Patent Publication Number: US-2022226035-A1

Title: Electrosurgical Generator and Method of Generating Electrosurgical Energy

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of priority to U.S. Provisional Application No. 62/854,380, filed May 30, 2019, the contents of which is hereby incorporated by reference in its entirety. 
    
    
     FIELD 
     The present disclosure generally relates to electrosurgery and, in particular, to an electrosurgical generators and methods of generating electrosurgical energy. 
     BACKGROUND 
     Electrosurgery involves applying a radio frequency (RF) electric current (also referred to as electrosurgical energy) to biological tissue to cut, coagulate, or modify the biological tissue during an electrosurgical procedure. Specifically, an electrosurgical generator generates and provides the electric current to a first electrode, which applies the electric current (and, thus, electrical power) to the tissue. The electric current passes through the tissue and returns to the generator via a second electrode. As the electric current passes through the tissue, an impedance of the tissue converts a portion of the electric current into thermal energy (e.g., via the principles of resistive heating), which increases a temperature of the tissue and induces modifications to the tissue (e.g., cutting, coagulating, ablating, and/or sealing the tissue). Accordingly, an extent to which the tissue is affected by the electrosurgery is related to the electrical power transmitted to the tissue. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The novel features believed characteristic of the illustrative examples are set forth in the appended claims. The illustrative examples, however, as well as a preferred mode of use, further objectives and descriptions thereof, will best be understood by reference to the following detailed description of an illustrative example of the present disclosure when read in conjunction with the accompanying drawings, wherein: 
         FIG. 1  depicts an electrosurgical system, according to an example. 
         FIG. 2  depicts a simplified block diagram of an electrosurgical system, according to an example. 
         FIG. 3  is a plot of a plotline representing a target power over a range of impedance values, according to an example. 
         FIG. 4A  depicts a current measured for a representative feedback cycle, according to an example. 
         FIG. 4B  depicts a voltage measured for the feedback cycle of  FIG. 4A , according to an example. 
         FIG. 5  depicts a simplified block diagram of an electrosurgical system, according to another example. 
         FIG. 6  is a flowchart of a method of generating electrosurgical energy, according to an example. 
         FIG. 7  is a flowchart of a method of generating electrosurgical energy for use with the method of  FIG. 6 , according to an example. 
         FIG. 8  is a flowchart of a method of generating electrosurgical energy for use with the method of  FIG. 6 , according to an example. 
         FIG. 9  is a flowchart of a method of generating electrosurgical energy for use with the method of  FIG. 8 , according to an example. 
         FIG. 10  is a flowchart of a method of generating electrosurgical energy for use with the method of  FIG. 8 , according to an example. 
         FIG. 11  is a flowchart of a method of generating electrosurgical energy for use with the method of  FIG. 8 , according to an example. 
         FIG. 12  is a flowchart of a method of generating electrosurgical energy for use with the method of  FIG. 6 , according to an example. 
         FIG. 13  is a flowchart of a method of generating electrosurgical energy for use with the method of  FIG. 6 , according to an example. 
         FIG. 14  is a flowchart of a method of generating electrosurgical energy for use with the method of  FIG. 13 , according to an example. 
         FIG. 15  is a flowchart of a method of generating electrosurgical energy for use with the method of  FIG. 13 , according to an example. 
         FIG. 16A  is a first portion of a flowchart of a method of generating electrosurgical energy, according to an example. 
         FIG. 16B  is a second portion of the flowchart of a method shown in  FIG. 16B , according to an example. 
     
    
    
     DETAILED DESCRIPTION 
     Disclosed examples will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all of the disclosed examples are shown. Indeed, several different examples may be described and should not be construed as limited to the examples set forth herein. Rather, these examples are described so that this disclosure will be thorough and complete and will fully convey the scope of the disclosure to those skilled in the art. 
     By the term “approximately” or “substantially” with reference to amounts or measurement values described herein, it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide. 
     As noted above, an extent to which the tissue is affected by the electrosurgery is related to the electrical power transmitted to the tissue. An electrosurgical generator may include sensors that can detect a voltage and a current of the electrosurgical energy transmitted to the tissue and use the voltage and the current as a basis for estimating the electrical power transmitted to the tissue. The electrosurgical generator can then use the estimated power as a basis for controlling a power of the electrosurgical energy generated by the electrosurgical generator during an electrosurgical procedure. 
     Conventionally, the electrosurgical generator digitally samples the current and the voltage at a relatively high frequency. This can result in a loss of information that was contained in original analog signals of the current and voltage that were digitally sampled, which can impair the accuracy of the estimated power and the control of the power by the electrosurgical generator. 
     Within examples, the present disclosure provides for an electrosurgical generator that can address at least some of the drawbacks described above. For instance, within examples, the present disclosure provides for an electrosurgical generator that can use analog measurements of the current and the voltage as a basis for determining the power of the electrosurgical energy transmitted to the tissue. By using analog measurements, the electrosurgical generator does not suffer from the loss of information associated with the conventional approaches described above. Accordingly, the electrosurgical generator can more precisely and accurately control the power of the electrosurgical energy to better achieve a desired clinical effect. 
     Referring now to  FIG. 1 , an electrosurgical system  100  is shown according to an example. As shown in  FIG. 1 , the electrosurgical system  100  can include an electrosurgical generator  110  and one or more electrosurgical tools  112 ,  114 ,  116 . In general, the electrosurgical generator  110  can generate electrosurgical energy that is suitable for performing electrosurgery on a patient. More particularly, as described in detail below, the electrosurgical generator  110  can include a power converter that can convert a supply power (e.g., grid power) to an output power, which is suitable for delivering electrosurgical energy to the patient. Also, as described in detail below, the electrosurgical generator  110  can include one or more electrical components that can control a voltage, a current, and/or a frequency of the output power to achieve a desired clinical effect. 
     In one example, the output power can have a frequency that is greater than approximately 100 kilohertz (KHz) to reduce (or avoid) stimulating a muscle and/or a nerve near the target tissue. In another example, the output power can have a frequency that is between approximately 300 kHz and approximately 500 kHz. In another example, the output power can have a frequency between approximately 440 kHz and approximately 500 kHz. In another example, the output power can have a frequency of approximately 472 kHz. 
     The electrosurgical generator  110  can be operable in a plurality of modes of operation. As examples, the modes of operation can include a cutting mode, a coagulating mode, an ablating mode, and/or a sealing mode. The modes of operation can correspond to respective levels of power and/or respective waveforms for the output power. Thus, within examples, the electrosurgical generator  110  can generate the output power with a level of power and/or a waveform respectively selected from a plurality of levels of power and/or a plurality of waveforms based on the mode of operation in which the electrosurgical generator  110  is operated. 
     Within examples, the electrosurgical generator  110  can include a user interface  118  that can receive one or more inputs from a user and/or provide one or more outputs to the user. As examples, the user interface  118  can include one or more buttons, one or more switches, one or more dials, one or more keypads, one or more touchscreens, and/or one or more display screens. In an example, the user interface  118  can be operable to select a mode of operation from among the plurality of modes of operation and/or set a level of power for one or more modes of operation for the electrosurgical generator  110 . As such, the electrosurgical generator  110  can generate the output power with the level of power and/or the waveform respectively selected from the plurality of levels of power and/or the plurality of waveforms based, at least in part, on one or more inputs received via the user interface  118 . 
     As shown in  FIG. 1 , the electrosurgical generator  110  can also include at least one tool input  120  that can facilitate coupling the electrosurgical generator  110  to the one or more electrosurgical tools  112 ,  114 ,  116 . In an example, each electrosurgical tool  112 ,  114 ,  116  can include an electrical conductor  122  having a plug, which can be coupled to a respective socket of the at least one tool input  120 . In this arrangement, the electrosurgical generator  110  can supply the output power to the one or more electrosurgical tools  112 ,  114 ,  116  via the coupling between the at least one tool input  120  of the electrosurgical generator  110  and the electrical conductor  122  of the one or more electrosurgical tools  112 ,  114 ,  116 . 
     In  FIG. 1 , the one or more electrosurgical tools  112 ,  114 ,  116  include a monopolar electrosurgical tool  112 , a dispersive electrode pad  114 , and/or a bipolar electrosurgical tool  116 . The monopolar electrosurgical tool  112  and the dispersive electrode pad  114  can be used to operate the electrosurgical system  100  in a monopolar mode. Whereas, the bipolar electrosurgical tool  116  can be used to operate the electrosurgical system  100  in a bipolar mode. 
     For example, to operate the electrosurgical system  100  in the monopolar mode, the monopolar electrosurgical tool  112  and the dispersive electrode pad  114  can be coupled to respective sockets of the at least one tool input  120  of the electrosurgical generator  110 . The electrosurgical generator  110  can supply electrosurgical energy by providing the output power to the monopolar electrosurgical tool  112 . The monopolar electrosurgical tool  112  can include an active electrode  124  for applying the electrosurgical energy to a target tissue of a patient, and the dispersive electrode pad  114  can include a neutral electrode  126  (also referred to as a “dispersive electrode”) for returning the electrosurgical energy from the target tissue to the electrosurgical generator  110 . The dispersive electrode pad  114  can contact the patient with a surface area that is suitable to mitigate a risk of unintended tissue damage due to the electrosurgical energy flowing through the tissue (i.e., damage to the tissue other than the target tissue). 
     As shown in  FIG. 1 , in some examples, the monopolar electrosurgical tool  112  can include at least one user input device  128  that can select between the modes of operation of the electrosurgical generator  110 . For instance, in one implementation, the at least one user input device  128  can be configured to select between a cutting mode of operation and a coagulation mode of operation. Responsive to actuation of the at least one user input device  128  of the monopolar electrosurgical tool  112 , the monopolar electrosurgical tool  112  can (i) receive the output power with a level of power and/or a waveform corresponding to the mode of operation selected via the at least one user input device  128  and (ii) supply the output power to the active electrode  124 . 
     To operate the electrosurgical system  100  in the bipolar mode, the bipolar electrosurgical tool  116  can be coupled to a respective socket of the at least one tool input  120  of the electrosurgical generator  110 . The bipolar electrosurgical tool  116  can have two active electrodes  130 , and the target tissue can be positioned between the active electrodes. When the electrosurgical generator  110  supplies the electrosurgical energy, (i) one of the active electrodes  130  applies the electrosurgical energy to the target tissue and (ii) the other one of the active electrodes  130  returns the electrosurgical energy to the electrosurgical generator  110 . 
     In some examples, the bipolar electrosurgical tool  116  can include at least one user input device  132  for controlling supply of the electrosurgical energy from the electrosurgical generator  110  to the active electrodes  130  (e.g., starting and/or stopping supplying the electrosurgical energy to the active electrodes  130 ). In other examples, the electrosurgical system  100  can additionally or alternatively include a footswitch for controlling supply of the electrosurgical energy from the electrosurgical generator  110  to the active electrodes  130 . 
     Referring now to  FIG. 2 , a simplified block diagram of the electrosurgical system  100  is shown according to an example. As shown in  FIG. 2 , the electrosurgical system  100  includes the electrosurgical generator  110  and the one or more electrosurgical tools  112 ,  114 ,  116 . Also, as described above, the electrosurgical generator  110  can include the user interface  118  and the at least one tool input  120 . 
     As shown in  FIG. 2 , the electrosurgical generator  110  can also include a power source  234 , a power converter  236 , a plurality of sensors  238 , and a controller  240 . The power source  234  is coupled to the power converter  236 , and the power converter  236  is coupled to the one more electrosurgical tools  112 ,  114 ,  116  via the at least one tool input  120 . Within examples, the power source  234  can be a grid power, a backup generator, a power storage device (e.g., a battery), and/or a renewable power source (e.g., a solar power source, a hydroelectric power source, and/or a windmill). Although  FIG. 2  shows the electrosurgical generator  110  including the power source  234 , the power source  234  can be separate from the electrosurgical generator  110  in other examples. 
     The power converter  236  can convert a supply power received from the power source  234  to the output power, which is suitable for delivering electrosurgical energy to a target tissue  242 . As shown in  FIG. 2 , the power converter  236  is coupled to the controller  240 . The controller  240  can communicate with the power converter  236  (e.g., by transmitting one or more control signals to the power converter  236 ) to control one or more electrical parameters of the output power such as, for example, a voltage, a current, a frequency, a waveform, and/or a duty cycle of the output power. The controller  240  can additionally or alternatively cause the power converter  236  to start and/or stop supplying the output power to the one or more electrosurgical tools  112 ,  114 ,  116 . 
     Within examples, the controller  240  can set and/or adjust the electrical parameter(s) of the output power based on the mode of operation and/or the one or more inputs received via the user interface  118 . Additionally, the controller  240  can set and/or adjust the electrical parameter(s) of the output power based on feedback information received from the sensors  238 . Accordingly, as shown in  FIG. 2 , the controller  240  can be in communication with the sensors  238 . 
     As shown in  FIG. 2 , the sensors  238  can include a current sensor  244  and a voltage sensor  246 . The current sensor  244  can sense a current of the output power and generate a logarithmic and analog representation of the current. For instance, in  FIG. 2 , the current sensor  244  can be a logarithmic root-mean-square (RMS) current detector that is coupled in series with a first conductor  248  transmitting the output power from the power converter  236  to the one or more electrosurgical tools  112 ,  114 ,  116  via the at least one tool input  120 . Thus, in this example, the current sensor  244  can sense the current of the output power as a RMS current value. Sensing the current of the output power as the RMS current value can help to simplify one or more calculations performed by the controller  240 . 
     The voltage sensor  246  can sense a voltage of the output power and generate a logarithmic and analog representation of the voltage. For instance, in  FIG. 2 , the voltage sensor  246  can be a logarithmic RMS voltage detector that is coupled in parallel with the power converter  236  (e.g., coupled between the first conductor  248  and a second conductor  250 , which transmits the electrosurgical energy from the one or more electrosurgical tools  114 ,  116  back to the electrosurgical generator  110  via the at least one tool input  120 ). Thus, in this example, the current sensor  244  can sense the current of the output power as a RMS voltage value. Sensing the voltage of the output power as the RMS voltage value can help to simplify one or more calculations performed by the controller  240 . 
     As noted above, the controller  240  can set and/or adjust the electrical parameter(s) of the output power based on feedback information received from the current sensor  244  and the voltage sensor. More particularly, the controller  240  is configured to (i) receive the logarithmic and analog representation of the current sensed by the current sensor  244 , (ii) receive the logarithmic and analog representation of the voltage sensed by the voltage sensor  246 , and (iii) adjust, based on the logarithmic and analog representation of the current and the voltage, a voltage of the output power. 
     In one example, the controller  240  can determine whether to adjust the voltage and/or determine an amount to adjust the voltage of the output power based on a plurality of the logarithmic and analog representations of the current and a plurality of the logarithmic and analog representations of the voltage over a sampling interval. This can allow the controller  240  to adjust the voltage of the output power based on a greater amount of information, which can help the electrosurgical generator  110  deliver the output power to the target tissue  242  with greater accuracy and precision and, thus, better achieve the desired clinical effect. 
     In an implementation, to adjust the voltage of the output power, the controller can determine, based on the logarithmic and analog representation of the current, a plurality of analog current values at a plurality of time points during a sampling interval, and determine, based on the logarithmic and analog representation of the voltage, a plurality of analog voltage values at the plurality of time points during the sampling interval. Additional details relating to the controller  240  determining the plurality of analog current values, the plurality of analog voltage values, the average current, and the average voltage will be described below with respect to  FIGS. 4A-4B . 
     The controller  240  can then determine an average current value by averaging the plurality of analog current values, and determine an average voltage value by averaging the plurality of analog voltage values. For example, to determine the average current value, the controller  240  can sum the plurality of analog current values and divide the sum by a quantity of the plurality of analog current values. Similarly, to determine the average voltage value, the controller  240  can sum the plurality of analog voltage values and divide the sum by a quantity of the plurality of analog voltage values. 
     In an example, to facilitate summing the analog current values and the analog voltage values, the controller  240  can store digital representations of the analog current values and the analog voltage values in a memory of the controller  240 . In such example, the controller  240  can include one or more analog-to-digital converters (ADC) to convert the analog current values and the analog voltage values to the digital representations. In contrast to conventional approaches that digitally sample the current and the voltage, the electrosurgical generator  110  can determine analog measurements of the current and the voltage at discrete time points and then store the analog measurements as digital values. As such, unlike the conventional approaches, the electrosurgical generator  110  does not suffer from the same loss of information challenges encountered using such conventional approaches. 
     After determining the average current value and the average voltage value, the controller  240  can use the average current value and the average voltage value as a basis for determining whether to adjust the voltage of the output power and/or the amount to adjust the voltage of the output power. For instance, the controller  240  can determine, based on the average current value and the average voltage value, at least one of a power value or an impedance value. The controller  240  can determine the power value using equation  1  below: 
     
       
         
           
             
               
                 
                   P 
                   = 
                   
                     
                       V 
                       avg 
                     
                     * 
                     
                       I 
                       avg 
                     
                   
                 
               
               
                 
                   ( 
                   
                     eq 
                     . 
                     
                         
                     
                     ⁢ 
                     1 
                   
                   ) 
                 
               
             
           
         
       
     
     where P is the power value, V avg  is the average voltage value, and I avg  is the average current value. The controller  240  can determine the impedance value using Ohm&#39;s law represented by equation 2 below: 
     
       
         
           
             
               
                 
                   Z 
                   = 
                   
                     
                       V 
                       
                         a 
                         ⁢ 
                         v 
                         ⁢ 
                         g 
                       
                     
                     / 
                     
                       I 
                       
                         a 
                         ⁢ 
                         v 
                         ⁢ 
                         g 
                       
                     
                   
                 
               
               
                 
                   ( 
                   
                     eq 
                     . 
                     
                         
                     
                     ⁢ 
                     2 
                   
                   ) 
                 
               
             
           
         
       
     
     where Z is the impedance value, V avg  is the average voltage value, and I avg  is the average current value. After determining the power value and the impedance value, the controller  240  can adjust, based on the at least one of the power value or the impedance value, the voltage of the output power. 
     For example, the controller  240  can store a plurality of target power values and a plurality of measured impedance values, where each target power value corresponds to a respective one of the measured impedance values. The target power value can relate to a desired power of the output power for a measured impedance of the target tissue, which can achieve a desired clinical outcome during electrosurgery. In some examples, the target power values can be based on one or more user inputs received via the user interface  118  of the electrosurgical generator  110 . 
     In practice, the power value determined by the controller  240  can deviate from the target power value corresponding to the impedance value determined by the controller  240 . The controller  240  can be configured to adjust the voltage of the output power to compensate for the difference between the power value (i.e., the actual measured power of the output power) and the target power value for the impedance value (i.e., the actual measured impedance of the target tissue). 
     To illustrate,  FIG. 3  depicts a graphical representation of the target power values plotted against a plurality of impedance values, according to an example. In particular,  FIG. 3  shows a plotline  354  that indicates the target power value that corresponds to each impedance value for this example. In  FIG. 3 , a measured data point  356  shows the actual power value (P actual ) and the impedance value (Z actual ) determined by the controller  240  for an example feedback cycle of the controller  240  (e.g., based on the average current and the average voltage as described above). 
     As shown in  FIG. 3 , the measured data point  356  is not on the plotline  354 . Rather, in  FIG. 3 , the plotline  354  includes a target data point  358  corresponding to a target power (P target ) at the impedance value (Z actual ). Accordingly, as shown in  FIG. 3 , there is a power difference  360  (P diff ) between (i) the actual power (P actual ) determined by the controller  240  at the impedance value determined by the controller  240  (Z actual ), and (ii) the target power (P target ) at the impedance value determined by the controller  240  (Z actual ). 
     Within examples, the controller  240  can adjust the power of the output power to reduce or eliminate the power difference (P diff ) between the actual power (P actual ) and the target power (P target ). In one implementation, the controller  240  can first decide based on the impedance value and the power value whether to adjust the power of the output power or maintain the power of the output power. For instance, the controller  240  can look up the impedance value in a table  252  to identify a target power value that corresponds to the impedance value, and perform a comparison of the power value determined by the controller  240  and the target power value to determine whether to adjust or maintain the power of the output power. In an example, the controller  240  can compare the power value and the target power value by determining a difference between the power value and the target value. If the controller  240  determines that the difference is less than the threshold value, the controller  240  can decide to maintain the voltage of the output power. Whereas, if the controller  240  determines that the difference is greater than a threshold value, the controller  240  can decide to adjust the voltage of the output power. As an example, the threshold value can be between 0 percent and approximately 5 percent of the target power value. 
     If the decision is to adjust the power of the output power, then the controller  240  can also determine, based on the comparison, an adjusted voltage value. As one example, the controller  240  can determine the adjusted voltage value based on the target power value and the power value determined by the controller  240  (i.e., based on the average current and the average voltage). The controller  240  can then adjust the voltage of the output power to the adjusted voltage value. Responsive to the controller  240  deciding to adjust the voltage of the output power and/or determining the adjusted voltage value, the controller  240  can transmit a control signal to the power converter  236  to cause the power converter  236  to adjust the voltage of the output power (e.g., adjust the voltage of the output power to the adjusted voltage value). For instance, the controller  240  can (i) reduce the voltage of the output power responsive to the controller  240  determining that the power value is greater than the target power value, and (ii) increase the voltage of the output power responsive to the controller  240  determining that the power value is less than the target power value. 
     In another implementation, to adjust the voltage of the output power, the controller  240  can additionally or alternatively be configured to look up the power value and the impedance value (determined by the controller  240  as described above) in the table  252  to identify an adjusted voltage value that corresponds to the power value and the impedance value, and the controller  240  can adjust the voltage of the output power to the adjusted voltage value. The table  252  can be stored in the memory of the controller  240 . The table  252  can map various adjusted voltage values to corresponding power values and impedance values. For instance, each adjusted voltage value can relate to a level of voltage that can achieve the target power corresponding to a respective one of the impedance values. In this arrangement, the controller  240  can be programmed to refer to the table  252  to select the adjusted voltage value that corresponds to the combination of the power value and the impedance value determined by the controller  240  based on the average current value and the average voltage value. 
     Within examples, the controller  240  can (i) determine the analog current values, the analog voltage values, the average current value, the average voltage value, the impedance value, and/or the power value and (ii) adjust or maintain the power of the output power on a periodic basis during an electrosurgery procedure. For instance, the controller  240  can perform the above-described operations during each feedback cycle of a series of feedback cycles to control the power of the output power during the electrosurgery procedure. In one implementation, each feedback cycle be performed within a respective time window having a duration between approximately 2 milliseconds (ms) and approximately 2.5 ms. In this implementation, the sampling interval during which the controller  240  determines the analog current values and the voltage current values can occur for only a portion of the time window such as, for example, over a period of time of approximately 132 microseconds. 
       FIGS. 4A-4B  graphically depict a representative feedback cycle that can be performed by the controller  240 , according to an example. Specifically,  FIG. 4A  depicts a plot of the logarithmic and analog representations of the current  462  sensed by the current sensor  244  over time, and  FIG. 4B  depicts a plot of the logarithmic and analog representations of the voltage  464  sensed by the voltage sensor  246  over time. Additionally,  FIGS. 4A-4B  show a time window  466  having a duration of approximately 2 ms to approximately 2.5 ms. 
     During a sampling interval  468  of the time window  466 , the controller  240  can determine the analog current values  470  and the analog voltage values  472 . In this example, the controller  240  can determine 32 analog current values  470  and 32 analog voltage values  472 , and the sampling interval is approximately  132  microseconds. However, the controller  240  can determine a lesser quantity or a greater quantity of the analog current values  470  and the analog voltage values  472  during the sampling interval  468  in other examples. Similarly, in other examples, the sampling interval  468  can be a lesser amount of time or a greater amount of time than 132 microseconds. 
     As noted above, the analog current values  470  and the analog voltage values  472  can be RMS current values and RMS voltage values in one example. Also, as described above, the controller  240  can then average the analog current values by summing the analog current values and dividing the sum by the quantity of samples (i.e., 32). Similarly, the controller  240  can average the analog voltage values by summing the analog voltage values and dividing the sum by the quantity of samples (i.e., 32). The controller  240  can then use the average current value and the average voltage value to determine the impedance value and/or the power value, and use the impedance value and/or the power value as a basis for adjusting or maintaining the power of the output power for the feedback cycle. 
     Within examples, the controller  240  can cause the power converter  236  to adjust the voltage of the output power responsive to the controller  240  making a decision to adjust the power of the output power. As shown in  FIGS. 4A-4B , after determining the analog current values  470  and the analog voltage values  472 , the controller  240  can wait for a period of time for the feedback cycle to end, and a next feedback cycle in the series to begin. When the next feedback cycle begins, the controller  240  can repeat the process of (i) determining the analog current values  470 , the analog voltage values  472 , the average current value, the average voltage value, the impedance value, and/or the power value, and (ii) adjusting or maintaining the power of the output power. As described above, the controller  240  can perform the series of feedback cycles on a periodic basis and, thus, the next feedback cycle can occur over another time window of approximately 2 ms to approximately 2.5 ms (i.e., every feedback cycle in the series can have the same duration). 
     As described above, the controller  240  can use the impedance value as a basis for deciding whether to adjust the power of the output power, and determining an amount to adjust the power of the output power. As described in further detail below, the controller  240  can also be configured to cause, based on the impedance value, the power converter  236  to stop the output power. 
     As described above, the controller  240  can control operation of the electrosurgical generator  110 . Within examples, the controller  240  can be implemented using hardware, software, and/or firmware. For instance, the controller  240  can include one or more processors and a non-transitory computer readable medium (e.g., volatile and/or non-volatile memory) that stores machine language instructions or other executable instructions. The instructions, when executed by the one or more processors, cause the electrosurgical generator  110  to carry out the various operations described herein. The controller  240 , thus, can receive data and store the data in the memory as well. 
     Referring now to  FIG. 5 , a simplified block diagram of the electrosurgical generator  110  is shown according to another example. In particular,  FIG. 5  shows additional components for one example implementation of the block diagram shown in  FIG. 2 . For instance, as shown in  FIG. 5 , the power source  234  can include a power supply  534 A and a plurality of voltage regulators  534 B- 534 D, and the power converter  236  can include a switched-mode power supply (SMPS)  536 A, a modulating gate  536 B, a cut-off gate  536 C, an output stage  536 D, and a cut/coag circuit  536 E. Also, as shown in  FIG. 5 , the controller  240  can include a supervisor microprocessor  540 A and a driver microprocessor  540 B, and the sensors  238  can include a bipolar sense module  538 A, a mono sense module  538 B, and a neutral sense module  538 C. 
     In this example, the power supply  534 A can receive a grid power  574  (e.g., from a wall outlet), and use the grid power  574  to supply a plurality of powers to various components of the electrosurgical generator  110 . For instance, the power supply  534 A can include a first output that provides the supply power to the power converter  236  and a second output that provides another power signal to the voltage regulators  534 B- 534 D. Thus, in this example, the power source can be operable to perform an initial power conversion to convert the grid power  574  to the supply power, which the power converter  236  can convert to the output power as described above. The voltage regulators  534 B- 534 D can help regulate the other power signal at a plurality of different voltage levels for operating various components of the electrosurgical generator  110  (e.g., a 12 volt signal, a 5 volt signal, and a 3.3 volt signal). 
     As shown in  FIG. 5 , the SMPS  536 A of the power converter  236  can receive the supply power from the power source  234  (e.g., via the power supply  534 A and the voltage regulator  534 C). In an example, the SMPS  536 A can provide to the output stage  536 D a power signal  578  with a voltage between approximately 5 volts and approximately 83 volts based on a control signal  576  provided by the driver microprocessor  540 B to the SMPS  536 A. In one implementation, the control signal  576  can be a digital-to-analog (DAC) signal having a voltage between approximately 0 volts and approximately 3 volts for controlling the SMPS  536 A. In this way, the controller  240  can set and/or adjust a voltage of the output power provided by the output stage  536 D of the power converter  236 . 
     The driver microprocessor  540 B can also transmit a modulation signal  580  to the output stage  536 D via the modulation gate  536 B and the cut-off gate  536 C. The modulation gate  536 B can use the modulation signal  580  to modulate the output power provided by the output stage  536 D (e.g., a MOSFET-based component and/or one or more transformers of the output stage  536 D). In this example, the modulation signal  580  causes the output stage  536 D to provide the output power with a frequency of approximately 470 kHz. However, as described, the modulation signal  580  can cause the output stage  536 D to provide the output power with a different frequency in other examples. 
     As described above, the controller  240  can set and/or adjust the electrical parameter(s) of the output power based on the mode of operation and/or the one or more inputs received via the user interface  118 . As shown in  FIG. 5 , the user interface  118  can be in communication with the supervisor microprocessor  540 A (e.g., via one or more communication terminals  582 ), and the supervisor microprocessor  540 A can be in communication with the driver microprocessor  540 B. In this arrangement, the supervisor microprocessor  540 A can receive the input(s) from the user interface  118  (e.g., relating to a level of power and/or a mode of operation), the supervisor microprocessor  540 A can communicate to the driver microprocessor  540 B control data based on the input(s), and the driver microprocessor  540 B can transmit the control signal  576  and/or the modulation signal  580  based, at least in part, on the control data. 
     Within examples, the supervisor microprocessor  540 A can perform additional operations. For instance, the supervisor microprocessor  540 A can monitor one or more subsystems of the electrosurgical generator  110  to determine when a fault condition occurs. As examples, the supervisor microprocessor  540 A is in communication with a temperature sensor  584 A, a DAC sensor  584 B, and one or more power source sensors  584 C. In this arrangement, the supervisor microprocessor  540 A can receive sensor information from the temperature sensor  584 A, the DAC sensor  584 B, and the one or more power source sensors  584 C, and determined, based on the sensor information, when the fault condition occurs. As examples, the fault condition can include an overheating condition, a DAC signal fault, and/or a fault relating to the power source  234 . Responsive to the supervisor microprocessor  540 A determining that a fault condition has occurred, the supervisor microprocessor  540 A can cause the cut-off gate  536 C of the power converter  236  to stop the output stage  536 D providing the output power (e.g., based on the impedance value determined by the controller  240 ). 
     In  FIG. 5 , the supervisor microprocessor  540 A can additionally or alternatively control one or more subsystems of the electrosurgical generator  110 . For example, in  FIG. 5 , the supervisor microprocessor  540 A is in communication with and operable to control a fan  586  of the electrosurgical generator  110 . In one implementation, the supervisor microprocessor  540 A can start, stop, speed up, and/or slow down the fan  586  based on sensor information received from the temperature sensor  584 A. 
     In  FIG. 5 , the electrosurgical generator  110  is operable in a manual bipolar mode, an automatic bipolar mode, and a monopolar mode. As such, the at least one tool input  120  includes a bipolar input  520 A, a monopolar input  520 B, and a neutral input  520 C that can be coupled to the output stage  536 D. The bipolar input  520 A can couple to the bipolar electrosurgical tool  116  (shown in  FIGS. 1-2 ), the monopolar input  520 B can couple to the monopolar electrosurgical tool  112  (shown in  FIGS. 1-2 ), and the neutral input  520 C can couple to the dispersive electrode pad  114  (shown in  FIGS. 1-2 ). 
     As shown in  FIG. 5 , the bipolar input  520 A can include a first terminal and a second terminal that can couple the bipolar electrosurgical tool  116  to the output stage  536 D via the bipolar sense module  538 A. The bipolar sense module  538 A can include one or more current sensors and/or one or more voltage sensors (e.g., the current sensor  244  and the voltage sensor  246  in  FIG. 2 ) for sensing the current and the voltage of the output power, respectively, when operating the electrosurgical generator  110  in a bipolar mode (as described above). 
     Additionally, the bipolar input  520 A can include a third terminal that can be in communication with the controller  240  (e.g., the driver microprocessor  540 B) via a bipolar switch sense module  588 . The third terminal can also be in communication with the at least one user input device  132  (shown in  FIG. 1 ) on the bipolar electrosurgical tool  116 . Thus, the third terminal of the bipolar input  520 A and the bipolar switch sense module  588  can be operable to determine and communicate to the controller  240  when the at least one user input device  132  is actuated so that the electrosurgical generator  110  can provide the output power with the corresponding waveform and/or power level for performing electrosurgery in the bipolar mode and using the bipolar electrosurgical tool  116 . Within examples, the electrosurgical generator  110  can be additionally or alternatively operated in the bipolar mode using a footswitch  590 , which is in communication with the controller  240  (e.g., the driver microprocessor  540 B). 
     When the electrosurgical generator  110  is operated in the manual bipolar mode, an electrosurgical procedure is initiated responsive to the user actuating the at least one user input device  132  and/or the footswitch  590 . In particular, when the at least one user input device  132  and/or the footswitch  590  is actuated, the driver microprocessor  540 B of the controller  240  can cause the power converter  236  to provide the output power to the bipolar electrosurgical tool  116  via the bipolar sense module  538 A and the bipolar input  520 A. While the power converter  236  provides the output power, the bipolar sense module  538 A senses the current and the voltage of the output power and generates the logarithmic and analog representations of the current and the voltage, as described above. Also, while the power converter  236  provides the output power, the driver microprocessor  540 B receives the logarithmic and analog representations of the current and the voltage, and performs the series of feedback cycles to control the power of the output power as described above. In the manual bipolar mode, the power converter  236  can stop providing the output power responsive to the operator ceasing actuation of the at least one user input device  132  and/or the footswitch  590 . 
     As noted above, the electrosurgical generator  110  can also be operated in an automatic bipolar mode. In the automatic bipolar mode, the electrosurgical generator  110  can automatically start and/or stop the electrosurgical procedure (i.e., automatically start and/or stop providing the output power to the bipolar electrosurgical tool  116 ). 
     Within examples, the controller  240  can be operable to cause the power converter  236  to automatically start providing the output power at the output stage  536 D based on an analysis of a secondary power signal. For instance, as shown in  FIG. 5 , the bipolar sense module  538 A can also be coupled to a secondary power source  594 . The secondary power source  594  can provide the secondary power signal to the at least one tool input  120  (e.g., the first terminal and the second terminal of the bipolar input  520 A) to apply the secondary power signal to the target tissue  242  (shown in  FIG. 2 ). In general, the secondary power signal has a power and/or a frequency that is less than a power and/or a frequency of the output power. More particularly, the secondary power source can provide the secondary power signal with a power and/or a frequency that is not suitable for performing electrosurgery on the target tissue  242 . As an example, the frequency of the secondary power signal can be between approximately 50 kHz and approximately 75 kHz. 
     The bipolar sense module  538 A can sense and communicate to the controller  240  a secondary current of the secondary power signal and sense a secondary voltage of the secondary power signal. The driver microprocessor  540 B of the controller  240  can determine a secondary impedance value based on the secondary current and the secondary voltage (e.g., based on Ohm&#39;s law). The driver microprocessor  540 B of the controller  240  can then cause, based on the secondary impedance value, the power converter  236  to start providing the output power to the bipolar electrosurgical tool  116 . 
     In one example, the driver microprocessor  540 B of the controller  240  can perform a comparison of the secondary impedance value to a reference impedance value. If the secondary impedance value is less than the reference impedance value, the driver microprocessor  540 B can decide to not start providing the output power. Whereas, if the secondary impedance value is greater than the reference impedance value, the driver microprocessor  540 B can decide to start providing the output power. Responsive to the driver microprocessor  540 B deciding to start providing the output power, the driver microprocessor  540 B can provide the control signal  576  and/or the modulation signal  580  to the power converter  236  to cause the power converter  236  to start providing the output power at the output stage  536 D. 
     Within examples, the driver microprocessor  540 B of the controller  240  can automatically stop providing the output power based on an impedance determined based on the output power (i.e., as opposed to the secondary power signal). In one example, the driver microprocessor  540 B can determine the impedance value based on the average current value of the output power and the average voltage value of the output power, as described above. The driver microprocessor  540 B of the controller  240  can then perform a comparison of the impedance value to a second reference impedance value. If the impedance value is less than the second reference impedance value, the driver microprocessor  540 B can decide to continue providing the output power. Whereas, if the impedance value is greater than the second reference impedance value, the driver microprocessor  540 B can decide to stop providing the output power. Responsive to the driver microprocessor  540 B deciding to stop providing the output power, the driver microprocessor  540 B can provide the control signal  576  and/or the modulation signal  580  to the power converter  236  to cause the power converter  236  to stop providing the output power at the output stage  536 D. 
     In another example, the bipolar sense module  538 A can additionally or alternatively sense a phase of the impedance of the output power and/or a magnitude of the impedance of the output power. The bipolar sense module  538 A can communicate the phase of the impedance and/or the magnitude of the impedance of the output power to the driver microprocessor  540 B, and the driver microprocessor  540 B can use the phase of the impedance and/or the magnitude of the impedance as a basis for determining when to stop providing the output power. For instance, the driver microprocessor  540 B can determine a real component of the impedance based on the phase of the impedance and/or the magnitude of the impedance, and then perform a comparison of the real component of the impedance to the second reference impedance value as described above. This can beneficially help to take into account an impedance and/or a capacitance of the electrical conductor  122  between the bipolar input  520 A and the bipolar electrosurgical tool  116 . 
     As also noted above, the electrosurgical generator  110  can be operated in a manual mode. For instance, as shown in  FIG. 5 , the monopolar input  520 B can include a first terminal that can couple the monopolar electrosurgical tool  112  to the output stage  536 D via the mono sense module  538 B. The mono sense module  538 B can include one or more current sensors and/or one or more voltage sensors (e.g., the current sensor  244  and the voltage sensor  246  in  FIG. 2 ) for sensing the current and the voltage of the output power, respectively, when operating the electrosurgical generator  110  in a monopolar mode (as described above). 
     The monopolar input  520 B can also include a second terminal and a third terminal that can be in communication with the controller  240  (e.g., the driver microprocessor  540 B) via a cut/coag sense module  592 . The second terminal and the third terminal of the monopolar input  520 B can also be in communication with respective input devices of the at least one user input device  128  (shown in  FIG. 1 ) on the monopolar electrosurgical tool  112 . Thus, the cut/coag sense module  592  can be operable to determine and communicate to the controller  240  when the at least one user input device  128  is actuated so that the electrosurgical generator  110  can provide the output power with the corresponding waveform and/or power level for performing electrosurgery in the cut mode or the coag mode and using the monopolar electrosurgical tool  112 . 
     Responsive to actuating the at least one user input device  128 , the driver microprocessor  540 B of the controller  240  can also actuate the cut/coag circuit  536 E to configure the power converter  236  for the selected mode of operation. For instance, the cut/coag circuit  536 E can include one or more electrical components that can facilitate the output stage  536 D providing the output power with the one or more electrical parameters that are suitable for operating the electrosurgical generator  110  in a cut mode of operation and/or a coagulation mode of operation. In one example, the driver microprocessor  540 B can communicate a second control signal to cause the cut/coag circuit  536 E to open and/or close a switch to connect or disconnect the electrical components of the cut/coag circuit  536 E. 
     The neutral input  520 C can include a first terminal and a second terminal that can couple to the dispersive electrode pad  114  to the output stage  536 D. As such, the neutral input  520 C can facilitate returning the electrosurgical energy delivered to the target tissue  242  (shown in  FIG. 2 ) via the monopolar electrosurgical tool  112 . 
     When the electrosurgical generator  110  is operated in the monopolar mode, an electrosurgical procedure is initiated responsive to the user actuating the at least one user input device  128 . In particular, when the at least one user input device is actuated, the driver microprocessor  540 B of the controller  240  can cause the power converter  236  to provide the output power to the monopolar electrosurgical tool  112  via the monopolar input  520 B and return the electrosurgical energy via the neutral input  520 C. While the power converter  236  provides the output power, the mono sense module  538 B senses the current and the voltage of the output power and generates the logarithmic and analog representations of the current and the voltage, as described above. Also, while the power converter  236  provides the output power, the driver microprocessor  540 B receives the logarithmic and analog representations of the current and the voltage, and performs the series of feedback cycles to control the power of the output power as described above. In the monopolar mode, the power converter  236  can stop providing the output power responsive to the operator ceasing actuation of the at least one user input device  128 . 
     Within examples, the electrosurgical generator  110  can be configured to use the secondary power signal from the secondary power source to determine that the dispersive electrode pad  114  sufficiently contacts the patient. For instance, as shown in  FIG. 5 , the first terminal and the second terminal of the neutral input  520 C can be coupled to the neutral sense module  538 C. The neutral sense module  538 C can include one or more current sensors and/or one or more voltage sensors (e.g., the current sensor  244  and the voltage sensor  246  in  FIG. 2 ) for sensing the secondary current and the secondary voltage of the secondary power signal, respectively, before, during, and/or after providing the output power to the target tissue  242  (as described above). 
     The neutral sense module  538 C can communicate the secondary current and/or the secondary voltage of the second power signal to the controller  240  (e.g., the driver microprocessor  540 B), and the controller  240  can determine the secondary impedance value based on the secondary current and the secondary voltage, as described above. The controller  240  can perform a comparison of the secondary impedance value to a third reference impedance value. If the secondary impedance value is greater than the third reference impedance value, the driver microprocessor  540 B can decide that a fault condition has not occurred. Whereas, if the secondary impedance value is less than the third reference impedance value, the driver microprocessor  540 B can decide that the fault condition has occurred. 
     Responsive to the driver microprocessor  540 B determining that the fault condition has occurred, the driver microprocessor  540 B can provide the control signal  576  and/or the modulation signal  580  to the power converter  236  to cause the power converter  236  to stop providing the output power at the output stage  536 D. Additionally, the controller  240  (e.g., the driver microprocessor  540 B and/or the supervisor microprocessor  540 A) can cause an output device  597  to generate at least one of a visual alarm or an audio alarm. In this way, the output device  597  can be configured to generate the at least one of a visual alarm or an audio alarm based on the secondary impedance value. 
     As shown in  FIG. 5 , the electrosurgical generator  110  can include a relay control  596  and a plurality of switches  598  that can facilitate operating the electrosurgical generator  110  in the manual bipolar mode, the automatic bipolar mode, and the monopolar mode. For instance, the bipolar input  520 A, the monopolar input  520 B, and/or the neutral input  520 C can each be coupled to the power converter  236  by respective ones of the switches  598 . Each switch  598  can be actuated between a closed state in which the switch  598  couples the power converter  236  to the at least one tool input  120  corresponding to the switch  598 , and an open state in which the switch  598  decouples the power converter  236  from the at least one tool input  120  corresponding to the switch  598 . 
     The relay control  596  is in communication with the driver microprocessor  540 B and the switches  598 . In this arrangement, when the at least one user input device  128  is actuated, the driver microprocessor  540 B can cause the relay control  596  to actuate the switches  598  such that the monopolar input  520 B and the neutral input  520 C are coupled to the power converter  236  and the bipolar input  520 A is decoupled from the power converter  236 . Whereas, when the at least one user input device  132  and/or the footswitch  590  is actuated, the driver microprocessor  540 B can cause the relay control  596  to actuate the switches  598  such that the monopolar input  520 B and the neutral input  520 C are decoupled to the power converter  236  and the bipolar input  520 A is coupled from the power converter  236 . 
     Referring now to  FIG. 6 , a flowchart for a process  600  of generating electrosurgical energy is shown according to an example. As shown in  FIG. 6 , the process  600  includes converting a supply power received from a power source to an output power at block  610 . The output power is suitable for delivering electrosurgical energy. At block  612 , the process  600  includes sensing, using a current sensor, a current of the output power. At block  614 , the process  600  includes generating a logarithmic and analog representation of the current sensed by the current sensor. At block  616 , the process  600  includes sensing, using a voltage sensor, a voltage of the output power. At block  618 , the process  600  includes generating a logarithmic and analog representation of the voltage sensed by the voltage sensor. At block  620 , the process  600  includes adjusting, using a controller and based on the logarithmic and analog representation of the current and the voltage, a voltage of the output power. 
       FIGS. 7-15  depict additional aspects of the process  600  according to further examples. As shown in  FIG. 7 , sensing the current of the output power at block  612  can include sensing, using a logarithmic RMS current detector, the current of the output power as a RMS current value at block  622 . Also, as shown in  FIG. 7 , sensing the voltage of the output power at block  616  can include sensing, using a logarithmic RMS voltage detector, the voltage of the output power as a RMS voltage value at block  624 . 
     As shown in  FIG. 8 , adjusting the voltage of the output power at block  620  can include (i) determining, based on the logarithmic and analog representation of the current, a plurality of analog current values at a plurality of time points during a sampling interval at block  626 , (ii) determining, based on the logarithmic and analog representation of the voltage, a plurality of analog voltage values at the plurality of time points during the sampling interval at block  628 , (iii) determining an average current value by averaging the plurality of analog current values at block  630 , (iv) determining an average voltage value by averaging the plurality of analog voltage values at block  632 , (v) determining, based on the average current value and the average voltage value, at least one of a power value or an impedance value at block  634 , and (vi) adjusting, based on the at least one of the power value or the impedance value, the voltage of the output power at block  636 . 
     As shown in  FIG. 9 , adjusting the voltage of the output power at block  636  can further include performing a comparison of the power value to a target power value at block  638 , determining, based on the comparison, an adjusted voltage value at block  640 , and adjusting the voltage of the output power to the adjusted voltage value at block  642 . 
     As shown in  FIG. 10 , adjusting the voltage of the output power at block  636  can include looking up the impedance value in a table to identify the target power value that corresponds to the impedance value at block  644 . 
     As shown in  FIG. 11 , the process  600  can further include making a determination, based on the impedance value, to stop providing the output power to at least one tool input at block  648  and, responsive to the determination at block  648 , stopping providing the output power to the at least one tool input at block  650 . 
     As shown in  FIG. 12 , converting the supply power to the output power at block  610  can include generating the output power with a frequency between approximately 440 kHz and approximately 500 kHz at block  652 . 
     As shown in  FIG. 13 , the process  600  can further include providing a secondary power signal to at least one tool input configured to at least one electrosurgical tool at block  654 . The secondary power signal can have a frequency that is less than a frequency of the output power. The process  600  can also include determining, using the current sensor, a secondary current of the secondary power signal at block  656 . Additionally, the process  600  can include determining, using the voltage sensor, a secondary voltage of the secondary power signal at block  658 . The process  600  can also include determining a secondary impedance value based on the secondary current and the secondary voltage at block  660 . 
     As shown in  FIG. 14 , the process  600  can further include making a determination, based on the secondary impedance value, to start providing the output power to the at least one tool input at block  662 . Responsive to the determination at block  662 , the process  600  can include starting to provide the output power to the at least one tool input at block  664 . 
     As shown in  FIG. 15 , the process  600  can further include making a determination, based on the secondary impedance value, that a fault condition has occurred at block  666 . Responsive to the determination at block  666 , the process  600  can include generating at least one of a visual alarm or an audio alarm at block  668 . 
     Referring now to  FIGS. 16A-16B , a flowchart for a process  1600  of generating electrosurgical energy is shown according to an example. As shown in  FIGS. 16A-16B , the process  1600  can include providing an output power from an electrosurgical generator to an electrosurgical tool at block  1610 . The process  1600  can also include sensing, using a current sensor, a current of the output power at block  1612  and generating a logarithmic and analog representation of the current sensed by the current sensor at block  1614 . The process  1600  can further include sensing, using a voltage sensor, a voltage of the output power at block  1616  and generating a logarithmic and analog representation of the voltage sensed by the voltage sensor at block  1618 . 
     Additionally, the process  1600  can include performing, using the logarithmic and analog representation of the current and the logarithmic and analog representation of the voltage, a series of feedback cycles to control a power of the output power at block  1620 . Each feedback cycle can include (i) determining, based on the logarithmic and analog representation of the current, a plurality of analog current values at a plurality of time points during a sampling interval of the feedback cycle at block  1622 , (ii) determining, based on the logarithmic and analog representation of the voltage, a plurality of analog voltage values at the plurality of time points during the sampling interval of the feedback cycle at block  1624 , (iii) determining an average current value by averaging the plurality of analog current values for the sampling interval of the feedback cycle at block  1626 , (iv) determining an average voltage value by averaging the plurality of analog voltage values for the sampling interval of the feedback cycle at block  1628 , (v) determining, based on the average current value and the average voltage value, at least one of an impedance value and a power value at block  1630 , (vi) deciding, based on the at least one of the impedance value and the power value, whether to adjust a power of the output power for a next feedback cycle in the series of feedback cycles or maintain the power of the output power for the next feedback cycle at block  1632 , (vii) if the decision is to adjust the power at block  1632 , then adjusting a voltage of the output power for the next feedback cycle at block  1634 , and (viii) if the decision is to maintain the power at block  1632 , then maintaining the voltage of the output power for the next feedback cycle at block  1636 . For at least one feedback cycle in the series of feedback cycles, the decision at block  1632  is to adjust the power of the output power. 
     One or more of the blocks shown in  FIGS. 6-16B  may represent a module, a segment, or a portion of program code, which includes one or more instructions executable by a processor for implementing specific logical functions or steps in the process. The program code may be stored on any type of computer readable medium or data storage, for example, such as a storage device including a disk or hard drive. Further, the program code can be encoded on a computer-readable storage media in a machine-readable format, or on other non-transitory media or articles of manufacture. The computer readable medium may include non-transitory computer readable medium or memory, for example, such as computer-readable media that stores data for short periods of time like register memory, processor cache and Random Access Memory (RAM). The computer readable medium may also include non-transitory media, such as secondary or persistent long term storage, like read only memory (ROM), optical or magnetic disks, compact-disc read only memory (CD-ROM), for example. The computer readable media may also be any other volatile or non-volatile storage systems. The computer readable medium may be considered a tangible computer readable storage medium, for example. 
     In some instances, components of the devices and/or systems described herein may be configured to perform the functions such that the components are actually configured and structured (with hardware and/or software) to enable such performance. Example configurations then include one or more processors executing instructions to cause the system to perform the functions. Similarly, components of the devices and/or systems may be configured so as to be arranged or adapted to, capable of, or suited for performing the functions, such as when operated in a specific manner. 
     Further, the disclosure comprises examples according to the following clauses: 
     Clause 1: In an example, an electrosurgical generator is described. The electrosurgical generator includes a power converter configured to convert a supply power received from a power source to an output power. The output power is suitable for delivering electrosurgical energy. The electrosurgical generator also includes a current sensor configured to sense a current of the output power and generate a logarithmic and analog representation of the current, and a voltage sensor configured to sense a voltage of the output power and generate a logarithmic and analog representation of the voltage. The electrosurgical generator further includes a controller configured to: (i) receive the logarithmic and analog representation of the current sensed by the current sensor, (ii) receive the logarithmic and analog representation of the voltage sensed by the voltage sensor, and (iii) adjust, based on the logarithmic and analog representation of the current and the voltage, a voltage of the output power. 
     Clause 2: In another example, a method of generating electrosurgical energy is described. The method includes converting a supply power received from a power source to an output power, wherein the output power is suitable for delivering electrosurgical energy. The method also includes sensing, using a current sensor, a current of the output power. The method further includes generating a logarithmic and analog representation of the current sensed by the current sensor. The method also includes sensing, using a voltage sensor, a voltage of the output power. Additionally, the method includes generating a logarithmic and analog representation of the voltage sensed by the voltage sensor. The method also includes adjusting, using a controller and based on the logarithmic and analog representation of the current and the voltage, a voltage of the output power. 
     Clause 3: In another example, a method of generating electrosurgical energy is described. The method includes providing an output power from an electrosurgical generator to an electrosurgical tool. The method also includes sensing, using a current sensor, a current of the output power, and generating a logarithmic and analog representation of the current sensed by the current sensor. The method further includes sensing a voltage of the output power and generating a logarithmic and analog representation of the voltage. The method further includes performing, using the logarithmic and analog representation of the current and the logarithmic and analog representation of the voltage, a series of feedback cycles to control a power of the output power. Each feedback cycle includes: (i) determining, based on the logarithmic and analog representation of the current, a plurality of analog current values at a plurality of time points during a sampling interval of the feedback cycle, (ii) determining, based on the logarithmic and analog representation of the voltage, a plurality of analog voltage values at the plurality of time points during the sampling interval of the feedback cycle, (iii) determining an average current value by averaging the plurality of analog current values for the sampling interval of the feedback cycle, (iv) determining an average voltage value by averaging the plurality of analog voltage values for the sampling interval of the feedback cycle, (v) determining, based on the average current value and the average voltage value, at least one of an impedance value and a power value, (vi) deciding, based on the at least one of the impedance value and the power value, whether to adjust a power of the output power for a next feedback cycle in the series of feedback cycles or maintain the power of the output power for the next feedback cycle, (vii) if the decision is to adjust the power, then adjusting a voltage of the output power for the next feedback cycle, and (viii) if the decision is to maintain the power, then maintaining the voltage of the output power for the next feedback cycle. For at least one feedback cycle in the series of feedback cycles, the decision is to adjust the power of the output power. 
     The description of the different advantageous arrangements has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the examples in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. Further, different advantageous examples may describe different advantages as compared to other advantageous examples. The example or examples selected are chosen and described in order to explain the principles of the examples, the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various examples with various modifications as are suited to the particular use contemplated.