated with current waveforms transmitted to the MOSFET device  10  during turn-on operations. This may also permit sympathetic control of drain-source voltages of the MOSFET device  10  during the turn-on operations. Furthermore, the techniques described herein may be used with an insulated-gate bipolar transistor (IGBT) or any other suitable switching devices. 
     The circuitry described above may be included within a switching system.  FIG. 15  is a block diagram of an example use of the circuit  8  and/or any of the embodiments of the circuit  8  described herein. The above-described circuitry is depicted as used in a power converter system  140 . In general, the power converter system  140  may include the circuit  8  within its switching network  142 , such as between the switch gate driver  12  and a power device  144  (e.g., a semiconductor power switching device, such as the MOSFET device  10 ). This placement enables the auxiliary control circuit  44  of the circuit  8 , which may be included within a larger control loop or feedback loop, to selectively guide the semiconductor power device through its various switching regions, reducing losses and permitting precise driving of the semiconductor power device. As described above, the current supplied to the power device  144  may be shaped by components of the circuit  8 . 
     The gate drivers  12  may be supplied by a source  146  coupled to a filter network  148 . The filter network  148  may include any suitable filtering components, such as an inductor  149  (L) and/or a capacitor  150  (C). In this depicted example, the filter network  148  is an LC filter that may be tuned for the particular switching system application. The source  146  may be any suitable voltage source to supply the filter network  148 . 
     Within the switching network  142 , the specific electrical couplings between the various components affect the output transmitted to a load  152 . The load  152  may be modelled similar to the load inductance model  14  but may include a particular value of a capacitor  154  and/or a particular value of a resistor  156  in addition to or in alternative of components of the load inductance model  14 . It is noted that each of the depicted capacitors, resistors, and/or inductors may be representative of an overall capacitance, an overall resistance, and/or an overall inductance value. The gate drivers  12  may operate together to cause the switching network  142  to supply a particularly configured voltage to the load  152  based on the frequency of the switching performed by the power devices  144 . 
     Technical effects of this disclosure include designs and methods of providing an auxiliary control circuit that facilitates switching operations of a first metal-oxide-semiconductor field-effect transistor (MOSFET). In particular, the disclosed auxiliary control circuit includes a time component, for example, a RC circuit, coupled to a second MOSFET that activates in response to a control signal, yielding a selectable control circuit that is able to provide a programed boost signal for a predetermined amount of time (e.g., a shaped current) in response to the second MOSFET being activated. Computing circuitry associated with the auxiliary control circuit may sense one or more parameters of the first MOSFET and determine one or more adjustments to perform to a time constant or suitable operation of the auxiliary control circuit to suitably compensate for output variations from the first MOSFET (e.g., as part of a control loop or feedback loop). Accordingly, the auxiliary control circuit may facilitate providing improved switching of the first MOSFET. 
     This written description uses examples to disclose the embodiments, including the best mode, and also to enable any person skilled in the art to practice the embodiments, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.